Assessment of Deli Watershed Flood Causing Damage in Medan City, Indonesia

The watershed (DAS) Deli is one of the priority watersheds in the Medium Term Development Plan in 2010-2014 according to the Ministry of Forestry decree (SK 328/Menhut-II/2009), Indonesia. DAS is a complex ecological system in which there is a dynamic equilibrium between the incoming material energy (input) and the material out (output). Naturally, the change in input and output balance is slow and does not pose a threat to humans and environmental sustainability on a watershed system with continuous land-use dynamics from dense vegetation forms to rare vegetation forms or from vegetation forms to non-vegetation forms. It has been concluded that Deli watershed land destruction is dominated by biophysical factors, especially land use, slope, landform, and rainfall in upstream Deli sub-watershed. This is what causes flooding in Medan city, Indonesia. The cause is extreme rainfall so that a number of rivers such as Deli River and Babura River overflowed, the water level of the Deli and Babura Rivers almost reached the bridge section and this was scarce.