Testing three approaches to estimate soil evaporation through a dry soil layer in a semi-arid area J. Hydrol. (IF 3.727) Pub Date : 2018-10-12 E. Balugani, M.W. Lubczynski, C. van der Tol, K. Metselaar
Bare soils and grasslands in arid and semi-arid conditions constitute a large portion of the earth surface. Evaporation, which is the main component of the water balance in these conditions, often takes place through a dry soil layer (DSL). There is no scientific agreement yet on the DSL effects on evaporation rates.The implementations of three conceptual models of DSL-evaporation were tested for the simulation of evaporation rates in a semi-arid study area in Central Spain: (i) the daily-average model, based on the assumption that the daily average vapour transport in a DSL can be represented in analogy to isothermal liquid flow; (ii) the numerical model solving the Richards equation, in this case HYDRUS1D was used; and (iii) the pore-scale model, based on soil column experiments in laboratory conditions. The evaporation rates estimated by the three conceptual models for semi-arid field conditions were compared with the evaporation rates measured by an eddy covariance tower in the same area.The results indicate that the daily-average conceptual model assumption, in which the DSL has no effects on evaporation, does not hold in very dry conditions. The numerical model solving the Richards equation was not able to simulate the effects of the DSL on evaporation rates. The evaporation estimates obtained by the pore-scale conceptual model were closest to the eddy covariance measurements during the dry season, however this model was applicable only to the relatively steady evaporation conditions during afternoons and only assuming spatially constant DSL thickness.
Identification of hydroclimate subregions for seasonal drought monitoring in the U.S. Great Plains J. Hydrol. (IF 3.727) Pub Date : 2018-10-12 Zachary T. Zambreski, Xiaomao Lin, Robert M. Aiken, Gerard J. Kluitenberg, Roger A. Pielke Sr
Identification of subregions that share similar historical drought variability provides useful information for drought monitoring, mitigation planning, and resource allocation. This study examined space-time historical drought variability for the Great Plains spanning from 1901 to 2015 by using rotated Empirical Orthogonal Functions (rEOFs). The Standardized Precipitation-Evapotranspiration Index (SPEI) on a three-month timescale was utilized to examine spatial and temporal changes in agricultural drought. We propose a new procedure for identifying the number of rEOFs to be selected for reconstructing subregions. Drought event intensities of moderate, severe, and extreme categories increased in recent years although the number of drought events decreased. Seasonal rEOFs demonstrated that 9 to 12 subregions were adequate to explain a significant proportion of the original variability in the Great Plains. The time series for each subregion was highly correlated to the original SPEI data and reflected the seasonal meteorological processes that drive drought variability. Several significant wetting trends were found, and there was statistical evidence that drought and wetting event severities had increased for a few subregions. Summer drought has become more variable across space and time, indicating that a more diverse set of resources and strategies might be needed to mitigate impacts of spatially-variable drought and wetting events in coming decades. Winter season drought has become less variable, indicating that perhaps resources could be consolidated when dealing with impacts on a larger scale; however, less variability implies that drought and wetting events may occur across larger regions of the Great Plains during a given season.
An empirical investigation into the effect of antecedent precipitation on flood volume J. Hydrol. (IF 3.727) Pub Date : 2018-10-13 Bree Bennett, Michael Leonard, Yu Deng, Seth Westra
The magnitude of floods depends not only on the intensity and pattern of precipitation during the flood event (the ‘flood-producing’ precipitation), but also on the moisture stored in the catchment, which arises from antecedent hydrological processes over many preceding timescales. To characterise this effect, an empirical study is conducted on the influence of antecedent precipitation on significant flood events across multiple climate zones and catchment conditions, using 100 Australian catchments with hourly streamflow and precipitation. Antecedent conditions are shown to have a significant influence on flood volume, with three quarters of catchments having at least a 50% difference in flood volume depending on whether the catchment is wet or dry before the flood-producing precipitation event. The study considers the sensitivity of flow to antecedent precipitation by means of an ‘elasticity’ metric, which indicates the proportional change in flow for a change in antecedent precipitation or flood-producing precipitation. Flood-producing precipitation nevertheless remains the dominant flood driver across most catchments, with the elasticity of flow to antecedent precipitation typically being between 28% and 37% of the elasticity to flood-producing precipitation. Importantly, the elasticity of flow to antecedent precipitation relative to flood-producing precipitation decreases with increasing event magnitude, highlighting that conclusions of future change based on annual maximum streamflow may not be reflective of the processes that operate for more extreme floods that have the greatest impact on society.
Hydrologic model predictability improves with spatially explicit calibration using remotely sensed evapotranspiration and biophysical parameters J. Hydrol. (IF 3.727) Pub Date : 2018-10-13 Adnan Rajib, Grey R. Evenson, Heather E. Golden, Charles R. Lane
A hydrologic model, calibrated using only streamflow data, can produce acceptable streamflow simulation at the watershed outlet yet unrealistic representations of water balance across the landscape. Recent studies have demonstrated the potential of multi-objective calibration using remotely sensed evapotranspiration (ET) and gaged streamflow data to spatially improve the water balance. However, methodological clarity on how to “best” integrate ET data and model parameters in multi-objective model calibration to improve simulations is lacking. To address these limitations, we assessed how a spatially explicit, distributed calibration approach that uses (1) remotely sensed ET data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and (2) frequently overlooked biophysical parameters can improve the overall predictability of two key components of the water balance: streamflow and ET at different locations throughout the watershed. We used the Soil and Water Assessment Tool (SWAT), previously modified to represent hydrologic transport and filling-spilling of landscape depressions, in a large watershed of the Prairie Pothole Region, United States. We employed a novel stepwise series of calibration experiments to isolate the effects (on streamflow and simulated ET) of integrating biophysical parameters and spatially explicit remotely sensed ET data into model calibration. Results suggest that the inclusion of biophysical parameters involving vegetation dynamics and energy utilization mechanisms tend to increase model accuracy. Furthermore, we found that using a lumped, versus a spatially explicit, approach for integrating ET into model calibration produces a sub-optimal model state with no potential improvement in model performance across large spatial scales. However, when we utilized the same MODIS ET datasets but calibrated each sub-basin in the spatially explicit approach, water yield prediction uncertainty decreased, including a distinct improvement in the temporal and spatial accuracy of simulated ET and streamflow. This further resulted in a more realistic simulation of vegetation growth when compared to MODIS Leaf-Area Index data. These findings afford critical insights into the efficient integration of remotely sensed “big data” into hydrologic modeling and associated watershed management decisions. Our approach can be generalized and potentially replicated using other hydrologic models and remotely sensed data resources – and in different geophysical settings of the globe.
Probabilistic inference of fracture-scale flow paths and aperture distribution from hydrogeophysically-monitored tracer tests J. Hydrol. (IF 3.727) Pub Date : 2018-10-13 A. Shakas, N. Linde, T. Le Borgne, O. Bour
Fracture-scale heterogeneity plays an important role in driving dispersion, mixing and heat transfer in fractured rocks. Current approaches to characterize fracture scale flow and transport processes largely rely on indirect information based on the interpretation of tracer tests. Geophysical techniques used in parallel with tracer tests can offer time-lapse images indicative of the migration of electrically-conductive tracers away from the injection location. In this study, we present a methodology to invert time-lapse ground penetrating radar reflection monitoring data acquired during a push-pull tracer test to infer fracture-scale transport patterns and aperture distribution. We do this by using a probabilistic inversion based on a Markov chain Monte Carlo algorithm. After demonstration on a synthetic dataset, we apply the new inversion method to field data. Our main findings are that the marginal distribution of local fracture apertures is well resolved and that the field site is characterized by strong flow channeling, which is consistent with interpretations of heat tracer tests in the same injection fracture.
Nierji reservoir flood forecasting based on a Data-Based Mechanistic methodology J. Hydrol. (IF 3.727) Pub Date : 2018-10-13 Guozhen Wei, Wlodek Tych, Keith Beven, Bin He, Fanggui Ning, Huicheng Zhou
The Nierji Basin, in the north-east of China, is one of the most important basins in the joint operation of the entire Songhua River, containing a major reservoir used for flood control. It is necessary to forecast the flow of the basin during periods of flood accurately and with the maximum lead time possible. This paper presents a flood forecasting system, using the Data Based Mechanistic (DBM) modeling approach and Kalman Filter data assimilation for flood forecasting in the data limited Nierji Reservoir Basin (NIRB). Examples are given of the application of the DBM methodology using both single input (rainfall or upstream flow) and multiple input (rainfalls and upstream flow) to forecast the downstream discharge for different sub-basins. Model identification uses the simplified recursive instrumental variable (SRIV) algorithm, which is robust to noise in the observation data. The application is novel in its use of stochastic optimisation to define rain gauge weights and identify the power law nonlinearity. It is also the first application of the DBM methodology to flood forecasting in China. Using the methodology allows the forecasting with lead times of 1-day, 2-day, 3-day, 4-day, 5-day with 98%, 97%, 96%, 96% and 93% forecast coefficient of determination respectively, which is sufficient for the regulation of the reservoirs in the basin.
Role of mudflat-creek sediment exchanges in intertidal sedimentary processes J. Hydrol. (IF 3.727) Pub Date : 2018-10-14 Weiming Xie, Qing He, Xianye Wang, Leicheng Guo, Keqi Zhang
Intertidal environments, including bare mudflats, tidal creeks, and vegetated salt marshes, are of significant physical and ecological importance in estuaries. Their morphodynamics are closely linked by mudflats and creek networks. Understanding water motion and sediment transport in mudflats and tidal creeks is fundamental to understand intertidal morphodynamics in intertidal environments. To explore dynamic interactions between tidal creeks and mudflats, we conducted field campaigns monitoring water depths, tidal currents, waves, suspended sediments, and bed-level changes at sites in both mudflats and tidal creeks in the Eastern Chongming tidal wetland in the Yangtze Delta for a full spring-neap tidal cycle. We saw that under fair weather conditions, the bed-level changes of the tidal creek site displayed a contrary trend compared with those of the mudflat site, indicating the source-sink relationship between tidal creek and mudflat. During over-marsh tides, the tidal creek site with relatively high bed shear stresses (averagely, 0.37 N/m2) was eroded by 35 mm whereas the mudflat site was accreted by 29 mm under low bed shear stresses (averagely, 0.18 N/m2). To the contrast, during creek-restricted tides, deposition occurred in the tidal creek site by 20 mm under low bed shear stresses (averagely, 0.09 N/m2) whereas erosion occurred in the mudflat site by 25 mm under relatively high bed shear stresses (averagely, 0.21 N/m2). Over a spring-neap tidal cycle, the net bed level changes were -15 mm (erosion) and 4 mm (deposition) in tidal creeks and mudflats, respectively. These results suggested that there were alternated erosion-deposition patterns in spring and neap tides, and a sediment source and sink shift between mudflats and creeks. We found that the eroded sediments in mudflats were transported landward into tidal creeks and deposited therein in neap tides, and these newly deposited sediments would be resuspended and transported to surrounding marshes (over-marsh deposition) at spring tides. The coherent sediment transport and associated erosion-deposition pattern within the mudflat-creek system at spring-neap tidal time scales thus played a fundamental role in intertidal morphodynamic development. These findings suggest that management and restoration of intertidal ecosystem need to take the entire mudflat-creek-marsh system as a unit into consideration rather than focusing on single elements.
