Analisis Neraca Air DAS Mentaya Kabupaten Kotawaringin Timur dan Pengaruh ENSO Terhadap Ketesediaan Air Wilayah

Abstract

Mentaya watershed is a catchment area in Kotawaringin Timur regency, Central Kalimantan Province as a source of water supply and transport pathways. DuringEl Nino Southern Oscilliation (ENSO) years rainfall will changeand affect the availabilityof water in the watershed. The purpose of this study is to estimate the amount of water available in Mentaya watershed at normal and ENSO years through landwater balance model. Method to analyze water balance components isMockwater accountingmethod that was modified for soil moisture (SM) and actual evapotranspiration (ETa). The study area is upstream part of Mentaya watershed with total area 5459.2 km2that has red-yellow podzolic soil with a sandy loam texture and forest cover. Annual rainfalls of El Nino (1997), Normal (2006) and La Nina (2000) years were1664.5 mm, 2941.2 mm and 3494.4 mm, respectively. Evapotranspirated water (ETa) in El Nino, La Nina, and normal years were 67%, 53% and 54 % of the annual rainfalls, respectively. Total runoff ( RO ) in the year of El Nino, La Nina, and the normal rate of 35%, 50%, and 47% of the annual rainfall. Precipitation, RO water balance and measurement were lower in El Nino (1997) year and higher in La Nina (2000) year than in normal year (2006)