The performance on prediction by mathematical models which represent the conceived image of a system such as hydrology is oftentimes represented through calibration and verification processes. Oftentimes a best fit be...The performance on prediction by mathematical models which represent the conceived image of a system such as hydrology is oftentimes represented through calibration and verification processes. Oftentimes a best fit between observed and predicted flows is obtained through correlation coefficient (R2) and the Nash Sutcliffe model efficiency (NSE) by minimizing the average Root Mean Square Error (RMSE) of the observed versus simulated flows. However, these days, a new paradigm is emerging wherein accounting for the flow variability for the protection of freshwater biodiversity and maintenance of goods and services that rivers provide is paramount. Therefore, from an ecohydrology perspective, it is not clear if the existing method of model calibration meets the needs of the riverine ecosystem at its best. Thus, this study investigates and proposes a methodology using entropy theory to gage the calibration of Soil and Water Assessment Tool (SWAT) from an ecohydrology perspective characterized by the natural flow-regime paradigm: Indicators of Hydrologic Alteration.展开更多
Hydrological modeling plays a crucial role in efficiently managing water resources and understanding the hydrologic behavior of watersheds. This study aims to simulate daily streamflow in the Godavari River Basin in M...Hydrological modeling plays a crucial role in efficiently managing water resources and understanding the hydrologic behavior of watersheds. This study aims to simulate daily streamflow in the Godavari River Basin in Maharashtra using the Soil and Water Assessment Tool (SWAT). SWAT is a process-based hydrological model used to predict water balance components, sediment levels, and nutrient contamination. In this research, we used integrated remote sensing and GIS data, including Digital Elevation Models (DEM), land use and land cover (LULC) maps, soil maps, and observed precipitation and temperature data, as input for developing the SWAT model to assess surface runoff in this large river basin. The Godavari River Basin under study was divided into 25 sub-basins, comprising 151 hydrological response units categorized by unique land cover, soil, and slope characteristics using the SWAT model. The model was calibrated and validated against observed runoff data for two time periods: 2003-2006 and 2007-2010 respectively. Model performance was assessed using the Nash-Sutcliffe efficiency (NSE) and the coefficient of determination (R2). The results show the effectiveness of the SWAT2012 model, with R2 value of 0.84 during calibration and 0.86 during validation. NSE values also ranged from 0.84 during calibration to 0.85 during validation. These findings enhance our understanding of surface runoff dynamics in the Godavari River Basin under study and highlight the suit-ability of the SWAT model for this region.展开更多
Interactions between surface water and groundwater are dynamic and complex in large endorheic river watersheds in Northwest China due to the influence of both irrigation practices and the local terrain. These interact...Interactions between surface water and groundwater are dynamic and complex in large endorheic river watersheds in Northwest China due to the influence of both irrigation practices and the local terrain. These interactions interchange numerous times throughout the middle reaches, making streamflow simulation a challenge in endorheic river watersheds. In this study, we modified the linear-reservoir groundwater module in SWAT(Soil and Water Assessment Tools, a widely used hydrological model) with a new nonlinear relationship to better represent