Quantifying the relationship between compound dry and hot events and El Niño–Southern Oscillation (ENSO) at the global scale J. Hydrol. (IF 3.727) Pub Date : 2018-10-11 Zengchao Hao, Fanghua Hao, Vijay P. Singh, Xuan Zhang
The compound dry and hot event has attracted much attention in recent decades due to their disastrous impacts on different sectors. The impact from compound dry and hot events is generally more severe than that from individual dry or hot event. Understanding the physical mechanism of this compound event is thus of particular importance for early warning to reduce potential impacts. In this study, we quantitatively assessed the relationship between the occurrence of compound dry and hot events and El Niño–Southern Oscillation (ENSO) during the warm season at the global scale. Monthly precipitation and temperature from the Climatic Research Unit (CRU) were used to estimate the occurrence of compound events, and Niño 3.4 index (NINO34) was used to represent the ENSO phenomenon. The logistic regression model was employed to model the occurrence of compound events with respect to NINO34. Results from the logistic regression model showed that ENSO played an important role in the occurrence of compound dry and hot events during the warm season in regions such as northern part of South America, southern Africa, southeastern Asia and Australia. A higher likelihood of the occurrence of compound dry and hot events in these regions was shown to be associated with higher values of NINO34 based on empirical analysis from observations. Results from this study will help improve our understanding of compound dry and hot events and aid with mitigation efforts for ameliorating their adverse impacts.
A New Normal for Streamflow in California in a Warming Climate: Wetter Wet Seasons and Drier Dry Seasons J. Hydrol. (IF 3.727) Pub Date : 2018-10-11 Iman Mallakpour, Mojtaba Sadegh, Amir AghaKouchak
In this study, we investigate changes in future streamflows in California using bias-corrected and routed streamflows derived from global climate model (GCM) simulations under two representative concentration pathways (RCPs): RCP4.5 and RCP8.5. Unlike previous studies that have focused mainly on the mean streamflow, annual maxima or seasonality, we focus on projected changes across the distribution of streamflow and the underlying causes. We report opposing trends in the two tails of the future streamflow simulations: lower low flows and higher high flows with no change in the overall mean of future flows relative to the historical baseline (statistically significant at 0.05 level). Furthermore, results show that streamflow is projected to increase during most of the rainy season (December to March) while it is expected to decrease in the rest of the year (i.e., wetter rainy seasons, and drier dry seasons). We argue that the projected changes to streamflow in California are driven by the expected changes to snow patterns and precipitation extremes in a warming climate. Changes to future low flows and extreme high flows can have significant implications for water resource planning, drought management, and infrastructure design and risk assessment.
A Budyko-type Model for Human Water Consumption J. Hydrol. (IF 3.727) Pub Date : 2018-10-12 Xiaowen Lei, Jianshi Zhao, Dingbao Wang, Murugesu Sivapalan
Budyko-type models in hydrology are simple but efficient descriptions of the vegetation-mediated hydrologic cycle in catchments. Based on hypothesized similarities between vegetation and human water consumption interactions in terms of water demand, constraints, and system functioning as well as catchment processes and outcomes, a corresponding Budyko-type framework is proposed here for human water consumption at the catchment scale. To validate this framework, socioeconomic data (human water consumption and economic and agricultural structure data), as well as hydrometeorological data, for 51 human-impacted catchments located in 10 major river basins in China were assembled. The results demonstrate 1) similar observed patterns to the traditional Budyko curves, with two limits and a monotonous increase shape; 2) the same functional form and mathematical features of the derived Budyko-type equation. Parameters of the new Budyko-type model for human consumption are estimated and analyzed based on the concept of water productivity. This study suggests that the functioning of both social and hydrologic subsystems within catchment systems can be explored within a common conceptual framework, thus providing a unified socio-hydrologic basis for the study of human–water systems.
Complementary data-intelligence model for river flow simulation J. Hydrol. (IF 3.727) Pub Date : 2018-10-12 Zaher Mundher Yaseen, Salih Muhammad Awadh, Ahmad Sharafati, Shamsuddin Shahid
Despite of diverse progressions in hydrological modeling techniques, the necessity of a robust, accurate, reliable, and trusted expert system for real-time stream flow prediction still exists. The intention of the present study is to establish a new complementary data-intelligence (DI) model called wavelet extreme learning machine (WA-ELM) for forecasting river flow in a semi-arid environment. The monthly river flow data for the period 1991-2010 is used to calibrate and validate the applied predictive model, developed using antecedent flow data as predictor. The prediction efficiency of the developed WA-ELM model is validated against stand-alone ELM model. The performance of the models is diagnosed using multiple statistical metrics and graphical analysis visualization. The results reveal that incorporation of data pre-processing wavelet approach with ELM model enhances the river flow predictability. In quantitative term, the root-mean-square error (RMSE) and mean absolute error (MAE) measurements are reduced by 65% and 67% using WA-ELM over ELM model, respectively. The Taylor diagram reveals much closer proximity and the Violin plot shows similar distribution of WA-ELM simulated river flow to the observed river flow compared to stand-alone ELM simulated river flow. The hybridization of wavelet decomposition method with ELM model improves the ability of ELM model to extract the required information for modeling the non-stationary and high stochastic river flow pattern. Overall, the study reveals that WA-ELM can be a reliable methodology for modeling river flow in semi-arid environment and for different regimes (i.e., low-, medium- and high-flow).
Coupled hydrogeophysical inversion of DNAPL source zone architecture and permeability field in a 3D heterogeneous sandbox by assimilation time-lapse cross-borehole electrical resistivity data via ensemble Kalman filtering J. Hydrol. (IF 3.727) Pub Date : 2018-10-11 Xueyuan Kang, Xiaoqing Shi, Yaping Deng, André Revil, Hongxia Xu, Jichun Wu
Characterization of dense non-aqueous phase liquid (DNAPL) distribution is important to facilitate the decision of remediation strategies. However, it is still a great challenge to characterize DNAPL source zone architecture with high resolution due to subsurface heterogeneity and relatively sparse data from traditional hydrogeological investigations. To overcome difficulties from such sparse data, electrical resistivity tomography (ERT) is introduced to locate DNAPL using time-lapse cross-borehole measurements. Due to the significant impact of geological heterogeneity on DNAPL source zone architecture, a data assimilation framework based on the coupled multiphase fluids-ERT model is developed to jointly invert DNAPL saturation and the permeability field using time-lapse ERT data. To validate the efficiency and performance of this framework, synthetic and laboratory experiments are both performed to monitor DNAPL migration and distribution in 3D heterogeneous sandbox with cross-borehole ERT. Result shows that time-lapse ERT and direct inversion can map the evolution of the DNAPL plume but loses details regarding the plume morphology due to the over-smoothing caused by geophysical inversion using an isotropic and homogeneous roughness-based regularization procedure. By contrast, the coupled inversion is successful to characterize both the permeability field and the evolution of the DNAPL plume with a higher resolution. This is because the coupled inversion is able to directly translate raw geophysical data into hydrologic meaningful information and therefore avoid artifacts caused by direct geophysical inversion.
Modeling the hydrological impact of land use change in a dolomite-dominated karst system J. Hydrol. (IF 3.727) Pub Date : 2018-10-11 Daniel Bittner, Tahoora Sheikhy Narany, Bernhard Kohl, Markus Disse, Gabriele Chiogna
Hydrological models represent valuable tools to investigate the impacts of land use changes on water resources. Most commonly, distributed, physically-based models are applied for land use change impact studies in hydrology. However, providing a physically-based and detailed description of subsurface flows in karst systems is challenging. Lumped models, in contrast, are easy to implement and widely used in karst hydrological research, albeit not applicable for land use change impact studies. To overcome these limitations, we developed a new semi-distributed model LuKARS (Land use change modeling in KARSt systems) that lumps the predominant hydrotopes (i.e. distinct landscape units characterized by homogeneous hydrological properties as a result of similar land use and soil types) present in a catchment as independent, non-linear units. Flows from each hydrotope represent a specific response of the vadose zone (soil-epikart-infiltration zone) in a defined recharge area. The saturated zone consists of a single linear storage unit recharged by each hydrotope independently. The main goal of this approach was to investigate land use change impacts in a dolomite karst system exploited for the water supply of the city of Waidhofen a.d. Ybbs (Austria) by changing the area covered by each hydrotope. Here, land use changes occured in the form of increasing spaces used for dolomite mining and at the expense of existing forest sites. With our parametrized model, we were able to reproduce the measured discharge in the largest spring of the Waidhofen karst system (Kerschbaum spring). Moreover, we succeeded in transferring the parametrized hydrotopes to other recharge areas (Hinterlug and Mitterlug) and validated the transferability of the modeling approach. Finally, we successfully showed the model’s applicability for land use change impacts studies by validating the calibrated model in a period in which the space of the dolomite quarries in the Kerschbaum recharge area almost doubled. The results of our study show that an increase of the dolomite quarries negatively affects the water supply of the city of Waidhofen a.d. Ybbs.
Quantifying Hourly Suspended Sediment Load Using Data Mining Models: Case Study of a Glacierized Andean Catchment in Chile J. Hydrol. (IF 3.727) Pub Date : 2018-10-10 Khabat Khosravi, Luca Mao, Ozgur Kisi, Zaher Mundher Yaseen, Shamsuddin Shahid
Suspended sediment has significant effects on reservoir storage capacity, the operation of hydraulic structures and river morphology. Hence, modeling suspended sediment loads (SSL) in rivers contributes to various water resource management and river engineering. An evaluation of stand-alone data mining models (i.e., reduced error pruning tree (REPT), M5P and instance-based learning (IBK)) and hybrid models, (i.e., bagging-M5P, random committee-REPT (RC-REPT) and random subspace-REPT (RS-REPT)) for predicting SSL resulting from glacial melting at an Andean catchment in Chile has been conducted in this study. The best input combinations are constructed based on Pearson correlation coefficient (PCC) of hourly SSL time series data with water discharge (Q), water temperature (T) and electrical conductivity (C) for different time lags. Seventy percent of the available data (one year of hourly data) is used to calibrate the models (dataset training) and the remaining 30% is used for model evaluation (dataset testing). The performances of the models are evaluated using several quantitative and graphical criteria, including coefficient of determination (R2), root mean square error (RMSE), mean absolute error (MAE), Nash-Sutcliffe efficiency (NSE), percentage of bias (PBIAS), the ratio of RMSE to the standard deviation of observation (RSR), a Taylor diagram and a boxplot. All the models performed well in predicting SSL. However, the Friedman and Wilcoxon signed rank tests revealed that predicted SSL significantly differed for different models except between IBK (or M5P) and REPT. The hybrid models performed better than individual models. The bagging-M5P had the best predictive capability while the REPT had the poorest.
