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  • Impacts of moisture sources on the temporal and spatial heterogeneity of monsoon precipitation isotopic altitude effects
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-16
    Yuanmei Jiao; Chengjing Liu; Zhilin Liu; Yinping Ding; Qiue Xu

    Moisture sources affect the temporal variations of the elevation effects on the stable isotopes in monsoon precipitation. However, whether it will lead to spatial variations and form a specific spatial–temporal heterogeneity pattern remains to be explored. Based on the monthly precipitation samples collected in Ailao Mountains of East Asian monsoon region, we computed and identified five moisture source regions to facilitate its comparison to the monthly oxygen isotope composition (δ18O) of precipitation with HYSPLIT model. We analysed the influence mechanisms of the moisture sources on the temporal and spatial heterogeneity of the elevation effect on the hydrogen and oxygen stable isotopes during dry and rainy seasons. We found that the temporal heterogeneity of the elevation effects on the precipitation 18O depends on the proportion of the moisture sources in the dominant direction, and as the proportion increases, the elevation effect becomes more significant. The spatial heterogeneity depends on the combination complexity of the moisture sources, the simpler the combinations, the more significant the elevation effects. The results demonstrate that for precipitation δ18O in Ailao Mountains, the dominant of monsoon moisture sources (the ratio higher than 50%) can result in significant elevation effects, while the mixtures of multiple moisture sources and the dominant of local moisture sources will lead to no elevation effects. Future studies should pay more attention to the influence mechanism of the spatial and temporal heterogeneity of the elevation effects on a relatively larger or global scale.

    更新日期:2020-01-17
  • Identification of changes in subsurface temperature and groundwater flow after the 2016 Kumamoto earthquake using long-term well temperature–depth profiles
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-15
    Akinobu Miyakoshi; Makoto Taniguchi; Kiyoshi Ide; Makoto Kagabu; Takahiro Hosono; Jun Shimada

    Repeated measurements of temperature–depth profiles were conducted in January 2017, June or November 2017, and February 2018 at 10 observation wells in the Kumamoto area, Japan, after the 2016 Mw7.0 Kumamoto earthquake to evaluate changes in post-earthquake subsurface temperature. These observation data were compared with pre-earthquake temperature data from the same wells measured during 2001 and 2009–2012 by previous studies. The observation and analysis of temperature–depth profiles are useful for studying groundwater flow but have not been used to determine coseismic changes in groundwater flow. This study detected earthquake-related changes in groundwater flow using observations and analyses of temperature–depth profiles and is the first to report on this type of evaluation of coseismic groundwater flow changes. The results indicated a general long-term subsurface warming from 2001 to 2018. Anomalous decreases and increases occurred in subsurface temperature at the western foot of the Aso caldera rim and western Takuma Plateau, respectively. The observed temperature decrease can be explained by the post-seismic release of mountain groundwater characterized by lower temperatures. A type curve match analysis indicated that increasing temperature anomalies were associated with downward groundwater flow. These results were consistent with a recently proposed coseismic groundwater drawdown model along new rupture systems. Although the first measurement was performed nine months after the earthquake, the groundwater level change data allowed the temperature measurements to successfully detect anomalies caused by hydrological changes that began immediately after the earthquake. However, these signals disappeared 14–19 months after the earthquake and were diminished by the original groundwater flow systems that control the local subsurface temperature. These results demonstrate the applicability of the observation and analysis of temperature–depth profiles to identify post-seismic changes in groundwater flow, which are required for the management of groundwater resources during earthquake disasters and reconstruction.

    更新日期:2020-01-15
  • Evaluation of severity changes of compound dry and hot events in China based on a multivariate multi-index approach
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-14
    Xinying Wu; Zengchao Hao; Xuan Zhang; Chong Li; Fanghua Hao

    Compound dry and hot events have received increasing attention due to their serious impacts on different sectors of the society. Understanding their variability is of critical importance for developing adaptation measures to reduce their adverse impacts. Previous studies have shown increased frequency of these compound events in past decades at regional and global scales; however, the investigation of changes in their severity has been rather rare. The objective of this study is to evaluate severity changes of compound dry and hot events for the warm season during the period 1961-2012 in China using two indices, namely, Standardized Compound Event Indicator (SCEI) and Standardized Dry Hot Index (SDHI), based on monthly precipitation and temperature. Results show a significant increase in the severity of compound dry and hot events in most parts of China, which is mainly dominated by temperature compared to precipitation. In addition, significant increase of the spatial extent of compound dry and hot events at different severity levels in China is observed, with more areas affected by these compound events after the 1990s. For large regions from northeast to southwest China, severe conditions of compound dry and hot events are shown to be associated with high risk of agricultural droughts. Both the two indices show similar trends in the severity of compound dry and hot events, which indicates the robustness of increased spatial and temporal patterns, highlighting the pressing need for improved understanding to reduce their adverse impacts.

    更新日期:2020-01-15
  • Estimation of Surface Heat Fluxes via Variational Assimilation of Land Surface Temperature, Air temperature and Specific Humidity into a Coupled Land Surface-Atmospheric Boundary Layer Model
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-14
    E. Tajfar; S.M. Bateni; V. Lakshmi; M. Ek

    Numerous studies have estimated surface heat fluxes by assimilating land surface temperature (LST) observations (as the state variable of land surface). A number of other studies have focused on the estimation of surface energy balance components by assimilating air temperature and specific humidity (as the state variables of atmosphere) into an atmospheric boundary layer model. This study advances these existing data assimilation approaches by the synergistic assimilation of LST, air temperature, and specific humidity into a coupled land surface-atmospheric boundary layer model. The unknown parameters are the neutral bulk heat transfer coefficient (CHN) and evaporative fraction (EF). CHN scales the sum of turbulent heat fluxes, and EF represents their partitioning. The developed approach is tested at the First International Satellite Land Surface Climatology Project Field Experiment (FIFE) site in the summer of 1987 and 1988. The results indicate that the new approach performs well in both wet and dry periods because it uses the implicit information in both the land surface and atmospheric state variables (i.e., LST, air temperature, and specific humidity). The root-mean-square-errors (RMSEs) of estimated daily sensible and latent heat fluxes are 21.80 Wm-2 (22.10 Wm-2) and 39.32 Wm-2 (36.89 Wm-2) for FIFE 87 (88). The corresponding mean-absolute-percentage-errors (MAPEs) are 22.16% (18.64%) and 13.98% (13.44%) for FIFE 87(88). The new variational data assimilation (VDA) system outperforms the previous studies that assimilated either LST or air temperature/specific humidity. For FIFE 87, this study decreases the RMSEs of daily sensible and latent heat fluxes estimates by 12.5% and 24.4% compared to assimilating only LST, and by 15.2% and 26.7% compared to assimilating only air temperature and specific humidity. A similar improvement is obtained for FIFE 88. The atmospheric boundary layer height, potential temperature, and specific humidity estimates from the VDA approach are also in good agreement with the corresponding radiosonde observations, and can capture their variations during the course of the day.

    更新日期:2020-01-15
  • Glacier retreat changes diurnal variation intensity and frequency of hydrologic variables in Alpine and Andean streams
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-14
    M. Kneib; S. Cauvy-Fraunié; N. Escoffier; M. Boix Canadell; Å. Horgby; T.J Battin

    The impacts of glacier mass and area loss are assumed to affect stream hydrology and related ecosystems. We applied wavelet analysis to high frequency time series of discharge, conductivity, turbidity, air and water temperature in mountain streams influenced by a gradient of diverse glacier catchment coverages from 0 to 28%. All parameters were recorded during 200 to 250 day period in 24 mountain streams in Switzerland and Ecuador. We interpreted the range of glacier coverage as a proxy of glacier melt effect linked to modification in glacier cover based on a space-for-time substitution approach. We used the diurnal variation power and frequency as hydrological parameters to quantify the intensity and occurrence of significant diurnal variations in the different mountain catchments. Our results show that the reduction in glacier cover would reduce the intensity and occurrence of diurnal variations in discharge, turbidity and conductivity, and the intensity of diurnal variations in water temperature. Discharge and conductivity were affected in a similar way, while the impact on turbidity was less significant. Furthermore, due to their different climatic regimes, the diurnal discharge in the tropical Andes was more impacted than in the Alps, indicating that the impacts of global change on glacier streams would be stronger in the tropical Andes than in the Alps.

    更新日期:2020-01-14
  • The Use of Support Vectors from Support Vector Machines for Hydrometeorologic Monitoring Network Analyses
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-14
    W.H. Asquith

    Hydrometeorologic monitoring networks are ubiquitous in contemporary earth-system science. Network stakeholders often inquire about the importance of sites and their locations when discussing funding and monitoring design. Support vector machines (SVMs) can be useful by their assigning each monitoring site as either a support or nonsupport vector. A potentiometric surface was created from synthetic data and 800 random observation locations (sites) as an analog to a groundwater-level network. Using generalized additive models for potentiometric surface prediction, simulations show that a subsample of support vectors from the 800 sites will out perform random samples of sample size equaling the support vector count. Support vector percentages from simulation quantify the recurrence that SVMs assign each site as a support vector, and these percentages in turn measure site importance. An example application of support vector percentages identifies important monitoring sites needed to regionalize the 0.1 annual exceedance probability peak streamflow. The results indicate that 152 of 283 streamgages with support vector percentages equalling 100 percent have not operated since about 2000 and generally have much smaller drainage areas than the greater streamgage network in Texas. The drainage area disparity is an indication of historical imbalance in peak streamflow data acquisition from various stream sizes in Texas.

    更新日期:2020-01-14
  • Exploring Real-time Control of Stormwater Systems for Sea Level Rise
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-14
    Jeffrey M. Sadler; Jonathan L. Goodall; Madhur Behl; Benjamin D. Bowes; Mohamed M. Morsy

    Low-lying, low-relief coastal cities have seen increased flooding due to climate change. In these cities, stormwater pipe outlets can be inundated by coastal waters at high tide or from storm surge, making drainage impossible. The objective of this research is to assess the utility of model predictive control (MPC) of stormwater actuators to reduce flooding in a coastal urban setting made worse by sea level rise. The stormwater system and the control scenarios are simulated using the United States Environmental Protection Agency Storm Water Management Model (SWMM5) coupled with a Python library, swmm_mpc. The study area is Norfolk, Virginia, USA, a city which is particularly vulnerable to coastal flooding. A simulated 2-year 12-hour design storm and sea level rise scenarios up to 3.5 ft are applied to the model for three control scenarios: 1) a passive system, 2) a passive system with a tide gate (backflow preventer), and 3) a tide gate and three actuators (a pump, a valve, and an inflatable dam) controlled through MPC. Flooding in the passive system reached a tipping point and increased dramatically after a sea level rise of 1.6 ft. The addition of a tide gate greatly mitigated this increase in flooding. MPC further reduced overall flooding with an average effective percent reduction of 32%. The rate of the increase in flooding was significantly smaller with MPC than without. MPC also reduced maximum node flood volume by an average of 52% for sea level increases of 2.0 ft and above. In addition to the installation of a tide gate, our results suggest that the use of actuators controlled by MPC could significantly reduce overall flood volumes and reduce flood severity at individual nodes in coastal cities.

