Morphometric analysis is an indispensable tool for hydrological investigation that involves the development and management of drainage basin. This study characterizes the micro watersheds in the Palar sub-watershed us...Morphometric analysis is an indispensable tool for hydrological investigation that involves the development and management of drainage basin. This study characterizes the micro watersheds in the Palar sub-watershed using morphometric analysis and assesses its risk by land use and land cover features in a particular micro watershed. Palar sub-watershed is divided into 6 micro watersheds for prioritization based on morphometric and land use analysis. Several morphometric parameters(linear, shape and relief)are determined from the drainage map; ranks are assigned based on their capacity to induce erodability and degradation. Final ranking is based on the composite index calculated from the sum of the ranks of each morphometric parameter. Morphometric analysis reveals micro watersheds 5 and 6 as most susceptible and 2 and 3 as low susceptible. Land use is mapped using IRS ID LISS III satellite data. The risk in terms of watershed degradation involved to each micro watershed is based on the ranks of each land use feature, obtained from a similar composite index as that of morphometric analysis. Land use analysis shows that micro watersheds 2 and 4 fall under high priority category while 5 and 6 under low priority category. Integration of the morphometric and land use analysis shows that only micro watershed 1 falls under the same category in both analyses. Control measures are suggested to contain degradation depending on its specific land use pattern and morphometric features. This study can be used to prepare a comprehensive watershed plan for the development or for planning resource conservation strategies, by integrating land use features with the drainage characteristics of the region, in particular for a hill ecosystem as the prioritization is at micro level.展开更多
Determining the relatively similar hydrological properties of the watersheds is very crucial in order to readily classify them for management practices such as flood and soil erosion control. This study aimed to ident...Determining the relatively similar hydrological properties of the watersheds is very crucial in order to readily classify them for management practices such as flood and soil erosion control. This study aimed to identify homogeneous hydrological watersheds using remote sensing data in western Iran. To achieve this goal, remote sensing indices including SAVI, LAI, NDMI, NDVI and snow cover, were extracted from MODIS data over the period 2000 to 2015. Then, a fuzzy method was used to clustering the watersheds based on the extracted indices. A fuzzy c-mean(FCM) algorithm enabled to classify 38 watersheds in three homogeneous groups.The optimal number of clusters was determined through evaluation of partition coefficient, partition entropy function and trial and error. The results indicated three homogeneous regions identified by the fuzzy c-mean clustering and remote sensing product which are consistent with the variations of topography and climate of the study area. Inherently,the grouped watersheds have similar hydrological properties and are likely to need similar management considerations and measures.展开更多
[Objective] The aim was to simulate the surface water flow of Dalinghe watershed based on SRTM DEM.[Method] By using ArcGIS ModelBuilder,and SRTM DEM data of Dalinghe watershed as input data,the model to simulate the ...[Objective] The aim was to simulate the surface water flow of Dalinghe watershed based on SRTM DEM.[Method] By using ArcGIS ModelBuilder,and SRTM DEM data of Dalinghe watershed as input data,the model to simulate the water flow of Dalinghe watershed was set up.[Result] The model realized automatic division of Dalinghe watershed area and extraction of stream network.In the meantime,it also made the choice of threshold during filling DEM and extracting stream network much easier.The division of the Dalinghe watershed was precise and the extraction result of Dalinghe and its corresponding level Ⅰ tributary river was close to actual stream network.However,the extraction of the smaller stream was less accurate.[Conclusion] The study provided scientific reference for the simulation of surface water network in future.展开更多
在贵州喀斯特地区,地表径流通过土壤裂隙、岩溶管道等途径流失,限制了地表径流的形成。文章以龙里羊鸡冲小流域为研究区,基于2013-2019年的实测数据,修正SWAT(Soil and Water Assessment Tool)模型的裂隙流模块,修改了裂缝入渗的表示方...在贵州喀斯特地区,地表径流通过土壤裂隙、岩溶管道等途径流失,限制了地表径流的形成。文章以龙里羊鸡冲小流域为研究区,基于2013-2019年的实测数据,修正SWAT(Soil and Water Assessment Tool)模型的裂隙流模块,修改了裂缝入渗的表示方法,对修正前后的日径流模拟进行对比分析。结果表明:率定期内纳什系数由0.32提升到0.60,决定系数由提高0.37提升到0.58。在验证期内,纳什系数由0.52提高到0.55,决定系数由0.56提高到0.60,修正后的模型与原模型相比具有更好的适用性。修正后模型的径流时间序列与实测数据更吻合,能合理估算研究区的入渗水量,为喀斯特小流域的水资源管理提供参考依据。展开更多