A nationwide regional flood frequency analysis at ungauged sites using ROI/GLS with copulas and super regions J. Hydrol. (IF 3.727) Pub Date : 2018-10-10 Martin Durocher, Donald H. Burn, Shabnam Mostofi Zadeh
Region of influence is a common approach to estimate runoff information at ungauged locations. To estimate flood quantiles from annual maximum discharges, the Generalized Least Squares (GLS) framework has been recommended to account for unequal sampling variance and intersite correlation, which requires a proper evaluation of the sampling covariance structure. Since some jurisdictions do not have clear guidelines to perform this evaluation, a general procedure using copulas and a nonparametric intersite correlation model is investigated to estimate sampling covariance structure in situations where no common at-site distribution is imposed or when some paired sites do not have common periods of record. The investigated methodology is applied on 771 sites in Canada. The Normal copula is verified to be an adequate model that better fit paired observations than other types of extreme copulas. A sensitivity analysis is carried out to evaluate the impact of either ignoring, or considering a simpler form of, intersite correlation. Additionally, super regions are defined based on drainage area and mean annual precipitation to improve the calibration of pooling groups across large territories and a wide range of climate conditions. Performance criteria based on cross-validation revealed that using super regions and a combination of geographic distance and similarity between catchment descriptors improves the calibration of the pooling groups by providing more accurate estimates.
Effects of a snow-compaction treatment on soil freezing, snowmelt runoff, and soil nitrate movement: A field-scale paired-plot experiment J. Hydrol. (IF 3.727) Pub Date : 2018-10-10 Yukiyoshi Iwata, Yosuke Yanai, Tomotsugu Yazaki, Tomoyoshi Hirota
Estimating monthly evapotranspiration by assimilating remotely sensed water storage data into the extended Budyko framework across different climatic regions J. Hydrol. (IF 3.727) Pub Date : 2018-10-09 Wanqiu Xing, Weiguang Wang, Quanxi Shao, Bin Yong, Catherine Liu, Xiaozhou Feng, Qing Dong
Assessment of Modern Recharge to Arid Region Aquifers Using an Integrated Geophysical, Geochemical, and Remote Sensing Approach J. Hydrol. (IF 3.727) Pub Date : 2018-10-09 Othman Abdurrahman Fallatah, Mohamed Ahmed, Dawn Cardace, Thomas Boving, Ali S. Akanda
The arid and semi-arid regions of the world are facing limited freshwater resources, minimal amounts of rainfall, and increasing population pressure and water demands. These resources, often groundwater, are vulnerable to both natural variability and anthropogenic interventions. Here, we develop and apply an integrated approach using geophysical, geochemical, and remote sensing observations to quantify the recharge rates of arid region aquifers that are witnessing rapid groundwater depletion. Focusing on the Saq aquifer system in the Arabian Peninsula, our study was three-fold: (1) to examine the areal extent of aquifer recharge domains using geologic, climatic, and remote sensing data; (2) to investigate the origin of, and modern contributions to, the aquifer system by examining the isotopic composition of groundwater samples; and (3) to estimate the magnitude of modern recharge to the aquifer utilizing estimates from the Gravity Recovery and Climate Experiment (GRACE) data and a continuous rainfall-runoff model, the Soil and Water Assessment Tool (SWAT) model. Isotopic examination of the groundwater from Saq revealed that deeper aquifers (fossil water) are more depleted compared to shallow reserves (alluvial aquifer; mixed waters). Analysis of GRACE-derived terrestrial and groundwater storage estimates indicates that the aquifer system received an annual recharge rate of 5.21 ± 0.10 km3/yr (11.85 ± 0.22 mm/yr), equal to about half of the withdrawal rate from wells during the investigation period (2002–2016). Analysis of SWAT results indicates that, from 1998 to 2014, the investigated watersheds received an average annual precipitation of 19.20 km3, of which approximately 51% is partitioned as potential recharge. The temporal variations in storage, depletion and recharge are related to the changes in regional groundwater extraction, rainfall, and extent of irrigated areas.
Investigation of Multi-model Spatiotemporal Mesoscale Drought Projections over India under Climate Change Scenario J. Hydrol. (IF 3.727) Pub Date : 2018-10-09 Vivek Gupta, Manoj Kumar Jain
Projected droughts for 21st century over India have been analysed using precipitation and temperature data obtained from Regional Climate Model (RCMs) under Representative Concentration Pathways (RCPs) 4.5 and 8.5. Standardized Precipitation Index (SPI), Standardized effective Precipitation Evapo-Transpiration Index (SP∗ETI) and Standardized Precipitation-Evapotranspiration Index (SPEI) at the timescale of 12 months have been used for drought characterization. K-means clustering algorithm have been utilized to delineate distinct drought homogeneous regions in India. Trends and periodicities in drought characteristics have also been analysed. The results of this study reveal that increase in evapotranspiration due to projected rise in temperature would play a major role in affecting future drought dynamics in most parts of India. Analysis indicates that computed magnitude of drought intensity, duration and frequency depends on the choice of drought indicator. SPEI drought index has been found to project highest drought risk as compared to other two indices used in this study. North India is more vulnerable to increase in drought severity and frequency in near future. However in far future, most parts of the country, except few southeastern states, are likely to face an escalation in drought severity and frequency. A shift in drought hazard from central India toward southeast-central India is likely to happen with increase in greenhouse gas (GHG) concetration. The areal extent of droughts has been found to be increasing historically which is expected to increase further in future for most parts of the country. Historically, drought dynamics were more influenced by decrease in precipitation. However, in future, the drought dynamics will be significantly influenced by increased evapotranspiration resulting from increase in temperature in spite of likely increase in precipitation. The periodicity analysis indicates inter-annual periodicities influencing monsoon months to be distributed uniformly across all clusters of the Indian subcontinent with dominant cycles of 2 to 3.6 years. Further, change in periodic cycles of drought due to climate change is found to be insignificant.
Variability, Teleconnection, and Predictability of Korean Precipitation in relation to Large Scale Climate Indices J. Hydrol. (IF 3.727) Pub Date : 2018-10-05 Jai Hong Lee, Jorge A. Ramirez, Tae Woong Kim, Pierre Y. Julien
Spatiotemporal variability, teleconnection, and predictability of the Korean precipitation related to large scale climate indices were examined based on leading patterns of observed monthly Rx5day and total precipitation through an empirical orthogonal teleconnection (EOT). Cross-correlation and lag regression analyses for the leading modes and global atmospheric circulation dataset were employed on a monthly basis. The spatial pattern of the leading EOT modes for Rx5day and total precipitation represents a northern inland mode for boreal summer and a southern coastal mode in boreal winter. The temporal evolution of the leading EOT modes exhibits increasing trends during summer season and decadal variability for winter season. The leading EOT patterns of Rx5day precipitation show more widespread coherent patterns than those of total precipitation during warm and cold seasons, while the former explains less variance in precipitation variability than the latter. The tropical ENSO forcing has a coherent teleconnection with September and November-December precipitation patterns, while the Indian Ocean dipole is identified as a driver for precipitation variability in September and November. The monsoon circulation over the western North Pacific also exhibits a significant negative correlation with winter precipitation EOTs, while tropical cyclone indices are positively correlated with the fall precipitation EOTs. The leading patterns of the September and December Rx5day precipitation time series are predictable at up to six month lead time from the tropical Pacific sea surface temperatures (SSTs), while a somewhat weak predictable response from Indian Ocean SSTs was only detected at longer lead times. In addition, predictability from the Pacific SSTs for above normal precipitation is greater than that for below normal precipitation.
Where does infiltrated stormwater go? Interactions with vegetation and subsurface anthropogenic features J. Hydrol. (IF 3.727) Pub Date : 2018-10-06 Jeremie Bonneau, Tim D Fletcher, Justin F Costelloe, Peter J Poelsma, Robert B James, Matthew J Burns
The practice of stormwater infiltration is widely used to reduce the amount of urban stormwater runoff delivered to drainage systems and receiving waters. In theory, the practice recharges groundwater, leading to increased urban stream baseflow. In reality, however, little is known about the fate of infiltrated stormwater. Because urban groundwater pathways are numerous and the interactions with subsurface infrastructure (e.g. trenches, pipes, etc.) are highly complex, the spatial and temporal variability of the contribution of infiltrated stormwater to baseflow is difficult to predict. We tracked the fate of infiltrated stormwater out of an 1800 m2 infiltration basin (3.5 % of its 5-ha impervious catchment) using a network of piezometers for over three years. We found that groundwater levels downslope of the basin were increased (by at least 4 m) while water levels in an array of reference piezometers lateral to the basin showed no change (dry at depths ranging 2-4 m). Monthly water balance calculations indicated that in summer, most of the infiltrated stormwater was evapotranspired by the vegetation downslope of the basin, and thus did not reach the receiving stream. In the colder months, some infiltrated stormwater did reach the stream as plant water use declined. Anthropogenic disturbances (a sewer pipe and stream re-alignment) interacted with the upper part of the plume of infiltrated stormwater, locally lowering the water table. The study provides evidence that the fate of infiltrated stormwater is complex, and that infiltrated stormwater does not always reach receiving streams as baseflow as is often assumed.
Finland’s cooperation in managing transboundary waters and the UNECE Principles for Effective Joint Bodies: Value for water diplomacy? J. Hydrol. (IF 3.727) Pub Date : 2018-10-06 Tuula Honkonen, Annukka Lipponen
Water diplomacy may be understood broadly as the measures that may be taken to prevent or peacefully resolve conflicts over water resources concerning their availability, allocation or use between and within states. The concept is preventive in nature as well as offering an approach for conflict resolution. Instruments of international water law, among them notably conventions and soft law developed on that basis – which promote equitable and reasonable use of transboundary waters and prevention of transboundary impact – can serve as tools for water diplomacy. The obligation to establish agreements on shared waters and joint bodies to govern them has contributed to gathering important experience, and some of this has been synthesized into the Principles for Effective Joint Bodies which were adopted by the Meeting of the Parties to the UNECE Water Convention in 2015. The Principles are intended as a resource to increase the effectiveness of joint bodies in transboundary water cooperation.This paper analyses Finland’s cooperation arrangements in the light of the Principles and assesses the extent to which Finland’s transboundary water commissions reflect the good practices specified in the Principles. Taking a wider perspective, the paper also examines the elements of the principles and their practical realisation with a view to understanding better their the promotion of water diplomacy. Relevant features include, inter alia, the competency and representation of the joint institution, its accountability and the extent to which public participation is permitted, and the cooperative mechanisms in place. Naturally the underlying transboundary water agreements specify the framework for cooperation between the riparian states to a great extent, but the established joint bodies often play a significant role, specifically in the equitable use and management of the shared water resources, but even beyond, in the prevention and settling of conflicts, and in the general promotion of cooperation and security at a regional level.