groundwater processes; we then applied the original SWAT and modified SWAT to the Heihe River Watershed, the second largest endorheic river watershed in Northwest China, to simulate streamflow. After calibrating both the original SWAT model and the modified SWAT model, we analyzed model performance during two periods: an irrigation period and a non-irrigation period. Our results show that the modified SWAT model with the nonlinear groundwater module performed significantly better during both the irrigation and non-irrigation periods. Moreover, after comparing different runoff components simulated by the two models, the results show that, after the implementation of the new nonlinear groundwater module in SWAT, proportions of runoff components changed-and the groundwater flow had significantly increased, dominating the discharge season. Therefore, SWAT coupled with the non-linear groundwater module represents the complex hydrological process in the study area more realistically. Moreover, the results for various runoff components simulated by the modified SWAT models can be used to describe the hydrological characteristics of lowland areas. This indicates that the modified SWAT model is applicable to simulate complex hydrological process of arid endorheic rivers.展开更多
Non-point source(NPS) pollution has become a major source of water pollution. A combination of models would provide the necessary direction and approaches designed to control NPS pollution through land use planning. I...Non-point source(NPS) pollution has become a major source of water pollution. A combination of models would provide the necessary direction and approaches designed to control NPS pollution through land use planning. In this study, NPS pollution load was simulated in urban planning, historic trends and ecological protection land use scenarios based on the Conversion of Land Use and its Effect at Small regional extent(CLUE-S) and Soil and Water Assessment Tool(SWAT) models applied to Hunhe-Taizi River Watershed, Liaoning Province, China. Total nitrogen(TN) and total phosphorus(TP) were chosen as NPS pollution indices. The results of models validation showed that CLUE-S and SWAT models were suitable in the study area. NPS pollution mainly came from dry farmland, paddy, rural and urban areas. The spatial distribution of TN and TP exhibited the same trend in 57 sub-catchments. The TN and TP had the highest NPS pollution load in the western and central plains, which concentrated the urban area and farm land. The NPS pollution load would increase in the urban planning and historic trends scenarios, and would be even higher in the urban planning scenario. However, the NPS pollution load decreased in the ecological protection scenario. The differences observed in the three scenarios indicated that land use had a degree of impact on NPS pollution, which showed that scientific and ecologically sound construction could effectively reduce the NPS pollution load in a watershed. This study provides a scientific method for conducting NPS pollution research at the watershed scale, a scientific basis for non-point source pollution control, and a reference for related policy making.展开更多
The Soil and Water Assessment Tool(SWAT)is widely used to relate farm management practices to their impacts on surface waters at the watershed scale,yet its smallest spatial unit is not generally defined by physically...The Soil and Water Assessment Tool(SWAT)is widely used to relate farm management practices to their impacts on surface waters at the watershed scale,yet its smallest spatial unit is not generally defined by physically meaningful boundaries.The hydrologic response unit(HRU)is the smallest spatial unit of the model,and the standard HRU definition approach lumps all similar land uses,soils,and