GIS Based DSS for Optimal Erosion Management: A Case Study of the Huai Talupkup Watershed, Thailand

  • Pongsai, S


A Geographic Information System based Decision Support System (GIS based DSS) was developed for evaluating the optimal erosion management (which includes soil and water conservation: SWC and crop management system: CMS) alternatives watershed based upon the multi-objectives such as greatest physical effectiveness, cost-benefit return and social benefit acceptance. The system has been developed by integrating the decision element models: erosion model (Universal Soil Loss Equation: USLE, Modified USLE: MUSLE, Potential Nutrient Loss Model), economic model (Cost-Benefit Analysis: CBA), and social benefit model (Net Benefit Index: NBI), with a SWC knowledge based system (SWC-KBS) and multi-objectives optimization approach, into one system, using Arc-View GIS and Visual Basic programming. The application was tested in the Huai Talupkup small watershed, Thailand, an area of 1,550 ha. The selected optimal erosion management for 10 land class units (LCUs), which were based upon the similarity of land management regime which include a variety of terrace practices and suitable crop management systems. The selected optimal erosion management from the system, using a discount rate of 8 % and a project lifetime of 10 years, was found to have a net present value (NPV) of about 9.52 million Thai baht, erosion (soil loss) could be reduced about 78 % while the social net benefit index increased by 47 % from current conditions. The system proposed in this research enables quick review of results for different erosion management alternatives using preference criteria settings, which might not be possible with a dispersed analytical systems computation. It is suggested that this system can be applied to other watersheds for evaluating and enhancing the accuracy in effective decision-making in the optimal erosion management at the small watershed level.