Discharge Load Research Articles

The Development of Catalyst Materials for the Advanced Lithium–Sulfur Battery

The lithium–sulfur battery is considered as one of the most promising next-generation energy storage systems owing to its high theoretical capacity and energy density. However, the shuttle effect in lithium–sulfur battery leads to the problems of low sulfur utilization, poor cyclability, and rate capability, which has attracted the attention of a large number of researchers in the recent years. Among them, the catalysts with efficient catalytic function for lithium polysulfides (LPSs) can effectively inhibit the shuttle effect. This review outlines the progress of catalyst materials for lithium–sulfur battery in recent years. Based on the structure and properties of the reported catalysts, the development of the reported catalyst materials for LPSs was divided into three generations. We can find that the design of highly efficient catalytic materials needs to consider not only strong chemical adsorption on polysulfides, but also good conductivity, catalysis, and mass transfer. Finally, the perspectives and outlook of reasonable design of catalyst materials for high performance lithium–sulfur battery are put forward. Catalytic materials with high conductivity and both lipophilic and thiophile sites will become the next-generation catalytic materials, such as heterosingle atom catalysis and heterometal carbide. The development of these catalytic materials will help catalyze LPSs more efficiently and improve the reaction kinetics, thus providing guarantee for lithium sulfur batteries with high load or rapid charge and discharge, which will promote the practical application of lithium–sulfur battery.

Storm event sediment fingerprinting for temporal and spatial sediment source tracing

AbstractSediment fingerprinting has been widely used to distinguish discrete sediment sources; however, application to intra‐storm sediment source variability has received relatively little focus despite the benefit being long recognized. In this investigation, sediment fingerprinting was applied to a 53‐hr storm event sampled hourly to determine sediment source dynamics throughout the event. Sediment sources were differentiated using 16 variables, and source contribution determined using Bayesian and Frequentist mixing models for comparison. Both models provided comparable source predictions for the dominant source estimates and the general temporal pattern. The Frequentist model appeared to exhibit some unreliable values coinciding with low GOF and attributed to inherent model structure. The Bayesian model showed higher uncertainty, likely due to the “process error” utilized associated with single sample mixtures. High variability in sediment source contribution was observed between hourly time steps; however, local smoothing reveals temporal trends during the event. A higher average proportion of mudstone is found in the falling limb (0.544) compared with the rising limb (0.464), and the reverse is observed for mountain range (0.218 vs. 0.283) and unconsolidated (0.073 vs. 0.055). In the initial hours of the storm, mudstone source contribution significantly drops, whereas mountain range and unconsolidated contributions peak. The SSC‐Q clockwise hysteresis indicates proximal sediment sources, suggesting the mudstone sediment is stored channel sediment and easily entrained. This sediment flushes through, coinciding with a drop as the distal mountain range and unconsolidated sources arrive to peak contribution. The wider Manawatū discharge and sediment load then arrive, delivering increasing levels of mudstone throughout the remainder of the event while mountain range sediment diminishes. Spatial representation of the sediment source contribution was derived from distributing sediment source loads to the spatial extent of the source material according to sub‐catchment sediment loads and was weighted according to slope. This provided an effective means to visualize the origin of the sediment and a better spatial interpretation of sediment fingerprinting results, which is typically limited by poor spatial resolution.

Allocation of unequally-weighted wastewater discharge loads using a simulation-optimization approach

In this study, a new simulation–optimization approach is proposed to solve the multi-pollutant waste load allocation (WLA) problems in surface water systems. The proposed approach simulates the fate and transport of multiple pollutants utilizing the AQUATOX model. Since AQUATOX is an independent model and its integration into the optimization process is computationally not efficient, a multi-pollutant concentration–response matrix (mpCRM) is developed by using the results of the AQUATOX model. This mpCRM is then integrated into an optimization model where a nonlinear generalized reduced gradient (GRG) optimization method is used. Unlike in previously conducted studies, a new optimization formulation is proposed wherein the multiple pollutant loads are allocated among the source locations depending on their pre-assigned load allocation weights. This formulation allows for an equal or variable pollutant load allocation plan among source locations depending on the water management strategy for the watershed. The applicability of the proposed approach is evaluated on a sub-watershed of the Küçük Menderes River Basin (KMRB) in Turkey by considering different load allocation scenarios. Furthermore, a detailed sensitivity analysis is conducted to evaluate the model results for different problem parameters. Identified results suggest that the proposed simulation–optimization approach is an effective way to solve the multi-pollutant WLA problem.