    更新日期:2020-01-14
  • Managing Underground Transfer of Floods for Irrigation: A Case Study from the Ramganga Basin, India
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-13
    V. Ratna Reddy; Sanjit Kumar Rout; Sarah Shalsi; Paul Pavelic; Andrew Ross

    Protecting flood prone locations through floodwater recharge of the depleted aquifers and using it for protecting dry season irrigated agriculture is the rationale for a form of intervention termed as ‘underground transfer of floods for irrigation’ (UTFI). This helps reduce the intensity of seasonal floods by tapping and storing excess floodwater in aquifers for productive agricultural use. This paper presents a case study of managing the recharge interventions in the context of the Ramganga basin, India. Using a case study approach, this study determines the socio-economic and institutional context of the study area, proposes three potential routes to institutionalize UTFI, and provides insights for scaling up the interventions in the Ganges and other river basins that face seasonal floods and dry season water shortages. Managing the interventions involves community participation in regular operations and maintenance tasks. Given the limited scale of the pilot UTFI intervention implemented to date, and the socio-economic and institutional context of the case study region, the benefits are not conspicuous, though the piloting helped in identifying potential ways forward for the long-term management of the pilot site, and for scaling up the interventions. Initially pilot site management was handled by the project team working closely with the community leaders and villagers. As the intervention was demonstrated to perform effectively, management was handed over to the district authorities after providing appropriate training to the government personnel to manage the system and liaise with the local community to ensure the site is operated and managed appropriately. The district administration is willing to support UTFI by pooling money from different sources and routing them through the sub-district administration. While this is working in the short term, the paper outlines a programmatic longer term approach for wider replication.

    更新日期:2020-01-13
  • 更新日期:2020-01-13
  • Partitioning the contributions of glacier melt and precipitation to the 1971-2010 runoff increases in a headwater basin of the Tarim River
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-13
    Zehua Li; Xiaogang Shi; Qiuhong Tang; Yongqiang Zhang; Huilin Gao; Xicai Pan; Stephen J. Déry; Ping Zhou

    Glacier retreat and runoff increases in the last few decades characterize conditions in the Kumalak River Basin, which is a headwater basin of the Tarim River with a catchment area of 12,800 km2. To address the scientific question of whether, and to what extent, the observed runoff increase can be attributed to enhanced glacier melt and/or increased precipitation, a glacier evolution scheme and precipitation-runoff model are developed. Using the glacio-hydrological model, we find that both glacier cover area and glacier mass in the study area have decreased from 1971 to 2010. On average, the contribution to total runoff from rainfall, glacier melt and snowmelt are 60.6%, 28.2% and 11.2%, respectively. Despite covering only 21.3% of the basin area, glacier areas contributed 43.3% (including rainfall, snowmelt and glacier melt) to the total runoff from our model estimates. Furthermore, as primary causes of increased runoff in response to the warmer and wetter climate over the period 1971-2010, contribution from increases in rainfall and glacier melt are 56.7% and 50.6%, respectively. In comparison to rainfall and glacier melt, snowmelt has a minor influence on runoff increase, accounting for -7.3%. The research has important implications for water resources development in this arid region and for some similar river basins in which glacial melt forms an important part of the hydrological cycle.

    更新日期:2020-01-13
  • Precipitation structure as an indicator of reduction of water amount supplying soil profile
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-13
    Małgorzata Biniak-Pieróg; Alicja Zielińska; Andrzej Żyromski; Kryspin Świder

    The objective of this study was the estimation of the effect of droplet structure of diurnal precipitation totals, measured with Thies Clima disdrometer, on the value of surface runoff from three kinds of surface used in urban areas, i.e. a roof surface covered with small-grain roofing paper, a car park surface of openwork concrete slabs, and a tarmac surface, and the resultant reduction of infiltration from atmospheric precipitation. The detailed comparative analysis of diurnal precipitation totals in the aspect of droplet structure, structure of increasing influx of precipitation water to the surface, and changes of air temperature-humidity conditions, allowed preliminary elucidation of the effect of those factors on the values of the runoff indices for the different hardened surfaces. The analysis of reduction of infiltration presents the level of supply losses resulting from the use of surface covering systems with various degrees of permeability to precipitation water. A solution that can minimise the indicated losses can be an approach to precipitation water management assuming interception of possibly the largest amounts of non-productive surface runoff waters, and then using that water.

    更新日期:2020-01-13
  • Dilution and precipitation dominated regulation of stream water chemistry of a volcanic watershed
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-13
    Guan-Zhong Huang; Ting-Chang Hsu; Cheng-Ku Yu Modeling; Jr-Chuan (River) Huang; Teng-Chiu Lin
    更新日期:2020-01-13
  • Unlined Trench as a Falling Head Permeameter: Analytic and HYDRUS2D Modeling versus Sandbox Experiment
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-11
    A. Al-Shukaili; A. Al- Mayahi; A. Al-Maktoumi; A.R. Kacimov
    更新日期:2020-01-13
  • Groundwater Recharge from Drywells Under Constant Head Conditions
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-11
    Salini Sasidharan; Scott A. Bradford; Jiří Šimůnek; Stephen R. Kraemer
    更新日期:2020-01-13
  • Effects of montane watershed development on vulnerability of domestic groundwater supply during drought
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-11
    Zeno F. Levy; Miranda S. Fram; Kirsten E. Faulkner; Charles N. Alpers; Evelyn M. Soltero; Kimberly A. Taylor

    Climate change is expected to reduce recharge to montane aquifers in the western United States, but it is unclear how this will impact groundwater resources in watersheds where intensive surface-water development has disrupted the natural hydrologic regime. To better understand sources of recharge and associated vulnerabilities of groundwater supply in this setting, we made a detailed geochemical survey of domestic wells finished in fractured bedrock throughout the Yuba and Bear River watersheds (Sierra Nevada foothills, northern California) during historic drought (2015 – 2016). Stable isotopes of water and noble gas recharge temperatures closely tracked atmospheric lapse rates across a broad elevation gradient (100 – 2000 m), indicating groundwater inputs are dominated by local precipitation that rapidly recharges fractured bedrock during the winter wet-season. However, nearly one-quarter of wells had water isotopes that were fractionated by evaporation and warm recharge temperatures, indicative of mixing with dry-season recharge by surface water. Monte Carlo mixing models suggest evaporation-impacted groundwater samples are mixtures of local rain with an average of 28% ± 13% from diverted surface waters that can recharge bedrock aquifers during the dry-season by either irrigation return flow or seepage from extensive distribution infrastructure. Wells that received recharge subsidies from diverted surface water had elevated levels of nitrate and coliform bacteria compared to those replenished exclusively by local precipitation, which are more vulnerable to supply shortage during drought. It is important to consider the impacts of increased surface-water development on the quantity and quality of groundwater recharge in rapidly developing montane watersheds.

    更新日期:2020-01-13
  • Parameter estimation of an overconsolidated aquitard subjected to periodic hydraulic head variations within adjacent aquifers
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-11
    Chao Zhuang; Zhifang Zhou; Walter A. Illman; Zhi Dou; Jinguo Wang

    Extensometers provide long-term records of deformation over a depth interval of interest. An overconsolidated aquitard undergoes elastic deformation if the hydraulic head within adjacent aquifers remains higher than the preconsolidation head within the aquitard. The vertical hydraulic conductivity Kv and elastic skeletal specific storage Sske are two critical parameters that control the deformation behavior of an overconsolidated aquitard, and they could be interpreted from valuable extensometer data. An analytical solution for the elastic aquitard deformation caused by periodic hydraulic head variations (PHHV) within adjacent aquifers is derived using the separation of variables method based on Euler’s formula. The phase difference in PHHV between adjacent aquifers is found to reduce the amplitude of periodic aquitard deformation. Meanwhile, the phase difference is found to cause no influence on the growth pattern of the phase shift, which is between the periodic aquitard deformation and PHHV, versus the period. A new parameter estimation method is further proposed to interpret aquitard Kv and Sske from periodic aquitard deformation data. This new method yields robust Kv and Sske estimates of a moderately thick aquitard, whose deformation history has been recorded by an extensometer, located in Shanghai, China. The field study confirms that the phase difference in PHHV between the aquifers adjacent to the overconsolidated aquitard of interest cannot be ignored.

    更新日期:2020-01-13
  • Quantitative assessment of the changes in regional water flow systems caused by the 2016 Kumamoto Earthquake using numerical modeling
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-10
    Yasuhiro Tawara; Takahiro Hosono; Youichi Fukuoka; Takafumi Yoshida; Jun Shimada

    Coseismic changes in water levels and discharges are well-known phenomena worldwide. Reliable hypotheses to explain these hydrological changes qualitatively have been proposed using various data and analyses. However, there are few quantitative assessments of these changes, which require hydrological simulators. A dense monitoring network revealed coseismic river and groundwater level changes induced by the 2016 Mw 7.0 Kumamoto crustal earthquake associated with many post-seismic fracture systems. In this study, we reproduced these changes using a physically based, fully distributed, integrated watershed modeling tool (GETFLOWS). In particular, the formation of new fracture systems is key to understanding the hydrological changes observed after the earthquake, which were incorporated into our model by changing parameters. Previous studies suggested that the observed water level drop immediately after the earthquake is explained by the drawdown of surface and aquifer waters to fill open spaces in the upper crust along the fracture systems generated under extensional stress field. After the initial water drop, water levels rose in the long-term because additional water sources were released from surrounding mountains due to the coseismic increase in the permeability of the soils and rocks around the compressional fracture systems. These hypotheses were validated in our model by adjusting the depths of fracture systems. Consequently, we constructed the three-dimensional distribution of these property changes over the study area. Furthermore, the model calculation yielded the volumes of missing and released mountain waters in the studied watershed (ca. 106 and 108 m3, respectively). This study demonstrates the utility of an integrated watershed modeling tool for investigating coseismic hydrological changes in active hydrological systems quantitatively.