This paper presents the study carried out for controlling agricultural non-point source pollution(NSP)in a medium-sized watershed covering 1.47×10^(4) km^(2) in Southeast China using quantitative analysis coupled...This paper presents the study carried out for controlling agricultural non-point source pollution(NSP)in a medium-sized watershed covering 1.47×10^(4) km^(2) in Southeast China using quantitative analysis coupled with geographic information system(GIS),universal soil loss equation(USLE),soil conservation service-curve number(SCS-CN),nutrient loss equations,and annualized agricultural nonpoint source model(AnnAGNPS).Based on the quantitative results derived from GIS and environmental models,five control division units were generated for NSP control in Jiulong River watershed,namely,controlling unit for soil losses,controlling unit for livestock breeding and soil losses,controlling unit for excessive fertilizer use and livestock breeding,controlling unit for soil losses and fertilizer use,and controlling unit for excessive fertilizer use and soil losses.This study proved that integrating GIS with environmental models can be adopted to efficiently evaluate major sources and contributors of NSP,and identify the critical source areas of NSP,which enables adjusting measures to local conditions by further control division units developed through such study for control and management of water quality degradation induced by NSP in the Jiulong River watershed.展开更多
We set up two experimental catchments to provide an improved understanding of hydrological processes in a subtropical forested area in the northern part of Okinawa Island, Japan. We calculated runoff using water level...We set up two experimental catchments to provide an improved understanding of hydrological processes in a subtropical forested area in the northern part of Okinawa Island, Japan. We calculated runoff using water level data (recorded by a pressure-type water level gauge installed in a box culvert) and a discharge rating curve (derived from in situ observations). Water balance calculations for 2010 showed that the rainfall, runoff and evapotranspiration losses (= rainfall – runoff) were 3403.6 mm, 2285.7 mm and 1117.4 mm, respectively. This result was in agreement with previous results from other forested experimental catchments in this region. Direct runoff, as a proportion of event total rainfall, can be expressed by the empirical equation (Qdirect = 0.0048, Pevent 1.7971, R2 = 0.9599). When Pevent was 100 mm or less, the ratios of Qdirect to Pevent were less than 15% in general. When Pevent exceeded 100 mm, the ratios were 20% - 30%.展开更多
文摘Morphometric analysis is an indispensable tool for hydrological investigation that involves the development and management of drainage basin. This study characterizes the micro watersheds in the Palar sub-watershed using morphometric analysis and assesses its risk by land use and land cover features in a particular micro watershed. Palar sub-watershed is divided into 6 micro watersheds for prioritization based on morphometric and land use analysis. Several morphometric parameters(linear, shape and relief)are determined from the drainage map; ranks are assigned based on their capacity to induce erodability and degradation. Final ranking is based on the composite index calculated from the sum of the ranks of each morphometric parameter. Morphometric analysis reveals micro watersheds 5 and 6 as most susceptible and 2 and 3 as low susceptible. Land use is mapped using IRS ID LISS III satellite data. The risk in terms of watershed degradation involved to each micro watershed is based on the ranks of each land use feature, obtained from a similar composite index as that of morphometric analysis. Land use analysis shows that micro watersheds 2 and 4 fall under high priority category while 5 and 6 under low priority category. Integration of the morphometric and land use analysis shows that only micro watershed 1 falls under the same category in both analyses. Control measures are suggested to contain degradation depending on its specific land use pattern and morphometric features. This study can be used to prepare a comprehensive watershed plan for the development or for planning resource conservation strategies, by integrating land use features with the drainage characteristics of the region, in particular for a hill ecosystem as the prioritization is at micro level.