Prediction of constant power delivery of lithium-ion cells at high loads

Abstract Available energy and available capacity are key factors for dimensioning batteries. Discharge duration of a battery and its dependency on discharge current amplitude are well described by Peukert’s law from low to medium current ranges. Other equations describe this dependency up to very high current rates, including the currents occurring during a short circuit. It is not current and capacity, but energy and power which are the key parameters for dimensioning battery systems. Thus, the available power of battery cells, vs. the discharge duration was investigated from low to high constant power discharge loads. Based on the results of these experiments, a correlation of the maximum discharge duration for low to medium discharge power pulses, similar to the Peukert’s equation was found. Additionally, a new equation is proposed, describing the power range from low to very high discharge power rates. The result of this work simplifies the design of battery systems, its electromechanical components, as well as improves the prediction of available boost power cost-effective way e.g. for hybrid electric vehicles.

Mitigation of eutrophication caused by wastewater discharge: A simulation-based approach

Mitigation of eutrophication, intensified by excessive nutrient load discharge in wastewaters regulated by restrictive legal requirements, remains one of today’s most important global problems. Despite implementation of the Water Framework Directive, the Urban Wastewater Directive and the HELCOM recommendations, the actual condition of surface water is still not satisfactory. In response to the above, the study presents an alternative approach for surface water protection against eutrophication based on the selection of appropriate nutrient removal technologies. An activated sludge model simulation was used to enable the identification of environmentally justified nutrient removal systems with lowest eutrophication potential of treated wastewater conditioned by bioavailable nutrient forms content. Based on the outcome of the study, the 3-stage Bardenpho system was identified as the most efficient for bioavailable phosphorus removal, while the Johannesburg system proved to have the highest efficiency for bioavailable nitrogen removal. The proposed eutrophication mitigation approach underlines the need for a reconsideration of current legal regulations which ignore nutrient bioavailability and key eutrophication limiting factors.

Sub-basin prioritization for assessment of soil erosion susceptibility in Kangsabati, a plateau basin: A comparison between MCDM and SWAT models

Kangsabati basin located in tropical plateau region faces multiple problems of soil erosion susceptibility (SES), soil fertility deterioration, and sedimentation in reservoirs. Hence, identification of SES zones in thirty-eight sub-basins (SB) for basin prioritization is necessary. The present research addressed the issue by using four multi-criteria decision-making (MCDM) models: VlseKriterijumska optimizacija I Kompromisno Resenje (VIKOR), technique for order preference by similarity to ideal solution (TOPSIS), simple additive weighing (SAW), compound factor (CF). To determine the best fitted method from MCDM for erosion susceptibility (ES), a comparison has been made with Soil and Water Assessment Tool (SWAT), where fifteen morphometric parameters were considered for MCDM, and meteorological data, soil, slope and land use land cover (LULC) were considered for SWAT model. Two validation indices of percentage change and intensity change were used for evaluation and comparison of MCDM results. With SWAT model performance, SWAT calibration and uncertainty analysis programs (CUP) was used for sensitive analysis of SWAT parameters on flow discharge and sediment load simulation. The results showed that 23, 16, 18 SB have high ES; therefore they were given 1 to 3 ranks, whereas 31, 37, 21SB have low ES, hence given 38 to 36 rank as predicted by MCDM methods and SWAT. MCDM validation results depict that VIKOR and CF methods are more acceptable than TOPSIS and SAW. Calibration (flow discharge R2 0.86, NSE 0.75; sediment load R2 0.87, NSE 0.69) and validation (flow discharge R2 0.79, NSE 0.55; sediment load R2 0.79, NSE 0.76) of SWAT model indicated that simulated results are well fitted with observed data. Therefore, VIKOR reflects the significant role of morphometric parameters on ES, whereas SWAT reflects the significant role of LULC, slope, and soil on ES. However, it could be concluded that VIKOR is more effective MCDM method in comparison to SWAT prediction.