    更新日期:2020-01-11
  • Distributions and origins of nitrate, nitrite, and ammonium in various aquifers in an urbanized coastal area, south China
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-10
    Ming Zhang; Guanxing Huang; Chunyan Liu; Ying Zhang; Zongyu Chen; Jincui Wang
    更新日期:2020-01-11
  • Exploring the Impact of Long-Term Evaporation on the Relationship Between Capillary Pressure and Water Saturation in Unsaturated Porous Media
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-10
    Aderonke O. Adegbule; Tohren C.G. Kibbey

    The focus of this work was on understanding the impact of evaporation on the capillary pressure-saturation (Pc-S) state of a porous medium. Evaporation is ubiquitous near the ground surface in the vadose zone, but little is known about how evaporation impacts the relationship between capillary pressure and saturation. The hypothesis driving the work was that the Pc-S relationship is the result of an equilibrium between evaporative water loss, capillary forces, and the upward flow of water to replenish evaporated water. Experiments were conducted using two different porous media, a coarse sand and a nylon membrane with a 20 μm pore size. Long-term evaporation experiments were conducted using different configurations to control evaporation within the media. Results found that increased accessibility to evaporation caused saturation in drainage Pc-S curves to decrease over time, causing the curves to become closer to imbibition Pc-S curves. In the membrane, the high external surface area to pore volume ratio introduced changes in evaporative flux to produce rapid changes in the Pc-S state of the medium. One implication of the work is that results suggest that long-term drainage experiments in vented columns may not necessarily provide a meaningful measurement of static Pc-S curve, but rather may be impacted by evaporation.

    更新日期:2020-01-11
  • Large contribution of non-aquaculture period fluxes to the annual N2O emissions from aquaculture ponds in Southeast China
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-10
    Ping Yang; Hong Yang; Derrick Y. F. Lai; Qianqian Guo; Yifei Zhang; Chuan Tong; Chaobin Xu; Xiaofei Li

    Nitrous oxide (N2O) is one of major potent long-lived atmospheric greenhouse gases (GHGs) with a global warming potential of 298 times higher than that of carbon dioxide (CO2) over a 100-year timespan. To date, only several studies have explored the contribution of N2O emission from aquaculture systems to global emission, but with large uncertainty. In this study, the spatiotemporal distribution of dissolved N2O concentrations along the water column within ponds, and the N2O fluxes over the whole annual cycle were determined in the shrimp ponds in the Min River Estuary, Southeast China. Our results showed that N2O concentrations did not differ among sampling depths, but varied significantly among sampling dates. The temporal variation of N2O concentration was significantly correlated with the concentrations of N-NH4+ and total dissolved nitrogen. The one year study found an annual mean N2O emission of 57.63 μg N2O m-2 h-1 that was equivalent to an annual emission of 504.9 mg N2O m-2 yr-1, demonstrating the aquaculture ponds as an important source of atmospheric N2O. The N2O fluxes during the non-aquaculture period were one to three orders larger than those in the aquaculture period, and accounted for approximately 97% of the annual total emissions from aquaculture ponds. Our results showed that the N2O emission during the non-aquaculture period should not be overlooked owing to its marked contribution to the annual N2O budget in mariculture ponds. Further studies on N2O production dynamics including the abundance and activity of nitrifying and denitrifying bacteria in coastal aquaculture ponds are needed to improve our understanding of N2O biogeochemical cycle and facilitate strategies to reduce N2O emission.

    更新日期:2020-01-11
  • Impact of earthquake on the communities of bacteria and archaea in groundwater ecosystems
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-10
    Heejung Kim; Dugin Kawon; Jeayeon Kim; In-Woo Park; Won-Tak Joun; Kang-Kun Lee

    We explored possible changes in microbial communities at the occurrence of an earthquake. For this, we examined effects of the 2016 Gyeongju Earthquake (ML 5.8) on the microbial communities in nearby aquifers, together with the associated hydrochemistry data. Fourteen water samples were collected from two types of wells (alluvial and fractured rock formation) for monitoring the hydrogeochemical parameters, groundwater level, radon concentration, strontium isotopes, and microbiological features. An earthquake could change the number of species or their abundance in groundwater ecosystems. The results obtained for microbial compositions and special bacteria were consistent with the hydrochemical results. We also observed distinctive microbial communities in groundwater samples taken adjacent to the earthquake epicenter. Flavobacterium and archaea showed center of movement of chemical data. The predominant bacteria were Pseudomonas and Flavobacterium in most samples. Radon concentrations, helium isotopes, and helium/neon ratio showed anomalies in one well (KW8) with microbial composition data. Strontium data indicate that the study site may have been affected by seawater intrusion, which is corroborated by the microbiological features of archaea. Therefore, microbial features might be a good additional indicator for analyzing effects of earthquake on the groundwater, together with major chemical parameters such as Rn, Sr, and He. This study highlights the microbiological features of an aquifer after an earthquake, in conjunction with chemical data. The microbiological features indicate that bacteria in the groundwater such as Pseudomonas and Flavobacterium are highly correlated with the Gyeongju Earthquake and the hydrochemical data.

    更新日期:2020-01-11
  • A risk-based fuzzy boundary interval two-stage stochastic water resources management programming approach under uncertainty
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-09
    Youzhi Wang; Zhong Li; Shanshan Guo; Fan Zhang; Ping Guo

    Establishing an optimal water allocation scheme is a challenging yet crucial task for effective risk management of water resources. The dynamic and complex interaction among various risk-related components in a water resources management system cannot be easily modeled to characterize the system response under different risk control settings. In this study, a risk-based fuzzy boundary interval two-stage stochastic water resources management programming (RFITSWMP) model is developed for the optimization of water consumption. This model incorporates a series of risk control constraints, such as water availability, maximum allowable penalty, and allowable benefit violation constraints into a fuzzy boundary interval two-stage stochastic programming framework for water resources management. It can address the uncertainties presented as fuzzy boundary intervals and probability distributions. It can also tackle the recourse action to minimize penalties based on interactive influences of different risk control measures, further generating optimal water allocation alternatives and guiding water resources management. This developed model is applied to a case study of water consumption optimization in the middle reaches of the Heihe River Basin in China. Feasible water allocation schemes under given risk levels, as well as the associated economic benefit, actual benefit and penalty loss are generated. The results can help decision makers to gain an insight into the inherent conflicts and tradeoffs amid risk, benefit and water allocation. The performance of developed model is further demonstrated by comparing it with a fuzzy boundary interval two stage stochastic water resources management programming (FITSWMP) model. In addition, a multiple factorial analysis (MFA) approach is employed to analyze the impacts of interactive risk parameters on the optimal decisions. The result disclosed that (1) the higher individual risk-parameter levels correspond to higher water shortage, penalty loss and benefit value-at-risk but higher economic benefit. (2) The combination of risk parameters can achieve robust water allocation and economic benefit as the constraints concerned with risk parameters affect and limited by each other. (3) The condition that water violated probability (p) is 0.2, penalty violated risk level (β) is 1 and benefit violated risk level (γ) is 1 has the highest water allocation and biggest economic benefit.

    更新日期:2020-01-09
  • Long-term Sustainability of Large Water Resource Systems under Climate Change: a Cascade Modeling Approach
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-09
    David Haro-Monteagudo; Leticia Palazón; Santiago Beguería

    The Pyrenees are the main source of water for a large region in Southern Europe. In recent decades, streamflow and snow accumulation in these mountains have decreased, and climate models predict that further reductions in water will threaten the sustainability of downstream regions. This article presents a cascading multi-model and multi-scenario approach to assess how future climate change may affect the hydrology and water management of Pyrenees-dependent systems. In particular, we combined future climate projections and management scenarios and applied them to the Gállego-Cinca River System in the Ebro River Basin of Spain. We developed a hydrologic model for the headwaters of this system (the source of most of the water), and then used a management model to simulate reservoir operation and water allocation among the different agricultural demand units of this system, the largest irrigated region in Spain. We assessed future headwater streamflow for 22 climate models, and translated this climate signal into a management model by using a delta change approach. Finally, we evaluated the performance and sustainability of the system with indicators based on the frequency, duration, and magnitude of the supply deficit. The results show that use of the current planned management scenarios will threaten to the system’s future sustainability, especially for irrigated agriculture. These results indicate a need to revise current water resource planning strategies in this region, and to establish long-term, robust, and sustainable measures for adaptation to climate change.

    更新日期:2020-01-09
  • Changes of groundwater flow systems after the 2016 Mw 7.0 Kumamoto earthquake deduced by stable isotopic and CFC-12 compositions of natural springs
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-09
    Kiyoshi Ide; T. Hosono; M. Kagabu; K. Fukamizu; T. Tokunaga; J. Shimada

    Large earthquakes change the hydrogeological properties of aquifer systems, such as permeability, and cause changes that impact groundwater flow. To understand these changes in mountain aquifer systems, we analyzed stable isotopic ratios of water molecular (δD and δ18O) of H2O and chlorofluorocarbons (CFCs) concentrations of natural spring waters and compared these values between before (2009) and after (2017) the 2016 Kumamoto crustal earthquake sequence in Kumamoto-Aso area, southern Japan. Stable isotope ratios were used to identify the spring source characteristics that reflected recharge elevations, whereas CFC age tracers were applied to evaluate the contribution of earthquake-induced additional waters from different pathways (shorter or longer) and/or CFC-enriched (contaminated) surface waters. In general, spring waters after the earthquake became more depleted in water isotopic compositions than those before the earthquake, suggesting an increased contribution of waters recharged from higher elevations across the area. In addition, changes observed in CFC-12 concentrations were classified into several increasing/decreasing patterns defined by the contribution of additional waters from different flow paths, such as older groundwater with longer flow paths, younger groundwater from shorter flow paths, and CFC-enriched (contaminated) water released from shallow aquifers and soils. These isotopic and chemical features, when combined with previously documented seismotectonic surface rupture distributions, demonstrated the occurrence of coseismic mountain water release due to enhanced permeability. These findings enabled us to document how groundwater flow changes in mountain aquifers. Although CFC age markers have rarely been applied as a tool to investigate coseismic hydrological changes, our study exemplifies their usefulness—in combination with stable isotope ratios—in such investigations.

    更新日期:2020-01-09
  • 更新日期:2020-01-09
  • Quantifying streamflow regulation services of wetlands with an emphasis on quickflow and baseflow responses in the Upper Nenjiang River Basin, Northeast China
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-09
    Yanfeng Wu; Guangxin Zhang; Alain N. Rousseau; Y. Jun Xu

    Although the hydrological services of individual wetlands have been much acknowledged, their cumulative effect at the watershed scale has not been assessed as extensively. In this study, a distributed hydrological modeling platform, the PHYSITEL/HYDROTEL, was used to (i) investigate watershed hydrological processes with and without abundant wetlands, and (ii) quantify the effect of wetlands on streamflow, specifically baseflow and quickflow in the Upper Nenjiang River Basin (Northeast China). The modeling results showed that wetlands can strongly affect quickflow and baseflow, consequently modifying the watershed hydrograph. The study demonstrated the flow regulation services of wetlands at various temporal (i.e., daily, monthly, seasonal and annual) and spatial scales (i.e., sub-watersheds of different sizes). Specifically, wetland presence seemed to have stronger influence on baseflow and quickflow in the summer season than in the winter. The cumulative effect of wetlands on quickflow and baseflow quantity enhanced with the increasing wetland area. Anthropogenic activities such as reclamation and settlements could affect the regulation services of wetlands to some extent. These findings indicate that wetlands exert significant effects on watershed hydrological processes by modifying the temporal variability of quickflow and baseflow in this region. Therefore, it is important to protect and restore wetlands in the upstream portion of a watershed as a means of sustaining flow regulation and water resources in river basins.