An Innovative Solution of Diurnal Heat Transport in Streambeds with Arbitrary Initial Condition and Implications to the Estimation of Water Flux and Thermal Diffusivity under Transient Condition J. Hydrol. (IF 3.727) Pub Date : 2018-10-06 Kewei Chen, Hongbin Zhan, Quanrong Wang
Diurnal heat signal has been widely used to infer the seepage flux and thermal diffusivity in streambeds. The theoretical basis is the one-dimensional (1-D) analytical solution of heat advection-dispersion equation with sinusoidal boundary condition and homogeneous initial condition (Stallman, 1965). However, the assumption of homogeneous initial condition made in Stallman (1965) is physically unrealistic and the assumption of steady flow is often violated when water level changes rapidly (e.g., flooding). To incorporate the realistic initial condition, an innovative solution for 1-D heat transport with sinusoidal boundary condition and arbitrary initial condition is proposed. This solution makes it possible to accurately simulate heat transport with transient flux by sequentially applying the new solution at small time interval. Synthetic temperature signals at different depth of streambeds are generated to study the impact of transient flux to the estimation of water flux and thermal diffusivity. Here are some major findings. Firstly, the calculated flux is sensitive to the flux dynamics. The faster the flux increases or decreases, the less accurate the calculated flux is. Secondly, using temperature time series from deep sensor pair is more likely to cause erroneous estimation of flux because heat signal damps fast with depth. Thirdly, the heat tracer method for estimating water flux is sensitive to the thermal properties of saturated sediments. Large thermal diffusivity leads to high uncertainty for flux estimation.
3D hydrodynamic investigation of thermal regime in a large river-lake-floodplain system (Poyang Lake, China) J. Hydrol. (IF 3.727) Pub Date : 2018-10-06 Yunliang Li, Qi Zhang, Rui Ye, Jing Yao, Zhiqiang Tan
A Model for the Assessment of the Effect of Mulching on Aquifer Recharging by Rainfalls in an Arid Region J. Hydrol. (IF 3.727) Pub Date : 2018-10-06 Mohammad Ebrahim Banihabib, Bahman Vaziri, Saman Javadi
In this paper, a model is proposed for the assessment of the effectiveness of various mulches in increasing deep percolation of rainfalls for enhancing arid zones aquifers. For this purpose, 8 precipitations were selected from the Intensity-Duration-Frequency (IDF) curves of the study area with a return period of 2 and 5 years. The deep percolation of these precipitations were examined in lysimeters with gravel, sand and mixed mulches and without any mulch. Then 192 data of soil moisture, daily maximum air-temperature and deep percolation were measured for driving empirical equations. Moreover, the efficiency and accuracy of these empirical equations were investigated using Coefficient of Determination (CD) and Nash–Sutcliffe Efficiency Coefficient (NSEC). The results showed that the obtained empirical equations could estimate deep percolation and evaporation with an acceptable accuracy. Using these equations and the soil-water balance equation, a soil moisture model was developed for the assessment of deep percolation. Then it was examined to evaluate the efficiency of the mulched soils in increasing soil moisture and aquifer recharging of three years’ precipitations in Shahrekord plain, Iran. The results showed that the deep percolation increased in all examined mulched soils compared to unmulched soil, its maximum and cumulative increase were in gravel mulch with 21.3% and 30%, respectively. Furthermore, groundwater modeling results showed that the mulching could improve groundwater level as 0.34 m over a three year period. Finally, this paper proposes soil mulching for enhancing groundwater resources and a model to assess it.
Determining the origin, circulation path and residence time of geothermal groundwater using multiple isotopic techniques in the Heyuan Fault Zone of Southern China J. Hydrol. (IF 3.727) Pub Date : 2018-10-06 Xiaolin Qiu, Ya Wang, Zhongzheng Wang, Klaus Regenauer-Lieb, Ke Zhang, Jie Liu
Medium–low temperature geothermal resources are abundant in Southern China, but their heat source and link to fault zones is poorly understood. Consequently, geothermal energy is only used at small scale. In order to broaden the footprint of geothermal energy use in Southern China, it is first necessary to understand and track the geothermal groundwater circulation pattern associated with fault zones. The Heyuan Fault Zone serves as a typical medium–low temperature geothermal system of South China. Here we show that the geothermal groundwater circulation pattern can be traced by using stable hydrogen and oxygen isotopes, helium and neon isotopes, carbon-13 and carbon-14 as well as hydrochemical parameters. The results show that: in the Heyuan Fault Zone, the main hydrochemical type of the hot springs is HCO3-Na+K, while the shallow cold groundwater is mainly enriched in HCO3-Ca. The results of the helium isotope and neon isotope indicate that the geothermal groundwater of this area is derived from the crust, thus excluding the possibility of extremely deep paths of groundwater tapping into mantle helium sources. Furthermore, the characteristics of the stable hydrogen and oxygen isotopes imply that geothermal groundwater is of local meteoric origin, and the recharge area located at the hilly area of the hanging wall of the Heyuan main fault, with the recharge elevations ranging from about 440m to 670m. The hot spring geothermometer shows that the highest reservoir temperature is about 157°C, and the deepest circulation depth is about 6500m. Carbon-14 isotope age dating suggests that the geothermal groundwater ages are mostly from 9.9kyr BP to 12.3kyrBP. According to the geological structural characteristics of the study area, the main upward channel for geothermal groundwater is the Heyuan main fault. Generally, the hot springs in this area are mixed with shallow cold groundwater and surface water, which raises the ratio of the Ca2+ in water and dilutes the heavy hydrogen and oxygen isotopes.
Relevance of erosion processes when modelling in-channel gravel debris flows for efficient hazard assessment J. Hydrol. (IF 3.727) Pub Date : 2018-10-06 Carlo Gregoretti, Laura Maria Stancanelli, Martino Bernard, Mauro Boreggio, Massimo Degetto, Stefano Lanzoni
A storm, composed of two delayed cells, hit the Monte Antelao slopes (Dolomites, North Eastern Italy) in the early morning of July 18th, 2009. The resulting runoff triggered two consecutive debris flows along the Rovina di Cancia channel. The detailed topographic data collected before and just after this event allowed an accurate reconstruction of the morphological changes experienced by the channel bed. These data are here used as benchmark to test the ability of numerical models to reproduce the dynamics of a real event, taking into account the morphology changes of the channel bed. The aim is to provide an efficient model for engineering applications on large scales, such as those required by debris flow hazard assessment. A rainfall-runoff transformation is applied to reconstruct the solid-liquid hydrograph needed for computing the debris flow propagation. Two routing models are used: a GIS-based movable bed model, and a widely used fixed bed model (FLO-2D). Although similar results are obtained in terms of areas subjected to deposition, significant differences emerge in terms of mobilized volumes. Only the simulation of both the deposition and entertainment processes allows to reliably reproduce the sediment volumes estimated from the pre- and post-event topographic data. This information is fundamental in any hazard assessment because the volume of sediment mobilized by debris flow events exerts a fundamental control on the extension of areas subjected to inundation and on the thickness of sediment deposits. The capability to reproduce correctly the mobilized volumes also entails a more reliable simulation of the evolution of the peak and volume of the solid-liquid hydrograph as the debris flow propagates downstream, allowing the identification of the channel reach where banks could be overflowed. Conversely, adopting a fixed bed model leads mainly to an underestimation of the both the transported sediments volumes and the area subjected to deposition. As a consequence, the maximum debris flow depth in the portion of the channel subjected to erosion is underestimated and that in the portion of the channel subjected to deposition is overestimated. All these types of information are of great importance for an effective hazard assessment.
Hydrologic Interpretation of Seasonally Dynamic Ambient Temperature Profiles in Sealed Bedrock Boreholes J. Hydrol. (IF 3.727) Pub Date : 2018-10-06 Donovan C. Capes, Colby M. Steelman, Beth L. Parker
This study evaluates the utility of ambient temperature profiles collected in sealed bedrock boreholes to assess variability in groundwater flow in discretely fractured shallow bedrock environments. A conceptual model for groundwater flow and groundwater-surface water temperature conditions and their interaction in a temperate climate is developed through a statistical interpretation of time-lapse thermal deviation logs. Temperature profiles were collected in three angled and three vertical boreholes drilled to 24 – 32 mbgs (meters below ground surface) and temporarily sealed with an impermeable fabric liner in a fractured dolostone bedrock aquifer adjacent to and extending beneath a bedrock river to monitor seasonal hydrodynamics. Ambient borehole temperature profiles collected every 1 – 8 weeks over a 12 month period identified zones of hydraulic activity during periods of intra-seasonal stability without the interference of open borehole cross-connection. Signal cross-correlation and Fourier spectra analysis of thermal deviation logs provided a novel way to observe the shallow bedrock flow system’s temperature evolution due to advection along discrete fractures in response to seasonal transience, and to identify and isolate noise caused by free-convection cells within the sealed borehole. This approach represents a diagnostic tool that improves confidence in identifying depth discrete, hydraulically active fracture zones from thermal deviation data sets in a shallow, fractured sedimentary bedrock environment. Variably scaled free-convection cells were observed within the borehole water columns during the colder winter periods. Although these periods were accompanied by higher signal noise near the river/atmospheric interface, these cells led to a temporary thermal disequilibrium between the borehole water column and formation water deeper in the bedrock. These conditions increased the maximum depth of thermal detections associated with discrete groundwater flow features from 14 mbgs in the summer to 26 mbgs in the winter, thereby enhancing the understanding of shallow groundwater flow systems under the direct influence of surface water.