文摘Determining the relatively similar hydrological properties of the watersheds is very crucial in order to readily classify them for management practices such as flood and soil erosion control. This study aimed to identify homogeneous hydrological watersheds using remote sensing data in western Iran. To achieve this goal, remote sensing indices including SAVI, LAI, NDMI, NDVI and snow cover, were extracted from MODIS data over the period 2000 to 2015. Then, a fuzzy method was used to clustering the watersheds based on the extracted indices. A fuzzy c-mean(FCM) algorithm enabled to classify 38 watersheds in three homogeneous groups.The optimal number of clusters was determined through evaluation of partition coefficient, partition entropy function and trial and error. The results indicated three homogeneous regions identified by the fuzzy c-mean clustering and remote sensing product which are consistent with the variations of topography and climate of the study area. Inherently,the grouped watersheds have similar hydrological properties and are likely to need similar management considerations and measures.
文摘[Objective] The aim was to simulate the surface water flow of Dalinghe watershed based on SRTM DEM.[Method] By using ArcGIS ModelBuilder,and SRTM DEM data of Dalinghe watershed as input data,the model to simulate the water flow of Dalinghe watershed was set up.[Result] The model realized automatic division of Dalinghe watershed area and extraction of stream network.In the meantime,it also made the choice of threshold during filling DEM and extracting stream network much easier.The division of the Dalinghe watershed was precise and the extraction result of Dalinghe and its corresponding level Ⅰ tributary river was close to actual stream network.However,the extraction of the smaller stream was less accurate.[Conclusion] The study provided scientific reference for the simulation of surface water network in future.
文摘在贵州喀斯特地区,地表径流通过土壤裂隙、岩溶管道等途径流失,限制了地表径流的形成。文章以龙里羊鸡冲小流域为研究区,基于2013-2019年的实测数据,修正SWAT(Soil and Water Assessment Tool)模型的裂隙流模块,修改了裂缝入渗的表示方法,对修正前后的日径流模拟进行对比分析。结果表明:率定期内纳什系数由0.32提升到0.60,决定系数由提高0.37提升到0.58。在验证期内,纳什系数由0.52提高到0.55,决定系数由0.56提高到0.60,修正后的模型与原模型相比具有更好的适用性。修正后模型的径流时间序列与实测数据更吻合,能合理估算研究区的入渗水量,为喀斯特小流域的水资源管理提供参考依据。
基金The authors acknowledge the government of Fujian province,China,for providing financial assistance to conduct this study(Grant No.2002H009).
文摘This paper presents the study carried out for controlling agricultural non-point source pollution(NSP)in a medium-sized watershed covering 1.47×10^(4) km^(2) in Southeast China using quantitative analysis coupled with geographic information system(GIS),universal soil loss equation(USLE),soil conservation service-curve number(SCS-CN),nutrient loss equations,and annualized agricultural nonpoint source model(AnnAGNPS).Based on the quantitative results derived from GIS and environmental models,five control division units were generated for NSP control in Jiulong River watershed,namely,controlling unit for soil losses,controlling unit for livestock breeding and soil losses,controlling unit for excessive fertilizer use and livestock breeding,controlling unit for soil losses and fertilizer use,and controlling unit for excessive fertilizer use and soil losses.This study proved that integrating GIS with environmental models can be adopted to efficiently evaluate major sources and contributors of NSP,and identify the critical source areas of NSP,which enables adjusting measures to local conditions by further control division units developed through such study for control and management of water quality degradation induced by NSP in the Jiulong River watershed.
文摘We set up two experimental catchments to provide an improved understanding of hydrological processes in a subtropical forested area in the northern part of Okinawa Island, Japan. We calculated runoff using water level data (recorded by a pressure-type water level gauge installed in a box culvert) and a discharge rating curve (derived from in situ observations). Water balance calculations for 2010 showed that the rainfall, runoff and evapotranspiration losses (= rainfall – runoff) were 3403.6 mm, 2285.7 mm and 1117.4 mm, respectively. This result was in agreement with previous results from other forested experimental catchments in this region. Direct runoff, as a proportion of event total rainfall, can be expressed by the empirical equation (Qdirect = 0.0048, Pevent 1.7971, R2 = 0.9599). When Pevent was 100 mm or less, the ratios of Qdirect to Pevent were less than 15% in general. When Pevent exceeded 100 mm, the ratios were 20% - 30%.