    更新日期:2020-01-09
  • Development of Reservoir Operation Functions in SWAT+ for National Water Quantity and Quality Assessments
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-09
    Jingwen Wu; Haw Yen Primary; Jeffrey G. Arnold; Yi-Chen E. Yang; Ximing Cai; Michael J. White; Chinnasamy Santhi; Chiyuan Miao; Raghavan Srinivasan

    The Soil and Water Assessment Tool (SWAT) model is one of the most extensively used watershed-scale models across the world. In recent years, in order to enhance the potential of SWAT code maintenance and future development, a completely reconstructed version of SWAT, dubbed SWAT+, has been just released. In addition to the new model structure in SWAT+, reservoir operation functions have been added to improve the performance of model simulations. Before conducting watershed-scale model simulations, reservoir functions of SWAT+ were further copulated to the automatic calibration tool, IPEAT, to better consider the interactions among reservoir parameters and the corresponding hydrologic processes. In this study, a total of 123 reservoirs were simulated at daily scale across the contiguous United States (CONUS). A series of reference values of reservoir parameters (total 15) were categorized based on different classifications: (i) reservoir capacity; (ii) reservoir release; (iii) climate conditions; and, (iv) reservoir storage and release. Overall results showed that the performance of reservoir simulations at daily scales is satisfactory by commonly adopted statistical measures. In different scenarios, SfNFD (seasonal flood control drawdown days during non-flood season) (from 5 to 126 days), EfFLD (exclusive flood control drawdown days) (from 0.1 to 2.1 days) and EfFLC (exclusive flood control constant flow) (from 4.8 to 6.5 ha-m) are sensitive parameters and the converged parameter ranges were close to each other but not for other parameters. The recommended parameter ranges may be embedded by varying sources of uncertainty. However, the proposed calibration guidelines provide fast and accessible reference for future SWAT+ studies especially in subjects related to reservoir operations.

    更新日期:2020-01-09
  • Poverty Mitigation through Optimized Water Development and Use: Insights from the Volta Basin
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-08
    Bernard Baah-Kumi; Frank A. Ward

    Ongoing challenges from population growth and climate stress on the water resources of the Volta River Basin raise the importance of finding economically sustainable water development and use patterns. Much research has been conducted on the impacts of water supply fluctuations, climate change, and population growth on effective economic access to water resources of the basin. However, no work to date has comprehensively investigated the sustainable economic performance of additional infrastructure development in the basin for handling ongoing challenges of climate water stress at the entire basin scale. The original contribution of this work is to investigate the capacity to mitigate poverty from new reservoir storage capacity if established in a flood-prone region in northern Ghana, using a basin-scale hydro-economic optimization framework, while accounting for five major water uses for six riparian countries. An integrated approach is formulated to link the hydrologic, agronomic, institutional, and economic dimensions of the basin into a unified framework for policy analysis. A dynamic optimization model is developed and applied to discover the level and distribution of economic impacts from the additional storage infrastructure development. Results indicate the potential to increase economic benefits to Ghana and Burkina Faso, with no economic loss to any other riparian, from the development and operation of additional storage infrastructure. Results show considerable potential to secure an Actual Pareto Improvement, by which Ghana and Burkina Faso are better off with the new storage infrastructure than without it, and no other riparian country in the basin is worse off. Additional storage infrastructure in the flood-prone area of the basin in northern Ghana carries the potential to store water during wet seasons and years and release water for use in dry seasons and years, reallocating water among seasons and years, elevating economic development to the Basin’s riparian countries. Despite our optimistic findings, considerable stakeholder negotiations and cooperation will be needed to secure the potential welfare gains uncovered.

    更新日期:2020-01-09
  • A Virtual Geographic Environment for Multi-Compartment Water and Solute Dynamics in Large Catchments
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-08
    Karsten Rink; Erik Nixdorf; Chengzi Zhou; Markus Hillmann; Lars Bilke

    We propose a visualisation framework for data exploration, analysis and presentation of complex hydrological studies in large catchments. This furthers a deeper understanding of the interrelations between the included datasets, allows for discussions among researchers from different disciplines and is the basis for illustrating complex phenomena to stakeholders or the interested public. Based on the 162,000 km2 catchment of Poyang Lake, the largest freshwater lake in China, we developed a Virtual Geographic Environment that combines a wide range of 2D and 3D observation data sets with simulation results from both an OpenGeoSys groundwater model and a COAST2D hydrodynamic model visualising water and solute dynamics within and across hydrologic reservoirs. The system aims for a realistic presentation of the investigation area and implements approaches of scientific visualisation to illustrate interesting aspects of multi-variate data in intuitive ways. It employs easy-to-learn interaction techniques for navigation, animation, and access to linked data sets from external sources, such as time series data or websites, to function as an environmental information system for any region of interest.

    更新日期:2020-01-09
  • 17-year study on the chemical composition of rain, snow and sleet in very dusty air (Cracow, Poland)
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-07
    Tomasz Kotowski; Jacek Motyka; M.S. Wiesław Knap; Jarosław Bielewski

    The paper presents the results of long-term (1996-2017) studies of the chemical composition of rain, snow and sleet in one of the cities with the highest concentrations of particulate matter in the air in Europe. The study included measurements of 45 chemical constituents of precipitation as well as its pH and EC. Concentrations of PM10, SO2 and meteorological parameters were also analysed. Differences in Cl and Na concentrations were found depending on the type of precipitation (snow or rain). These differences are most probably caused by anthropogenic factors, however, to a small extent (∼18-19%), they are associated with the total variability of the concentrations of these chemical constituents. The differences between the concentrations of the remaining constituents of precipitation analysed are of lesser or negligible importance. The main processes affecting the chemical composition of precipitation are the chemical weathering of suspended dust and the formation of mineral acid aerosols. These processes shape the chemical composition of both rain and snow in a similar manner. The differences between the chemical composition of rain and snow are the result of the concentrations of and mutual relations between selected chemical constituents and precipitation pH. An important factor affecting the pH of precipitation is the effectiveness of the chemical weathering of suspended dust, which may make the precipitation more alkaline. It is very likely that pH-buffering will occur, which can prevent the pH of precipitation from decreasing, especially in cold periods. Long-term observations of variability in the concentrations of the chemical constituents indicate a slight, but rather constant decrease in concentrations of most of the chemical constituents analysed, as well as in the concentrations of PM10 and SO2 in the air in Cracow. The directions of these changes reflect, to a certain extent, the complex transformations of industrial, economic and social conditions in Cracow within that period. The typical ranges of variability of the recorded values of concentrations/measurement values of 22 chemical constituents and the physical characteristics of rain, sleet and snow presented in the paper can be used as reference ranges of these parameters, typical for an area with a significant degree of atmospheric dust pollution.

    更新日期:2020-01-07
  • Temporal changes of hydraulic properties of overburden aquifer induced by longwall mining in Ningtiaota coalfield, northwest China
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-07
    Shen Qu; Guangcai Wang; Zheming Shi; Pengpeng Zhou; Qingyu Xu; Zejun Zhu

    Characterizing the mining induced temporal changes of hydraulic properties of the overburden aquifer is significant for groundwater resource protection. Conventional hydrogeological methods (e.g. hydraulic test, physical model test and numerical simulation) of determining hydraulic properties of the overburden aquifer cannot quantitatively analyze the temporal changes of the hydraulic properties induced by mining disturbances. This paper presents a quantitative determination for the temporal changes of parameters (compressibility, porosity and specific storage) in the overburden aquifer influenced by the mining processes, based on in-situ continuous measurements of groundwater level that was affected by earth tide, atmospheric loading and mining disturbances. The results showed that, when working face reached a certain distance (127 m from borehole J6 in this study), those parameters (compressibility, porosity and specific storage) of overburden aquifer began to show gradual decrease, with approximately up to two order of magnitudes. After the working face passed by the observation borehole J6, those properties of overburden aquifer recovered in about 80 days, which might reflect the characteristic of elastic deformation of the aquifer. Those findings of the mining induced parameters’ temporal changes could improve our understanding of the mining effects on aquifer system and could be meaningful in groundwater resource protection.

    更新日期:2020-01-07
  • An indicator system for assessing the impact of human activities on river structure
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-07
    Yinjun Zhao; Lan Zeng; Yongping Wei; Junming Liu; Jianming Deng; Qucheng Deng; Kai Tong; Jiaxu Li

    The impact of human activities on river systems has reached a state in which they can no longer be considered to be controlled only by natural processes of the Earth but also by anthropogenic forces in many regions of world. However, most approaches for assessing the impact still consider human activities to be an external influence in the study of feedback mechanisms between human activities and river systems, and they are usually complicated and specialized. This paper aims to develop an indicator system that includes the artificial water surface ratio (AWSR), artificial water surface density ratio (AWSDR), disruption of longitudinal connectivity ratio (DLCR), artificial river ratio (ARR), sinuosity of artificial cutoff (SAC), channelization ratio (CR), artificial levee ratio (ALR), road along river ratio (RARR), artificial sediment transport ratio (ASTR) and the integrated river structure impact index (IRSII) to quantitatively assess the impact of human activities on river structure by comparing natural and anthropogenic forces in a river system. The Nanliu River basin under the dramatic impact of human activities was selected to validate the indicator system. The case results showed the Nanliu River has become an anthropogenic river according to its high IRSII value (> 0.49). The artificial water surface area and artificial sediment discharge were 2.96 (AWSR = 2.96) and 2.51 (ASTR = 2.51) times of the outcome of natural process. The river was dramatically blocked by human-made buildings (DLCR = 68.63) and artificial channel accounts for 54.23% of total length of natural river (ARR = 0.54). Within the river basin, upper and lower sub-basins in areas with a higher economic level were more affected by human activities. Future management of the Nanliu River basin should focus on restoration of river connectivity, sand mining and irrigation issues. Unlike most previous assessment methods, the approach developed in this study is simple and readily comprehensible by the public and decision makers, cost-effective for long-term monitoring and not subject to the reference condition.

