Dampak Perubahan Tutupan Lahan Hutan Terhadap Limpasan Permukaan di SubDAS Cianten DAS Cisadane

Abstract

Penelitian ini mengkaji dampak perubahan tutupan lahan hutan terhadap limpasan permukaan di subDAS Cianten menggunakan metode Soil Conservation Service - Curve Number. Penelitian ini menemukan bahwa pada tahun 2012-2020 terjadi perubahan tutupan lahan. Ditemukan sebelas jenis tutupan lahan yaitu danau, hutan lahan kering primer, hutan lahan kering sekunder, hutan tanaman, pemukiman, perkebunan, pertanian lahan kering, pertanian lahan kering campur, sawah, semak/belukar dan tanah terbuka. Tutupan lahan yang luasannya tidak berubah adalah danau, hutan lahan kering primer, perkebunan dan tanah terbuka. Tutupan lahan yang luasannya menurun adalah hutan tanaman, pertanian lahan kering, sawah dan semak/belukar. Tutupan lahan yang luasannya fluktuatif adalah hutan lahan kering sekunder dan pertanian lahan kering campur. Tutupan lahan yang luasannya meningkat adalah pemukiman. Perubahan tutupan lahan menyebabkan jumlah limpasan permukaan (Q) berubah. Nilai Q meningkat pada tahun 2016 dan menurun pada tahun 2020. Peningkatan nilai Q disebabkan oleh peningkatan luas pemukiman dari pertanian lahan kering dan sawah sedangkan penurunan nilai Q disebabkan oleh peningkatan luas hutan lahan kering sekunder dari hutan tanaman. Kata kunci: Curve Number, limpasan permukaan, Soil Conservation Sercvice Curve Number, tutupan lahan, ABSTRACT HAMZAH NUR AHMAD. Impact of forest land cover changes on surface run-off in the Cianten subbasin Cisadane Watershed. Supervised by NINING PUSPANINGSIH. This study examines the impact of forest land cover changes on surface runoff in the Cianten subbasin using the Soil Conservation Service – Curve Number method. This study found that land cover in 2012-2020 were changed. Eleven types of land cover were found, namely lakes, primary dry land forest, secondary dry land forest, plantation forest, settlements, plantations, dry land agriculture, mixed dry land agriculture, rice fields, shrubs and open land. Area of land cover that didn’t change were lakes, primary dryland forest, plantations and open land. Area of land cover that decreased were plantation forests, dry land agriculture, rice fields and shrubs. Area of land cover that fluctuated were secondary dryland forest and mixed dryland agriculture. Area of land cover that increased was settlements. The amount of surface runoff (Q) changed due to land cover changes. In 2016, Q value was increased while in 2020 Q value was decreased. Increased Q value due to increase of settlement area from dry land agriculture and rice fields. While the decrease Q value was caused by increased area of secondary dryland forest from plantation forest. Keywords: Curve number, land cover, Soil Conservation Service Curve Number surface run-off