Full-scale N removal from centrate using a sidestream process with a mainstream carbon source.

An innovative approach to treat centrate for rapid nitrogen load discharge reduction was investigated and applied at the Truckee Meadows Water Reclamation Facility (TMWRF) in Reno, NV. This process allowed TMWRF to circumvent an anticipated exceedance of the individual waste load allocation in 2018. Existing infrastructure and equipment were re-purposed in a full-scale suspended growth biological centrate treatment system, attaining simultaneous nitrification, and denitrification with no additional capital investment. Functioning within a few days of start-up, the average ammonia reduction was 81% (1,106kg/day) and the average total nitrogen reduction in the sidestream was 53% (757kg/day) using primary effluent as carbon source. Alkalinity and carbon limitations were both anticipated and observed; however, adaptive operations allowed for balancing of nitrification and denitrification processes, providing pH stability and success in meeting treatment goals. Immediately after the sidestream treatment system was placed into service, nitrogen in the mainstream facility was measured at concentrations significantly lower than typical and was sustained at historically low concentrations throughout the operation. This translated into a significant methanol cost savings of $1,500 per day (USD). The system has become a critical supplemental treatment process during upcoming rehabilitation projects to address aging infrastructure of existing nitrogen treatment facilities. PRACTITIONER POINTS: Full scale demonstration of sidestream N removal using a hybrid process. Integration of the sidestream N process to reduce N effluent load without alkalinity or supplementary carbon augmentation. Operational solution to reduce operating costs without new infrastructure.

Developing a hydro-chemical model of Ise Bay watersheds and the evaluation of climate change impacts on discharge and nitrate-nitrogen loads

The objective of this study was to develop a hydro-chemical model using the Soil and Water Assessment Tool (SWAT) and to evaluate the climate change impacts on discharge and nitrate-nitrogen loads from Ise Bay watersheds (the Kiso, Nagara, Ibi, and Shonai rivers). Using a regional climate model, through the dynamic downscaling approach, present and future climate data were generated at a 2 km spatial resolution. The pseudo-global warming downscaling approach under the A1B scenario was adopted for future climate prediction. Then, the optimized SWAT model, driven by the present and future climate data, was executed. The following results were obtained: (1) the significant increase of precipitation in May and June and decrease in August in the future climate scenario, and consequent discharge from the target watersheds also increased in May and June and decreased in August and September; (2) Due to the change in discharge, nitrate-nitrogen loads of the Kiso, Nagara, and Ibi rivers also increased in May and June and decreased in August and September; and (3) While nitrate-nitrogen load from deciduous forest tends to decrease, the one from evergreen forest tends to increase. The response of the model indicated the possibility of an increase in nitrogen uptake by deciduous forests.

Hydrodynamic and geomorphic adjustments of channel bars in the Yichang-Chenglingji Reach of the Middle Yangtze River in response to the Three Gorges Dam operation

The evolution of channel bars in response to upstream damming has significant impacts on channel stability, navigation, and aquatic habitats. Here, the effects of the Three Gorges Dam (TGD) operation on downstream channel bars in the Yichang-Chenglingji Reach (YCR) were comprehensively analyzed using remote sensing images, cross-sectional profiles, and hydrological datasets. The morphodynamic adjustments of channel bars in the YCR were significantly different during the pre- and post-TGD periods (i.e., before and after the construction of the TGD). Specifically, the total area of channel bars did not exhibit any significant trend in the pre-TGD period, but displayed a significant reduction following the construction of the TGD, although the morphodynamic response of each sub-reach was different. The channel bars in the YCR were relatively stable in the pre-TGD period, but became more erodible in the post-TGD period. The length/width ratio (LWR) of the bars showed an overall increase trend during the whole period from 1992 to 2017, not changing before and after the dam construction. The water discharge that led to the greatest channel bars adjustment was 27,000–30,000 m3/s (corresponding to bankfull discharge) in the pre-TGD period and 15,000–18,000 m3/s (corresponding to the medium discharge that can submerge the surface of the bars) in the post-TGD period. In addition, the grain size of non-uniform sediment with the highest replenishment degree gradually reduced downstream; these finer sediments were the main sources of material for the channel bars in the YCR. Quantitative relationships between bars area, the most effective bar-forming discharge and suspended sediment load with the highest replenishment degree, were proposed based on the improved Delayed Response Model (DRM). Results indicate that geomorphic adjustments of channel bars in the YCR are closely related to the previous four-year flow and sediment regimes, implying a delayed response of the fluvial system to damming.