    更新日期:2020-01-07
  • How does resolution of sedimentary architecture data affect plume dispersion in multiscale and hierarchical systems?
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-07
    Zhenxue Dai; Chuanjun Zhan; Shuning Dong; Shangxian Yin; Xiaoying Zhang; Mohamad Reza Soltanian
    更新日期:2020-01-07
  • Evaluation of surface water and groundwater interactions in the upstream of Kui river and Yunlong lake, Xuzhou, China
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-07
    Jing Yang; Zhongbo Yu; Peng Yi; Shaun K. Frape; Meng Gong; Yuting Zhang

    Understanding the interaction between groundwater and surface water is of great significance to the rational development and utilization of water resources and the protection of ecological environment. Here we present a combination of several methods (radon balance method, EC conservation method and flow balance method) for evaluating the hydraulic exchange of groundwater and surface water in a small watershed of Kui river and Yunlong lake. The exchange fluxes of Kui river, Yunlong lake and groundwater were estimated by one-dimensional steady state model and box model. The results indicate that the lake water is mainly recharged by groundwater from the surrounding mountains and the lake renewal time is about 26 days. Meanwhile, multiple transformations occur between groundwater and river water, and river water leakage is dominant. The existence of several tributaries complicates the hydraulic exchange, and groundwater discharge is also evident. Furthermore, the advantages and disadvantages of these three methods were analyzed. This study successfully demonstrated that radon and EC as tracers can be used to estimate the exchange flux between groundwater and surface water, particularly in areas lacking conventional hydrological data. Combining these three methods, the hydraulic exchange between groundwater and surface water can be evaluated more effectively. The analysis of hydraulic exchange is also crucial for Xuzhou area where water resources are extraordinary scarce and polluted.

    更新日期:2020-01-07
  • Use of multiple modules and Bayesian Model Averaging to assess structural uncertainty of catchment-scale wetland modeling in a Coastal Plain landscape
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-07
    Sangchul Lee; Haw Yen; In-Young Yeo; Glenn E. Moglen; Martin C. Rabenhorst; Gregory W. McCarty

    Wetland hydrology differs by landscapes and thus a modeling structure that best characterize wetland hydrological processes may vary. However, structural uncertainty of wetland modeling has been assessed in few landscapes. Limited understanding of structural uncertainty remains for a landscape dominated by groundwater. This study used Soil and Water Assessment Tool (SWAT) to assess structural uncertainty in catchment-scale wetland hydrology on the Coastal Plain of the Chesapeake Bay watershed, where landscape hydrology is greatly affected by groundwater. This study investigated the differences in streamflow prediction and quantification of wetland loss impacts on streamflow among three wetland modeling structures. Two lumped structures (SS and RS) and one semi-spatial structure (RG) were examined in this study. Bayesian Model Averaging (BMA) was used to generate the ensemble of three model structures. To reduce parameter uncertainty on model outputs, streamflow parameters were constrained by using the same streamflow parameter set that was mutually acceptable for the three wetland modeling structures. Results showed that the three model structures exhibited different streamflow predictions and hydrologic changes by wetland loss. The RG structure provided the best streamflow simulation results due to its accurate prediction on low-flow conditions relative to the two other structures (SS and RS). The BMA results also indicated less accurate model prediction of streamflow compared to the RG. Hydrologic changes resulting from wetland loss were best captured by the RG structure that mimicked wetland water storage functions such as peak flow changes and annual streamflow variation. In contrast, the results from the two other structures and BMA did not accurately reflect those functions in responses to wetlands loss. The RG structure showed superior simulation of wetland hydrology due to its semi-spatial model structure. In contrast, poor BMA results were attributed to poor predictions from lumped model structures (SS and RS). These results suggest that a spatial model structure is critical to simulate wetland hydrologic processes in a landscape with a high dependency on groundwater processes, and wetland modeling development should be toward an explicit spatial characterization of wetlands.

    更新日期:2020-01-07
  • A novel nonlinear Arps decline model with salp swarm algorithm for predicting pan evaporation in the arid and semi-arid regions of China
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-07
    Haomin Wang; Hui Yan; Wenzhi Zeng; Guoqing Lei; Chang Ao; Yuanyuan Zha

    Accurate prediction of water surface evaporation (Ep) is important in the fields of both hydrology and irrigation engineering. This study evaluated the potential ability of a new hybrid model based on the salp swarm algorithm (SSA) and the kernel-based nonlinear Arps decline (KNEA) in predicting Ep. Two other common machine learning models, including the M5 model tree (M5) and the multivariate adaptive regression splines (MARS), were also applied in this study for comparison. All models were developed using daily records between 2000 and 2015 from 12 meteorological stations in the arid and semi-arid regions of northwest China. These daily records, including the maximum and minimum temperatures, solar radiation, wind speed and relative humidity, were randomly divided into two parts, with 70% of which used for model calibration and the others applied for validation. Four different parameter input combinations were equipped to explore the possibility of improving model accuracy. Two data application scenarios and five statistical indicators including the root-mean-square-error (RMSE), mean absolute error (MAE), scatter index (SI), d-index and determination coefficient (R2) were used for model evaluation. In the scenario of using local data as inputs for model calibration and validation, the impacts of wind speed and relative humidity on Ep were both greater than that of solar radiation, and SSA-KNEA was consistently superior to MARS or M5 across all the input combinations. In the scenario of using cross-station data, in which models using the best input combination were developed by local data of each station but validated by data from each of the remaining 11 stations, SSA-KNEA models performed better than MARS or M5 models on average. In addition, the SSA-KNEA model established by data from Station 51777 was the most suitable generalized model in this research area. Overall, our findings suggested that the new hybrid algorithm (i.e., SSA-KNEA) has high potential for Ep estimation in the arid and semi-arid regions of China, with local or cross-station data.

    更新日期:2020-01-07
  • Production Analysis of Multifractured Horizontal Wells with Composite Models: Influence of Complex Heterogeneity
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-07
    Shanshan Yao; Xiangzeng Wang; Qingwang Yuan; Zixi Guo; Fanhua Zeng

    Multi-linear analytical models are of high computational convenience to simulate the fluid production out of low-permeability unconventional (tight and shale) reservoirs stimulated with multifractured horizontal wells (MFHWs). But multi-linear models cannot accurately describe the flow behavior in such reservoirs since the fluid flow around hydraulic fracture tips is not linear flow. This creates barriers for the multi-linear models to consider pressure/stress-dependent fracture and reservoir characteristics. In addition, multi-linear models in the literature cannot consider or fully consider heterogeneity conditions including the reservoir heterogeneity and well completion heterogeneity. In this study, a composite model is developed to model the fluid flow in unconventional reservoirs with MFHWs under various heterogeneity conditions. In the composite model, the reservoir is divided into sub-systems and each sub-system is further divided into flow regions. The fluid flow in one flow region can be simply linear, radial or source/sink flow. The composite model considers the pressure/rate distribution characteristics beyond fracture tips with fast calculations. The composite model is applicable to one or combinations of the following three heterogeneous conditions-fractured horizontal wells with heterogeneous completions, reservoir heterogeneity around the horizontal well and reservoir heterogeneity around a hydraulic fracture. The model’s applicability in heterogeneous reservoirs is demonstrated by the comparison with the trilinear-flow model, five-region model and numerical solutions. In this study solutions of the composite model are utilized to analyze two sets of production data from fractured horizontal wells in heterogeneous conditions.

    更新日期:2020-01-07
  • Effects of reduced grazing pressure on sediment and nutrient yields in savanna rangeland streams draining to the Great Barrier Reef
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-07
    Jack Koci; Roy C. Sidle; Anne E. Kinsey-Henderson; Rebecca Bartley; Scott N. Wilkinson; Aaron A. Hawdon; Ben Jarihani; Christian H. Roth; Luke Hogarth
    更新日期:2020-01-07
  • The modified Hydrological model for assessing effect of pH on fate and transport of Escherichia coli in the Athabasca River Basin
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-07
    Tesfa Worku Meshesha; Junye Wang; Nigus Demelash Melaku

    Quantifying bacteria fluxes and contaminants from the point and nonpoint sources in a watershed are important for the management of water quality and safeguard public health. Therefore, the appropriate characterization of bacteria from different sources is necessary for understanding of fate and transport of bacteria in watersheds. However, it is challenging to simulate the effects of pH on bacteria, such as Escherichia coli (E. coli) in the original version of Soil and Water Assessment Tool (SWAT). This study aimed to augment SWAT-bacteria module to evaluate the potential effect of pH on E. coli concentrations. We modified SWAT-bacteria module to incorporate pH factor and to check E. coli observations from four sites of Athabasca River Basin. The modified SWAT-bacteria model demonstrated a linear relationship between observed and simulated daily E. coli data with R2 values found between 0.70 to 0.80; NSE: 0.59 to 0.68; PBIAS: 7.94% to 17.85% during calibration for all monitoring sites (2010-2012). While during the validation (2013-2014) the performance statistics found to be: R2: 0.59 to 0.72; NSE: 0.55 to 0.66; PBIAS: 10% to 22%. The results of the sensitivity analysis confirmed that pH is one of the most significant fate factors of E. coli. The modified SWAT-bacteria module provides an improved estimate of E. coli concentration from the river basin. This study contributes new insight to E. coli modelling. Therefore, the modified SWAT-bacteria model could be a powerful tool for the future regional to global scale model of E. coli concentrations thus significantly contribute for the application of effective river basin management.

    更新日期:2020-01-07
  • Spatial Patterns of Temporal Changes in Canadian Prairie Streamflow using an alternative trend assessment approach
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-03
    Paul H Whitfield; K.R. Shook; J.W. Pomeroy

    Changes in Canadian Prairie streamflow, particularly trends over time, have not been well studied but are particularly relevant for food and water security in this vast agricultural region. Streamflow records for this region are often unsuitable for conventional trend analysis; streams are often intermittent and have only a few days per year with flow, and stations operate only during the warm season, because of a lack of flow during the very cold Prairie winter. This study takes an alternative approach; streamflow data for the period from March to October for individual years between 1910 to 2015 from 169 hydrometric stations from the Prairie and adjacent areas in Canada were converted to annual cumulative runoff series. These 5895 individual station-years were then clustered based upon their shape, using dynamic time warping. Three clusters of cumulative annual runoff were found; the first and most common type has infrequent days with flow and low total annual runoff [0-50 mm], the second has more days with flow and slightly greater runoff [48-175 mm], and the least common third type has the fewest days without flow, includes perennial streams, and has much greater annual runoff [>173mm]. For each hydrometric station a time series of annual cluster memberships was created. Trends in the fractions of cluster types were determined using logistic regression, with spatial groupings of these time series over five-year periods. Trends in the fractions of types within an ecoregion indicate spatially consistent and organized changes in the pattern of runoff over the region. In the western Canadian Prairies, particularly in the Mixed Grassland and Cypress Upland ecoregions, drying is occurring, as indicated by the increased frequency of the dry type. In the northern and eastern Canadian Prairies, conditions are shifting to greater runoffs, particularly in the Aspen Parkland, where the wet types are increasing in frequency.

