Few studies have investigated the effects of N application in a wheat/maize rotation system on soil moisture, residual nitrate‐N (NR), growth, grain yield (GY) and nitrogen use efficiency (NUE) in northwest China under dryland conditions. A five‐season (June 2013–October 2015) field experiment was conducted using N fertilizer rates of 0, 86, 172 and 258 kg ha−1 during the summer maize growing season

To prevent the development of plant diseases, irrigation water needs to be disinfected. The commonly applied cleaning methods do not allow the possibility of activation and enrichment of irrigation water with nutrients. The target of this study is to develop an environmentally friendly method for disinfecting and activating irrigation water by treatment with high‐voltage discharges in an electro‐hydraulic

There is a critical need for a national agroecosystem model for conservation policy and environmental planning, driven by issues including harmful algal blooms, water scarcity, flooding, and other weather‐related extremes. In this study, we illustrate the feasibility of a national agroecosystem model that will downscale processes to individual fields and first‐order channels. We propose to conceptually

The Savannah River Basin (SRB), a highly stressed southeastern river in United States is a conservation priority for State, Federal government, and nongovernment organizations. A four‐stage sustainable development tool was developed in this study using meta‐analysis and the drivers–pressures–state–impacts–responses (DPSIR) framework. Through the synthesis of ~150 references in the SRB this study addressed

The flat topography, large natural storage features, backwater effects, and boundary conditions all play different roles in the flood response of rivers in low‐gradient environments. The combined effects of these factors result in frequent episodes of reverse flows, slow recession of flood waters, and complex flow interactions. This study investigates the value of varying degrees of model complexity

A three‐dimensional unstructured‐grid hydrodynamic and water quality model (Semi‐implicit Cross‐scale Hydroscience Intergrated System Model‐Integrated Compartment Model) is applied successfully for Chesapeake Bay. The model is validated with observations of salinity, chlorophyll‐a, dissolved oxygen, nutrients, and phytoplankton productions from the year 1991 to 1995 for the mainstem and some major

The microbiologically influenced corrosion (MIC) is a serious issue that should be considered for effective risk-based integrity management of offshore systems under MIC. This paper presents a proper methodology by using a hybrid Bayesian network (BN) and Markov process to predict the MIC rate, failure probability, and critical failure year of an internally corroded subsea pipeline. The BN model is

This paper proposes a novel data-driven approach to estimate the navigable capacity of busy waterways, focusing on ships entering and leaving port, based on the structural characteristics of traffic flow driven by the Automatic Identification System (AIS) data. First, we collect the ship traffic flow in a busy waterway by processing the original AIS data and then identify the structural characteristics

Subsea pipelines with a free suspended span segment may be subject to upheaval buckling under high temperature, which may lead to a failure mode such as local buckling, fracture and fatigue. Mathematical models are established to study the upheaval buckling behaviour of subsea pipelines with a free span segment. Then, the accurate locations of the maxima of displacement and stress are obtained. The

A submerged floating tunnel (SFT) is a promising alternative to conventional bridges and tunnels, and can be potentially built in the Qiongzhou Strait in China. However, this area is under the threat of disasters including mega tsunamis and severe storm surges. To evaluate the hydrodynamic loads of the SFT in this hazardous zone subject to severe tsunami and typhoon impacts, the Delft3D-FLOW hydrodynamic

Oscillating water column (OWC) device is possibly the most studied among various wave energy converters and many different realizations of the technology have been investigated. To study the complex hydrodynamic behaviour of an OWC, a two-dimensional numerical wave tank based on the weakly compressible smoothed particle hydrodynamics (SPH) method is developed in this paper. A simplified pneumatic model

Tidal current energy is considered as one of the most important topics to be analyzed due to the penetration of renewable energy sources into the grid. The influence of unsteady wave is playing a crucial role on the tidal currents speed forecasting and its extracted power as well as its integration into the grid. The influence is not significant in case of single turbine or ducted tidal turbines. That

This paper solves the trajectory tracking problem for underactuated autonomous surface vessels in the presence of uncertainty dynamics and unavailable velocities. A robust controller is proposed by employing a neural network, command filtered backstepping method, and adaptive control method. Moreover, all tracking errors are guaranteed to be uniformly ultimately bounded on the basis of the Lyapunov

A general expression is formulated from the first principles for wave and current forces acting on a body. Morison's equation is recovered as a special case of the general formulation, thus establishing this heuristic-regarded equation on a firm theoretical ground. The drag force is clearly seen to be originating from the advective acceleration and the skin friction resistance, which is not explicitly

This paper investigates the position of the instantaneous center of rotation in pitch response of a moored vessel submitted to regular head waves. The vessel is assumed to respond only in surge, heave and pitch, which allows a 2D approach in the x-z plane due to symmetry. The concept is formalized via an analytical approach in a previous study, showing that even though this point is time dependent