Anchoring water diplomacy – The legal nature of international river basin organizations J. Hydrol. (IF 3.727) Pub Date : 2018-10-06 Susanne Schmeier, Zaki Shubber
Water diplomacy needs institutional anchoring. International River Basin Organizations (RBOs) – being the result of diplomatic efforts by riparian states intending to create a framework for cooperation between themselves over shared water bodies – can provide such institutional anchors. RBOs ensure that agreements to cooperate are turned into a long-term commitment by riparian states to jointly manage shared water resources and, in turn, foster mutually beneficial cooperation over time. RBOs have been the subject of detailed examinations of their conceptual core, of their manifold functions, of their effectiveness in achieving their goals and so forth. However, the legal nature of these entities has so far received limited attention notwithstanding its significance in empowering RBOs to act as institutional anchors for water diplomacy. Legitimate questions arise, for instance, in relation to their legal personality, or lack thereof, or to matters such as immunities and privileges. This paper will review key legal aspects of RBOs and illustrate them with examples. A sound understanding of such issues is crucial to supporting fruitful discussions between state members about the legal design of an RBO in order to fulfill their particular needs in the context of water diplomacy.
Water diplomacy and conflict management in the Mekong: from rivalries to cooperation J. Hydrol. (IF 3.727) Pub Date : 2018-10-05 Anoulak kittikhoun, Denise Michèle Staubli
The Mekong region, home to one of the world’s great rivers – the Mekong – is also one of the world’s most geostrategic regions, featuring seemingly conflicting interests among regional states including Viet Nam, Thailand, Myanmar, Laos and Cambodia and world powers such as China and the United States of America.For nearly a century, some of the riparian states have developed parts of the basin in their territories – to great benefits and harm – and recently the remaining late developing countries are catching up with water and related resources development plans to dam, withdraw and use the mighty Mekong to fund national progress and alleviate poverty.World leaders, academics, NGOs, media and even some government officials have warned that the current rush to development is not only bringing a sure death to a great previously untamed river, potentially displacing millions of people, and threatening livelihoods, but would also usher in an era of aggravated tensions and possibly even conflict. The Mekong River Commission (MRC), tasked to manage the river for the sake of the environment and the people, is failing its mission with work that has been ineffective, uninfluential and wasted, critics say.Yet this scenario is both wrong in its thesis about Mekong development and misleading in its understanding of MRC’s role and work. While past and current water resources development in the region has brought challenges and risks associated with changes in the river system, these have not led to widespread destruction of livelihoods and conflict among riparian countries.A critical factor preventing conflict and managing tensions as well as supporting optimal and sustainable development is the MRC and its water diplomacy framework, which has a technical core to provide objective scientific advices and legal, institutional and strategic mechanisms that facilitate and support negotiated solutions to complex water and related problems. While the challenges remain for the MRC as an organization, its water diplomacy framework has gradually been established and strengthened as the cases of managing tensions and potential conflicts in the Mekong for the past twenty years illustrate.
Water Diplomacy as an approach to regional cooperation in South Asia: A case from the Brahmaputra Basin J. Hydrol. (IF 3.727) Pub Date : 2018-10-05 Anamika Barua
The Yarlung Zangbo-Brahmaputra – Jamuna river basin (further referred to as Brahmaputra River Basin) is one of the most important river systems in South Asia. It originates on the Tibetan Plateau and links Bangladesh, Bhutan, China, and India. Despite being an important river system of South Asia, with an immense potential for regional development, very little progress has been made so far at regional level to manage this transboundary river. Apart from stereotypical upstream-downstream syndromes, a lack of trust, an atmosphere of hostility, and an asymmetric information and power situation as also the absence of regional principles or frameworks make transboundary interaction between the Brahmaputra riparian countries complex and challenging. The lack of information and knowledge regarding the river itself makes decision-making further complicated. Negotiation for a basin-wide treaty on cooperation in the absence of trust is a non-starter for the Brahmaputra basin, for it may result in asymmetric cooperation, opening up ground for future conflicts. To avoid such asymmetric cooperation, information-rich, multilateral informal dialogues need to take place to develop an accepted definition of cooperation, which meets the needs of all riparian states.The article provides an outline of the current issues in the Brahmaputra river basin and illustrates the need for multitrack and multi-stakeholder dialogues in the Brahmaputra region. The paper is inspired by the ‘Brahmaputra Dialogue’ project initiated in 2013, that demonstrates that water diplomacy has to be an inclusive, open, and transparent process involving multiple actors, because such interaction facilitates sustainable water cooperation, not only between riparian countries but also between riparian communities.
Links between different classes of storm tracks and the flood trends in Spain J. Hydrol. (IF 3.727) Pub Date : 2018-10-05 Marcus Suassuna Santos, Luis Mediero, Carlos Henrique Ribeiro Lima, Leonardo Zandonadi Moura
The identification of storm tracks that generate the annual maximum floods and the quantification of their air-moisture content is proposed to understand better the atmospheric generation processes of floods in Spain, as well as their decreasing trends identified previously. In this work, the role of the atmospheric component on hydrological changes on Spain by using storm track data generated by the hybrid single particle Lagrangian integrated trajectory model (HYSPLIT) is examined. Storm tracks associated with annual maximum flood series from 14 streamflow gauges located across Spain are obtained by using NCEP/NCAR Reanalysis data. They are classified into five clusters through use of the K-means algorithm. It was also shown that the use of five clusters was able to reproduce the five major types of storms identified in Spain reported in the literature. The posterior grouping of the five associated storm types into two bigger groups (Oceanic and Continental storms), led to a coherent seasonal and spatial behaviour of hydrological regimes. For some gauges, it was observed that distinct flood statistics, such as mean and variance, differ significantly as a result of atmospherically distinct generation processes, suggesting that local annual maximum flood series may be non-homogeneous as a result of contrasting atmospheric generation processes. By means of logistic regression, it is estimated that the probability of occurrence of Oceanic storms reduced significantly in the Spanish Atlantic region along the studied period. Furthermore, the existence of low-frequency cycles introduces significant variation in the occurrence of storm types in the country, with them being much more frequent during the period 1975-1979, while Oceanic storms were more frequent during the 1983-1987 and 1996-1999 periods. Those storms classified as Continental are observed in 59.3% of the studied cases, while those termed Oceanic in 40.7%. Continental storms also contribute with more moisture in the studied cases, that is to say, 63.1% of total moisture content, while Oceanic storms contributed with 36.9%.
Combining COSMO-SkyMed satellites data and numerical modeling for the dynamic management of artificial recharge basins J. Hydrol. (IF 3.727) Pub Date : 2018-09-29 Marco Masetti, Simone Pettinato, Son V. Nghiem, Simonetta Paloscia, Daniele Pedretti, Emanuele Santi
Many urbanized areas in the world are using artificial recharge basins (ARB) as an efficient solution to maintain adequate groundwater recharge while coping with flooding problems. The effective management of these basins to adequately maintain their functionality over mid-to-long term requires a suitable monitoring network. Here, we explored the use of a temporal satellite analysis to closely evaluate the efficiency of the ARB in terms of infiltration capacity, depending on hydraulic conditions of the topsoil transitioning from unclogged to clogged conditions in the ARB.COSMO-SkyMed synthetic aperture radar (SAR) images were integrated with ground data and numerical modeling to advance the capability for monitoring low water levels and flooded areas within the ARB. The understanding of biofilm development and effects was achieved by identifying anomalous drawdown phases, by constraining ponding boundary conditions in the numerical model, and by estimating subsequent infiltration rate changes under progressive clogging.With appropriate meteorological conditions (consecutive rainfall events separated by few dry days), the biofilm could develop rapidly and cover large surfaces (e.g., 22 ha) in about two months. During this process, the hydraulic conductivity of the basin surface could decrease by more than three orders of magnitude, completely altering the relationship with the local groundwater regime. Quantitative estimation of the evolution of the infiltration rate provides crucial insights about the overall recharge behavior of ARBs to make reliable economical plans in both the design and monitoring phase.
An application of hydraulic tomography to a deep coal mine: combining traditional pumping tests with water inrush incidents J. Hydrol. (IF 3.727) Pub Date : 2018-09-29 Deqiang Mao, Zaibin Liu, Wenke Wang, Shucai Li, Yaoquan Gao, Zhenhao Xu, Chi Zhang
Water inrush incidents threaten the safety of coal mining. Understanding of hydrogeologic parameter distributions is critical for preventing water-related hazards in coal mines. During the deep mining (> 1000 m) under the North China Plain, water from water-bearing strata discharges into coal seams through geologic conduits (i.e. water inrush) due to the fractured zone under the floor of working faces . In this study, a water inrush incident was exploited as an active stimulus. A 3D groundwater flow model was built for the eighth member of the Middle Ordovician system in Xingdong coal mine. Using this model and an inverse approach, we first checked if the data from the incident and an independent pumping test carry non-redundant information about the heterogeneity of the mine. Afterward, we combined these datasets to conduct a large-scale (approximately 10 km) hydraulic tomography (HT) analysis. The estimated hydraulic conductivity distribution from the HT analysis is found consistent with the distribution of known geologic faults. That is, a cluster of faults is characterized as a high-conductivity zone. A high conductivity zone is identified at locations close to the water inrush location, which is the high cement consumption zone during the grouting project. Finally, results of this study promote exploiting the water inrush events as a HT survey for mapping geologic structures over a large area.
Intercomparison and evaluation of three global high-resolution evapotranspiration products across China J. Hydrol. (IF 3.727) Pub Date : 2018-09-29 Peng Bai, Xiaomang Liu
Accurate quantification of large-scale evapotranspiration (ET) has an important scientific and practical significance. In this study, three global high-resolution ET products were intercompared and evaluated across China; the evaluated ET products were the Global Land Evaporation Amsterdam Model (GLEAM) version 3.2, the Global Land Data Assimilation System (GLDAS) version 2.0 Catchment Land Surface Model (CLSM) dataset, and the Numerical Terradynamic Simulation Group (NTSG) dataset. The evaluations were performed at the site scale with eddy covariance (EC) based observations from eight flux stations, and at the basin scale with water balance-based ET estimates from 22 river basins in China. The intercomparison results indicated that the three products consistently presented an increasing trend over a large proportion of China but large differences in the trend of the annual ET and the mean annual ET estimates. The trends of the annual ET estimates derived from the GLEAM, GLDAS, and NTSG products are 0.449, 0.904 and 1.261 mm/yr2, respectively; the countrywide mean annual ET derived from the three products are 390.2, 443.4 and 419.9 mm/yr, respectively. The site-scale evaluation results indicated that the GLEAM and NTSG products achieved comparable consistencies with the monthly gauge observations and outperformed the GLDAS product; GLEAM was more consistent with the daily gauge observations than GLDAS. At the basin scale, all three products were unable to reasonably reproduce the water balance-based annual ET time series in most basins; the three products systematically overestimated ET in the wet basins compared with the water balance-based ET estimates. The differences in the ET estimates among the ET products may be largely attributed to the discrepancies in the forcing data and model algorithms.
