Rainfall Intensity–Duration–Frequency (IDF) curves are among the most essential datasets used in water resources management across the globe. Traditionally, they are derived from observations of historical rainfall, under the assumption of stationarity. Change of climatic conditions makes use of historical data for development of IDFs for the future unreliable, and in some cases, may lead to underestimated infrastructure designs. The IDF_CC tool is designed to assist water professionals and engineers in producing IDF estimates under changing climatic conditions. The latest version of the tool (Version 4) provides updated IDF curve estimates for gauged locations (rainfall monitoring stations) and ungauged sites using a new gridded dataset of IDF curves for the land mass of Canada. The tool has been developed using web-based technologies and takes the form of a decision support system (DSS). The main modifications and improvements between version 1 and the latest version of the IDF_CC tool include: (i) introduction of the Generalized Extreme value (GEV) distribution; (ii) updated equidistant matching algorithm (QM); (iii) gridded IDF curves dataset for ungauged location and (iv) updated Climate Models. Full article

Basic information on global reservoirs is well documented in databases such as GRanD (Global Reservoir and Dam) and ICOLD (International Commission on Large Dams). However, though playing a critical role in estimating reservoir storage variations from remote sensing or hydrological models, area–storage curves of reservoirs are not conveniently obtained nor publicly shared. In this paper, we combine the GRanD database and Landsat-based global surface water extent (GSW) data to derive area–storage curves of reservoirs. The reported storage capacity in the GRanD database and water surface area from GSW data were used to constrain the area–storage curve. The proposed method has the potential to derive area–storage curves of reservoirs larger than 1 km² archived in the GRanD database. The derived curves are validated with in situ reservoir data collected in US and China, and the results show that in situ records are well captured by the derived curves both in large and small reservoirs with various shapes. The derived area–storage curves could be employed to advance global monitoring or modeling of reservoir storage dynamics. Full article

The use of potential fields in fluid dynamics is retraced, ranging from classical potential theory to recent developments in this evergreen research field. The focus is centred on two major approaches and their advancements: (i) the Clebsch transformation and (ii) the classical complex variable method utilising Airy’s stress function, which can be generalised to a first integral methodology based on the introduction of a tensor potential and parallels drawn with Maxwell’s theory. Basic questions relating to the existence and gauge freedoms of the potential fields and the satisfaction of the boundary conditions required for closure are addressed; with respect to (i), the properties of self-adjointness and Galilean invariance are of particular interest. The application and use of both approaches is explored through the solution of four purposely selected problems; three of which are tractable analytically, the fourth requiring a numerical solution. In all cases, the results obtained are found to be in excellent agreement with corresponding solutions available in the open literature. Full article

The Water Framework Directive (WFD) is typically a framework directive that tries to encourage integration of policies for water quality and agriculture. Nutrients (nitrates, phosphates) from agricultural sources remain a ‘wicked problem’ in realizing the aims of the WFD, partly because the directive has to rely on other, neighboring policies to tackle to problem pressure of nutrients; it seems to lack instruments and measures to directly intervene in relevant agricultural policies. This contribution describes the different governance approaches of five member states and regions (The Netherlands, Flanders in Belgium, Lower Saxony- in Germany, Denmark and Ireland) to the nutrients problem and specifically focuses on the relationship between the nature of governance and the nature of measures taken. On the one hand, countries can vary in terms of a more consensual or antagonistic approach to dealing with water quality and diffuse pollution by agriculture, and emphasize more integration or separation in organization and programs. On the other hand, they can vary in the ‘outcomes’ in terms of more source-based measures or effect-based measures and the emphasis in policy instruments used. This article is based on the screening of policy documents, 44 interviews and several (international) feedback workshops. We found a great variety in governance approaches, while the nature of measures, in terms of source-based and effect-based, is only slightly different. On closer inspection, there are interesting differences in the consensual or antagonist discourses and differences in the use of more mandatory instruments or area-based policies. In many countries, the major challenge is to strike a balance between taking source-based measures, where necessary, and accommodating the difficult situations farmers very often find themselves in, as the reduction of nutrients (as a source-based measure) use can lead to lower yields and higher costs for manure disposal. Full article

