Estimation of Soil Erosion and Sediment Yield Using GIS at Catchment Scale

A GIS-based method has been applied for the determination of soil erosion and sediment yield in a small watershed in Mun River basin, Thailand. The method involves spatial disintegration of the catchment into homogenous grid cells to capture the catchment heterogeneity. The gross soil erosion in each cell was calculated using Universal Soil Loss Equation (USLE) by carefully determining its various parameters. The concept of sediment delivery ratio is used to route surface erosion from each of the discritized cells to the catchment outlet. The process of sediment delivery from grid cells to the catchment outlet is represented by the topographical characteristics of the cells. The effect of DEM resolution on sediment yield is analyzed using two different resolutions of DEM. The spatial discretization of the catchment and derivation of the physical parameters related to erosion in the cell are performed through GIS techniques.     

GIS Based Estimation of Sediment Discharge and Areas of Soil Erosion and Deposition for the Torrential Lukovska River Catchment in Serbia

In the present study the SHETRAN river basin modelling system was used in conjunction with Geographic Information System (GIS) to estimate potential erosion and deposition rates within the catchment and the concentrations of sediment in a flow at the catchment outlet on the example of the 114.31 km² mountainous torrential Lukovska River catchment in Serbia. The streams in the Lukovska River catchment are short, steep and often produce hazardous torrential floods as a consequence of strong rainfall of short duration. The soil erosion and sediment discharge were analysed in view of the catchment response to physical characteristics of the catchment. Considering that the most of total annual sediment discharge in watersheds of torrential character is achieved during storm events, the SHETRAN modelling system was calibrated on the example of a storm event in 1986 and validated for three other storm events in 1974, 1976 and 1979. The simulated results of discharges and sediment concentrations at the catchment outlet for both calibration and validation events were compared with the observed data and found to be reasonable. The changes of erosion and deposition rates within the catchment and in the course of time were estimated for the calibration event in 1986. The simulated erosion rates were within the range of 1 to 10.5 t/ha and corresponded to the observed rates of erosion in Europe during extreme rain events. The presented methodology is useful in identifying the erosion vulnerable regions in a catchment where erosion control measures should be implemented.     

Finite Element Method and GIS Based Distributed Model for Soil Erosion and Sediment Yield in a Watershed

The objective of this study is to develop a soil erosion and sediment yield model based on the kinematic wave approximation using the finite element method, remote sensing and geographical information system (GIS) for calculating the soil erosion and sediment yield in a watershed. Detachment of soil particles by overland flow occurs when the shear stress at the surface overcomes the gravitational forces and cohesive forces on the particles. Deposition occurs when the sediment load is greater than the transport capacity. Beasley et al.’s (Trans ASAE 23:938–944, 1980) transport equations for laminar and turbulent flow conditions are used to calculate the transport capacity. The model is capable of handling distributed information about land use, slope, soil and Manning’s roughness. The model is applied to the Catsop watershed in the Netherlands and the Harsul watershed in India. Remotely sensed data has been used to extract land use/land cover map of the Harsul watershed, and other thematic maps are generated using the GIS. The simulated results for both calibration and validation events are compared with the observed data for the watersheds and found to be reasonable. Statistical evaluation of model performance has been carried out. Further, a sensitivity analysis has also been carried out to study the effect of variation in model parameter values on computed volume of sediment, peak sediment and the time to peak sediment. Sensitivity analysis has also been carried out for grid size variation and time step variation of the Catsop watershed. The proposed model is useful in predicting the hydrographs and sedigraphs in the agricultural watersheds.     

Estimation of Soil Erosion for a Himalayan Watershed Using GIS Technique

The fragile ecosystem of the Himalayas has been an increasing cause of concern to environmentalists and water resources planners. The steep slopes in the Himalayas along with depletedforest cover, as well as high seismicity have been major factors in soil erosion and sedimentation in river reaches. Prediction ofsoil erosion is a necessity if adequate provision is to be madein the design of conservation structures to offset the ill effects of sedimentation during their lifetime.In the present study, two different soil erosion models, i.e. theMorgan model and Universal Soil Loss Equation (USLE) model, have been used to estimate soil erosion from a Himalayan watershed.Parameters required for both models were generated using remotesensing and ancillary data in GIS mode. The soil erosion estimated by Morgan model is in the order of 2200 t km^-2 yr^-1 and is within the limits reported for this region.The soil erosion estimated by USLE gives a higher rate. Therefore, for the present study the Morgan model gives, for area located in hilly terrain, fairly good results.     

