Water Balance Prediction as Impact Land Use Change By GIS Based SCS-CN and Thornhtwaite-Mather Method

Land use change due to urbanization and deforestation have affected on water balance condition of a watershed. Infiltration rate, surface runoff and groundwater storage are key factors in determining condition of water balance by GIS base on SS-CN and Thornhtwaite-Mather methods. The traditional SCS-CN method for calculating the water balance is very tedious and consumes a major portion time. Therefore, GIS based SCS-CN method are now being used. SCS-CN (Soil Conservation Service-Curve Number) and Thornhtwaite-Mather method was used to predict the water balance consisting of surface run off, infiltration and groundwater storage in Upper Cisadane Watershed. The result showed that the land use has a significant impact on watershed balance conditions, especially from the total rainfall in the Upper Cisadane Watershed from 3647.8 mm/year resulting in surface runoff 2230.1 mm (61.1%), infiltration 557.8 mm (15.5%), and deficit of groundwater storage 82.9 mm (2.3%).