slopes within a subbasin based upon user-defined thresholds.This standard method provides an efficient way to discretize large watersheds where simulation at the field scale may not be computationally feasible.In relatively smaller watersheds,however,defining HRUs to specific spatial locations bounded by property lines or field borders would often be advantageous,yet this is not currently possible within the ArcSWAT interface.In this study,a simple approach is demonstrated that defines HRUs by field boundaries through addition of uniquely named soils to the SWAT user soil database and creation of a field boundary layer with majority land use and soil attributes.Predictions of nitrogen,phosphorus,and sediment losses were compared in a case study watershed where SWAT was set up using both the standard HRU definition and field boundary approach.Watershed-scale results were reasonable and similar for both methods,but aggregating fields by majority soil type masked extremely high soil erosion predicted for a few soils.Results from field-based HRU delineation may be quite different from the standard approach due to choosing a majority soil type in each farm field.This approach is flexible such that any land use and soil data prepared for SWAT can be used and any shapefile boundary can divide HRUs.展开更多
Although many sensitivity analyses using the soil and water assessment tool(SWAT) in a complex watershed have been conducted, little attention has been paid to the application potential of the model in unique plots. I...Although many sensitivity analyses using the soil and water assessment tool(SWAT) in a complex watershed have been conducted, little attention has been paid to the application potential of the model in unique plots. In addition, sensitivity analysis of percolation and evapotranspiration with SWAT has seldom been undertaken. In this study, SWAT99.2 was calibrated to simulate water balance components for unique plots in Southern China from 2000 to 2001, which included surface runoff, percolation, and evapotranspiration. Twenty-one parameters classified into four categories, including meteorological conditions, topographical characteristics, soil properties, and vegetation attributes, were used for sensitivity analysis through one-at-a-time(OAT) sampling to identify the factor that contributed most to the variance in water balance components. The results were shown to be different for different plots, with parameter sensitivity indices and ranks varying for different water balance components. Water balance components in the broad-leaved forest and natural grass plots were most sensitive to meteorological conditions, less sensitive to vegetation attributes and soil properties, and least sensitive to topographical characteristics. Compared to those in the natural grass plot, water balance components in the broad-leaved forest plot demonstrated higher sensitivity to the maximum stomatal conductance(GSI) and maximum leaf area index(BLAI).展开更多
恒河是印度最长的河流,目前正遭受人类活动和气候变化的影响,其中瓦拉纳西区域所受的影响尤为严重。预计气候变化和不断扩张的人口会进一步影响水资源的有效利用。本研究利用水土评价工具(soil and water assessment tool,SWAT)模型进...恒河是印度最长的河流,目前正遭受人类活动和气候变化的影响,其中瓦拉纳西区域所受的影响尤为严重。预计气候变化和不断扩张的人口会进一步影响水资源的有效利用。本研究利用水土评价工具(soil and water assessment tool,SWAT)模型进行水文模拟,研究区选择恒河流经的印度北方邦南部地区,覆盖面积达15 621.612 km^2。本研究主要目标如下:(1)检验SWAT模型在径流和产沙量预测方面的可行性和适用性,(2)对序贯不确定性分析(SUFI-2)、普适似然不确定性估计(GLUE)和并行求解(ParaSol)这3种常规校准算法进行对比分析,并确定出最佳校准算法。SWAT模型中输入数据的来源为航天飞机雷达地形测绘任务(SRTM)获取的数字高程模型(DEM)、Landsat-8卫星图像、土壤数据和逐日气象数据。首先,本研究将研究流域划分为46个子流域,使用土地利用/土地覆被(LULC)图和土壤图创建了水文响应单元(HRU)。然后,构建了基于SUFI-2、GLUE和ParaSol算法的模型,并基于5类标准对这些校准算法进行了比较,标准包括目标函数、使用概念、性能、P因子和R因子值。研究结果表明:(1) SUFI-2算法需要的运行时间较少,同时校准结果最好,ParaSol算法最差;(2)使用SUFI-2算法对模型进行校准后,获得对模拟结果影响最显著的5个敏感参数——主河道水力传导率(CH_K2)、USLE方程水土保持因子(USLE_P)、主河道曼宁系数值(CH_N2)、地表径流滞后时间(SURLAG)以及土壤有效含水量(SOL_AWC);(3) 40号子流域(SW#40)产生的径流量最大,土地利用类型为荒地的36号子流域(SW#36)的产沙量最大,达到50 t·a^(–1)。研究区的平均蒸散量为411.55 mm·a^(–1)。校准后的模型可以用于探究未来LULC的变化、气候变化和土壤侵蚀的影响。展开更多