The efficient use of limited water resources and improving the water use efficiency (WUE) of arid agricultural systems is becoming one of the greatest challenges in agriculture production and global food security because of the shortage of water resources and increasing demand for food in the world. In this study, we attempted to investigate the interannual trends of evapotranspiration and WUE and the responses of biophysical factors and water utilization strategies over a main cropland ecosystem (i.e., seeded maize, Zea mays L.) in arid regions of North-Western China based on continuous eddy-covariance measurements. This paper showed that ecosystem WUE and canopy WUE of the maize ecosystem were 1.90 ± 0.17 g C kg⁻¹ H₂O and 2.44 ± 0.21 g C kg⁻¹ H₂O over the observation period, respectively, with a clear variation due to a change of irrigation practice. Traditional flood irrigation generally results in over-irrigation, providing more water than actual crop requirements. Unlike flood irrigation, which can infiltrate into deep soil layers, drip irrigation can only influence the shallow soil moisture, which can lead to decreases of soil moisture of approximately 27–32% and 36–42% compared with flood irrigation for shallow and deep layers, respectively. Additionally, drip irrigation decreases evapotranspiration by 13% and transpiration by 11–14%, leading to increases in ecosystem and canopy WUE of 9–14% and 11%, respectively, compared to the traditional irrigation practice. Therefore, the drip irrigation strategy is an effective method to reduce irrigation water use and increase crop WUE in arid regions. Our study provides guidance to water-saving cultivation systems and has implications for sustainable water resources management and agriculture development in water-limited regions. Full article

Pesticide residues in foodstuffs can lead to several undesirable effects. A simple and high-throughput targeted screening method analyzing multi-residue pesticide in aquaculture water based on ultra-high-performance liquid chromatography-Q/Orbitrap mass spectrometry (UHPLC-Q/Orbi MS) was developed and validated. In this technique, the peaks of the compound using precursor ions were recorded by the full scan, which was used for rough quantitative analysis with single point matrix matched calibration. The qualitative identification was performed following the stringent confirmation criteria with fragment ions, retention time, and an isotopic pattern. Additionally, solid-phase extraction with an HLB (Hydrophilic/Lipophilic Balanced) column was selected to enrich and separate target pesticides from water. The screening detection limit of 33 compounds are less than 2 ng·L⁻¹, while 26 compounds range from 2 ng·L⁻¹ to 10 ng·L⁻¹, 19 compounds are at the range of 10–200 ng·L⁻¹, and the other two compounds are 200 ng·L⁻¹ and 1000 ng·L⁻¹. Most of the recovery results were found to be between 60~130%. Finally, the method was successfully applied to the analysis of pesticide residues in 30 water samples from aquaculture environment in Shanghai, indicating its applicability in pesticide screening for environmental monitoring. Full article

Runoff reduction in most river basins in China has become a hotpot in recent years. The Gushanchuan river, a primary tributary of the middle Yellow river, Northern China, showed a significant downward trend in the last century. Little is known regarding the relative contributions of changing environment to the observed hydrological trends and response on the runoff generation process in its watershed. On the basis of observed hydrological and meteorological data from 1965–2010, the Mann-Kendall trend test and climate elasticity method were used to distinguish the effects of climate change and human activities on runoff in the Gushanchuan basin. The results indicate that the runoff in the Gushanchuan Basin has experienced significant declines as large as 77% from 1965 to 2010, and a mutation point occurred around 1997; the contribution rate of climate change to runoff change is 12.9–15.1%, and the contribution rate of human activities to runoff change is 84.9–87.1%. Then we divided long-term data sequence into two stages around the mutation point, and analyzed runoff generation mechanisms based on land use and cover changes (LUCC). We found that the floods in the Gushanchuan Basin were still dominated by Excess-infiltration runoff, but the proportion in 1965–1997 and 1998–2010 decreased gradually (68.46% and 45.83% in turn). The proportion of Excess-storage runoff and Mixed runoff has increased, which means that the runoff is made up of more runoff components. The variation law of the LUCC indicates that the forest area increased by 49.61%, the confluence time increased by 50.42%, and the water storage capacity of the watershed increased by 30.35%. Full article

