ECONOMIC EVALUATION OF SOIL CONSERVATION AND WATERSHED MANAGEMENT PRACTICES USING NPV IN TALEGHAN WATERSHED, IRANParviz Garshasbi, Mahzrom Galestyan and Ali Salajeghe
Soil erosion is one of the serious problems of watersheds in Iran. Soil conservation effects have not been evaluated quantitatively with standard methods and in Iran the existing methods are ambiguous. Economic evaluation of soil conservation activities is difficult due to the effect of combined indexes and lack of market economic evaluation. In this study, the spatial and temporal effects of soil conservation practices have been analyzed using NPV method based on different opportunity costs in Mian Bishe watershed. Mian Bishe watershed was chosen as a pilot site, because of its similar natural conditions and land uses to Taleghan watershed, and soil conservation practices, which constructed in it, have appropriate age for analyzing and technical evaluation. At first, basic information was updated using GIS, field studying, identifying and measuring benefit to cost ratio were done. Economic values of three main indices of cost and six combined indices of benefit were evaluated. Benefit to cost ratio has been evaluated integrating data about the effects of soil conservation practices and different opportunity costs of lands, and finally, economic indices consisting of NPV, and benefit to cost ratio was evaluated. Evaluation shows that rehabilitation of Mian Bishe watershed with discount rate of 15 percent during a period of 30 years will be justified economically in lands with low and relative productivity, and implementing soil conservation activities in mountainous rangelands and hilly badlands with highly soil erosion will have a positive net present value. Also, developing new springs, the potential of their irrigation, conserving lands, roads and buildings against flood hazard and conserving reservoir against sediment deposition consist of 48, 20 and 7 percent of total benefits of NPV in rehabilitated watershed.
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