Studi Kasus Pengaruh Pembagian DAS untuk Analisis Debit Banjir DAS Menengan di Kabupaten Tuban

Abstract

The flood discharge of a watershed is influenced by the division of the area of the watershed or sub-watershed. This study uses two methods to find the appropriate watershed area distribution in the theoretical flood discharge closest to the existing flood discharge in the Menengan watershed. In the first method, the overall watershed area is 114.04 km 2 with a length of the main river of 19.11 km. Meanwhile, in the second method, the watershed is divided into three sub-watersheds with respective areas of 14.05 km 2 , 45.87 km 2 and 54.12 km 2 , and the length of the main river is 3.46 km, 7.65 km and 8 km respectively. The results show that by dividing the watershed into three sub-watersheds, a flood discharge of 120.86 m 3 /s is obtained which close to the existing flood discharge of 135.075 m 3 /s with a maximum tide elevation control of +2.2 m. AbstrakKata kunci: daerah aliran sungai, debit banjir, waktu konsentrasi, hidrograf satuan sintetik, nakayasu.