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1.
Application of the Soil and Water Assessment Tool (SWAT) model is limited in plain polders, where hydrological and nutrient processes are confined by water conservancy facilities such as dikes and pumping stations. Watershed delineation techniques are proposed to enable SWAT to simulate these processes in a plain polder in Jiangxiang Town (Nanchang County, Jiangxi Province, China). Drainage unit division and multiple-outlet modelling approaches are introduced, and the main river network and land features are incorporated into a digital elevation model (DEM), so that drainage unit delineation can agree well with real flow direction and concentration. The impoundments of pumping stations are regarded as functioning like reservoirs, which are set up in the SWAT model to simulate confined hydrological processes. The results show that confined hydrological and nutrient processes in plain polders are simulated well; the retention rates of total nitrogen and total phosphorus are estimated as, respectively, 39% and 29% in both streams and impoundments. 相似文献
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平原圩区磷素流失过程模拟 总被引：1，自引：0，他引：1
圩区是太湖流域平原区的主要地理单元,其磷素流失是造成平原区水污染的重要原因之一,定量模拟圩区磷素流失过程是非点源磷污染控制的重要环节.以太湖流域的典型圩区——尖圩为研究对象,根据物质守恒原理构建圩区磷素流失过程模型,模型考虑了圩区自然降雨、人工灌溉、洪涝排水、地面渗漏、作物需水、水面蒸发、沟渠磷素拦截等过程,充分体现了圩区系统磷素流失特征;通过已有研究案例、实地监测与野外调研相结合的方法确定模型参数;模拟结果表明:(1)与太湖流域平原非圩区相比,圩区的年度磷素流失量较低(-0.17~0.54 kg/(hm2·a)),并且年度差异显著;(2)人工灌溉与自然降雨是圩区磷素输入的主要渠道,其磷素输入量分别为0.27~0.69、1.05~1.19 kg/(hm2·a);水体下渗和洪涝排水是圩区磷素的输出途径,其磷素输出量分别为1.04~1.06、0.65~0.93 kg/(hm2·a). 相似文献
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Two hydrological models with different structures and spatial capabilities are selected to simulate the runoff and actual evapotranspiration (AET) in Yingluoxia watershed, the upper reaches of Heihe River basin in northwest of China, to validate their performances in simulating hydrological processes. They are calibrated against the observed runoff at the watershed outlet (Yingluoxia station) for the period from 1990 to 1996 and validated for the period from 1997 to 2000. Results show that in terms of the simulated hydrograph against observations and the two selected objective functions, the conceptual, lumped Water And Snow balance MODeling system (WASMOD) with simple model structure could give the same, even better results than the semi‐distributed Soil and Water Assessment Tool (SWAT) with complex structure. Compared with other model applications to the watershed, simulation for monthly runoff made in this study seems better. With regard to AET, results calculated from both models are comparable as well. Both WASMOD and SWAT are proved to be suitable and satisfactory tools in simulating hydrological processes in the study area, although both of them have strengths and limitations in applications. WASMOD model may be one of the promising alternatives in hydrological modelling. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Integrated river basin models should provide a spatially distributed representation of basin hydrology and transport processes to allow for spatially implementing specific management and conservation measures. To accomplish this, the Soil and Water Assessment Tool (SWAT) was modified by integrating a landscape routing model to simulate water flow across discretized routing units. This paper presents a grid‐based version of the SWAT landscape model that has been developed to enhance the spatial representation of hydrology and transport processes. The modified model uses a new flow separation index that considers topographic features and soil properties to capture channel and landscape flow processes related to specific landscape positions. The resulting model is spatially fully distributed and includes surface, lateral and groundwater fluxes in each grid cell of the watershed. Furthermore, it more closely represents the spatially heterogeneous distributed flow and transport processes in a watershed. The model was calibrated and validated for the Little River Watershed (LRW) near Tifton, Georgia (USA). Water balance simulations as well as the spatial distribution of surface runoff, subsurface flow and evapotranspiration are examined. Model results indicate that groundwater flow is the dominant landscape process in the LRW. Results are promising, and satisfactory output was obtained with the presented grid‐based SWAT landscape model. Nash–Sutcliffe model efficiencies for daily stream flow were 0.59 and 0.63 for calibration and validation periods, and the model reasonably simulates the impact of the landscape position on surface runoff, subsurface flow and evapotranspiration. Additional revision of the model will likely be necessary to adequately represent temporal variations of transport and flow processes in a watershed. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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Predicting phosphorus dynamics in complex terrains using a variable source area hydrology model 
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下载免费PDF全文 Amy S. Collick Daniel R. Fuka Peter J. A. Kleinman Anthony R. Buda Jennifer L. Weld Mike J. White Tamie L. Veith Ray B. Bryant Carl H. Bolster Zachary M. Easton 《水文研究》2015,29(4):588-601