Modeling Colloid Transport in Fractures with Spatially Variable Aperture and Surface Attachment J. Hydrol. (IF 3.727) Pub Date : 2018-09-29 Scott C. James, Lichun Wang, Constantinos V. Chrysikopoulos
A particle-tracking algorithm was developed to simulate colloid transport subject to wall effects on diffusion and colloid surface attachment as described by DLVO kinetics. The effects of spatially variable fracture surface potential, which contributed to spatially variable attachment strength affecting colloid transport, were investigated. The fracture surface potential was assumed to be either positively, neutrally (zero), or negatively correlated with the lognormally distributed local fracture aperture, described with a mean, variance, and isotropic correlation length. The results from several model simulations indicated that wall effects were negligible for the welded, rhyolitic tuff fractures studied here. When fracture surface potential was negatively correlated with local aperture, colloids were preferentially transported through the fracture, because they tend to enter high-flow, large-aperture regions where they undergo less attachment (have the largest first moment measured upon exit of the first colloid from the fracture). The variance (second moment) increased for flowing colloids when comparing negatively to zero and then positively correlated surface potentials to fracture apertures, because spreading notably increased when suspended colloids were temporarily attached onto fracture surfaces. For colloids attached onto fracture surfaces, both first and second moments decreased from negatively, to neutrally (zero), to positively correlated surface potentials to apertures. This is an intuitive result, consistent with fewer colloids attaching in the larger aperture preferential flow paths.
Occurrence of pharmaceuticals and personal care products in the urban aquifer of Zaragoza (Spain) and its relationship with intensive shallow geothermal energy exploitation J. Hydrol. (IF 3.727) Pub Date : 2018-09-29 Alejandro García-Gil, Eduardo Garrido Schneider, Miguel Mejías, Damià Barceló, Enric Vázquez-Suñé, Silvia Díaz-Cruz
Comment on: H.S. Lim and X.X. Lu “Sustainable Urban Stormwater Management Problem in the Tropics: An Evaluation of Singapore’s ABC Waters Program” (2016) J. Hydrol. (IF 3.727) Pub Date : 2018-09-29 Sin Zhi Goh, Huiling Guo, Fang Yee Lim, Lai Yoke Lee, Jiangyong Hu, Say Leong Ong
This paper serves to communicate concerns including misleading presentation of information and the use of incomplete monitoring data in a recent journal article by Lim and Lu (2016) published in the Journal of Hydrology.
A computer vision-based approach to fusing spatiotemporal data for hydrological modeling J. Hydrol. (IF 3.727) Pub Date : 2018-09-29 Shijie Jiang, Yi Zheng, Vladan Babovic, Yong Tian, Feng Han
This study develops a novel approach to data-driven hydrological modeling. The approach adopts the feature representation technique in computer vision to effectively exploit spatial information contained in time-variant input data fields and seamlessly fuse multisource information via machine learning. The new approach overcomes a major limitation of existing approaches in which the spatial heterogeneity of input variables cannot be sufficiently accounted for. The approach is applied to predict the streamflow in a watershed on the northern margin of the Qinghai-Tibetan Plateau, and its performance is compared with various data-driven and process-based models. The major findings are as follows. First, the new approach represents a general framework for the fusion of multisource spatiotemporal data for hydrological modeling and demonstrates great potential to incorporate fast-growing environmental big data. Second, the new approach demonstrates satisfactory short-term forecasting, long-term simulation, and transfer learning performances and is promising for addressing predictions in ungauged basins. Third, the predictors, including precipitation, temperature, leaf area index, and historical streamflow, play markedly distinct roles in modeling streamflow with the novel approach. Finally, topographic information is not a necessary model input in the proposed approach because spatial patterns can be well embodied by other inputs (e.g., temperature) that have high similarities with topography. This study represents the first attempt to bring computer vision into data-driven hydrological modeling and may inspire future studies in this promising direction.
Spatial-temporal changes in the longitudinal functional connectivity of river systems in the Taihu Plain, China J. Hydrol. (IF 3.727) Pub Date : 2018-09-29 Xiaojun Deng, Youpeng Xu, Longfei Han, Song Song, Guanglai Xu, Jie Xiang
The longitudinal functional connectivity of river systems refers to the process-based connections between upstream and downstream areas and is fundamental to understanding the dynamic and nonlinear hydrological behaviour of river basins. However, the quantification of such connectivity remains a challenge due to the absence of a consensus on the appropriate data and methods, especially in delta plains. In this study, based on the difference between water level fluctuations at adjacent stations, a new and quantitative longitudinal functional connectivity index (LFCI) was developed for delta plains. Focusing on the Taihu Plain, we then analysed the spatial-temporal changes in the LFCI during 1960–2012 and investigated the correlations between the LFCI and climate change and human activities. We found that the decadal, annual and seasonal changes in the average LFCI all presented slightly increasing trends in the recent 50 period, but the annual average LFCI increased significantly after 1978; the average LFCIs in June, July, and August of the flood season were less than those in other months in the Taihu Plain. We also found that the spatial-temporal changes in the average LFCI exhibited larger differences at the subregional and station scales; those in the Wu-Cheng-Xi-Yu subregion were least, and the average LFCIs at stations near the borders of adjacent subregions were less than those at other stations. Moreover, we found that the average LFCI had significant correlations with precipitation, river density and water surface ratio. Our results were consistent with common sense facts, which demonstrated that the indicator developed in this study can quite effectively quantify the longitudinal functional connectivity of river systems in delta plains.
Calibration of the Global Flood Awareness System (GloFAS) using daily streamflow data J. Hydrol. (IF 3.727) Pub Date : 2018-09-27 Feyera A. Hirpa, Peter Salamon, Hylke E. Beck, Valerio Lorini, Lorenzo Alfieri, Ervin Zsoter, Simon J. Dadson
This paper presents the calibration and evaluation of the Global Flood Awareness System (GloFAS), an operational system that produces ensemble streamflow forecasts and threshold exceedance probabilities for large rivers worldwide. The system generates daily streamflow forecasts using a coupled H-TESSEL land surface scheme and the LISFLOOD model forced by ECMWF IFS meteorological forecasts. The hydrology model currently uses a priori parameter estimates with uniform values globally, which may limit the streamflow forecast skill. Here, the LISFLOOD routing and groundwater model parameters are calibrated with ECMWF reforecasts from 1995 to 2015 as forcing using daily streamflow data from 1287 stations worldwide. The calibration of LISFLOOD parameters is performed using an evolutionary optimization algorithm with the Kling-Gupta Efficiency (KGE) as objective function. The skill improvements are quantified by computing the skill scores as the change in KGE relative to the baseline simulation using a priori parameters. The results show that simulation skill has improved after calibration (KGE skill score > 0.08) for the large majority of stations during the calibration (67% globally and 77% outside of North America) and validation (60% globally and 69% outside of North America) periods compared to the baseline simulation. However, the skill gain was impacted by the bias in the baseline simulation (the lowest skill score was obtained in basins with negative bias) due to the limitation of the model in correcting the bias in streamflow. Hence, further skill improvements could be achieved by reducing the bias in the streamflow by improving the precipitation forecasts and the land surface model. The results of this work will have implications on improving the operational GloFAS flood forecasting (www.globalfloods.eu).
Daily pan evaporation modeling from local and cross-station data using three tree-based machine learning models J. Hydrol. (IF 3.727) Pub Date : 2018-09-27 Xianghui Lu, Yan Ju, Lifeng Wu, Junliang Fan, Fucang Zhang, Zhijun Li
Accurate estimation of pan evaporation (Ep) is required for many applications, e.g., water resources management, irrigation system design and hydrological modeling. However, the estimation of Ep for a target station can be difficult as a result of partial or complete lack of local meteorological data under many conditions. In this study, daily Ep was estimated from local (target-station) and cross-station data in the Poyang Lake Watershed of China using four empirical models and three tree-based machine learning models, including M5 model tree (M5Tree), random forests (RFs) and gradient boosting decision tree (GBDT). Daily meteorological data during 2001-2010 from 16 weather stations were used to train the models, while the data from 2011 to 2015 were used for testing. Two cross-station applications were considered between each of the 16 stations and the other 15 stations. The results showed that the radiation-based Priestley-Taylor model (on average RMSE=1.13 mm d-1, NSE=0.53, R2=0.57, MBE=0.21 mm d-1) gave the most accurate daily Ep estimates among the four empirical models during testing, while the mass transfer-based Trabert model (on average RMSE=1.38 mm d-1, NSE=0.25, R2=0.46, MBE=0.65 mm d-1) performed worst. The GBDT model outperformed the RFs model, M5Tree model and the empirical models under the same input combinations in terms of prediction accuracy (on average RMSE=0.86 mm d-1, NSE=0.68, R2=0.73, MBE=0.07 mm d-1) and model stability (average percentage increase in testing RMSE=16.3%). The RMSE values generally increased with the increase in the distance of two cross stations. A distance of less than 100 km between two cross stations is highly recommended for cross-station applications with satisfactory prediction accuracy (median percentage increase in RMSE < 5% for cross-station application #1 and < 20% for application #2) in the Poyang Lake Watershed of China and maybe elsewhere with similar climates.
A network scale, intermediate complexity model for simulating channel evolution over years to decades J. Hydrol. (IF 3.727) Pub Date : 2018-09-28 Roderick W. Lammers, Brian P. Bledsoe
Model-Data Interaction in Groundwater Studies: Review of Methods, Applications and Future Directions J. Hydrol. (IF 3.727) Pub Date : 2018-09-28 Mohammad Mahdi Rajabi, Behzad Ataie-Ashtiani, Craig T. Simmons
We define model-data interaction (MDI) as a two way process between models and data, in which on one hand data can serve the modeling purpose by supporting model discrimination, parameter refinement, uncertainty analysis, etc., and on the other hand models provide a tool for data fusion, interpretation, interpolation, etc. MDI has many applications in the realm of groundwater and has been the topic of extensive research in the groundwater community for the past several decades. This has led to the development of a multitude of increasingly sophisticated methods. The progress of data acquisition technologies and the evolution of models are continuously changing the landscape of groundwater MDI, creating new challenges and opportunities that must be properly understood and addressed. This paper aims to review, analyze and classify research on MDI in groundwater applications, and discusses several related aspects including: (1) basic theoretical concepts and classification of methods, (2) sources of uncertainty and how they are commonly addressed, (3) specific characteristics of groundwater models and data that affect the choice of methods, (4) how models and data can interact to provide added value in groundwater applications, (5) software and codes for MDI, and (6) key issues that will likely form future research directions. The review shows that there are many tools and techniques for groundwater MDI, and this diversity is needed to support different MDI objectives, assumptions, model and data types and computational constraints. The study identifies eight categories of applications for MDI in the groundwater literature, and highlights the growing gap between MDI practices in the research community and those in consulting, industry and government.