The numerical results of local scour for bridge piers are significantly affected by the inlet turbulent boundary conditions. A novel self-sustaining model (SSM) and corresponding the new inlet turbulent boundary conditions are proposed to quickly obtain a stable flow field of horizontal homogeneity. The Reynolds averaged Navier-Stokes (RANS) equations, and standard k-ԑ turbulence model are employed

Free hanging is vulnerable to dynamic motion at the top end inducing axial compression at the touchdown point. Numerical approaches in consideration with multiple degrees of freedom and nonlinear drag force have been succeeded at evaluating dynamic characteristics of free-hanging slender structures accurately. On the other hand, analytical investigations into the mechanism determining dynamic tension

Global offshore wind power is rapidly developing and has a broad market. China has the advantage of developing offshore wind power, which is the direction of future development of China's power generation industry. Because of the high maintenance and repair costs as well as the large sizes of wind power structures, damage to them could cause loss of lives and property. In this paper, a health monitoring

Field observations over decades have found that the surface roughness of coral reefs is typically one or two order of magnitude larger than that of sandy beaches. To better reproduce the solitary wave transformation and run-up over fringing reefs with large bottom roughness, a numerical wave tank based on the CFD tool OpenFOAM® is developed in this study. The Reynolds-Averaged Navier-Stokes (RANS)

The hydrodynamic characteristics of a novel twin-protuberance hydrofoil design mimicking the two prominent tubercles present on a humpback whale flipper are investigated. The foil has NACA 634-021 section with a span/chord ratio of 2, having twin leading-edge protuberances- each of amplitude 10% of the chord length. A characteristic feature of this foil is its capability to restrict the separation

To promote collaboration on water management between farmers and government agencies, both parties must have a mutual understanding of the measurement and management of available water resources using existing infra‐ and non‐infrastructure management tools. They are required to provide collaborative water management through appropriate technology, with capacity building and knowledge management. In

Sediment yield is important for maintaining soil health, reservoir sustainability, environmental pollution, and conservation of natural resources. The main aim of the present work is to develop four machine learning models, artificial neural networks (ANNs), radial basis function (RBF), support vector machine (SVM) and multiple model (MM)-ANNs for forecasting daily sediment yield. These models were

Besides benefits associated to increased water availability for irrigation, reuse projects of urban water can also provide positive environmental impacts, as they contribute to improve water quality of the receiving bodies by diverting wastewater from their outlet. This represents a typical win-win situation where significant synergies can be achieved between urban and agricultural sector, and the

A large-time Eulerian–Lagrangian stochastic approach is employed to: (1) estimate centroid position uncertainty of contaminant plumes that originate from instantaneous point sources in statistically stationary and isotropic porous formations; (2) assess the time needed for achieving ergodic conditions, which would allow for the evaluation of local concentration values based on the only ensemble mean

Predicting dam inflow is necessary for effective water management. This study created machine learning algorithms to predict the amount of inflow into the Soyang River Dam in South Korea, using weather and dam inflow data for 40 years. A total of six algorithms were used, as follows: decision tree (DT), multilayer perceptron (MLP), random forest (RF), gradient boosting (GB), recurrent neural network–long

With the rise of large-scale environmental models comes new challenges for how we best utilize this information in research, management and decision making. Interactive data visualizations can make large and complex datasets easier to access and explore, which can lead to knowledge discovery, hypothesis formation and improved understanding. Here, we present a web-based interactive data visualization

Irrigation management is a key factor in attaining optimal yields, as different irrigation strategies lead to different yields even when using the same amount of water or under the same weather conditions. Our research aimed to simulate the water-use efficiency (WUE) of crops considering different irrigation strategies in the Central Valley of Chile. By means of AquaCrop-OS, we simulated expected yields

To evaluate long-term temperature changes caused by the operation of a geothermal heat pump (GHP) system, temperatures near borehole heat exchangers (BHEs) of the GHP system in Korea were measured. The temperature measurements showed increasing rates of 0.135 °C/year at a depth of 10 m and 0.118 °C/year at a depth of 50 m for approximately 10 years. Simulations for the analysis of climate change effects

Superlative levels of arsenic (As) in groundwater and sediment often result from industrial pollution, as is the case for a coastal aquifer in Southern Italy, with a fertilizer plant atop. Understanding conditions under which As is mobilized from the sediments, the source of that As, is necessary for developing effective remediation plans. Here, we examine hydrogeological and geochemical factors that