Phosphorus (P) loss from agricultural watersheds has long been a critical water quality problem, the control of which has been the focus of considerable research and investment. Preventing P loss depends on accurately representing the hydrological and chemical processes governing P mobilization and transport. The Soil and Water Assessment Tool (SWAT) is a watershed model commonly used to predict run‐off and non‐point source pollution transport. SWAT simulates run‐off employing either the curve number (CN) or the Green and Ampt methods, both assume infiltration‐excess run‐off, although shallow soils underlain by a restricting layer commonly generate saturation‐excess run‐off from variable source areas (VSA). In this study, we compared traditional SWAT with a re‐conceptualized version, SWAT‐VSA, that represents VSA hydrology, in a complex agricultural watershed in east central Pennsylvania. The objectives of this research were to provide further evidence of SWAT‐VSA's integrated and distributed predictive capabilities against measured surface run‐off and stream P loads and to highlight the model's ability to drive sub‐field management of P. Thus, we relied on a detailed field management database to parameterize the models. SWAT and SWAT‐VSA predicted discharge similarly well (daily Nash–Sutcliffe efficiencies of 0.61 and 0.66, respectively), but SWAT‐VSA outperformed SWAT in predicting P export from the watershed. SWAT estimated lower P loss (0.0–0.25 kg ha?1) from agricultural fields than SWAT‐VSA (0.0–1.0+ kg ha?1), which also identified critical source areas – those areas generating large run‐off and P losses at the sub‐field level. These results support the use of SWAT‐VSA in predicting watershed‐scale P losses and identifying critical source areas of P loss in landscapes with VSA hydrology. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献
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A conceptual water‐balance model was modified from a point application to be distributed for evaluating the spatial distribution of watershed water balance based on daily precipitation, temperature and other hydrological parameters. The model was calibrated by comparing simulated daily variation in soil moisture with field observed data and results of another model that simulates the vertical soil moisture flow by numerically solving Richards' equation. The impacts of soil and land use on the hydrological components of the water balance, such as evapotranspiration, soil moisture deficit, runoff and subsurface drainage, were evaluated with the calibrated model in this study. Given the same meteorological conditions and land use, the soil moisture deficit, evapotranspiration and surface runoff increase, and subsurface drainage decreases, as the available water capacity of soil increases. Among various land uses, alfalfa produced high soil moisture deficit and evapotranspiration and lower surface runoff and subsurface drainage, whereas soybeans produced an opposite trend. The simulated distribution of various hydrological components shows the combined effect of soil and land use. Simulated hydrological components compare well with observed data. The study demonstrated that the distributed water balance approach is efficient and has advantages over the use of single average value of hydrological variables and the application at a single point in the traditional practice. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
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A flood emergency storage area (polder) is used to reduce the flood peak in the main river and hence, protect downstream areas from being inundated. In this study, the effectiveness of a proposed flood emergency storage area at the middle Elbe River, Germany in reducing the flood peaks is investigated using hydrodynamic modelling. The flow to the polders is controlled by adjustable gates. The extreme flood event of August 2002 is used for the study. A fully hydrodynamic 1D model and a coupled 1D–2D model are applied to simulate the flooding and emptying processes in the polders and flow in the Elbe River. The results obtained from the 1D and 1D–2D models are compared with respect to the peak water level reductions in the Elbe River and flow processes in the polders during their filling and emptying. The computational time, storage space requirements and modelling effort for the two models are also compared. It is concluded that a 1D model may be used to study the water level and discharge reductions in the main river while a 1D-2D model may be used when the study of flow dynamics in the polder is of particular interest. Further, a detailed sensitivity analysis of the 1D and 1D–2D models is carried out with respect to Manning's n values, DEMs of different resolutions, number of cross-sections used and the gate opening time as well as gate opening/closing duration. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Using a mass balance algorithm, this study develops an extension module that can be embedded in the commonly used Soil and Water Assessment Tool (SWAT). This module makes it possible to assess effects of riparian wetlands on runoff and sediment yields at a watershed scale, which is very important for aquatic ecosystem management but rarely documented in the literature. In addition to delineating boundaries of a watershed and its subwatersheds, the module groups riparian wetlands within a subwatershed into an equivalent wetland for modelling purposes. Further, the module has functions to compute upland drainage area and other parameters (e.g. maximum volume) for the equivalent wetland based on digital elevation model, stream network, land use, soil and wetland distribution GIS datasets. SWAT is used to estimate and route runoff and sediment generated from upland drainage area. The lateral exchange processes between riparian wetlands and their hydraulically connected streams are simulated by the extension module. The developed module is empirically applied to the 53 km2 Upper Canagagigue Creek watershed located in Southern Ontario of Canada. The simulation results indicate that the module can make SWAT more reasonably predict flow and sediment loads at the outlet of the watershed and better represent the hydrologic processes within it. The simulation is sensitive to errors of wetland parameters and channel geometry. The approach of embedding the module into SWAT enables simulation of hydrologic processes in riparian wetlands, evaluation of wetland effects on regulating stream flow and sediment loading and assessment of various wetland restoration scenarios. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