Modelling Watershed Scale Soil Loss Prediction and Sediment Yield Estimation

Computer simulation models are becoming increasingly popular in predicting soil loss for various land use and management practices. A GIS-based system, GeoUSLE, was developed in this study for soil loss prediction and sediment yield estimation in the watershed scale. The Universal Soil Loss Equation (USLE) and watershed analysis models are incorporated in the system. The required watershed information and USLE factors are derived from digital elevation models (DEMs) and remote sensing data. The GIS-based system can flexibly delineate drainage networks and watersheds and rapidly query the sediment yield at any point or watershed outlet via the point-and-click interface. The study presents an example application of the system to an agricultural reservoir watershed in central Taiwan. The estimated result shows that the developed system scales up USLE applications from the slope to the watershed, which can be used to assess the erosion hot spots in a watershed for the management decision making.     

RUSLE2 Model Application for Soil Erosion Assessment Using Remote Sensing and GIS

The study is focused on the estimation of rate of soil erosion, using Revised Universal Soil Loss Eq. 2 (RUSLE2), in the Veppanapalli subwatershed of Krishnagiri catchment located in Tamil Nadu, India. The soil erosion is estimated for each of the hillslope units in the study area. The factors considered are intensity of rainfall, type of soil, land use classification and the existing soil conservation practices. Detailed analysis of soil samples were done to assess the texture, structure, permeability and organic matter content of the soil samples of each hillslope unit. The required data for the other parameters were estimated by carrying out intense field investigations and by the analysis of the satellite imagery of 5.6 m resolution. A data base was created with all the subfactor values for the hillslope units. Incorporation of remote sensing technique and Geographic Information System (GIS) made the spatial analysis of the study more reliable and accurate. The annual average soil erosion rate is estimated as 25 t/ha/year, which is on a higher range. This indicates the immediate need for the adoption of proper conservation strategies in this area to control the eutrophication in the Krishnagiri reservoir and to prevent further watershed degradation.     

Estimation of Soil Erosion and Sediment Yield During Individual Rainstorms at Catchment Scale

Lushi basin, named after the Lushi County, is one of the sub-basins of the Yellow River basin in China. The basin is suffering from severe soil erosion problems, especially during the “wet” season. In order to identify the proper soil management approaches for the basin, an erosion model is designed to estimate the soil erosion and sediment yield during single events. The hydrological model used for the estimations in the study is the BTOPMC model, which is developed based on the TOPMODEL. Under the model structure of BTOPMC, a modified form of the Universal Soil Loss Equation (USLE) was incorporated as a core module of the erosion component. In the modification, the runoff ratio, an important determinant of soil erosion, was brought into the USLE equation and consequent modifications were made to the soil erodibility and slope length factors. A concept of total sediment transport capacity for single events is applied in the model to route the surface erosion from each discrete cell to the basin outlet. The BTOPMC model was used in simulating the river discharges and sediment yields for 29 events in the Lushi basin. Its acceptable performance validates the model’s predictive ability in simulating the basin-scale erosions during individual rainstorms.     