将SWAT(Soil and Water Assessment Tool)模型应用于库区大尺度流域的污染模拟研究,对其进行适用性评价及模拟应用分析。模型校验采用的是2002—2008年的水文月数据及水质水期数据,径流模拟效果最好,评价指标ENS(Nash-Suttclife Effi...将SWAT(Soil and Water Assessment Tool)模型应用于库区大尺度流域的污染模拟研究,对其进行适用性评价及模拟应用分析。模型校验采用的是2002—2008年的水文月数据及水质水期数据,径流模拟效果最好,评价指标ENS(Nash-Suttclife Efficiency)均在0.9以上;泥沙模拟评价指标ENS在0.46~0.9;营养盐模拟评价指标ENS个别出现了〈0.36的情况,但总体模拟效果满足要求。应用SWAT模型对库区降水与地表产流、产沙、营养盐负荷进行了研究。结果表明:库区地表产流与降水的相关性趋势最好;地表产沙与产流、降水的总体趋势一致,但偶尔出现4、5月份地表产沙先于产流出现峰值的情况,这可能是由于春耕对地表扰动后又逢较强降水引起的水土流失;营养盐污染负荷尤其是TP的峰值趋势与地表产流相比,更接近地表产沙趋势。本文还对库区不同土地利用类型的污染负荷做了分析,得到各类土地利用类型的年均污染负荷总量排序及单位面积污染负荷,再次验证了SWAT模型在三峡库区流域的适用性。根据分析结果,库区耕地为非点源污染产出的主要源头,可将耕地耕种措施转变及土地利用类型转换作为库区非点源污染削减的重要手段。展开更多
应用SWAT(Soil and Water Assessment Tool)分布式水文模型对汉江流域1971—2000年30年逐月径流进行了模拟。结果表明:模型模拟精度高于评价标准(模拟效率Ens>0.5,相关系数r2>0.6),SWAT模型适用于汉江流域的径流模拟;水量平衡各...应用SWAT(Soil and Water Assessment Tool)分布式水文模型对汉江流域1971—2000年30年逐月径流进行了模拟。结果表明:模型模拟精度高于评价标准(模拟效率Ens>0.5,相关系数r2>0.6),SWAT模型适用于汉江流域的径流模拟;水量平衡各要素中,30年月、年平均蒸散发量、地表径流量、土壤对地下水补给量、土壤含水变化量、地下水侧流量分别占降水量的55.97%、25.88%、17.64%、0.26%、0.25%,蒸散发是该流域水量的主要输出项;各月30年平均降水量变化趋势与地表径流量变化趋势较一致,而与基流量变化趋势一致性较差;30年流域降水量年变化趋势与地表径流量、基流量的变化趋势较一致;30年月、年地表径流量对降水的响应程度高于基流。展开更多
生态环境问题受到了日益广泛的关注,生态恢复也在各地蓬勃开展,但生态恢复工程的开展迫切需要相关理论研究的指导。采用假定生态恢复情景的方法,在遥感和地理信息系统的支持下,利用分布式水文模型SWAT(Soil and Water Assessment Tool)...生态环境问题受到了日益广泛的关注,生态恢复也在各地蓬勃开展,但生态恢复工程的开展迫切需要相关理论研究的指导。采用假定生态恢复情景的方法,在遥感和地理信息系统的支持下,利用分布式水文模型SWAT(Soil and Water Assessment Tool)对陇西黄土高原的典型流域——华家岭南河流域进行了多种生态恢复情景模型的设计,并模拟了不同生态恢复情景下径流和蒸散发的响应情况。得出:在南河流域草地比森林植被涵养水源的作用更强,模拟年均径流深比林地低9.1%,而蒸散发却高2.2%,所以南河流域生态恢复过程中种草是十分必要的。结果同时表明,应用SWAT模型进行流域尺度的生态恢复水文响应研究是可行高效的。展开更多
为解决地形复杂区域因无法及时获取数据而影响旱灾监测的问题,该研究以湖北省清江流域中上游为例,基于具有较强物理机制的分布式水文模型(soil and water assessment tool,SWAT),建立作物水分亏缺指数进行农业旱情监测,其中,利用该流域...为解决地形复杂区域因无法及时获取数据而影响旱灾监测的问题,该研究以湖北省清江流域中上游为例,基于具有较强物理机制的分布式水文模型(soil and water assessment tool,SWAT),建立作物水分亏缺指数进行农业旱情监测,其中,利用该流域的土地覆被、土壤、地形、气象以及2003-2005年和2007-2010年水文观测数据构建了流域SWAT模型,模拟作物水分亏缺指数的有关参量,包括潜在蒸散量和降水量。研究结果表明:1)SWAT模型模拟的潜在蒸散量与气象数据计算得到的潜在蒸散量拟合相关度达到97%以上;2)与标准化降水指数监测结果进行对比,基于SWAT模型建立的作物水分亏缺指数能够从机理方面客观反映监测区域作物生长期的受旱程度,有效实现了流域尺度的旱灾监测,克服了复杂地形区利用少数气象站点建立气象干旱指标评价旱情的局限性。该研究可为复杂地形区旱灾评估提供可行途径。展开更多
分析国内外应用SWAT(Soil and Water Assessment Tool)模型模拟流域径流的研究现状,以及流域模型构建,包括流域基础数据和模拟算法的选取、敏感性参数的分析和模型输出的验证.提出模型的应用研究存在3个问题:(1)模型模拟效率受到基础数...分析国内外应用SWAT(Soil and Water Assessment Tool)模型模拟流域径流的研究现状,以及流域模型构建,包括流域基础数据和模拟算法的选取、敏感性参数的分析和模型输出的验证.提出模型的应用研究存在3个问题:(1)模型模拟效率受到基础数据和主观因素的综合影响,而已有的成果参数选取缺乏可比性,大多侧重某个因素如何影响模型效率的研究.(2)流量是各种水文过程综合作用的结果,已有模型验证方法研究多是采用流域出口总径流量模拟效率来检验模型的适用性,这使得模型在水文过程模拟中缺乏可靠性.(3)模型应用研究主要进行土地覆被变化和气候波动的水文效应研究,且多是建立在虚拟情景和简化影响因素基础上.因此,在模型的应用研究上需要综合考虑影响因素,以提高模型模拟效率问题.展开更多
文摘The performance on prediction by mathematical models which represent the conceived image of a system such as hydrology is oftentimes represented through calibration and verification processes. Oftentimes a best fit between observed and predicted flows is obtained through correlation coefficient (R2) and the Nash Sutcliffe model efficiency (NSE) by minimizing the average Root Mean Square Error (RMSE) of the observed versus simulated flows. However, these days, a new paradigm is emerging wherein accounting for the flow variability for the protection of freshwater biodiversity and maintenance of goods and services that rivers provide is paramount. Therefore, from an ecohydrology perspective, it is not clear if the existing method of model calibration meets the needs of the riverine ecosystem at its best. Thus, this study investigates and proposes a methodology using entropy theory to gage the calibration of Soil and Water Assessment Tool (SWAT) from an ecohydrology perspective characterized by the natural flow-regime paradigm: Indicators of Hydrologic Alteration.