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Manuel Esteban Lucas-Borja Bruno Gianmarco Carrà João Pedro Nunes Léonard Bernard-Jannin Santo Marcello Zimbone 《水文科学杂志》2020,65(11):1956-1973
ABSTRACT Surface runoff generation capacity can be modified by land-use and climate changes. Annual runoff volumes have been evaluated in a small watershed of tropical forest (Brazil), using the Soil and Water Assessment Tool (SWAT) model. Firstly, the accuracy of SWAT in runoff predictions has been assessed by default input parameters and improved by automatic calibration, using 20-year observations. Then, the hydrological response under land uses (cropland, pasture and deforested soil) alternative to tropical forest and climate change scenarios has been simulated. SWAT application has showed that, if forest was replaced by crops or pasture, the watershed’s hydrological response would not significantly be affected. Conversely, a complete deforestation would slightly increase its runoff generation capacity. Under forecasted climate scenarios, the runoff generation capacity of the watershed will tend to decrease and will not be noticeably different among the representative concentration pathways. Pasture and bare soil will give the lowest and highest runoff coefficients, respectively. 相似文献
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Model calibration is important for streamflow simulations using distributed hydrological models, especially in highland and cold areas of northwest China with scarce data. Quantitative analysis of water balance based on the accurate simulation is also essential for reasonably planning and managing water resources in these river basins facing a severe water shortage. In this study, a comprehensive method was proposed to calibrate the Soil and Water Assessment Tool (SWAT) model in the Yingluoxia watershed, upstream area of the Heihe River basin; it was based on multi-temporal, multi-variable and multi-site integrated drainage characteristics. Meanwhile a fresh approach of the parameter transferability and model validation was used by applying the set of calibrated parameters in its tributary to other area of the watershed. The results indicated that the method was effective and feasible; the values of Nash–Sutcliffe Efficiency (NSE) and Coefficient of Determination (r2) were greater than 0.81 and as high as 0.94 and the absolute values of the Percent Bias (PBIAS) were less than 2. Based the output of model the water balance in the Yingluoxia watershed was analyzed, that the mean annual precipitation, evapotranspiration, and discharge of the watershed from 1990 to 2000 were 491.8 mm, 334 mm, and 157.8 mm, respectively. The comprehensive calibration method based on multi-temporal, multi-variable and multi-site integrated drainage characteristics can better portray the hydrological processes of watershed and improve the model simulation; and the output of the model then provide a reliable reference for assessing and managing water resource of the watershed. 相似文献
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Pandara V. Femeena Indrajeet Chaubey Antoine Aubeneau Sara K. McMillan Paul D. Wagner Nicola Fohrer 《水文研究》2020,34(11):2599-2611
Hydrological models have long been used to study the interactions between land, surface and groundwater systems, and to predict and manage water quantity and quality. The soil and water assessment tool (SWAT), a widely used hydrological model, can simulate various ecohydrological processes on land and subsequently route the water quality constituents through surface and subsurface waters. So far, in-stream solute transport algorithms of the SWAT model have only been minimally revised, even though it has been acknowledged that an improvement of in-stream process representation can contribute to better model performance with respect to water quality. In this study, we aim to incorporate a new and improved solute transport model into the SWAT model framework. The new process-based model was developed using in-stream process equations from two well established models—the One-dimensional Transport with Inflow and Storage model and the Enhanced Stream Water Quality Model. The modified SWAT model (Mir-SWAT) was tested for water quality predictions in a study watershed in Germany. Compared to the standard SWAT model, Mir-SWAT improved dissolved oxygen (DO) predictions by removing extreme low values of DO (<6 mg/L) simulated by SWAT. Phosphate concentration peaks were reduced during high flows and a better match of daily predicted and measured values was attained using the Mir-SWAT model (R2 = 0.17, NSE = −0.65, RSR = 1.29 with SWAT; R2 = 0.28, NSE = −0.04, RSR = 1.02 with Mir-SWAT). In addition, Mir-SWAT performed better than the SWAT model in terms of Chlorophyll-a content particularly during winter months, improving the NSE and RSR for monthly average Chl-a by 74 and 42%, respectively. With the new model improvements, we aim to increase confidence in the stream solute transport component of the model, improve the understanding of nutrient dynamics in the stream, and to extend the applicability of SWAT for reach-scale analysis and management. 相似文献