Spatial and Temporal Variability of Nutrient Dynamics and Ecosystem Metabolism in a Hyper-eutrophic Reservoir Differ Between a Wet and Dry Year

Climate change alters hydrologic regimes, including their variability. Effects will be pronounced in aquatic ecosystems, where resource subsidies (e.g., nutrients, carbon) drive key ecosystem processes. However, we know little about how changing hydrologic regimes will modulate the spatiotemporal dynamics of lake biogeochemistry and ecosystem metabolism. To address this, we quantified ecosystem metabolism and nutrient dynamicsat high spatial resolution in Acton Lake, a hyper-eutrophic reservoir in the Midwestern US. We captured two consecutive growing seasons with markedly different watershed discharge and nutrient loading. Temporal variability often exceeded spatial variability in both wet and dry years. However, relative spatial variability was higher in the dry year, suggesting that internal processes are more important in structuring spatial dynamics in dry years. Strikingly, marked differences in watershed discharge and nutrient loading between years produced relatively small differences in many lake metrics, suggesting resilience to hydrologic variability. We found little difference in gross primary productivity between wet and dry years, but ecosystem respiration was higher in the wet year, shifting net ecosystem production below zero. Discrete storm events produced strong, yet ephemeral and spatially explicit effects, reflective of the balance of stream input and discharge over the dam. Increases in limiting nutrients were restricted to near stream inlets and returned to pre-storm baseline within days. Ecosystem metabolism was suppressed during storm events, likely due to biomass flushing. Understanding how changing hydrologic regimes will mediate spatiotemporal dynamics of ecosystem metrics is paramount to preserving the ecological integrity and ecosystem services of lakes under future climates.

The hydrologic model as a source of nutrient loading uncertainty in a future climate

Hydrologic models are applied increasingly with climate projections to provide insights into future hydrologic conditions. However, both hydrologic models and climate models can produce a wide range of predictions based on model inputs, assumptions, and structure. To characterize a range of future predictions, it is common to use multiple climate models to drive hydrologic models, yet it is less common to also use a suite of hydrologic models. It is also common for hydrologic models to report riverine discharge and assume that nutrient loading will follow similar patterns, but this may not be the case. In this study, we characterized uncertainty from both climate models and hydrologic models in predicting riverine discharge and nutrient loading. Six climate models drawn from the Coupled Model Intercomparison Project Phase 5 ensemble were used to drive five independently developed and calibrated Soil and Water Assessment Tool models to assess hydrology and nutrient loadings for mid-century (2046–2065) in the Maumee River Watershed,the largest watershedsdraining to the Laurentian Great Lakes. Under those conditions, there was no clear agreement on the direction of change in future nutrient loadings or discharge. Analysis of variance demonstrated that variation among climate models was the dominant source of uncertainty in predicting future total discharge, tile discharge (i.e. subsurface drainage), evapotranspiration, and total nitrogen loading, while hydrologic models were the main source of uncertainty in predicted surface runoff and phosphorus loadings. This innovative study quantifies the importance of hydrologic model in the prediction of riverine nutrient loadings under a future climate.

