PENGARUH PERUBAHAN PENGGUNAAN LAHAN TERHADAP KOEFISIEN LIMPASAN PERMUKAAN DI KECAMATAN NGAGLIK, KABUPATEN SLEMAN

One of the indicators to identify the quality of recharge function in a region is the amount of runoff coefficient. It is important to calculate the existing runoff coefficient and its changes, as a result of land use changes occurred. In according to the backround, the purpose of this research is to 1) examine land use change which occurred in Ngaglik sub-district, Sleman, 2) examine and analyze changes in surface runoff coefficient caused by land use changes in Ngaglik subdistrict, Sleman, and 3 ) examine the suitability of land use with the land use plan and regulation of Coverage Building Ratio (CBR) in RDTR Ngaglik sub-district. This research uses descriptive analytical method and comparative analysis. Descriptive method is a further description or depiction of the calculation results and the relationship between land use and runoff with spatial planning region.Whereas comparative method is to compare the land use and runoff coefficient by 2000 and 2006. The study and analysis indicates there was increase of built up area in Ngaglik sub-district in the period of 2000-2006, ie from 993.19 Ha (25.78%) increased into 1179.73 Ha (30.63%). Built up in the southern region is relatively higher than the north. Built upa area experiencing the greatest increase in this area is residential / housing is 845.43 Ha (21.95%) in 2000 and then to 996.05 Ha (25,86%) in 2006. Improved of Built up area lead to increase of surface run off coefficient. In 2000, a C-weighted of each Sub Block in Ngaglik Sub District ranged from 17,64 to 66,90% and in 2006 increased into 18,81 to 68,47%. The problem that happens in there is a discrepancy between the existing land use with land use plan and CBR regulation.Deviations that negatively impact the function of water absorption are a built up area on area designated as unbuilt area and the existing CBR exceeds the CBR regulation for residential and commercial/services are concentrated in the corridor of Kaliurang and Palagan Tentara Pelajar Road. In the next, it is necessary to control utilization of space and land use change