Steel slag, a byproduct of the steel making process, has been adopted as a material to reduce non-point phosphorus (P) losses from agricultural land. Although substantial studies have been conducted on characterizing P removed by steel slag, few data are available on the removal of P under different conditions of P input, slag mass, and retention time (RT). The objective of this study was to investigate P removal efficiency as impacted by slag mass and RT at different physical locations through a horizontal steel slag column. Downstream slag segments were more efficient at removing P than upstream segments because they were exposed to more favorable conditions for calcium phosphate precipitation, specifically higher Ca²⁺ concentrations and pH. These results showed that P is removed in a moving front as Ca²⁺ and slag pH buffer capacity are consumed. In agreement with the calcium phosphate precipitation mechanism shown in previous studies, an increase in RT increased P removal, resulting in an estimated removal capacity of 61 mg kg⁻¹ at a RT of 30 min. Results emphasized the importance of designing field scale structures with sufficient RT to accommodate the formation of calcium phosphate. Full article

Highly populated river deltas are experiencing marine environment degradation resulting from the tremendous input of terrestrial dissolved substances (TeDS). The Pearl River Delta is one of the deltas with degradation of the water quality and ecological condition. The Pearl River Estuary (PRE) was investigated to reveal the fate and transport timescales of TeDS in order to provide guidance on water resource management and pollutant transport prediction. By using passive tracers in a calibrated 3D numerical model, the TeDS transports from five different outlet groups were investigated systematically. The TeDS transport time was computed by using the concept of water age, which is a measure of the time that has elapsed since the tracer was transported from the upstream boundary to the downstream concerned area. The tracer impacted area was defined by the area with tracer concentrations > 0.2 (arbitrary unit). The domains that were impacted by the tracer coming from each outlet group were identified separately. In the wet season, the impacted area was larger than in other seasons. The most prominent variations appeared in the Jiaomen–Hengmen–Hongqili (JHH) and Modaomen (MD) outlets. The hydrodynamic conditions controlled the offshore spreading of the TeDS. Assuming the TeDS were conservative, it took approximately 10–20 days for the TeDS to be transported from the head water to the entrance of the outlet. For the TeDS coming from the head water of the Humen outlet, it took approximately 40 (80) days for the TeDS to be transported out of the mouth of the Lingding Bay during the wet (dry) season. For the case of the TeDS coming from the head water of the JHH outlets, it took approximately 20 (40) days for the TeDS to be transported out of the Lingding Bay during the wet (dry) season. For the MD, Jiti and Yamen–Hutiao outlets, it usually took approximately 10 days for the TeDS to be transported from the head water to the inner shelf. The correlation coefficient between the river flow and tracer concentrations was 0.78, and between the river flow and transport time it was −0.70 at a station in the lower Lingding Bay. At the estuary mouth, the impacts of other forcing fields got stronger. Full article

A novel meso- and microporous tire-derived-carbon support with magnetic iron oxide nanoparticle adsorbents that selectively adsorbs Se(IV) ions from simulated contaminated water has been developed. In this work, the physicochemical characteristics of the composite adsorbent are characterized with respect to porosity and surface area, chemical composition, and microstructure morphology. The kinetics of this composite adsorbent in a fixed-bed setting has been determined. Several column runs were conducted and analyzed by inductively coupled plasma-optical emission spectroscopy (ICP-OES) to determine the concentration gradient vs time. These results were then fit to a pseudo-second order rate law to obtain equilibrium values. Combining calculated equilibrium values with effluent concentration data, enabled the application of the Adams–Bohart model to determine reaction constants and column coefficients. Column parameters obtained from different flow rates and fittings of the Adams–Bohart model were remarkably consistent. These findings enable the application of this sorbent to fixed-bed column systems and opens up further research into mixed pollutants tests with real wastewater and scaling of selenium pollutant removal. Full article

The scale of a wind turbine is getting larger with the development of wind energy recently. Therefore, the effect of the wind turbine blades deformation on its performances and lifespan has become obvious. In order to solve this research rapidly, a new elastic actuator line model (EALM) is proposed in this study, which is based on turbinesFoam in OpenFOAM (Open Source Field Operation and Manipulation, a free, open source computational fluid dynamics (CFD) software package released by the OpenFOAM Foundation, which was incorporated as a company limited by guarantee in England and Wales). The model combines the actuator line model (ALM) and a beam solver, which is used in the wind turbine blade design. The aeroelastic performances of the NREL (National Renewable Energy Laboratory) 5 MW wind turbine like power, thrust, and blade tip displacement are investigated. These results are compared with some research to prove the new model. Additionally, the influence caused by blade deflections on the aerodynamic performance is discussed. It is demonstrated that the tower shadow effect becomes more obvious and causes the power and thrust to get a bit lower and unsteady. Finally, this variety is analyzed in the wake of upstream wind turbine and it is found that the influence on the performance and wake flow field of downstream wind turbine becomes more serious. Full article

