In this cyber era of innumerable number of Geographical Information System (GIS) packages and functionalities, the problem faced by the users from different research domains are different from each other’s. They require technical skill and expertise on this advanced software. The ready to use GIS packages may not have the exact functionality required by the user or the functionality, being part of commercial package comes at very high cost. These limitations have hindered the wide spread use of GIS packages in majority of sectors and especially in the sector of natural resource management. This gap can be filled by customizing specific GIS applications as required by the end users in the open source environment. With this background, an attempt has been made in present study to develop a tool for estimating distributed soil erosion and sediment yield using an open source environment. In general the available tools for soil erosion and sediment yield estimation are not tightly coupled, this makes the task of estimation of sediment yield time consuming and less dynamic in nature. In present tool, called ‘SedYield’ hence forth, the spatially distributed soil erosion-sediment yield models are tightly coupled. The soil erosion estimation in the model has been done using Revised Universal Soil Loss Equation (RUSLE). The topographical factors of RUSLE (i.e. 2 dimensional LS factor) have been derived using DEM hydro-processing tools incorporated in the developed the tool. The ‘SedYield’ has been developed using Python and the interface has been designed using PyQt4. The sediment routing for estimation of distributed sediment yield has been done using the surface sediment transport schema suggested by Verstraeten et. al, (2007). The developed tool has been tested (calibrated and validated) using observed data of Naula Watershed, a sub-watershed of Ramganga reservoir catchment, Uttarakhand, India. The ‘SedYield’ has been designed in modular structure with four main modules viz., (1) HydPro (Processing the DEM), (2) Erosion (Estimation of gross soil erosion), (3) Calibration of Sediment Yield and (4) Validation. The ‘SedYield’ has been calibrated using four years observed data (1979-1982) of Naula Watershed. The predicted gross soil erosion obtained from the Erosion module of the ‘SedYield’ were found to be ranging from 24.9 to 38.6 t ha-1 yr-1. The calibrated Transport Capacity Coefficient (Ktc) value was found to be 0.000063 for Naula Watershed. Validation of ‘SedYield’ tool has been done using two years observed data of Naula and two years data of Chaukhutia observation stations. A model efficiency (ME) of 0.62 and a RRMSE of 0.12 were achieved through validation module. The time taken by the tool to perform one iteration of sediment yield routing for one year was less than 1 minute.
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