Analisis Daerah Resapan Air DAS Ciliwung Hulu Menurut Penutupan Lahan dan RTRW

Abstract

Recharge areas are associated with rainwater seeps that will be ground water reserves later. The upper watershed is a recharge area which serves to keep the balance and sustainability of the water system, as well as to protect the downstream from erosion, environmental degradation, and floods. The purpose of this study is to identify land cover change of the upper Ciliwung watershed in 2000, 2005, and 2013 in relation to the recharge areas, and then to estimate the surface runoff as a response to land cover change, and to compare land cover in RTRW Kabupaten Bogor 2005-2025 with land cover in 2013. The approach used in the recharge areas analysis is land cover identifying. Land cover is an important indicator that can represent the condition of recharge areas. The identification of land cover utilizes remote sensing applications and Geographic Information System (GIS). Estimation of surface runoff in this study is using SCS (Soil Conservation Service) which is a function of rainfall with land cover and soil hydrologic group. The result shows that there has been a land cover change in the time period of 2000 to 2013, a decreasing forest areas, and an increasing urban areas, respectively 6,3% and 11,2% of upper Ciliwung watershed areas of 14,837 Ha. It shows from the change in the original forest area of 4975,6 hectares to 4043 hectares, while the urban area changes from 1135 hectares to 2789,3 hectares. These changes in land cover causes an increasing surface runoff up to 55.5% from its original condition in 2000 of 385 mm. Besides, there was an unsuitable spatial planning in the year 2013 of RTRW Kabupaten Bogor 2005-2025, especially the land use changes in protected areas and recharge areas. There is a total of 47,8% unsuitable land use areas in the upper Ciliwung watershed. These deviations is from the conversion of protected areas into cultivated areas, such as plantation areas, urban areas, and dry land agricultural areas. Overall results of the research shows that the decrease of forest areas and the increase of urban areas causes the effective land for recharge area to decrease, so that water does not seep optimally into the soil and causes the surface runoff to increase. It indicates that the function upper Ciliwung watershed as a recharge area has decreased. Besides, the conversion of protected forest land areas and recharge area into cultivated areas causes the function of upper Ciliwung watershed as a recharge area to be unmaintained.