Spatial modelling of watershed health assessment by using GIS

Abstract

Watershed assessment methods have been developed in many types of approaches and purposes. However, the assessment concepts which are explicitly considering spatial aspects of a watershed remain unclear. The present study performed a spatial modeling for watershed health assessment in a Geographic Information System (GIS). Five indicators presented in GIS raster maps such as annual rainfall, land slope, land use/land cover (LULC) types, soil types and population density were used for the assessment and applied in Progo watershed, Central Java Province, Indonesia. A quantitative scoring was applied to classify indicator value and to categorize the watershed health level in five zones (very poor, poor, moderate, good and very good). The result shows that the study site is covered by three health level zones (poor, moderate and good). About 47.85% of the watershed area has a moderate health level. While, 39.04% and 13.11% of the watershed area are covered by areas with poor and good health level, respectively. Spatially, the area with poor health level is dominated by farmland and steep sloping area. Spatial modeling enables a watershed health assessment with a more specific and understandable result for watershed problems control.