Multiple Şen-innovative trend analyses and partial Mann-Kendall test J. Hydrol. (IF 3.727) Pub Date : 2018-09-28 Yavuz Selim Güçlü
The climate change is an important event that affects hydrological, agricultural and water resources planning variables, and therefore, the hydrologists and meteorologists frequently try to identify trend possibilities especially in rainfall, runoff and temperature time series. For this purpose, the classical Mann-Kendall (MK), Spearman’s rho (SR), Sen’s slope, and linear regression approaches are applied frequently in the literature. Recently, innovative trend analysis (ITA) provides visual inspection and identification of categorical trends, which is one of the main concerns in this paper. On the basis of ITA methodology, several improvements namely double-ITA (D-ITA) and triple-ITA (T-ITA) procedures are suggested using with simple ITA together. These methods are attractive for the trend stability assessment by comparing partial trend components during different sub-periods of a given record series. Furthermore, partial MK test approach is proposed in this paper for the same purpose. These procedures and approach are applied to a set of annual rainfall records at many stations in different regions of Turkey. As a result, the comparison of the suggested methods based on partial sub-series of the same time series helps to improve trend detection with stability identification.
Fractional derivative approach to non-Darcian flow in porous media J. Hydrol. (IF 3.727) Pub Date : 2018-09-28 H.W. Zhou, S. Yang
Fractional Darcian model and fractional Swartzendruber model are proposed for non-Darcian flows with high and low velocity in the paper, respectively. The analytical solutions of the fractional derivative models are given and all parameters are determined based on test data. The dependence of fractional derivative models on parameters such as fractional derivative order and threshold hydraulic gradient are analyzed by sensitivity studies. The fractional derivative models provide better description of non-Darcian flow in porous media under the conditions of high and low velocity. Furthermore, the memory effectiveness of fractional calculus is discussed, showing that the fractional derivative order is an indicator of non-Darcian flow in porous media.
Retention and release of nutrients and dissolved organic carbon in a nutrient-rich stream: a mass balance approach J. Hydrol. (IF 3.727) Pub Date : 2018-09-28 Claudia Feijoó, María Laura Messetta, Cecilia Hegoburu, Alicia Gómez Vázquez, José Guerra-López, Josep Mas-Pla, Laura Rigacci, Victoria García, Andrea Butturini
Stable alluvial channel design using evolutionary neural networks J. Hydrol. (IF 3.727) Pub Date : 2018-09-28 Saba Shaghaghi, Hossein Bonakdari, Azadeh Gholami, Ozgur Kisi, Jalal Shiri, Andrew D. Binns, Bahram Gharabaghi
Accurate prediction of the long-term average dimensions of alluvial stable channels is a significant problem in river engineering. The goal of this research is to investigate the effect of flow discharge (Q), mean sediment size (d50) and Shields parameter (τ∗) on the stable channel dimensions by employing non-linear regression (NLR) and two Artificial Intelligence (AI) methods, including: Generalized Structure of Group Method of Data Handling (GS-GMDH) neural network and Gene Expression Programming (GEP). Discharge, grain size and Shields parameter from 85 gaging stations situated in three stable Iranian rivers were used as input data for the three methods to estimate the water-surface width (W), average flow depth (D) and longitudinal slope (S) of the rivers. Based on the results, it was found that the GS-GMDH produced more accurate results for simulating the channel width with a Mean Absolute Relative Error (MARE) value of 0.055; and GEP produced better estimations for channel depth and slope with MARE values of 0.035 and 0.03, respectively. Furthermore, by employing Artificial Intelligence (AI) methods (GS-GMDH and GEP), the RMSE values decreased by 22%, 25% and 75% in predicting width, depth, and slope, respectively, compared to NLR method. The overall results showed that the AI methods generally produced better estimations than the non-linear regression method. To determine the effect of each input variable (Q, d50, τ∗) on the target variables (W, D, S), a sensitivity analysis comprising various combinations of input variables was conducted. Based on the results, the flow discharge had a dominant role on depth and width estimation of stable channels. In slope estimation, the most important parameter was τ∗ and then d50, while the discharge had a weak effect on slope prediction. In general, the Shields parameter was the most effective parameter in depth and specially slope estimation of stable channels.
Developing a Non-Cooperative Optimization Model for Water and Crop Area Allocation Based on Leader-follower Game J. Hydrol. (IF 3.727) Pub Date : 2018-09-26 Abbas Sedghamiz, Mohammad Reza Nikoo, Manouchehr Heidarpour, Mojtaba Sadegh
In this paper, a mathematical model for conflict resolution among a diverse set of agricultural water users in Golestan province, Iran, is developed. Given the bi-level nature of the distribution of power in the current problem, a combination of Leader–Follower game and Nash–Harsanyi bargaining solution method is employed to find optimal water and crop area allocations. The Golestan Regional Water Authority is the leader in this setting, controlling the total water allocations; and the agricultural sectors are the followers, competing over the allocated water. Two objectives for the leader are (i) maximizing profits, and (ii) maximizing share of green water in total agricultural production through selecting more efficient crop patterns. The followers’ objective is merely maximizing obtained benefits for the selected crop patterns. Virtual water concept is also factored into the related objective functions, and the water allocation problem is solved considering spatio-temporal crop pattern along with a dynamic water pricing system. This involves using a hybrid optimization structure as a new approach to solving two level optimization problems. The results show that the leader’s income is independent of total water allocation and is only affected by crop pattern and crop area, two factors which drive water price too. The followers’ benefit also depends on crop pattern and crop area, as they influence the crop yield, cost and water price. Finally, green water plays a key role in selecting the optimal crop pattern and crop area.
The Role of Evapotranspiration in Streamflow Modeling-an Analysis Using Entropy J. Hydrol. (IF 3.727) Pub Date : 2018-09-27 W. Lee Ellenburg, J.F. Cruise, Vijay P. Singh
Informational entropy can be used to elucidate some important relationships between precipitation, evapotranspiration (ET), and discharge over a range of spatial and temporal scales. Entropy does not suffer from any a priori assumptions of linearity or distributional characteristics. In a study of the Southeastern United States, entropy and mutual information were used to identify relationships between hydrologic variables over spatial scales from a few hundred to several thousand km2 and temporal scales from days to months. Two distinct ET data sets were compared- one based on a highly parameterized energy budget approach and the other based on a complex iterative solution and a modified Penman method. It was found that there was a considerable difference in uncertainty between the two methods and that, although they each contained some amount of explanatory information regarding streamflow the more complex approach contained the most shared information. Further, it was found that streamflow entropy, or uncertainty, increased with drainage area, indicating that larger basins have more uncertainty to be reduced, in that more information can possibly be gained through the knowledge of other variables. However, the knowledge of ET reduces a greater proportion of uncertainty in smaller basins (less than 1500 km2), while larger basins have more unexplained variability.
Assessing the trade-off between shallow groundwater conservation and crop production under limited exploitation in a well-irrigated plain of the Haihe River basin using the SWAT model J. Hydrol. (IF 3.727) Pub Date : 2018-09-27 Xueliang Zhang, Li Ren, Li Wan
Groundwater overdraft due to extensive irrigation has led to a shallow aquifer depletion crisis in the Haihe River basin. Quantitative simulation of the variations in shallow groundwater and crop yield under different conditions of limited exploitation using a distributed hydrological model is important in the well-irrigated plain of this basin. Based on multiple modeling experiments by a modified Soil and Water Assessment Tool (SWAT) model, three limited irrigation schemes for winter wheat (Triticum aestivum L.) were selected as simulation scenarios. The simulated results using the SWAT model showed that under scenario 1 (applying two rounds of irrigation corresponding to the jointing and heading stages of winter wheat), the average rate of decline in the shallow groundwater table was approximately 2/3 of that under the basic scenario (current irrigation schedule), but the winter wheat yield decreased by 13% compared with the basic scenario. Under scenario 2 (applying one round of irrigation at the jointing stage of winter wheat), the average rate of decline in the shallow groundwater table was approximately 1/4 of that under the basic scenario, but the reduction in the winter wheat yield compared with the basic scenario increased to 28%. The amount of overexploited shallow groundwater in the cropland area decreased from 17.5×108 m3 a-1 (under the basic scenario) to 11.0×108 m3 a-1 under scenario 1 and 4.5×108 m3 a-1 under scenario 2. Under scenario 3 (rain-fed conditions during the winter wheat season), the regional variation in the shallow groundwater table shifted to a recovery trend with an average rate of 0.22 m a-1, which was equivalent to restoring 3.5×108 m3 a-1 of shallow aquifer storage in the cropland area. However, the reduction in the winter wheat yield compared with the basic scenario reached 54% under the rain-fed scheme. Considering the trade-off between groundwater conservation and crop production under limited exploitation, linear programming was used to optimize the irrigation schedule at the subbasin scale. As a result, to satisfy the constraint of stopping groundwater drawdown, the average minimal reduction in the winter wheat yield would be 42% under the optimal irrigation schedule. By contrast, to satisfy the constraint of restricting the reduction in the crop yield to within the threshold required to maintain winter wheat self-sufficiency, the minimal rate of decline in the shallow groundwater table would be 0.26-0.52 m a-1 under the optimal irrigation schedule. In addition, the uncertainty in the simulated shallow groundwater variation in this study was acceptable, indicating that the above assessments could provide reasonable references for regional groundwater management.
On modeling reference crop evapotranspiration under lack of reliable data over Iran J. Hydrol. (IF 3.727) Pub Date : 2018-09-27 Milad Nouri, Mehdi Homaee
This study was conducted to evaluate the performance of temperature-based models i.e. temperature-based Penman-Monteith FAO 56 fed with average wind speed (U) value (TPMU) and default U quantity (TPM2), Hargreaves-Samani (HS) and FAO Blaney-Criddle (FBC) against Penman-Monteith FAO 56 (PM) using data recorded in 1993-2015 at 146 sites over Iran. Two statistics i.e. normalized Root Mean Square (nRMSE) and relative Mean Bias Error (rMBE) were calculated to analyze the absolute error and bias magnitude of the temperature-based ET0 estimation, respectively. Except for the December-January-February (DJF), the models gave reliable seasonal estimates (i.e. nRMSE of 30 > %) for the majority of studied areas. At monthly scale, FBC gave poor estimates of ET0 in DJF for more than 60 % of semi-arid and sub/humid-humid sites. ET0 in December and January was not also modeled reliably by TPM2 for 61 and 52 % of the semi-arid and sub/humid-humid sites, respectively. Hence, application of FBC and TPM2 appears not to be recommendable in cold areas and months over Iran. Overall, TPMU and HS are better suited at all temporal scales under data limitation over the studied areas. In the case of data availability, calculation of TPM with local average U (instead of default quantity of 2 m s-1) is highly likely to improve the estimation accuracy. Seasonal and monthly ET0 were mostly underestimated over the hyper-arid/arid sites during the March-April-May (MAM) and June-July-August (JJA). However, TPM2 and HS overestimated ET0 for the majority of semi-arid and sub-humid/humid areas. The U anomalies were identified as the primary contributing factor to the error in temperature-based ET0 estimation for most cases. TPM2, HS and FBC provided more accurate estimates for the U range of 1.5-2.5 m s-1. These findings are of significant practical importance for agricultural, hydrological and climatic studies and applications under data sparse condition.