    更新日期:2020-01-04
  • Stochastic Simulation on Reproducing Long-term Memory of Hydroclimatological Variables using Deep Learning Model
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-03
    Taesam Lee; Ju-Young Shin; Jong-Suk Kim; Vijay P. Singh

    Stochastic simulation has been employed for producing long-term records and assessing the impact of climate change on hydrological and climatological variables in the future. However, traditional stochastic simulation of hydroclimatological variables often underestimates the variability and correlation structure of larger timescale due to the preservation of long-term memory. However, the Long Short-Term Memory (LSTM) model, one type of recurrent neural network (RNN), employed in different fields, exhibits a remarkable long-term memory characteristic owing to the recursive hidden and cell states. The current study, therefore, applied the LSTM model to the stochastic simulation of hydroclimatological variables to examine how good the LSTM model can preserve the long-term memory and overcome the drawbacks of conventional time series models. The simulation involved a trigonometric function and the Rössler system as well as real case studies for hydrological and climatological variables. Results showed that the LSTM model reproduced the variability and correlation structure of the larger timescale as well as the key statistics of the original time domain better than the traditional models. The hidden and cell states of the LSTM containing the long-memory and oscillation structure following the observations allows better performance compared to the other tested conventional models. This better representation of the long-term variability can be critical in water manager since future water resources planning and management is highly related with this long-term variability. Thus, it is concluded that the LSTM model can be a potential alternative for the stochastic simulation of hydroclimatological variables. Also, note that another long-term memory model such as Gated Recurrent Unit can be also applicable.

    更新日期:2020-01-04
  • Effects of earthquakes on the discharge of groundwater systems: the case of the 2016 seismic sequence in the Central Apennines, Italy
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-03
    Di Matteo Lucio; Dragoni Walter; Azzaro Salvatore; Pauselli Cristina; Porreca Massimiliano; Bellina Giovanni; Cardaci Walter
    更新日期:2020-01-04
  • Work conjugate stress and strain variables for unsaturated frozen soils
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-03
    Xiangtian Xu; Ruiqiang Bai; Ying Lai; Mingyi Zhang; Jingge Ren

    In general, most of the foundations of structures in the cold regions rest on frozen soils which are often under unsaturated state and subject to mechanical and thermal loads. The thermal loads will induce water migration and water-ice phase change, as a result, the dynamic phase transition between unfrozen water and ice occurs and degree of saturation in frozen soils is affected. These complicate the understanding of the strength and deformation characteristics of frozen soils under mechanical and thermal loads. Furthermore, it leads to a necessity to develop a coupling thermo-hydro-mechanical model for practical permafrost engineering. Up to date, there are limited studies to quantify this complicated problem by a framework with proper stress and strain variables for unsaturated frozen soils. This study derives the expression of input work rate for unsaturated frozen soils based on the multiphase porous media theory. Work conjugate stress and strain variables have been determined based on the expression of input work rate. This set of variables not only can smoothly transit from unsaturated frozen state to unsaturated unfrozen state when temperature is above freezing point, but also can smoothly transit from unsaturated state to saturate state. The proposed framework can be consistently applied to multi-phase soils with unsaturated frozen soils, unsaturated soils and saturated soils. Moreover, the application of the framework can be further extended to other porous mediums. Additionally, the selected variables in this framework are validated against published experimental results. This framework can subsequently be used to establish the coupled thermo-hydro-mechanical models for unsaturated and saturated frozen soils.

    更新日期:2020-01-04
  • Modeling and comparative analysis of a flow and heat coupling model of the riparian zone based on thermal conductivity empirical models
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-03
    Wenbing Zhang; Zhenzhong Shen; Jie Ren; Lei Gan; Fei Wang; Bihan Yu; Chenglin Li

    Recently, the use of heat as a tracer to evaluate the process of hyporheic exchange in riparian zones has attracted wide attention. A more accurate flow-heat coupling model of riparian zones could help us understand the patterns of water flow and heat transfer in riparian zones and provide a scientific basis for the comprehensive management and efficient utilization of these zones. In this paper, a flow-heat coupling model of a riparian zone based on thermal conductivity empirical models (TCEMs) was built by customizing partial differential equations (PDEs) based on the simulation of soil water flow using porous media and the subsurface flow module in COMSOL. Combined with the data collected from the field heat tracer test in the riparian zone, the flow-heat coupling model of the riparian zone under 12 types of TCEMs was validated and compared. The results show that the use of the PDE module instead of the heat transfer in porous media (HTPM) module is very effective for modeling; the PDE module could basically replace the HTPM module in the heat transfer calculation. The performance of the flow-heat coupling model varies under different types of TCEMs, and the Chung & Horton (1987) model shows better simulation effects, with a root mean square error (RMSE), coefficient of determination (R2), mean absolute error (MAE), and mean relative error (MRE) ranging from 1.37–2.48℃, 0.73–0.94, 1.06–2.08℃, and 11.94–15.79%, respectively. Therefore, this model could better reflect the dynamic temperature variations in the riparian zone. The sensitivity analysis results illustrate that the hydraulic conductivity (Ks), van Genuchten parameter (β), volumetric heat capacity of dry solids (Cs), and porosity (n) of the flow-heat coupling model greatly influence riparian zone temperature variations, and the parameters β, Ks, and residual water content (θr) significantly affect the lateral hyporheic exchange rate in the riparian zone, of which β has the largest effect.

    更新日期:2020-01-04
  • Extended growing season reduced river runoff in Luanhe River basin
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-02
    Xiaojun Geng; Xuancheng Zhou; Guodong Yin; Fanghua Hao; Xuan Zhang; Zengchao Hao; Vijay P. Singh; Yongshuo H. Fu

    Global warming has substantially altered vegetation growth and phenology in temperate biomes worldwide, whose impacts on river runoff have not been fully understood, especially at the watershed scale. Investigating the relationships among phenological shift, changes in vegetation growth, and river runoff is essential to improve our understanding of the ecosystem response to ongoing climate change. Using in-situ runoff records, phenological dates that were extracted from the normalized difference vegetation index (NDVI) over the period 1982-2015, and grey relational analysis, this study investigated the relationships between changes in river runoff and phenological variables in Luanhe River basin, China. It was found that the growing season in the Luanhe basin was significantly extended by 0.60 ± 0.08 d per year associated with climate warming over the period 1982-2015, which is mainly related to the earlier start of growing season (SOS, 0.40 ± 0.05 d per year), rather than the delayed end of growing season (EOS, 0.11 ± 0.01 d per year). The vegetation growth, defined as the average growing season NDVI (GS_NDVI), significantly increased in more than 88.4% of the study area, on average the GS_NDVI increased by 1.30 ± 0.03×10-3 d per year. On the other hand, runoff significantly reduced by 1.42 mm per year over the study period, but large differences were observed between upper and middle-lower reaches region of the Luanhe basin. The grey relational analysis confirmed the primary regulation of river runoff by precipitation, but the length of growing season and vegetation growth also played a key role in the changes of runoff. These results provide new insights into the interaction between vegetation dynamics and water balance at the watershed scale, and highlight to couple the phenological processes into eco-hydrological models to improve the modelling accuracy.

    更新日期:2020-01-02
  • Multiscale Hydrological Drought Analysis: Role of Climate, Catchment and Morphological variables and associated Thresholds
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-02
    Anoop Valiya Veettil; Ashok k. Mishra

    Identification of thresholds associated with key climate, catchment and morphological variables for hydrological droughts can further improve our understanding of evolution and propagation of droughts in a complex water resource system. These thresholds are associated with complex interaction between climate and catchment variables and they are often connected through hierarchical as well as non-linear relationships. The advantage of selecting a multi-factor predictor domain can detect multiple thresholds that may not be observed by analyses limited to single predictors. In the present study, we developed a conceptual modeling framework by integrating a hydrological model developed based on the Soil and Water Assessment Tool (SWAT) and statistical models to quantify the potential influence of climate, catchment, and morphological variables and their thresholds on hydrological drought duration and severity for the watersheds located in Savannah River Basin (SRB). The concept of standardized runoff index (SRI) was used to derive the multiscale hydrological drought time series (i.e., SRI 1, SRI 6, and SRI 12) to investigate short term, medium term, and long term drought events based on their duration and severity. It was observed that the linear models developed based on the climate variables may not be capable for predicting the duration of multiscale hydrological droughts, whereas, the performance of statistical models can be significantly improved by the addition of catchment and morphological variables. In addition, among the morphological variables stream order seems to have a significant control over short, medium and long term drought duration across the study area. In the second phase of our analysis, we employed classification and regression tree (CART) algorithm for quantifying the thresholds associated with climate, catchment, and morphological variables that have potential influence on the hydrological drought. The result indicates that the variables and its associated threshold vary for short, medium, and long term drought. The proposed modeling framework can be extended for ungauged basins to improve the drought management.

    更新日期:2020-01-02
  • An assessment of metaheuristic approaches for flood assessment
    J. Hydrol. (IF 4.405) Pub Date : 2020-01-02
    Hamid Reza Pourghasemi; Seyed Vahid Razavi Termeh; Narges Kariminejad; Haoyuan Hong; Wei Chen
    更新日期:2020-01-02
  • Migration of active particles in a surface flow constructed wetland
    J. Hydrol. (IF 4.405) Pub Date : 2019-12-31
    Y. Yang; S.W. Tan; L. Zeng; Y.H. Wu; P. Wang; W.Q. Jiang
    更新日期:2020-01-01
  • Real-time simulation of hydrodynamic and scalar transport in large river-lake systems
    J. Hydrol. (IF 4.405) Pub Date : 2019-12-31
    Dechao Hu; Shiming Yao; Chengkun Duan; Songping Li

    Real-time coupling of a hydro-environmental model and an optimization model is difficult because hydrodynamic model (HDM) and scalar transport model (STM) are both time-consuming, especially when the computational domain is large (e.g., river-lake system). This study presents a new 1D hydro-environmental model for free-surface flows and scalar transport in large river-lake systems. Using a prediction–correction method, hydrodynamic is simulated by solving local linear systems based on domain decomposition. A flux-form Eulerian-Lagrangian method (ELM) is constructed to solve advective transport of scalars in 1D grid systems, and a nested technique is proposed to reduce its startup cost. The resulting STM and HDM both allow large time steps for which the Courant–Friedrichs–Lewy number (CFL) is greater than 1, and they are parallelized using the open multiprocessing technique (OpenMP). Moreover, the STM is good at solving multiscalar transport and has low startup cost. The new model is tested using the Jing-Dongting (JDT) system which is covered by a grid of 2,382 cells (with 113,600 sub-grids). Stable and accurate simulations are achieved at large time steps for which the CFL can be larger than 5. A sequential run of the new model runs tens of times faster than that of a conventional 1D model such as the Mike11. Moreover, the efficiency of the new model can be further improved by the OpenMP parallel technique. In the test of scale property of the HDM+STM model (using 32 kinds of scalars and 16 cores), a parallel run is 11.8 times faster than a sequential run, and it only takes the new model 33.3 s to complete a simulation of a 1-year process of unsteady flow and scalar transport in the JDT system.

