Analisis Perubahan Tata Guna Lahan Terhadap Kuantitas dan Kualitas Air Sungai Percut

Abstract

Over the past 10 years there has been a change in land use in the Percut Watershed in the form of a decrease in forest area and an increase in developed land and agricultural areas. The dynamics of land use change have an impact on changes in the quantity and quality of Percut river water. This Research aims to analyze changes in land cover that occur in the Percut Watershed and its relation to the quantity and quality of the Percut River water. Changes in land use were analyzed based on land cover maps from the Ministry of Environment and Forestry (KLHK). Water quality is based on reports from the Sumatra River Basin II (BWSS II) and the North Sumatra Provincial Environment Agency (DLH). Water samples were taken at five sampling points along the Percut river flow from upstream to downstream. Water quality status was analyzed by the Water Quality Index (WQI) and Pollution Index (IP) method. Runoff coefficient changes occur with changes in land cover. The decrease of forest area in sub-watershed 1 and sub-watershed 2 increases the value of runoff coefficient while in subwatershed 5 there is a decrease in runoff coefficient due to the use of land for ponds. Water quality status in each Percut sub-watershed is lightly polluted with different parameter values depending on the surrounding land use. The source of pollution is dominated by organic waste. Appropriate land use management by maintaining the condition of the forest. It is expected to overcome changes in the quantity and quality of water (pollution) in the Percut Watershed.

Selama kurun waktu 10 tahun terakhir telah terjadi perubahan tataguna lahan di DAS Percut berupa menurunnya luas hutan dan meningkatnya lahan terbangun serta areal pertanian. Dinamika perubahan tataguna lahan berdampak pada perubahan kuantitas dan kualitas air sungai Percut. Penelitian ini bertujuan untuk menganalisis perubahan tutupan lahan yang terjadi di DAS Percut dan kaitannya dengan kuantitas serta kualitas air Sungai Percut. Perubahan tataguna lahan dianalisis berdasarkan peta tutupan lahan dari Kementerian Lingkungan Hidup dan Kehutanan (KLHK). Kualitas air berdasarkan laporan dari Balai Wilayah Sungai Sumatera II (BWSS II) dan Dinas Lingkungan Hidup (DLH) Provinsi Sumatera Utara. Sampel air diambil pada lima titik sampling sepanjang aliran sungai Percut dari hulu ke hilir. Status kualitas air dianalisis dengan metode Water Quality Index (WQI) dan Indeks Pencemaran (IP). Terjadi perubahan koefisien limpasan seiring dengan perubahan tutupan lahan. Penurunan luas hutan pada subDAS 1 dan subDAS 2 meningkatkan nilai koefisien limpasan sedangkan pada subDAS 5 terjadi penurunan koefisien limpasan karena adanya pemanfaatan lahan untuk tambak. Status kualitas air pada masing-masing subDAS Percut tercemar ringan dengan nilai parameter berbeda tergantung tataguna lahan disekitarnya. Sumber pencemaran didominasi oleh limbah organik. Pengelolaan tataguna lahan yang tepat dengan mempertahankan kondisi hutan diharapkan dapat mengatasi perubahan kuantitas dan kualitas air (pencemaran) pada DAS Percut.