Sediment dynamics and temporal variation of runoff in the Yom River, Thailand

The Yom River is one of the four major sediment sources to the Chao Phraya River in Thailand. Human activities and changes in climate over the past six decades may have affected the discharge and sediment load to some extent. In the current study, the river discharge and sediment characteristics in the mainstream of the Yom River were investigated using the field observation data from 2011 to 2013 and the historical river flow and sediment data from 1954 to 2014 at six hydrological stations operated by the Royal Irrigation Department of Thailand (RID). The non-parametric Mann-Kendall test and double mass curve were used to analyze the sediment dynamics and temporal changes in the discharge of the Yom River. The results revealed that the sediment was mainly transported in suspension, and the bed-to-suspended sediment loads ratio varied between 0 and 0.05. The daily suspended sediment load (SSL) in the upper and middle basins had a strong correlation with the daily discharge and could be represented by power equations with coefficients of determination higher than 0.8. The daily suspended sediment load in the lower basin did not directly depend on the corresponding discharge because of the reduction in river slope and water diversion by irrigation projects. It also appeared that the river discharges and sediment loads were mainly influenced by climate variation (floods and droughts). Moreover, the average sediment transport of the upper, middle, and lower reaches were 0.57, 0.71, and 0.35 million t/y, respectively. The sediment load in the lower basin decreased more than 50% as a result of changes in the river gradient (from mountainous to floodplain areas). The results from sediment analysis also indicated that the construction of the Mae Yom Barrage, the longest diversion dam in Thailand, and land-use changes did not significantly affect the sediment load along the Yom River.

Evaluation of Stage–Discharge Relationships in Alluvial Rivers (Case Study: Shahroud River, Qazvin province, Iran)

Many rivers are classified in alluvial rivers. Stage–discharge curve of these rivers is reliable just in measured conditions and for the sections by the use of measured data. Most of the stage–discharge equations are not able to consider flow resistance, and it causes some errors in qualitative and quantitative modeling. Therefore, it seems necessary to determine the accuracy of stage–discharge curve methods in the river sections without hydrometric stations. In this study, Einstein and Barbarossa (Trans ASCE 117:1121–1132, 1952), Engelund and Hansen (A monograph on sediment transport in alluvial streams. Technical University of Denmark, Copenhagen, Denmark, 1967) and White et al. (A new general method for predicting the frictional characteristics of alluvial streams. Report No IT 187. Hydraulics Research Station, Wallingford, England, 1979) methods were investigated in four hydrometric stations in Shahroud River. To do so, after field data collection, the stage–discharge curve of studied hydrometric stations was obtained by the mentioned methods. Results revealed that effect of flow resistance factors increased in maximum discharge. Einstein and Barbarossa’s (1952) method enjoyed the most accuracy in the stations with ripple bed form and discharge less than 20 cms. By increasing discharge or changing the bed form, the accuracy of this method decreased, so in this condition Engelund and Hansen (1967) and White et al.’s (1979) methods showed reliable accuracy. In the rivers with anti-dune bed form, White et al.’s (1979) equation had the most accuracy. Additionally, evaluating the effect of bed form, discharge, bed slope and bed load sediment size indicated that all the methods are highly sensitive to discharge flow and river bed form; on the other hand, bed slope and bed load sediment size are not determining factors in choosing proper method for the development of stage–discharge curve in alluvial rivers.

Effects of Dam Regulation on the Hydrological Alteration and Morphological Evolution of the Volta River Delta

The Volta River in West Africa is one of the most regulated rivers influenced by dams in the world, and the regulation has resulted in substantial impacts on the hydrological alteration and morphological evolution of the Volta River Delta. However, comprehensive analyses of the relevant effects are still lacking to date. In this study, inter-annual variations of river discharge and sediment load for pre- and post-Akosombo Dam periods (1936 to 2018) were analyzed through simple regression and Mann–Kendall (MK) trend analysis whereas the intra-annual variations were dictated by the non-uniformity and regulated coefficients. The shoreline changes were further evaluated using Landsat remote sensing images (1972 to 2018) to explore the effects of hydrological alteration on the morphological evolution of the Volta River Delta. Hydrological analyses show that the inter- and intra-annual variations are much higher in the pre-dam period, suggesting the substantial regulation of the Akosombo Dam on the Volta River. The dam regulation has more significant effects on the sediment load delivered to the delta than the river discharge, which decreased by 92.32% and 23.23%, respectively. Morphological analyses show that the progradation-erosion of the Volta River Delta constantly fluctuates within a relatively small range (maximum 0.5%) after the 1970s. The relationship between the variations of the delta area and sediment load implicates that a quasi-equilibrium state may have been established at the Volta River Delta, given the current sediment load. Our findings provide references for the future regulation and restoration of the Volta River Delta.