    更新日期:2019-12-31
  • Comparison and evaluation of multiple land surface products for the water budget in the Yellow River Basin
    J. Hydrol. (IF 4.405) Pub Date : 2019-12-31
    Yonghe Liu; Zongliang Yang; Peirong Lin; Ziyan Zheng; Shengjin Xie

    Multiple global datasets simulated by different land surface models (LSMs) are useful for providing information to decision-makers on the water balance in different subareas of a river basin. As a large basin covering a vast area, the Yellow River Basin (YRB) represents a typical case to evaluate the water cycle components in LSM products. The main objective of this study is to evaluate and compare multiple LSM products with respect to precipitation, runoff, evapotranspiration (ET) and terrestrial water storage anomaly (TWSA). The datasets analyzed include different Global Land Data Assimilation System (GLDAS) products, ERA-Interim/Land datasets, and augmented Noah LSM products with multiple parameterization options (Noah-MP) driven by different GLDAS forcing datasets. The evaluation is conducted with reference to gauge-based precipitation datasets, reconstructed natural streamflow and Gravity Recovery and Climate Experiment (GRACE)-derived TWSA. Several statistical metrics and the partitioning of runoff and ET were emphasized. The results show that the products generated diverse spatial patterns for the water cycle components. The ERA-Interim/Land data present the best performance almost for all water cycle components. The three models (variable infiltration capacity (VIC), Mosaic and community land model (CLM)) driven by GLDAS version 1 generated different but large systematic biases, and the Noah model performs the best among the four models. The Noah simulation of GLDAS version 2.0 (GLDAS-2.0) and the Noah-MP simulation with the Princeton Global Forcing also have systematically large biases for runoff. The different Noah-MP simulations perform better for runoff (although overestimated) than other models used in GLDAS, but present the poorest correlations of TWSA to GRACE-derived TWSA. The ensemble averages of multiple products perform the best for precipitation and ET than any other individual product but not for runoff.

    更新日期:2019-12-31
  • Comment on “Plot-based experimental study of raindrop detachment, in interrill wash and erosion-limiting degree on a clayey loessal soil”
    J. Hydrol. (IF 4.405) Pub Date : 2019-12-31
    P.I.A. Kinnell

    Zhang et al (2019) reported results from experiments where 80 cm long clayey lossal soil surfaces eroded by rain-impacted flow produced by artificial rainfalls. The target was surrounded by a 30 cm buffer area and slots along the sides of the target enabled splashed material to be collected during the experiments that lasted about 40 mins. Both splashed material and material discharged by the rain-impacted flow were collected in order to produce data on splash and sediment discharge rates for each rainfall event. Slope gradients ranging from 7o to 25o and rainfall intensities varying from 42 mm hr-1 to 90 mm hr-1 were used in the experiments. Splash rates initially decreased rapidly before reaching relatively steady values. Sediment discharge rates for 90 mm hr-1 rainfalls showed a similar pattern. However, with 42 mm hr-1 and 60 mm hr-1 rainfalls, there was an initial increase in sediment discharge rate followed by a peak before sediment discharges declined towards steady values which were not achieved with 42 mm hr-1 rainfalls. Given current understanding of sediment transport in flows deeper than 1 to 2 millimetres, it is suggested here that particles of different sizes and densities travel at different rates in the very shallow flows that operated in these experiment and, because the steady state discharge is not achieved until the slowest moving particle detached at the top of the slope is discharged, that the effects of slope gradient, rainfall intensity and time on the sediment discharge rates observed result from the numerous time scales that operate to transport eroded material over the surface. Also, because results using other soils in the same apparatus by others show temporal variations in sediment discharges that differ between different soils, it is suggested that additional work is required beyond experiments such as those reported by Zhang et al before the processes that operate in very shallow flows are well understood.

    更新日期:2019-12-31
  • Characteristics of Hydroseismograms in Jingle Well, China
    J. Hydrol. (IF 4.405) Pub Date : 2019-12-30
    Anhua He; Weiping Deng; Ramesh P. Singh; Fang Lyu

    Hydroseismograms reflect the oscillations of well water levels caused by seismic waves. In this study, the relationships between the hydroseismogram oscillation amplitude and three factors (seismic magnitude, epicentral distance, and focal depth) in Jingle well, China were analyzed. The results revealed that hydroseismogram amplitude increases exponentially with seismic magnitude as Hmag=7.848×10-8×e2.1690×m+0.047(m>Mw5.8) (m - seismic magnitude), decreases exponentially with epicentral distance as Hdis=-2.1108×10-5×e2.3864×γ+0.011 (γ - epicentral distance), and decreases exponentially with focal depth as Hdep=-1.6438×10-3×e0.0254×d-0.203 (d is focal depth). However, these relationships become uncertain when the epicentral distance exceeds 4000 km and are not applicable to nuclear explosions. Based upon the single well–aquifer model constructed for Jingle well, the amplification (μ) of the water level oscillation by ground vibrations (μ=AbAa=R2-r2r2) depends on the frequency of the water-level oscillations. For relatively high-frequency oscillations (caused by earthquakes with relatively small epicentral distances), the amplification will be small, while for low-frequency oscillations (caused by earthquakes with relatively large epicentral distances), the amplification will be large. Using the S-transform, the dominant hydroseismogram period increases with the epicentral distance as τ=0.5826×γ+12.51, which means that the amplification (μ) increases with the epicentral distance. Of course, the amplitude of ground oscillations will be greatly attenuated with increasing epicentral distance. Due to the anisotropy of the earth and seismic wave superposition, the relationships between the hydroseismogram amplitude and the seismic magnitude, epicentral distance, and focal depth become blurred or even uncertain with increasing epicentral distance and focal depth, leading to poor goodness-of-fit between the dominant hydroseismogram period and epicentral distance. The quantitative relationships between the hydroseismogram amplitude and the seismic magnitude, epicentral distance, and focal depth, which determine the ratio between the amplitudes of water-level oscillations and ground vibrations and the relationship between groundwater oscillations and seismic wave transmission, are proposed for the first time in the present work. These results will improve understanding of hydrogeological conditions and could also be important in identifying reliable earthquake precursors.

    更新日期:2019-12-31
  • How does precipitation recharge groundwater in loess aquifers? Evidence from multiple environmental tracers
    J. Hydrol. (IF 4.405) Pub Date : 2019-12-30
    Tianming Huang; Baoqiang Ma; Zhonghe Pang; Zhi Li; Zhenbin Li; Yin Long

    Characterization of the rainfall infiltration mechanism, whether piston or preferential flow, through an unsaturated zone is necessary for groundwater resource assessment and for analysis of environmental geological hazards. However, several limitations and difficulties remain in determining the infiltration mechanism in arid and semiarid areas. This study combines the evaluations of soil water infiltration characteristics, recharge rate, and determination of groundwater age at a water table in a semiarid loess tableland to examine the recharge processes. The case study is the Xifeng loess tableland in the Loess Plateau of China, which has an unsaturated zone depth of 40–75 m and an obvious 1963-3H peak at a depth of 7.5 m. According to the piston flow, the soil water infiltration velocity is 0.12–0.14 m/yr, corresponding to a recharge rate of 37–41 mm/yr, based on the 1963-3H peak and chloride mass balance method. All of the groundwater from the water table and wells is old (tritium-free), with ages ranging from hundreds of years to 20,000 years, which suggests that no rapid modern recharge has occurred since the 1950s. The chloride content of soil water in the deep unsaturated zone, with an average value of 10.8 mg/L in the unsaturated zone below 30 m, overlaps with that in groundwater, at 4.0–10.9 mg/L. The comprehensive isotopic and chemical compositions for soil water and groundwater showed that piston flow was dominant during soil water infiltration at the field scale, resulting in the delay of modern water and related solutes entering the groundwater. Combined evaluations of the unsaturated zone with those of the saturated zone and the use of multiple environmental tracers, such as Cl, Br, 2H, 18O, 13C, 3H and 14C, can be regarded as a generic framework for studying the recharge processes in arid and semiarid areas with thick unsaturated zones at macroscopic and field scales.

    更新日期:2019-12-31
  • Relative influence of forest and cropland on fluvial transport of soil organic carbon and nitrogen in the Nen River basin, northeastern China
    J. Hydrol. (IF 4.405) Pub Date : 2019-12-30
    Sen Wang; Xiaoyuan Wang; Bin He; WenpingYuan

    Riverine transport of carbon and nitrogen strongly impacts terrestrial and aquatic ecosystem functions but is itself affected by changes in land cover and land use. China’s Nen River basin has experienced widespread conversion from forest to cropland in the past century, making it representative of similar global land use changes. We assessed organic carbon and nitrogen transport in this basin during 2018 and 2019, using water samples collected at one-hour intervals during the twelve flood events in two sub-basins (the Yalu and Yin rivers) dominated by forests and cropland, respectively. We also assessed dissolved organic carbon (DOC) and total dissolved nitrogen (TDN) concentrations from 19 sampling sites distributed throughout the Nen River basin, in combination with hydrological records, to investigate the impacts of land cover on riverine carbon and nitrogen fluxes. The forested Yalu river basin showed significantly higher DOC content and lower TDN content than Yin river basin. Riverine DOC concentrations during non-flood periods in the forested Yalu river basin were significantly higher than in the cultivated Yin river basin, but riverine TDN concentrations were lower. Throughout the Nen River basin and its sub-basins, riverine TDN content was proportional to cropland area. During the twelve flood events, riverine DOC and TDN varied widely over time in the Yin and Yalu river basins, possibly due to dilution effects of water originating from different land covers within the basins. Our results demonstrate that land cover is the principal cause of changes in riverine DOC and TDN content in this region.

    更新日期:2019-12-30
  • A comparison of conventional and wavelet transform based methods for streamflow record extension
    J. Hydrol. (IF 4.405) Pub Date : 2019-12-30
    D. Nalley; J. Adamowski; B. Khalil; A. Biswas

    Sufficient hydrological data, such as streamflow, are essential to represent the long-term characteristics of a watershed in order to support decision-making, policy and management. Lack of data remains one of the main challenges of hydrological analyses. Therefore, the main goal of this study is to extend streamflow records using a proposed approach where the wavelet transform (WT) is incorporated as a pre-processing method into eight existing record extension techniques, namely the ordinary least-square regression (OLS), maintenance of variance (MOVE) types 1-4, Kendall-Theil robust line (KTRL), KTRL2 and robust line of organic correlation (RLOC). The performance of the WT-based methods in estimating individual data values, means and standard deviations of the extended records, and a series of percentiles of the extended records was then compared with that of the respective conventional methods (i.e., without the WT). The data used in the analysis consisted of 67 pairs of target-index stations that were obtained from Canada’s Reference Hydrometric Basin Network database, all of which contain outliers. As such, the results and discussions obtained are applicable for cases where the data contain outliers. The WT-based methods (particularly the KTRL-WT, KTRL2-WT and RLOC-WT) demonstrated consistent improvements in precision and accuracy compared with their conventional counterparts, especially in estimating the means and standard deviations of the extended records. In estimating individual data values, the WT-based methods showed inconsistent improvements. Finally, in terms of percentiles, greater improvements were seen in the estimation of higher percentiles, more specifically for the MOVE1-WT, MOVE2-WT, KTRL2-WT and RLOC-WT compared with their conventional counterparts.