文摘Hydrological modeling plays a crucial role in efficiently managing water resources and understanding the hydrologic behavior of watersheds. This study aims to simulate daily streamflow in the Godavari River Basin in Maharashtra using the Soil and Water Assessment Tool (SWAT). SWAT is a process-based hydrological model used to predict water balance components, sediment levels, and nutrient contamination. In this research, we used integrated remote sensing and GIS data, including Digital Elevation Models (DEM), land use and land cover (LULC) maps, soil maps, and observed precipitation and temperature data, as input for developing the SWAT model to assess surface runoff in this large river basin. The Godavari River Basin under study was divided into 25 sub-basins, comprising 151 hydrological response units categorized by unique land cover, soil, and slope characteristics using the SWAT model. The model was calibrated and validated against observed runoff data for two time periods: 2003-2006 and 2007-2010 respectively. Model performance was assessed using the Nash-Sutcliffe efficiency (NSE) and the coefficient of determination (R2). The results show the effectiveness of the SWAT2012 model, with R2 value of 0.84 during calibration and 0.86 during validation. NSE values also ranged from 0.84 during calibration to 0.85 during validation. These findings enhance our understanding of surface runoff dynamics in the Godavari River Basin under study and highlight the suit-ability of the SWAT model for this region.
基金Under the auspices of Natural Science Foundation of Qinghai Province(No.2017-ZJ-961Q)National Natural Science Foundation of China(No.91125010,41530752)Scherer Endowment Fund of Department of Geography,Western Michigan University
文摘Interactions between surface water and groundwater are dynamic and complex in large endorheic river watersheds in Northwest China due to the influence of both irrigation practices and the local terrain. These interactions interchange numerous times throughout the middle reaches, making streamflow simulation a challenge in endorheic river watersheds. In this study, we modified the linear-reservoir groundwater module in SWAT(Soil and Water Assessment Tools, a widely used hydrological model) with a new nonlinear relationship to better represent groundwater processes; we then applied the original SWAT and modified SWAT to the Heihe River Watershed, the second largest endorheic river watershed in Northwest China, to simulate streamflow. After calibrating both the original SWAT model and the modified SWAT model, we analyzed model performance during two periods: an irrigation period and a non-irrigation period. Our results show that the modified SWAT model with the nonlinear groundwater module performed significantly better during both the irrigation and non-irrigation periods. Moreover, after comparing different runoff components simulated by the two models, the results show that, after the implementation of the new nonlinear groundwater module in SWAT, proportions of runoff components changed-and the groundwater flow had significantly increased, dominating the discharge season. Therefore, SWAT coupled with the non-linear groundwater module represents the complex hydrological process in the study area more realistically. Moreover, the results for various runoff components simulated by the modified SWAT models can be used to describe the hydrological characteristics of lowland areas. This indicates that the modified SWAT model is applicable to simulate complex hydrological process of arid endorheic rivers.
基金Under the auspices of National Natural Science Foundation of China(No.41171155,40801069)National Science and Technology Major Project of China:Water Pollution Control and Governance(No.2012ZX07505-003)
文摘Non-point source(NPS) pollution has become a major source of water pollution. A combination of models would provide the necessary direction and approaches designed to control NPS pollution through land use planning. In this study, NPS pollution load was simulated in urban planning, historic trends and ecological protection land use scenarios based on the Conversion of Land Use and its Effect at Small regional extent(CLUE-S) and Soil and Water Assessment Tool(SWAT) models applied to Hunhe-Taizi River Watershed, Liaoning Province, China. Total nitrogen(TN) and total phosphorus(TP) were chosen as NPS pollution indices. The results of models validation showed that CLUE-S and SWAT models were suitable in the study area. NPS pollution mainly came from dry farmland, paddy, rural and urban areas. The spatial distribution of TN and TP exhibited the same trend in 57 sub-catchments. The TN and TP had the highest NPS pollution load in the western and central plains, which concentrated the urban area and farm land. The NPS pollution load would increase in the urban planning and historic trends scenarios, and would be even higher in the urban planning scenario. However, the NPS pollution load decreased in the ecological protection scenario. The differences observed in the three scenarios indicated that land use had a degree of impact on NPS pollution, which showed that scientific and ecologically sound construction could effectively reduce the NPS pollution load in a watershed. This study provides a scientific method for conducting NPS pollution research at the watershed scale, a scientific basis for non-point source pollution control, and a reference for related policy making.