Changing Rainfall Patterns Over the Western Lake Erie Basin (1975–2017): Effects on Tributary Discharge and Phosphorus Load

AbstractIn agricultural watersheds, shifting climate and hydrologic patterns present an immediate and future risk to both farm productivity and downstream aquatic ecosystems. Here, our objective was to evaluate long‐term spatiotemporal trends in rainfall amount and intensity within the Maumee River‐Lake Erie system and quantify the effects of rainfall patterns on streamflow and phosphorus loading. Across the watershed, annual rainfall increased by 102 ± 115 mm (11 ± 13%) from 1975–2017. Heavy (25.4–76.2 mm) and very heavy (>76.2 mm) rainfall accounted for most of the increase in total rainfall, with observed increases of 45 ± 32% that occurred primarily during spring and summer. Trends in streamflow for 12 monitored subwatersheds generally followed patterns in rainfall, as discharge increased by 19 ± 32%. Discharge‐to‐rainfall ratio increased in 9 of 12 subwatersheds despite no change or increases in watershed storage capacity, suggesting that increasing rainfall intensity that exceeds short‐term watershed storage capacity (i.e., during/immediately following the rainfall event) may control patterns of discharge more than long‐term gains in watershed storage (i.e., changes in soil water holding capacity). Long‐term trends in phosphorus (total phosphorus and soluble reactive phosphorus) load indicate that changes in rainfall amount and intensity have substantially contributed to increased loading through increased discharge volumes. Differences in total phosphorus and soluble reactive phosphorus concentration trends also highlight how concomitant changes in rainfall and land management practices have influenced loading. Findings therefore suggest that changing patterns in rainfall amount and intensity have and will likely continue to pose a significant challenge to conservation efforts in agricultural landscapes aiming to decrease phosphorus delivery to surface waters.

Comparing seepage and selenium desorption in blasted-rock fills using two reclamation techniques

Geomorphic reclaimed landforms aim to improve groundwater movement and diminish contaminant transport through increased runoff and reduced groundwater infiltration. The objective of this research was to determine if geomorphic reclamation techniques result in improved selenium concentrations of discharge water as compared to conventional reclamation for valley-fills constructed of blasted rock. Comparisons investigated if groundwater and contaminant desorption could be improved by altering valley-fill construction. Three-dimensional finite-element groundwater modelling was performed on two valley-fill geometries and was coupled with laboratory testing of selenium leaching from blasted-rock overburden. Selenium desorption characteristics and distributions were compared. Lower water volumes and shorter contact times with overburden fill resulted in lower masses of selenium desorbed from geomorphic fills as compared to conventional techniques. When results were normalized by varying fill areas and volumes, the geomorphic valley-fill exhibited 23% lower surface infiltration, 27% lower discharge volumes and 39% lower selenium discharge loads as compared to the conventional reclamation. To achieve these advantages in geomorphic reclamation, infiltration must be reduced through both the construction of curvilinear slopes of the fill surface and the creation of a low infiltration-capacity reclaimed stream.

River suspended sediment load prediction based on river discharge information: application of newly developed data mining models

ABSTRACTSuspended sediment load (SSL) is one of the essential hydrological processes that affects river engineering sustainability. Sediment has a major influence on the operation of dams and reservoir capacity. This investigation is aimed at exploring a new version of machine learning models (i.e. data mining), including M5P, attribute selected classifier (AS M5P), M5Rule (M5R), and K Star (KS) models for SSL prediction at the Trenton meteorological station on the Delaware River, USA. Different input scenarios were examined based on the river flow discharge and sediment load database. The performance of the applied data mining models was evaluated using various statistical metrics and graphical presentation. Among the applied data mining models, the M5P model gave a superior prediction result. The current and one-day lead time river flow and sediment load were the influential predictors for one-day-ahead SSL prediction. Overall, the applied data mining models achieved excellent predictions of the SSL process.