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A process‐based, spatially distributed hydrological model was developed to quantitatively simulate the energy and mass transfer processes and their interactions within arctic regions (arctic hydrological and thermal model, ARHYTHM). The model first determines the flow direction in each element, the channel drainage network and the drainage area based upon the digital elevation data. Then it simulates various physical processes: including snow ablation, subsurface flow, overland flow and channel flow routing, soil thawing and evapotranspiration. The kinematic wave method is used for conducting overland flow and channel flow routing. The subsurface flow is simulated using the Darcian approach. The energy balance scheme was the primary approach used in energy‐related process simulations (snowmelt and evapotranspiration), although there are options to model snowmelt by the degree‐day method and evapotranspiration by the Priestley–Taylor equation. This hydrological model simulates the dynamic interactions of each of these processes and can predict spatially distributed snowmelt, soil moisture and evapotranspiration over a watershed at each time step as well as discharge in any specified channel(s). The model was applied to Imnavait watershed (about 2·2 km2) and the Upper Kuparuk River basin (about 146 km2) in northern Alaska. Simulated results of spatially distributed soil moisture content, discharge at gauging stations, snowpack ablations curves and other results yield reasonable agreement, both spatially and temporally, with available data sets such as SAR imagery‐generated soil moisture data and field measurements of snowpack ablation, and discharge data at selected points. The initial timing of simulated discharge does not compare well with the measured data during snowmelt periods mainly because the effect of snow damming on runoff was not considered in the model. Results from the application of this model demonstrate that spatially distributed models have the potential for improving our understanding of hydrology for certain settings. Finally, a critical component that led to the performance of this modelling is the coupling of the mass and energy processes. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
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Development and application of a physically based landscape water balance in the SWAT model 总被引：1，自引：0，他引：1
Eric D. White Zachary M. Easton Daniel R. Fuka Amy S. Collick Enyew Adgo Matthew McCartney Seleshi B. Awulachew Yihenew G. Selassie Tammo S. Steenhuis 《水文研究》2011,25(6):915-925
Watershed scale hydrological and biogeochemical models rely on the correct spatial‐temporal prediction of processes governing water and contaminant movement. The Soil and Water Assessment Tool (SWAT) model, one of the most commonly used watershed scale models, uses the popular curve number (CN) method to determine the respective amounts of infiltration and surface runoff. Although appropriate for flood forecasting in temperate climates, the CN method has been shown to be less than ideal in many situations (e.g. monsoonal climates and areas dominated by variable source area hydrology). The CN model is based on the assumption that there is a unique relationship between the average moisture content and the CN for all hydrologic response units (HRUs), and that the moisture content distribution is similar for each runoff event, which is not the case in many regions. Presented here is a physically based water balance that was coded in the SWAT model to replace the CN method of runoff generation. To compare this new water balance SWAT (SWAT‐WB) to the original CN‐based SWAT (SWAT‐CN), two watersheds were initialized; one in the headwaters of the Blue Nile in Ethiopia and one in the Catskill Mountains of New York. In the Ethiopian watershed, streamflow predictions were better using SWAT‐WB than SWAT‐CN [Nash–Sutcliffe efficiencies (NSE) of 0·79 and 0·67, respectively]. In the temperate Catskills, SWAT‐WB and SWAT‐CN predictions were approximately equivalent (NSE > 0·70). The spatial distribution of runoff‐generating areas differed greatly between the two models, with SWAT‐WB reflecting the topographical controls imposed on the model. Results show that a water balance provides results equal to or better than the CN, but with a more physically based approach. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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Watershed delineation is a required step when conducting any spatially distributed hydrological modelling. Automated approaches are often proposed to delineate a watershed based on a river network extracted from the digital elevation model (DEM) using the deterministic eight‐neighbour (D8) method. However, a realistic river network cannot be derived from conventional DEM processing methods for a large flat area with a complex network of rivers, lakes, reservoirs, and polders, referred to as a plain river network region (PRNR). In this study, a new approach, which uses both hydrographic features and DEM, has been developed to address the problems of watershed delineation in PRNR. It extracts the river nodes and determines the flow directions of the river network based on a vector‐based hydrographic feature data model. The river network, lakes, reservoirs, and polders are then used to modify the flow directions of grid cells determined by D8 approach. The watershed is eventually delineated into four types of catchments including lakes, reservoirs, polders, and overland catchments based on the flow direction matrix and the location of river nodes. Multiple flow directions of grid cells are represented using a multi‐direction encoding method, and multiple outflows of catchments are also reflected in the topology of catchments. The proposed approach is applied to the western Taihu watershed in China. Comparisons between the results obtained from the D8 approach, the ‘stream burning’ approach, and those from the proposed approach clearly demonstrate an improvement of the new approach over the conventional approaches. This approach will benefit the development of distributed hydrological models in PRNR for the consideration of different types and multiple inlets and outlets of catchments. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