基金Primary funding for this work came from a USDA NRCS Conservation Innovation GrantThis work was also partially funded by the University of Michigan Graham Sustainability Instituteby the Great Lakes Restoration Initiative(administered by USEPA)through a NOAA-GLERL SOAR project.
文摘The Soil and Water Assessment Tool(SWAT)is widely used to relate farm management practices to their impacts on surface waters at the watershed scale,yet its smallest spatial unit is not generally defined by physically meaningful boundaries.The hydrologic response unit(HRU)is the smallest spatial unit of the model,and the standard HRU definition approach lumps all similar land uses,soils,and slopes within a subbasin based upon user-defined thresholds.This standard method provides an efficient way to discretize large watersheds where simulation at the field scale may not be computationally feasible.In relatively smaller watersheds,however,defining HRUs to specific spatial locations bounded by property lines or field borders would often be advantageous,yet this is not currently possible within the ArcSWAT interface.In this study,a simple approach is demonstrated that defines HRUs by field boundaries through addition of uniquely named soils to the SWAT user soil database and creation of a field boundary layer with majority land use and soil attributes.Predictions of nitrogen,phosphorus,and sediment losses were compared in a case study watershed where SWAT was set up using both the standard HRU definition and field boundary approach.Watershed-scale results were reasonable and similar for both methods,but aggregating fields by majority soil type masked extremely high soil erosion predicted for a few soils.Results from field-based HRU delineation may be quite different from the standard approach due to choosing a majority soil type in each farm field.This approach is flexible such that any land use and soil data prepared for SWAT can be used and any shapefile boundary can divide HRUs.
基金supported by the National Natural Science Foundation of China(Grants No.51569007 and 41301289)the Natural Science Foundation of Guangxi Province,China(Grant No.2015GXNSFCA139004)+1 种基金the Fund of the IRCK by UNESCO(Grant No.KDL201601)the Project of High Level Innovation Team and Outstanding Scholar in Guangxi Colleges and Universities(Grant No.002401013001)
文摘Although many sensitivity analyses using the soil and water assessment tool(SWAT) in a complex watershed have been conducted, little attention has been paid to the application potential of the model in unique plots. In addition, sensitivity analysis of percolation and evapotranspiration with SWAT has seldom been undertaken. In this study, SWAT99.2 was calibrated to simulate water balance components for unique plots in Southern China from 2000 to 2001, which included surface runoff, percolation, and evapotranspiration. Twenty-one parameters classified into four categories, including meteorological conditions, topographical characteristics, soil properties, and vegetation attributes, were used for sensitivity analysis through one-at-a-time(OAT) sampling to identify the factor that contributed most to the variance in water balance components. The results were shown to be different for different plots, with parameter sensitivity indices and ranks varying for different water balance components. Water balance components in the broad-leaved forest and natural grass plots were most sensitive to meteorological conditions, less sensitive to vegetation attributes and soil properties, and least sensitive to topographical characteristics. Compared to those in the natural grass plot, water balance components in the broad-leaved forest plot demonstrated higher sensitivity to the maximum stomatal conductance(GSI) and maximum leaf area index(BLAI).