侵蚀产沙模型研究进展和GIS应用

近年来随着地理信息系统 (GIS)技术的发展 ,侵蚀产沙模型与GIS的结合成为必然 ;作者阐述了近年来国际上流行的基于GIS的侵蚀产沙模型 :RUSLE、WEPP、ANSWERS等模型的主要内容、特点及适用范围 ,并对我国以陡坡为代表基于GIS的侵蚀产沙模型进行了介绍和评述 ;提出了目前侵蚀产沙模拟研究中存在的主要问题 ,并对基于GIS的侵蚀产沙模型的研究工作进行了展望。能反映侵蚀产沙时空过程的、基于GIS的分布式侵蚀产沙模型成为研究的重点     

Integrated Water Resource Development Plan for Sustainable Management of Mayurakshi Watershed, India using Remote Sensing and GIS

Integrated watershed management requires a host of inter-related information to be generated and studied in relation to each other. Remote sensing technique provides valuable and up-to-date spatial information on natural resources and physical terrain parameters. Geographical Information System (GIS) with its capability of integration and analysis of spatial, aspatial, multi-layered information obtained in a wide variety of formats both from remote sensing and other conventional sources has proved to be an effective tool in planning for watershed development. In this study, area and locale specific watershed development plans were generated for Mayurakshi watershed, India using remote sensing and GIS techniques. Adopting Integrated Mission for Sustainable Development (IMSD) guidelines, decision rules were framed. Using the overlay and decision tree concepts water resource development plan was generated. Indian Remote Sensing Satellite (IRS-1C), Linear Imaging Self Scanner (LISS-III) satellite data along with other field and collateral data on lithology, soil, slope, well inventory, fracture have been utilized for generating land use/land cover and hydro geomorphology of the study area, which are an essential prerequisites for water resources planning and development. Spatial data integration and analyses are carried out in GIS environment.     

Watershed Management Technique to Control Sediment Yield in Agriculturally Dominated Areas

Abstract

Non-point source pollution is recognized internationally as a critical environmental problem. In Illinois, soil erosion from agricultural lands is the major source of such pollution. The erosion process, which has been accelerated by human activity, tends to reduce crop productivity and leads to subsequent problems from deposition on farmlands and in water bodies. Comprehensive watershed management, however, can be used to protect these natural resources. In this study, a discrete time optimal control methodology and computational model are developed for determining land use and management alternatives that minimize sediment yield from agriculturally-dominated watersheds. The solution methodology is based on an interface between a genetic algorithm and the U.S. Department of Agriculture's Soil and Water Assessment Tool. Model analyses are performed on a farm field basis to allow capture of different, local stakeholder perspectives, and crop management alternatives are based on a three-year rotation pattern. The decision support tool is applied to the Big Creek watershed located in the Cache River basin of Southern Illinois. The application demonstrates that the methodology is a valuable tool in advancing comprehensive watershed management. The study represents part of an ongoing research effort to develop an even more comprehensive decision support tool that uses multi-criteria evaluation to address social, economic, and hydrologic issues for integrative watershed management.     

Soil Erosion Assessment in a Hilly Catchment of North Eastern India Using USLE, GIS and Remote Sensing

In the present study, soil erosion assessment of Dikrong river basin of Arunachal Pradesh (India) was carried out. The river basin was divided into 200 × 200 m grid cells. The Arc Info 7.2 GIS software and RS (ERDAS IMAGINE 8.4 image processing software) provided spatial input data and the USLE was used to predict the spatial distribution of the average annual soil loss on grid basis. The average rainfall erositivity factor (R) for Dikrong river basin was found to be 1,894.6 MJ mm ha⁻¹ h⁻¹ year⁻¹. The soil erodibility factor (K) with a magnitude of 0.055 t ha h ha⁻¹ MJ⁻¹ mm⁻¹ is the highest, with 0.039 t ha h ha⁻¹ MJ⁻¹ mm⁻¹ is the least for the watershed. The highest and lowest value of slope length factor (LS) is 53.5 and 5.39 respectively for the watershed. The highest and lowest values of crop management factor (C) were found out to be 0.004 and 1.0 respectively for the watershed. The highest and lowest value of conservation factor (P) were found to be 1 and 0.28 respectively for the watershed. The average annual soil loss of the Dikrong river basin is 51 t ha⁻¹ year⁻¹. About 25.61% of the watershed area is found out to be under slight erosion class. Areas covered by moderate, high, very high, severe and very severe erosion potential zones are 26.51%, 17.87%, 13.74%, 2.39% and 13.88% respectively. Therefore, these areas need immediate attention from soil conservation point of view.     