    更新日期:2019-12-30
  • Flow hydraulic responses to near-soil surface components on vegetated steep red soil colluvial deposits
    J. Hydrol. (IF 4.405) Pub Date : 2019-12-30
    Si-Yi Zhang; Cheng Li; Bin Huang; Tong Liu; Tailong Guo; Zhaijian Yuan; Bin He; Dingqiang Li

    The effects of vegetation restoration on the hydraulic processes of steep colluvial deposits at collapsing gullies in South China have rarely been evaluated. This study quantified the influences of canopy, biocrusts, and roots on 30° deposit slopes planted with Melinis minutifora and Chrysopogon zizanioides via rainfall simulation experiments. Intact M. minutifora and C. zizanioides effectively decreased flow velocities (v) by 35.3% and 29.5%, and increased Darcy-Weisbach friction coefficients (f) by 239.6% and 130.8% compared to that of the control treatments, respectively. The roots of M. minutifora contributed most to the decrease of v and the increase of f, while roots and canopy of C. zizanioides decreased v and increased f to the greatest extents, respectively. Biocrusts increased f and decreased v for all rain intensities when they were combined with roots. However, when they grew on bare slopes, these positive effects were only observed in response to 60 mm h-1 rain events, but were reversed for 120, and 180 mm h-1 rain events. Canopy decreased flow shear stress (τ) and stream power (ω), while roots showed a contrasting result, and the effects of biocrusts varied on different slopes. The influences of plants and components also varied with rain intensities. Sediment yield rates showed significant relationships with v, Re, τ, and ω and could be predicted using linear regression of τ or ω. This study highlights the effects of canopies, roots of different vegetation types, and biocrusts on the hydraulic process on steep colluvial deposit. The presented results aid the decision-making and management of vegetation restoration of collapsing gullies.

    更新日期:2019-12-30
  • Interlinkages between human agency, water use efficiency and sustainable food production
    J. Hydrol. (IF 4.405) Pub Date : 2019-12-30
    Haoyang Lyu; Zengchuan Dong; Saket Pande

    Efficient use of water and nutrients in crop production are critical for sustainable water and crop production systems. Understanding the role of humans in ensuring water and nutrient use efficiency is therefore an important ingredient of sustainable development. Crop production functions are often defined either as functions of water and nutrient deficiency or are based on economic production theory that conceptualizes production as a result of economic activities that take in inputs such as water, capital and labor and produce crop biomass as output. This paper fills a gap by consistently treating water and nutrient use and human agency in crop production, thus providing a better understanding of the role humans play in crop production. Uptake of water and nutrients are two dominant biophysical processes of crop growth while human agency, including irrigation machine power, land-preparing machine power and human labor force, determine limits of water and nutrient resources that are accessible to crops. Two crops, i.e., winter wheat and rice, which account for the majority of food crop production are considered in a rapidly developing region of the world, Jiangsu Province, China, that is witnessing the phenomenon of rural to urban migration. Its production is modeled in two steps. First water and nutrient efficiencies, defined as the ratios of observed uptake to quantities applied, are modeled as functions of labor and machine power (representing human agency). In the second step, crop yields are modeled as functions of water and nutrient efficiencies multiplied by amounts of water and fertilizers applied. As a result, crop production is predicted by first simulating water and nutrient uptake efficiencies and then determining yield as a function of water and nutrients that are actually taken up by crops. Results show that modeled relationship between water use efficiency and human agency explains 68% of observed variance for wheat and 49% for rice. The modeled relationship between nutrient use efficiency and human agency explains 49% of the variance for wheat and 56% for rice. The modeled relationships between yields and actual uptakes in the second step explain even higher percentages of observed the variance: 73% for wheat and 84% for rice. Leave-one-out cross validation of yield predictions shows that relative errors are on average within 5% of the observed yields, reinforcing the robustness of the estimated relationship and of conceptualizing crop production as a composite function of bio-physical mechanism and human agency. Interpretations based on the model reveal that after 2005, mechanization gradually led to less labor being used relative to machinery to achieve same levels of water use efficiency. Labor and irrigation equipment, on the other hand, were found to be complimentary inputs to water use efficiency. While the results suggest interventions targeting machinery are most instrumental in increasing wheat productivity, they may exasperate rural – urban migration. Policy strategies for alleviating rural-urban migration while ensuring regional food security can nonetheless be devised where appropriate data are available.

    更新日期:2019-12-30
  • Temporal characteristics of groundwater chemistry affected by the 2016 Kumamoto earthquake using self-organizing maps
    J. Hydrol. (IF 4.405) Pub Date : 2019-12-28
    Kei Nakagawa; Zhi-Qiang Yu; Ronny Berndtsson; Takahiro Hosono

    Possibilities to perform pre- and post-seismic groundwater chemical comparisons on regional groundwater flow systems are rare due to lack of data and observations. The Kumamoto earthquake provides an unusual opportunity to improve the knowledge on earthquake hydrology and earthquake effects on hydrochemistry of groundwater due to a wealth of pre- and post-quake observations. We analyzed 12 physiochemical parameters (SiO2, (NO3-+NO2-)-N, Fetotal, Mntotal, pH, F-, Cl-, SO42-, Na+, K+, Ca2+, and Mg2+) using self-organizing maps (SOM) combined with hydrological and geological characteristics to improve the understanding of changes in groundwater chemistry after a major earthquake. The results indicate that the earthquake induced hydrological and environmental change via fault forming (Suizenji fault systems), liquefaction, rock fracturing, and ground shaking. These geological processes created rock fresh reactive surfaces, rock loosening, and enhancement of hydraulic conductivity. In turn, this lead to secondary processes in groundwater chemistry by advection, dilution, and chemical reaction. The most obvious indicator of hydrological and environmental change was from the increased dissolved silica content stemming from fracturing and Si-O bond cleavage in silicate rocks. Besides this, decreasing concentration of common ions (Cl-, F-, Na+, K+, Ca2+) was found due to dilution from mountain-side water release. Increase in (NO3-+NO2-)-N, SO42-, and Mg2+ concentration occurred locally due to soil leaching of contaminants or agricultural fertilizers through surface ruptures in recharge areas. Increase of SO42- content also originated from leaching of marine clay in coastal areas and possibly sporadic deep crustal fluid upwelling. Increase in (NO3-+NO2-)-N and Cl- content occurred from sewage water pipe breaks in the Suizenji fault formation in urban areas. Decrease of pH occurred in a few wells due to mixing of river water and different types of aquifer groundwater. Increase of Fetotal and Mntotal concentration possibly originated from leaching of marine clay by liquefaction in coastal areas. However, in most cases the water chemistry changes were subtle, thus not resulting in any groundwater quality deterioration of water supplies.

    更新日期:2019-12-29
  • Super-diffusion affected by hydrofacies mean length and source geometry in alluvial settings
    J. Hydrol. (IF 4.405) Pub Date : 2019-12-28
    Maosheng Yin; Yong Zhang; Rui Ma; Geoffrey Tick; Marco Bianchi; Chunmiao Zheng; Wei Wei; Song Wei; Xiaoting Liu

    Dissolved-phase contaminants experiencing enhanced diffusion (i.e., “super-diffusion”) with a pronounced leading plume edge can pose risk for groundwater quality. The drivers for complex super-diffusion in geological media, however, are not fully understood. This study investigates the impacts of hydrofacies’ mean lengths and the initial source geometry, motivated by a hydrofacies model built recently for the well-known MADE aquifer, on the spatial pattern of super-diffusion for two-dimensional alluvial aquifer systems. Monte Carlo simulations show that the bimodal velocity distribution, whose pattern is affected by the hydrofacies’ mean lengths, leads to super-diffusion of solutes with a bi-peak plume snapshot in alluvial settings where advection dominates transport. A larger longitudinal mean length (i.e., width) for hydrofacies with high hydraulic conductivity (K) enhances the connectivity of preferential pathways, resulting in higher values in the bimodal velocity distribution and an enhanced leading front for the bi-peak plume snapshot, while the opposite impact is identified for the hydrofacies’ vertical mean length (i.e., thickness) on the bi-peak super-diffusion. A multi-domain non-local transport model is then proposed, extending upon the concept of the distributed-order fractional derivative, to quantify the evolution of bi-peak super-diffusion due to differential advection and mobile-mobile mass exchange for solute particles moving in hydrofacies with distinct K. Results show that the bi-peak super-diffusion identified for the MADE site and perhaps the other similar aquifers, which is affected by the initial source geometry at an early stage and the thickness and width of high-K hydrofacies during all stages, can be quantified by the mobile-mobile fractional-derivative model. Porous medium dimensionality and stochastic model comparison are also discussed to further explore the nature of bi-peak super-diffusion in alluvial systems.

    更新日期:2019-12-29
  • lTransboundary water sharing problem; a theoretical analysis using evolutionary game and system dynamics
    J. Hydrol. (IF 4.405) Pub Date : 2019-12-28
    Liang Yuan; Weijun He; Dagmawi Mulugeta Degefu; Zaiyi Liao; Xia Wu; Min An; Zhaofang Zhang; Thomas Stephen Ramsey

    Water is the backbone of socio-economic and environmental systems. Increasing demand and unpredictable availability due to anthropogenic climate change is making water an extremely scarce resource in different parts of the world when the resources facing scarcity are shared between different administrative boundaries, conflicts could arise. Transboundary river basins are typical examples. Water sharing problems within these transboundary river basins are very difficult to solve because of the socio-economic and environmental asymmetries among the water claiming stakeholders. In addition, water-sharing problems have a systemic feature that evolves through time. Previous studies did not comprehensively capture these features. This article attempts to fill this research gap by combining the evolutionary game and system dynamic model to predict the equilibrium outcomes of different strategic scenarios. When the riparian states choose polarizing strategies, the equilibrium evolves either quickly, initiated by the countries’ need to avoid the loss that could result from water conflict or very slowly if the countries opt to maintain the benefits that result from their polarized strategies. In the scenario where both choose a tolerance strategy, the equilibrium evolves very slowly. If either of the countries chooses a polarizing strategy irrespective of its neighbor choosing a compromise strategy, the equilibrium evolves much faster. The results depicted that the equilibrium under different scenarios does not always lead to concessions. Therefore, the countries should strengthen the cooperation in water resource management to ensure that a zero-sum game and the inception of a new strategic evolution are prevented.

    更新日期:2019-12-29
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