Artificial Neural Network Model for Estimation of Suspended Sediment Load in Krishna River Basin, India

The correct assessment of amount of sediment during design, management and operation of water resources projects is very important. Efficiency of dam has been reduced due to sedimentation which is built for flood control, irrigation, power generation etc. There are traditional methods for the estimation of sediment are available but these cannot provide the accurate results because of involvement of very complex variables and processes. One of the best suitable artificial intelligence technique for modeling this phenomenon is artificial neural network (ANN). In the current study ANN techniques used for simulation monthly suspended sediment load at Vijayawada gauging station in Krishna river basin, Andhra Pradesh, India. Trial & error method were used during the optimization of parameters that are involved in this model. Estimation of suspended sediment load (SSL) is done using water discharge and water level data as inputs. The water discharge, water level and sediment load is collected from January 1966 to December 2005. This approach is used for modelled the SSL. By considering the results, ANN has the satisfactory performance and more accurate results in the simulation of monthly SSL for the study location.

Effects of dynamic land use/land cover change on water resources and sediment yield in the Anzali wetland catchment, Gilan, Iran

Land use/land cover (LULC) changes strongly affect catchment hydrology and sediment yields. The current study aims at analyzing the hydrological consequences of dynamic LULC changes in the Anzali wetland catchment, Iran. The Soil and Water Assessment Tool (SWAT 2012) model was used to assess impacts on evapotranspiration, water yield, and sediment yield. Two model runs were performed using static and dynamic LULC inputs to evaluate the effects of LULC change between 1990 and 2013. For the static model, the LULC map of 1990 was used, whereas for the dynamic model, a gradual change of the LULC distribution was interpolated from 1990, 2000, and 2013 LULC data. The major LULC changes were identified as an increase of agricultural area by 7% of the catchment area and a decrease of forest coverage by 6.8% between 1990 and 2013. At the catchment scale, the differences in the long-term mean annual values for the main water balance components and sediment yield were smaller than 10 mm (<2.8%) and 3 t/km2 (<2.6%), respectively. However, at the sub-basin scale the increase of agricultural land use resulted in an increase of evapotranspiration, water yield, and sediment yield by up to 8.3%, 7%, and 169%, respectively, whereas urban expansion led to a decrease of evapotranspiration, water yield, and sediment yield by up to −3.5%, −2.3%, and −9.4%. According to the results of the monthly time scale analysis, the most significant impact of LULC changes occurs during the dry season months, when the increase of irrigation agriculture results in an increase in water discharge and sediment loads to the Anzali wetland. Overall, the results showed that the implementation of dynamic LULC change into the SWAT model could be adopted as a planning tool to manage LULC change of the Anzali wetland catchment in the future.

Suitability of the SWAT Model for Simulating Water Discharge and Sediment Load in a Karst Watershed of the Semiarid Mediterranean Basin

This paper presents a case study conducted in the Upper Argos River, in southeast Spain, to verify the applicability of the SWAT model for prediction of the water discharge and sediment load in a Mediterranean semiarid karst basin. For this purpose, the monthly and yearly discharge and sediment load records at the Argos reservoir gauge during the period 1976–2000 were used to calibrate the model, while data from 2001 to 2017 were used for validation. For both stages of the modeling the performance of the NSE, RSR, and PBIAS indices was good in the case of the monthly flow rate (NSE = 0.62 and 0.70 for calibration and validation, respectively; RSR = 0.61 and 0.54; PBIAS = −20.60% and − 16.09%) and acceptable for the estimation of the monthly sediment load (NSE = 0.52 and 0.58; RSR = 0.70 and 0.64; PBIAS = 10.65% and 15.20%). These indices showed a substantial improvement in the annual simulations, particularly in the calibration, for which the respective values of NSE and RSR were 0.89 and 0.32 for the flow rate and 0.81 and 0.42 for the sediment transport.