基于遥感和GIS的流域社会经济数据空间化方法研究

人口和社会经济数据及其空间分布,在资源、环境及自然灾害评估中的重要性已被广泛认知。把遥感和GIS技术相结合,是探讨解决社会经济统计数据空间化的重要思路。以东江流域为例,以多期人口、GDP、土地利用数据为基础,建立东江流域人口与土地利用、GDP和土地利用的多元线性回归模型;以土地利用数据和100 m×100 m网格数据为基础,构建东江流域人口和GDP空间分布约束力指标图层;然后结合统计模型和面积内插,实现了东江流域2009年人口、GDP统计数据的空间化。在县域空间尺度上对模拟结果进行了验证,与同尺度研究工作进行了对比,结果显示模拟得到的人口和GDP空间分布数据,与同尺度的研究工作处于同一精度或者略高的精度水平,表明该方法是一种进行流域社会经济数据空间化处理的有效方法。     

径流侵蚀功率理论在不同尺度坡面侵蚀产沙中的应用

基于次暴雨洪水过程中径流深、洪峰流量模数2个的重要水文特征参数,提出了用以描述坡面次暴雨水蚀动力的径流侵蚀功率的概念,并以岔巴沟流域团山沟不同空间尺度径流场历年实测次暴雨径流泥沙资料为基础,分析了径流侵蚀功率与坡面径流场次暴雨侵蚀模数之间的相关性,提出了适用于坡面次暴雨侵蚀产沙计算的基于径流侵蚀功率的坡面次暴雨水沙响应关系.研究结果表明:径流侵蚀功率与坡面次暴雨侵蚀模数之间存在极显著的幂函数相关关系,径流侵蚀功率可以较好地表征坡面次暴雨水力侵蚀动力.本研究成果可为黄土高原坡面次暴雨侵蚀产沙模型侵蚀动力因子的确定提供参考.     

Integrating Remote Sensing and GIS Techniques with Groundwater Flow Modeling for Assessment of Waterlogged Areas

False Colour Composites (FCC's) of IRS-1A LISS-II sensor pertaining to the dates 9th April 1989 and 7th December 1989 are used to delineate the pre-monsoon and post-monsoon surface waterlogged areas in a region around Habibpur sub-distributary bounded by Vaishali branch canal and Gandak river in North Bihar, India for the year 1989 using visual interpretation technique. Also, digital data of IRS-1C LISS-III sensor pertaining to the dates 7th December 1998 and 6th April 1999 are analyzed in a digital image processing software – ERDAS Imagine 8.3.1, to delineate the pre-monsoon and post-monsoon surface waterlogged areas for the year 1998–1999. Further, for the study area, the waterlogging conditions are delineated for the year 1991–1992 using the groundwater flow modeling software package, MODFLOW. The results obtained using satellite remote sensing data and groundwater flow modeling are integrated in a GIS environment in ERDAS Imagine for assessment of the waterlogging areas.     

基于RS的滦河山区土壤侵蚀调查

滦河山区是京津地区的重要生态屏障,其中的潘大水库更是天津、唐山两市的供水水源地.随着人口不断增加和经济社会的发展,水土流失情况日益严重.利用遥感技术与地理信息系统技术,结合野外实地调查,对不同土地利用类型和不同植被覆盖上的土壤侵蚀的空间分布及其大小进行了定量分析,为将来开展该区域的水土保持规划和治理工作提供参考.     

Multi-Criteria Decision Making Approach for Watershed Prioritization Using Analytic Hierarchy Process Technique and GIS