Control of dry and wet Januaries and winters in the Mediterranean Basin by large-scale atmospheric moisture flux and its convergence J. Hydrol. (IF 3.727) Pub Date : 2018-09-27 Sinan Şahin, Martin Ivanov, Murat Türkeş
The associations between the seasonal moisture budget (precipitation minus evaporation) and atmospheric and oceanic teleconnections related with dry and wet conditions in the greater Mediterranean Basin are investigated. The driest and wettest Mediterranean winters are selected according to the Standardized Precipitation Index (SPI), and the differences in the moisture budget among them and average conditions (i.e. climatology) are investigated. The analysis focuses on the role of major teleconnection indices for the conditions of the driest/wettest winters. According to the results, the Arctic Oscillation (AO) index is the best indicator of variability in the driest/wettest conditions, which are conventionally associated with the North Atlantic Oscillation (NAO). Large-scale climate variability over the Mediterranean Basin is strongly linked with significant changes of the moisture fluxes in the Gulf of Mexico region and partially in the east coast region of the United States (US), especially for wet years in the Western Mediterranean. The displacement of the prevailing atmospheric centres of action located over the subtropical mid-east Atlantic (Azores high) to the Northwest Atlantic determines the wet conditions over the Western and Eastern Mediterranean basins, respectively. It is speculated that the relative strengths and positions of these large-scale systems control the Eastern and Western patterns of the Mediterranean climate variability.
Response of macroinvertebrate communities to hydrological and hydrochemical alterations in Mediterranean streams J. Hydrol. (IF 3.727) Pub Date : 2018-09-27 Anna Menció, Dani Boix
Genetic programming in water resources engineering: A state-of-the-art review J. Hydrol. (IF 3.727) Pub Date : 2018-09-27 Ali Danandeh Mehr, Vahid Nourani, Ercan Kahya, Bahrudin Hrnjica, Ahmed M.A. Sattar, Zaher Mundher Yaseen
The state-of-the-art genetic programming (GP) method is an evolutionary algorithm for automatic generation of computer programs. In recent decades, GP has been frequently applied on various kind of engineering problems and undergone speedy advancements. A number of studies have demonstrated the advantage of GP to solve many practical problems associated with water resources engineering (WRE). GP has a unique feature of introducing explicit models for nonlinear processes in the WRE, which can provide new insight into the understanding of the process. Considering continuous growth of GP and its importance to both water industry and academia, this paper presents a comprehensive review on the recent progress and applications of GP in the WRE fields. Our review commences with brief explanations on the fundamentals of classic GP and its advanced variants (including multigene GP, linear GP, gene expression programming, and grammar-based GP), which have been proven to be useful and frequently used in the WRE. The representative papers having wide range of applications are clustered in three domains of hydrological, hydraulic, and hydroclimatological studies, and outlined or discussed at each domain. Finally, this paper was concluded with discussions of the optimum selection of GP parameters and likely future research directions in the WRE are suggested.
Hydrological characterization and prediction of flood levels of acidic pit lakes in the Tharsis mines, Iberian Pyrite Belt J. Hydrol. (IF 3.727) Pub Date : 2018-09-27 Raúl Moreno González, Manuel Olías, Francisco Macías, Carlos Ruiz Cánovas, Rubén Fernández de Villarán
Opencast mining operations frequently lead to the creation of large voids that become anthropogenic lakes when the water table recovers. In the case of sulfide mining the stored water is of an acidic nature with significant concentrations of toxic metals and, therefore, a high pollutant potential. The main goal of the present work is to characterize the hydrological functioning and evolution of four acidic mine pit lakes in the abandoned mines of Tharsis, which is the second most important mine district in the Iberian Pyrite Belt (IPB). We present a simple methodology based on the use of the available orthophotographs and a Digital Terrain Model (DTM) together with the water balance of the pit lakes, which could be applied to other abandoned mining sites, where there is often a lack of hydrogeological information that prevents the application of more complex models. The accumulation of large volumes (5.2 x 106 m3) of acidic and metal-rich waters in these pit lakes poses a serious environmental concern, with dissolved concentrations up to 2000 mg/L of Fe, 223 mg/L of Al, etc. Sierra Bullones and Filón Norte are connected underground and present the same evolution, with water transfers from Sierra Bullones to Filón Norte. The water level in both pit lakes is increasing, with an average rise of 2.8 m/yr since the beginning of flooding. However, the increase in the evaporation rate, as a result of the larger flooded area as the water level rise, would induce a hydrological equilibrium before reaching the overflow level, leading to the formation of a terminal lake. On the other hand, the water level in Filón Centro and Filón Sur pit lakes remain approximately stable. The first behaves as a flow-through or terminal lake, depending on the annual rainfall, while the second acts permanently as a flow-through lake.
Development of a Landscape Indicator to Evaluate the Effect of Landscape Pattern on Surface Runoff in the Haihe River Basin J. Hydrol. (IF 3.727) Pub Date : 2018-09-27 Lingling Bin, Kui Xu, Xinyi Xu, Jijian Lian, Chao Ma
The Haihe River Basin has become a watershed that suffers from intensive interference from human activities, as landscape patterns and runoff processes have significantly changed in recent decades. Investigating the effect of landscape patterns on surface runoff is helpful for establishing the synergistic evolution relationship between the landscape and the hydrological cycle, providing a theoretical basis and effective way for the future management of water resources. In this study, a landscape metrics approach is used to describe the spatial patterns of landscapes, measure changes in landscape patterns, and relate spatial patterns to surface runoff processes of water resources at a watershed scale. Given that commonly used landscape metrics not considering undulating terrain characteristics, soil properties and landcover conditions, which have significant effects on the surface runoff, a Runoff Landscape Index (RLI) is developed to evaluate the effect of watershed landscape factors on surface runoff. Factors relating to landcover, soil and topography are analyzed, weighed, and integrated during the indicator development. Then, correlation between landscape indicators (RLI and commonly used indicators) and surface runoff is examined. The results show a significant positive correlation between RLI and surface runoff, and the average correlation coefficient is 0.831, much greater than the correlation coefficients for commonly used landscape indices. With potential applications for remote sensing and GIS technology, RLI could be used to efficiently predict annual runoff in ungauged basins even in future land cover scenarios and possibly provide a new perspective for water resource management at the river basin scale.
Model Predictive Control for Optimising the Operation of Urban Drainage Systems J. Hydrol. (IF 3.727) Pub Date : 2018-09-27 Yves Abou Rjeily, Oras Abbas, Marwan Sadek, Isam Shahrour, Fadi Hage Chehade
This work presents a methodology for developing a Model Predictive Control (MPC) for enhancing the operation of Urban Drainage Systems (UDS). The objective of the MPC is to apply a proactive management strategy that uses optimised time-state schedules for operating the actuators of UDS in real time. Aiming to mitigate flooding consequences, the MPC uses EPA-SWMM hydrologic-hydraulic simulation engine and Genetic Algorithm (GA) to optimise the time-state schedules for the actuators of UDS. The efficiency of the MPC was tested on the Lille University Campus, resulting in satisfying improvements in the use of storage capacity of retention elements within the UDS.
Evaluating performances of green roofs for stormwater runoff mitigation in a high flood risk urban catchment J. Hydrol. (IF 3.727) Pub Date : 2018-09-27 Giulia Ercolani, Enrico Antonio Chiaradia, Claudio Gandolfi, Fabio Castelli, Daniele Masseroni
Urbanization modifies the hydrologic cycle, resulting in increased runoff rates, volumes, and peak flows in the drainage network. In this paper, the implementation of green roofs as source control solutions for mitigating the impacts of urbanization is analysed at the urban catchment scale. The hydrologic-hydraulic response of a 2 km2 urban basin is investigated under various implementation scenarios and rainfall characteristics. In particular, a distributed hydrologic model is employed to assess the impact of 4 spatially homogeneous installations of green roofs (25%, 50%, 75%, 100% of roofs area converted) when forced by 6 storms differing in both duration and return period. In addition, a spatially heterogeneous configuration is tested, with green roofs concentrated where the drainage network is more prone to high degrees of filling. Results show that implementing green roofs at the urban watershed scale can be considered a valuable strategy to reduce both flow peak and volume in urban drainage networks, although the approach is more effective for frequent storms of smaller magnitude. In addition, it is found that the urban system may respond non-linearly to the extent of green roofs implementation in terms of peak flow reduction at the network outlet, and that non-linearity is mainly related to the network being close to its flow convey capability. Finally, planning redevelopment efforts on the basis of local insufficiencies in network convey capacity has the potential of increasing the effectiveness of Low Impact Development solutions.
Uncertainties of 3D Soil Hydraulic Parameters in Streamflow Simulations using a Distributed Hydrological Model System J. Hydrol. (IF 3.727) Pub Date : 2018-09-27 Yize Yang, Huiling Yuan, Wei Yu
Parameter calibration and uncertainty estimation are crucial for hydrological simulations in the distributed land surface-hydrological model. To investigate soil properties impacting hydrological processes, five conventional pedo-transfer functions (PTFs) are applied to create a 3D soil hydraulic parameter (SHP) ensemble in the Weather Research and Forecasting-Hydrological extension (WRF-Hydro), a distributed, multi-physics land surface hydrological model. The SHPs are generated, based on a high-resolution Chinese soil property dataset, over the heterogeneous Upper Huaihe River basin. The results show that the SHPs can influence the streamflow in WRF-Hydro, which is similar to the impact of the scaling parameters on the streamflow over the study basin. Analyses of the uncertainty in the SHP ensemble reveal that SHPs mainly constrain the peak flow during the flood rise and impact the baseflow during the flood recession. A hydrological Bayesian model average (BMA) method is constructed to postprocess the streamflow ensemble based on the 3D SHPs. Probabilistic streamflow estimations by the BMA method are more skillful than the simulations using the individual 3D SHP ensemble members for all five studied hydrological stations, especially for high flows. Therefore, improved estimation of the uncertainty in the 3D SHPs may enhance the spatial representation of flood processes, resulting in more accurate estimates of the streamflow in the main streams in a heterogeneous basin.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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