Analysis of Cidanau River Discharge using SWAT Application.

Abstract

management. The water demand always increases in line with the growths of population, industry and business, but the water availability is ascertained to satisfy those needs continuously. Therefore, it is necessary to analyze water availability in a specified watershed integrated with various aspects in hydrology. The objective of this study was to determine water availability in Cidanau watershed by analysing the relationship of rainfall and river discharge using the Soil and Water Assesment Tool (SWAT). The watershed is located in Banten Province and covering 22 620 ha. Input data were Digital Elevation Models, land use, and soil map. The procedures were including collection and process of climate data, trend analysis of water availability, determination of dry periods, discharge measurements, discharge analysis and calibration using SWAT. The results showed that water demand would reach 2.854 m3/s in 2020 while the estimated of average discharge was 5.282 m3/s, and the minimum discharge was 0.5 to 1 m3/s. Dry periods occurred from May to October with the average of 171 days per year. SWAT has generated 461 HRU that described the spatial condition of the whole watershed. Calculated discharges with SWAT compared to the measured discharges having The Nash-Sutcliffe Index of 0.534, and correlation coefficient of 0.68. Since this study used limited data then further studies should be continued by collecting more data of discharges and climates.

Perubahan tata guna lahan yang terjadi pada suatu kawasan menyebabkan terjadinya perubahan kondisi catchment area dan dapat menyebabkan perubahan aliran permukaan. Hal ini berpengaruh terhadap kondisi debit sungai di outlet sub DAS dan DAS tersebut. Daerah Aliran Sungai (DAS) Cidanau merupakan salah satu DAS yang terdapat di Provinsi Banten, dengan luas 22 620 ha. Secara geografis lokasi ini terletak pada 105o49’00” – 106o04’00” BT dan 06o07’30” - 06o18’00” LS. Air Sungai Cidanau dimanfaatkan untuk berbagai kepentingan, baik untuk pertanian, perikanan, industri dan kebutuhan domestik. Tujuan dari penelitian ini adalah (1) untuk menduga kecenderungan perubahan ketersediaan air di DAS Cidanau, (2) mengidentifikasi parameter SWAT untuk DAS Cidanau, (3) menganalisis hubungan curah hujan dengan debit Sungai Cidanau dengan menggunakan SWAT. Analisis debit Sungai Cidanau dilakukan untuk mendapatkan ketersediaan air pada DAS Cidanau dan menggambarkan perubahan yang terjadi terkait ruang dan waktu. Adapun tahapan yang dilakukan pada penelitian ini antara lain : (i) pengumpulan dan pengolahan data iklim, (ii) analisis kecenderungan ketersediaan air, (iii) penentuan hari kering DAS Cidanau, (iv) penghitungan debit Sungai Cidanau, (v) menganalisis debit Sungai Cidanau menggunakan MWSWAT, (vi) kalibrasi data debit Sungai Cidanau, (vii) mendapatkan hubungan curah hujan dengan debit Sungai Cidanau