Morphometric characteristics of the Alas-Singkil drainage basins

Abstract The Alas-Singkil drainage basin is the broadest watershed and an essential ecosystem for maintaining hydrology and ecosystems in the northern Sumatera. This study aims to describe the morphometric and hydrological characteristics of the Singkil watershed. The data sourced from Google Earth, DEM data and the results of team expeditions at the sub-watershed locations. The data analysis is related to the characteristics of the Singkil watershed, which include watershed area, watershed shape, river network, river flow pattern, river flow density, and watershed hydrology. Analysis of hydrological characteristics by calculating the peak of the flood was also carried out. The results showed that the Singkil watershed is a broad watershed with an area of 12027.18 km2. The Alas-Singkil drainage basin consists of 7 sub-watersheds, with the length of the main river reaching 368 km. The order of Singkil watershed reaches 8 orders and consists of 7235 orders 1, 1964 orders 2, 390 orders 3, 92 orders 4, 26 orders 5, 6 orders 6, 4 orders 7. The shape of Alas-Singkil drainage basin is elongated with RC value of 0.16. The level of river branching in the Alas-Singkil watershed is 4.76. The maximum discharge in the Alas-Singkil watershed reaches 59,178 m3/sec.