The paper presents the comparison of soil particle size distribution determined by standard pipette method and laser diffraction. Based on the obtained results (542 soil samples from 271 sites located in the Nitra, Váh and Hron River basins), regression models were calculated to convert the results of the particle size distribution by laser diffraction to pipette method. Considering one of the most common soil texture classification systems used in Slovakia (according to Novák), the emphasis was placed on the determination accuracy of particle size fraction <0.01 mm. Analysette22 MicroTec plus and Mastersizer2000 devices were used for laser diffraction. Polynomial regression model resulted in the best approximation of measurements by laser diffraction to values obtained by pipette method. In the case of particle size fraction <0.01 mm, the differences between the measured values by pipette method and both laser analyzers ranged in average from 3% up to 9% and from 2% up to 11% in the case of Analysette22 and Mastersizer2000, respectively. After correction, the differences decreased to average 3.28% (Analysette22) and 2.24% (Mastersizer2000) in comparison with pipette method. After recalculation of the data, laser diffraction can be used alongside the sedimentation methods. Full article

To better evaluate and enhance the performance and benefit of sustainable stormwater management (SSWM) in developing countries, this study proposes a comprehensive evaluation framework based on thorough literature review. This framework re-classifies evaluation goals and indicators into four aspects—stormwater system, integrated management, social engagement, and urban development. The purpose of this review is to provide a guideline for decision makers to choose appropriate goals and indicators according to different regional context. Meanwhile, a structured procedure for comprehensive evaluation of SSWM is proposed to guide a well-organised decision-making process. Furthermore, pros and cons of eight decision support tools, as well as their functional focus, are compared, aiming to provide references for SSWM in developing countries. Outcomes presented in this review are expected to support decision makers in the process of screening optimal SSWM strategies and monitoring SSWM projects. Full article

The vadose zone is the main host of surface and subsurface water exchange and has important implications for ecosystems functioning, climate sciences, geotechnical engineering, and water availability issues. Geophysics provides a means for investigating the subsurface in a non-invasive way and at larger spatial scales than conventional hydrological sensors. Time-lapse hydrogeophysical applications are especially useful for monitoring flow and water content dynamics. Largely dominated by electrical and electromagnetic methods, such applications increasingly rely on seismic methods as a complementary approach to describe the structure and behavior of the vadose zone. To further explore the applicability of active seismics to retrieve quantitative information about dynamic processes in near-surface time-lapse settings, we designed a controlled water infiltration experiment at the Ploemeur Hydrological Observatory (France) during which successive periods of infiltration were followed by surface-based seismic and electrical resistivity acquisitions. Water content was monitored throughout the experiment by means of sensors at different depths to relate the derived seismic and electrical properties to water saturation changes. We observe comparable trends in the electrical and seismic responses during the experiment, highlighting the utility of the seismic method to monitor hydrological processes and unsaturated flow. Moreover, petrophysical relationships seem promising in providing quantitative results. Full article

To analyze the effect of runoff on shallow landslides, a model coupling one-dimensional rainfall–runoff and two-dimensional infiltration was established to simulate rainfall, infiltration, and runoff processes. Based on Bishop’s limit equilibrium method, the slope failure of a hypothetical footslope was studied. First, conditions with and without inflow were compared. The results reveal a remarkable difference in factors of safety (FS) between the two conditions, suggesting that considering the effect of runoff is crucial for landslide modeling. In terms of a series of tests of the various magnitudes, durations, lag-time, and peak position of the hydrograph, analyses show that larger inflow leads to more accumulated infiltration and triggers landslides earlier. A long-term duration inflow decreases the stability more than short intensive inflow does. With subsequent surface inflow, slope failure may occur after rainfalls stop, owing to the inflow, and the shape of inflow hydrographs could slightly affect the variance in FS. Results also indicate the necessity of considering the surface runoff when using a numerical model to analyze landslide, particularly on a footslope. Full article