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Flooding risk in polders is dictated by not only rainfall, topography, and land use, but also massive pumping. Unfortunately, existing models are inadequate for resolving floods as water transfer due to pumping is insufficiently accounted for. Here an improved hydrological model (MGB-MP) is proposed under the framework of the large-scale hydrological model (MGB) based on the principle of water balance, explicitly incorporating massive pumping within a polder and also out to external rivers. The proposed model is calibrated and validated for the Lannihu basin, a typical polder with an area of 1353 km2 and 126 pumping stations in the Dongting Lake District, China and surrounded by Xiangjiang River and Zishui River. The model performs fairly well, with Nash-Sutcliffe efficiencies concerning water levels over 0.76 for the calibration and over 0.73 for the validation. The model is applied to the Lannihu basin under different pumping station settings and rainfall scenarios to unravel how and to what extent massive pumping affects the flood processes as characterized by water levels and discharge hydrographs. It is shown that massive pumping considerably alters the discharge hydrographs and accordingly leads to substantial decrease in the water levels of rivers, which are independent unit-polders, due to water transfer between unit-polders within the basin and out of the basin. The closer the unit-polders are to pumping stations, the more the water levels in unit-polders decrease. The water levels in unit-polders away from a pumping station is affected by the pumping station capacity to a greater extent than the pumping station's threshold water level for initiating pumping. 相似文献
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Yanlin Zhang Guodong Cheng Xin Li Xujun Han Lei Wang Hongyi Li Xiaoli Chang G. N. Flerchinger 《水文研究》2013,27(25):3762-3776
Snow and frozen soil prevail in cold regions worldwide, and the integration of these processes is crucial in hydrological models. In this study, a combined model was developed by fully coupling a simultaneous heat and water model with a geomorphologically based distributed hydrological model. The combined model simulates vertical and lateral water transfer as well as vertical heat fluxes and is capable of representing the effects of frozen soil and snowmelt on hydrological processes in cold regions. This model was evaluated by using in situ observations in the Binggou watershed, an experimental watershed for cold region hydrology of the Watershed Allied Telemetry Experimental Research Project. Results showed that the model was able to predict soil freezing and thawing, unfrozen soil water content, and snow depth reasonably well. The simulated hydrograph was in good agreement with the in situ observation. The Nash–Sutcliffe coefficient of daily discharge was 0.744 for the entire simulation period, 0.472 from April to June, and 0.711 from June to November. This model can improve our understanding of hydrological processes in cold regions and assess the impacts of global warming on hydrological cycles and water resources. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
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The integration of a two-dimensional, raster-based rainfall–runoff model, CASC2D, with a raster geographical information system (GIS), GRASS, offers enhanced capabilities for analysing the hydrological impact under a variety of land management scenarios. The spatially varied components of the watershed, such as slope, soil texture, surface roughness and land-use disturbance, were characterized in GRASS at a user-specified grid cell resolution for input into the CASC2D model. CASC2D is a raster-based, single-event rainfall–runoff model that divides the watershed into grid cell elements and simulates the hydrological processes of infiltration, overland flow and channel flow in response to distributed rainfall precipitation. The five-step integration of CASC2D and GRASS demonstrates the potential for analysing spatially and temporally varied hydrological processes within a 50 square mile semi-arid watershed. By defining possible land-use disturbance scenarios for the watershed, a variety of rainfall–runoff events were simulated to determine the changes in watershed response under varying disturbance and rainfall conditions. Additionally, spatially distributed infiltration outputs derived from the simulations were analysed in GRASS to determine the variability of hydrological change within the watershed. Grid cell computational capabilities in GRASS allow the user to combine the scenario simulation outputs with other distributed watershed parameters to develop complex maps depicting potential areas of hydrological sensitivity. This GIS–hydrological model integration provides valuable spatial information to researchers and managers concerned with the study and effects of land-use on hydrological response. 相似文献