文摘将SWAT(Soil and Water Assessment Tool)模型应用于库区大尺度流域的污染模拟研究,对其进行适用性评价及模拟应用分析。模型校验采用的是2002—2008年的水文月数据及水质水期数据,径流模拟效果最好,评价指标ENS(Nash-Suttclife Efficiency)均在0.9以上;泥沙模拟评价指标ENS在0.46~0.9;营养盐模拟评价指标ENS个别出现了〈0.36的情况,但总体模拟效果满足要求。应用SWAT模型对库区降水与地表产流、产沙、营养盐负荷进行了研究。结果表明:库区地表产流与降水的相关性趋势最好;地表产沙与产流、降水的总体趋势一致,但偶尔出现4、5月份地表产沙先于产流出现峰值的情况,这可能是由于春耕对地表扰动后又逢较强降水引起的水土流失;营养盐污染负荷尤其是TP的峰值趋势与地表产流相比,更接近地表产沙趋势。本文还对库区不同土地利用类型的污染负荷做了分析,得到各类土地利用类型的年均污染负荷总量排序及单位面积污染负荷,再次验证了SWAT模型在三峡库区流域的适用性。根据分析结果,库区耕地为非点源污染产出的主要源头,可将耕地耕种措施转变及土地利用类型转换作为库区非点源污染削减的重要手段。
文摘应用SWAT(Soil and Water Assessment Tool)分布式水文模型对汉江流域1971—2000年30年逐月径流进行了模拟。结果表明:模型模拟精度高于评价标准(模拟效率Ens>0.5,相关系数r2>0.6),SWAT模型适用于汉江流域的径流模拟;水量平衡各要素中,30年月、年平均蒸散发量、地表径流量、土壤对地下水补给量、土壤含水变化量、地下水侧流量分别占降水量的55.97%、25.88%、17.64%、0.26%、0.25%,蒸散发是该流域水量的主要输出项;各月30年平均降水量变化趋势与地表径流量变化趋势较一致,而与基流量变化趋势一致性较差;30年流域降水量年变化趋势与地表径流量、基流量的变化趋势较一致;30年月、年地表径流量对降水的响应程度高于基流。
文摘生态环境问题受到了日益广泛的关注,生态恢复也在各地蓬勃开展,但生态恢复工程的开展迫切需要相关理论研究的指导。采用假定生态恢复情景的方法,在遥感和地理信息系统的支持下,利用分布式水文模型SWAT(Soil and Water Assessment Tool)对陇西黄土高原的典型流域——华家岭南河流域进行了多种生态恢复情景模型的设计,并模拟了不同生态恢复情景下径流和蒸散发的响应情况。得出:在南河流域草地比森林植被涵养水源的作用更强,模拟年均径流深比林地低9.1%,而蒸散发却高2.2%,所以南河流域生态恢复过程中种草是十分必要的。结果同时表明,应用SWAT模型进行流域尺度的生态恢复水文响应研究是可行高效的。
文摘为解决地形复杂区域因无法及时获取数据而影响旱灾监测的问题,该研究以湖北省清江流域中上游为例,基于具有较强物理机制的分布式水文模型(soil and water assessment tool,SWAT),建立作物水分亏缺指数进行农业旱情监测,其中,利用该流域的土地覆被、土壤、地形、气象以及2003-2005年和2007-2010年水文观测数据构建了流域SWAT模型,模拟作物水分亏缺指数的有关参量,包括潜在蒸散量和降水量。研究结果表明:1)SWAT模型模拟的潜在蒸散量与气象数据计算得到的潜在蒸散量拟合相关度达到97%以上;2)与标准化降水指数监测结果进行对比,基于SWAT模型建立的作物水分亏缺指数能够从机理方面客观反映监测区域作物生长期的受旱程度,有效实现了流域尺度的旱灾监测,克服了复杂地形区利用少数气象站点建立气象干旱指标评价旱情的局限性。该研究可为复杂地形区旱灾评估提供可行途径。
文摘分析国内外应用SWAT(Soil and Water Assessment Tool)模型模拟流域径流的研究现状,以及流域模型构建,包括流域基础数据和模拟算法的选取、敏感性参数的分析和模型输出的验证.提出模型的应用研究存在3个问题:(1)模型模拟效率受到基础数据和主观因素的综合影响,而已有的成果参数选取缺乏可比性,大多侧重某个因素如何影响模型效率的研究.(2)流量是各种水文过程综合作用的结果,已有模型验证方法研究多是采用流域出口总径流量模拟效率来检验模型的适用性,这使得模型在水文过程模拟中缺乏可靠性.(3)模型应用研究主要进行土地覆被变化和气候波动的水文效应研究,且多是建立在虚拟情景和简化影响因素基础上.因此,在模型的应用研究上需要综合考虑影响因素,以提高模型模拟效率问题.