Watershed prioritization based on the natural resources and physical processes involves locating critical areas of erosion, which produce maximum sediment yield to take up conservation activities on priority basis. The present study was taken up with a specific objective of prioritization of micro-watersheds using Multi-Criteria Decision Approach – Analytic Hierarchy Process (AHP) based SYI model (AHPSYI) under GIS environment for a case study area of Mayurakshi watershed in India. This method basically uses information of Potential Erosion Index (PEI) and Sediment Delivery Ratio (SDR), indicative of transport capacity. In the present study, sediment delivery factors viz., topography, vegetation cover, proximity to water courses and soil were translated into GIS layers and integrated using Boolean conditions to create a data layer of spatially distributed SDIs’ across the watershed. For assessment of PEI, important watershed parameters viz., land use/land cover, soil, slope, and drainage density maps were integrated in the GIS environment using Weighted Linear Combination method (WLC) by assigning weights to themes and ranks to features of individual theme using AHP technique. A comparison between AHPSYI based sub watershed prioritization map with that of prioritization map based on the observed sediment yield data revealed that about 78 % of the area showed concurrence. Thus, it can be inferred that the watershed prioritization based on only thematic layers can be dependable to maximum extent. Subsequently, proposed approach was adopted for prioritization of the study area at micro watershed scale, where area under high and very high categories together constitutes around 33 % of the study area. Around 100 micro-watersheds out of 276 watersheds are under moderate to very high category respectively, signifying the need for watershed management.     

花瓶沟水库泥沙淤积分析及小流域水土流失治理思路

通过对花瓶沟水库泥沙淤积观测资料分析,阐述了花瓶沟流域产沙量与降雨因素关系及水库淤积特点,提出了山区水土保持综合治理思路及花瓶沟水库控制运用要求。     

Runoff and Sediment Yield Modelling for a Treated Hilly Watershed in Eastern Himalaya Using the Water Erosion Prediction Project Model

The Water Erosion Prediction Project (WEPP) watershed model was calibrated and validated for a hilly watershed treated with graded bunding and water-harvesting tank in high rainfall condition of eastern Himalayan range in India. The performance of the model for the treated watershed was unacceptable with percent deviation of −45.81 and −38.35 respectively for runoff and sediment yield simulations when calibrated parameter values for the nearby untreated watershed were used. This was possibly due to differences in soil properties and average land slope. When soil parameters were calibrated for the treated watershed, the model performance improved remarkably. During calibration, the model simulated surface runoff and sediment yield with percent deviations equal to +6.24 and +9.02, and Nash–Sutcliffe simulation coefficients equal to 0.85 and 0.81, respectively. During validation period, the model simulated runoff and sediment yield with percent deviations equal to +8.56 and +9.36, and Nash–Sutcliffe simulation coefficients equal to 0.81 and 0.80, respectively. The model tended to slightly under-predict runoff and sediment yield of higher magnitudes. The model performance was quite sensitive to soil parameters namely, rill erodibility, interrill erodibility, hydraulic conductivity, critical shear stress and Manning’s roughness coefficient with varying levels. The WEPP model picked up the hydrology associated with bund and water-harvesting tank, and simulated runoff and sediment yield well with overall deviations within ±10% and Nash–Sutcliffe simulation coefficients >0.80. Simulation results indicate that in high slope and high rainfall conditions of eastern Himalayan region of India where vegetative measures are not adequate to restrict soil loss within the permissible limit, the WEPP model can be applied to formulate structure-based management strategies to control soil loss and to develop water resources.     

辽河各水沙来源区对下游泥沙沉积的影响

以辽河中下游有关水文站年系列资料为基础,运用泥沙收支平衡法,研究辽河中下游泥沙时空分布,结果表明：巨流河至六间房河段为辽河中下游强烈沉积区。运用统计学方法,研究巨流河-六间房河段泥沙沉积量与上游不同水沙来源区水沙量相关关系。分析结果表明：辽河下游巨流河-六间房河段沉积量与辽河支流柳河产沙区产沙量具有较好的相关关系,柳河产沙量的变化对辽河下游河道泥沙沉积量的变化起着主要的控制作用,且柳河汛期单位来水来沙量较全年单位来水来沙量对辽河下游沉积量的贡献率更大。因此,为缓解辽河下游河道沉积问题,柳河水土流失的治理亟待加强。     

山西土壤侵蚀与泥沙特征分析探讨

文中分析了山西自然地理因素对土壤侵蚀的影响，同时对河流泥沙特征、分布规律、时空变化等方面进行了探讨。