DECREASING THE QUALITY OF WATER RESOURCES IN THE RAWAS WATERSHED DUE TO LAND DEGRADATION

Abstract

There is an urgent need to regulate and monitor land degradation through quantitative assessments and mapping critical land to increase national capacity as stated in the Sustainable Development Goals (SDGs). This can be achieved by introducing an innovative approach to monitoring the necessary land at the national, provincial, and district city levels. Moreover, the sub-watershed scale analysis associated with the distribution of degraded land through multi-temporal geospatial layers [1,2] helps provide a regionally consistent dataset needed to support the agendas aligned with sustainable development goals (SDGs) [3]. The analysis of topographical conditions, types of land cover, and the amount of kinetic energy for rain intensity of 30 minutes with a return period of 2 to 100 years is the basis for predicting critical land using the RUSLE method [4]. Predicted essential distribution of land and potential for land degradation that occurred in the last 10 years (2010-2020), covering an area of 2,215,303 Km² (37.95%) land in the critical category, 10,780 Km² (0.18%) very critical, 629,301 Km² (10.78%) is slightly critical, 2,256.92 Km² (38.7 %) potentially critical and only 725,875 Km² (12.43%) which is not vital. The most dominant problem of watershed degradation is land cover loss due to forest encroachment in areas with slopes over 25%. The expansion of land conversion is typical of oil palm plantations, which triggers soil erosion, flooding, and a decrease in pristine water quality due to river water pollution.