This study reports the adsorption capacity of lead Pb2+ and cadmium Cd2+ of biochar obtained from: peanut shell (BCM), “chonta” pulp (BCH) and corn cob (BZM) calcined at 500, 600 and 700 °C, respectively. The optimal adsorbent dose, pH, maximum adsorption capacity and adsorption kinetics were evaluated. The biochar with the highest Pb2+ and Cd2+ removal capacity is obtained from the peanut shell (BCM)

In this study, the supercavitating flow of a high-velocity moving body near air-water surface is calculated and analyzed based on a commercial CFD software ANSYS Fluent. The effect of regular wave parameters including both wave height and wavelength on the cavitating flow and force characteristics of a body at different velocities is investigated. It is found that the cavity shape, lift coefficient

This paper presents detailed laboratory experiments investigating the effect onshore and offshore wind conditions have on nearshore wave dynamics, including extreme winds. The experiments were performed using monochromatic waves and a linearly sloping bed. The results show that offshore wind conditions delay wave breaking and promote steep breakers, while onshore wind conditions extend the surf zone

In the present study, regular water wave interaction with rubble mound offshore breakwaters (RMOB) is investigated. The porosity of the RMOB is uniform, and the breakwaters are placed on the uniform seabed. Three different types of breakwaters such as (i) RMOB with still water level at the crest, (ii) emerged RMOB, and (iii) submerged RMOB are considered for the present analysis. The associated boundary

An event-triggered controller (ETC) for global full-state stabilization of under-actuated surface vessels (USVs) is proposed. Based on an inner–outer loop structure with Lyapunov control design technique, the USV dynamics are separated into two subsystems to facilitate the design and stability analysis. A time-varying variable is constructed to design the desired velocities used as virtual control

The floating platform with taut or semi-taut mooring systems is the main option for oil and gas exploitations in deep sea. However, it has been reported that the reciprocating motion of the mooring line tends to induce the seabed trench near the anchor, which consequently reduces the anchor capacity. In this paper, two parts of work have been carried out to enhance the understanding of the seabed trench

Surf-riding phenomenon occurs when a ship sailing in following waves is accelerated to wave celerity. In this paper, surf-riding occurrence is studied for the parent hull of the Systematic Series D by 3 degrees of freedom (DOF) CFD simulations. Simulation cases are chosen following IMO recommendations for a wavelength to ship length range and following IMO criterion for ship speed cases. Initial conditions

This article presents a detailed numerical flow assessment of the boundary layer and wake of a full-scale cargo ship. The assessment was conducted using a sophisticated numerical approach that is able to resolve large turbulent scale vortices contained in the flow. The physical flow features of the boundary layer and wake investigated include mean-velocity, near-wall shear stress and vorticity fields

In this paper, high-speed impacting different size water-filled containers by projectiles have been performed experimentally, particular attention is given to characterizing the container confinement effects on the cavity characteristics induced by regular projectiles impacting into the confined containers. Experimental results indicate that the confinement effect on the cavity evolution is mainly

In this paper neural-network (NN) based adaptive trajectory tracking control scheme has been designed for underactuated Autonomous Underwater Vehicles (AUVs) which are subjected to unknown asymmetrical actuator saturation and unknown dynamics. First, some control preliminaries and assumptions along with AUV kinematic & kinetic models and trajectory tracking problems are elaborated. Secondly, the tracking

The light-weight gravity installed plate anchor (L-GIPLA) is a plate-shaped anchor for securing offshore floating structures, which is dynamically installed with the aid of a booster. Therefore, it is necessary to investigate the hydrodynamic characteristics of the hybrid anchor (L-GIPLA + booster) during free fall in water. Model tests are conducted in the present study to investigate the drag coefficient

In this study, a meshless simulation model based on the element-free Galerkin method (EFGM) is proposed for the coupled simulation of groundwater flow and contaminant transport (GFCT) in the two-dimensions. EFGM discretizes the governing GFCT equations using the Galerkin integral approach and shape functions generated through the moving least squares (MLS) approximation method. It results into the

Few models are capable of simultaneously simulating the sequences of landslide occurrence and sediment export. Quantification of the temporarily stored sediment within the watershed plays a key role to link hillslope landslides with fluvial sediment export. In this study, two coupled models were proposed to simulate time-series total landslide area and the subsequent sediment export on a daily basis

Since late 2014, the Mexican Caribbean coast has periodically received massive, atypical influxes of pelagic Sargassum spp. (sargasso). Negative impacts associated with these influxes include mortality of nearshore benthic flora and fauna, beach erosion, pollution, decreasing tourism and high management costs. To understand the dynamics of the sargasso influx, we used Landsat 8 imagery (from 2016 to

