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AVSWAT- a Spatial Decision Support System for Land and water management and its application for watershed management in Bankura district of West Bengal
Applications
developed for Watershed management in Bankura.
Water yield and silt yield maps for the watersheds in Chhatna Block Water yield is the amount of water that leaves the sub-basin and contributes to stream flow at the sub-basin outlet. it is the sum of surface runoff, lateral flow in the root zone, and ground water flow minus transmission losses in channels within the sub-basin minus any pond abstractions. Sediment yield is the sediment from a sub-basin that reaches the sub-basin outlet. This is the amount that would be measured at the sub-basin outlet (pond deposition has already been subtracted). Sediment yield is computed for each sub-basin with the Modified Universal Soil Loss Equation (MUSLE) (Williams and Berndt, 1977). Maps Generation
  Potential Crop production map for the Gandheswari watershed in Chhatna Block . SWAT utilizes a single plant growth model to simulate all types of land covers. The model is able to differentiate between annual and perennial plants. Annual plants grow from the planting date to the harvest date or until the accumulated heat units equal the potential heat units for the plant. Perennial plants maintain their root systems throughout the year, becoming dormant after frost. They resume growth when the average daily air temperature exceeds the minimum, or base, temperature required. The plant growth model is used to assess removal of water and nutrients from the root zone, transpiration, and biomass/yield production. The potential increase in plant biomass on a given day is defined as the increase in biomass under ideal growing conditions. The potential increase in biomass for a day is a function of intercepted energy and the plant's efficiency in converting energy to biomass. Energy interception is estimated as a function of solar radiation and the plant’s leaf area index. The potential yield is estimated by multiplying the potential biomass production with Harvest Index i.e. Economic yield/ Biological yield. In the present study SWAT was implemented for estimating the potential production of Aman paddy, which is the main crop of the area. The Basi.. sbs file which contains HRU wise estimate of potential biomass production and crop yield for a sub-basin or watershed was converted into Basi.dbf and imported into the project It was then joined to the attribute table of the water yield map. From legend editor, Unique value legend type was selected and then the field for Total Crop production was selected to generate the crop production theme for each sub-basin respectively and converted into shape files. A map for potential production of Aman paddy for the Gandheswari sub-basin is in Fig.9. Application of the SDSS for Watershed Management. In view of the stress on district level planning in the country, watershed based planning of natural resources is becoming increasingly important activity in a district. For watershed management, the foremost application of a SDSS like AVSWAT is in digitally delineating the watersheds and sub-watersheds , at present which is entirely dependent on the experience and skill of the district officials. The initial investment in digital data generation justifies subsequent lesser investment in repeated survey for the purpose and improvement in watershed delineation. In a SDSS like AVSWAT, the SWAT model provides the capability of quantitatively simulating land and water related processes important for watershed management like potential water and silt yield . The spatial representation of the results in the form of maps provides added information to the Decision-makers. The silt yield map presents potential silt production rate from different watersheds, thus, depicts the erosion status of them and helps in prioritizing the watersheds for soil and water conservation measures. Similarly, the water yield map presents the amount of water that can be available from each watershed under different management options, thus can help in land use planning, water management planning and in deciding proper land and water management options. A potential crop production map along with the other two maps could be of immense help in crop management and land use planning Apart of producing these static spatial representations, the SWAT model helps in generating alternate management scenarios for land and water management by changing the values of input parameters. Thus, providing a dynamic tool to the decision-makers involved in watershed management programmes in a district. The SDSS along with the products were demonstrated to the district level decision-makers through a workshop organized at Bankura district. References
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