Fe0@Fe3O4 nanoparticles with dispersibility and stability better than single nano zero-valent iron (nZVI) were synthesized and combined with hydrogen peroxide to constitute a heterogeneous Fenton-like system, which was creatively applied in the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D). The effects of different reaction conditions like pH, hydrogen peroxide concentration, temperature, and

The present study is based on the application of an interval two-stage stochastic programming (ITSP) model in the Yinma River Basin. A robust method based on interval two-stage robust (ITSR) optimization is introduced to construct an optimization model of water resource distribution in order to solve the problems of water shortage in low-income and high-income areas caused by the unreasonable distribution

Large-domain hydrological models are increasingly needed to support water-resource assessment and management in large river basins. Here, we describe results for the first Brazilian application of the SPAtially Referenced Regression On Watershed attributes (SPARROW) model using a new open-source modeling and interactive decision support system tool (RSPARROW) to quantify the origin, flux, and fate

Sand mining, among the many activities that have significant effects on the bed changes of rivers, has increased in many parts of the world in recent decades. Numerical modeling plays a vital role in simulation in the long term; however, computational time remains a challenge. In this paper, we propose a sand mining component integrated into the bedload continuity equation and combine it with high-performance

The computational tool InSTHAn (indicators of short-term hydrological alteration) was developed to summarize data on subdaily stream flows or water levels into manageable, comprehensive and ecologically meaningful metrics, and to qualify and quantify their deviation from unaltered states. The pronunciation of the acronym refers to the recording interval of input data (i.e., instant). We compared InSTHAn

Note: In lieu of an abstract, this is an excerpt from the first page. The authors wish to make the following corrections to this paper [...]

Population growth, global warming, and increased demand for water have caused global concern about increasing water scarcity. Chile has an unequal geographical distribution of water resources. The north-central area where more than half of the country’s population lives has an availability of less than 1000 m3/hab/year. Particularly, the Coquimbo Region has been one of the most affected by drought

We analyzed the complex dynamics that are involved the groundwater level variations due to the episodic rainfall supply in the Ionian coastal plain surficial aquifer located in Southern Italy. In this aquifer, as a consequence of the particular hydrogeological framework, both direct and lateral recharge mechanisms coexist. Hence, the dynamics of groundwater level variations are quite complex and strongly

Natural disturbances (windthrow, bark beetle, and fire) have reduced forest cover in the Tatra National Park (Slovakia) by 50% since the year 2004. We analyzed carbon fluxes and streamflow ten years after the forest destruction in three small catchments which differ in size, land cover, disturbance type and post-disturbance management. Point-wise CO2 fluxes were estimated by chamber methods for vegetation-dominated

Soils are the dominant source of atmospheric nitrous oxide (N2O), especially agricultural soils that experience both waterlogging and intensive nitrogen fertilization. However, soil heterogeneity and the irregular occurrence of hydrological events hamper the prediction of the temporal and spatial dynamics of N2O production and transport in soils. Because soil moisture influences soil redox potential

Modeling and prediction of soil hydrologic processes require identifying soil moisture spatial-temporal patterns and effective methods allowing the data observations to be used across different spatial and temporal scales. This work presents a methodology for combining spatially- and temporally-extensive soil moisture datasets obtained in the Shale Hills Critical Zone Observatory (CZO) from 2004 to

The paper is focused on the evaluation of long-term changes in the chemical composition of precipitation in the mountain forests of Slovakia. Two stations with long-term measurements of precipitation quality were selected, namely the station of the EMEP (European Monitoring and Evaluation Programme) network Chopok (2008 m a.s.l.) and the station of the ICP Forests (International Co-operative Programme

Note: In lieu of an abstract, this is an excerpt from the first page. Abstract Polycyclic aromatic hydrocarbons (PAHs) and phenolic compounds had been widely recognized as priority organic pollutants in wastewater with toxic effects on both plants and animals [...]

Unsteady flow induced by hydropower stations exerts a significant impact on the water level in multi-approach channels, which directly threatens the safe passage of ships. In this study, a one-dimensional and a two-dimensional hydrodynamic model are adopted to simulate the water level fluctuations at the entrance of multi-approach channels and the lower lock head of a ship lift with consideration of

This paper provides an introduction to, and an overview of, the Special Issue on the application of systems approach to the management of complex water systems. The main motivation in proposing this Special Issue was that today, more than ever, we need a systems approach to assist in dealing with the difficulties introduced by the increase in the complexity of water resource problems, consideration

Spatio-temporal dynamics of riverine nitrogen (N) and phosphorus (P) in karst regions are closely linked to hydrological conditions, human activities and karst features in upstream catchments. From October 2017 to September 2019, we undertook 22 sampling campaigns in 11 nested catchments ranging from 21.00 to 373.37 km2 in Huixian karst wetland to quantify forms, concentrations, and fluxes of riverine