This research aims to analysis the biophysical characteristics of watershed of Deli River to know potential flooding in Medan. The research is conducted at Deli River, which is located in 3 locations in North Sumatera namely Karo Regency, Deli Serdang and Medan City. Indonesia. This research used field survey method, survey activity in the form of observation and verification of characterization and biophysical identification of watershed in each location. Some properties of soil samples were analyzed in the laboratory. Field surveys are also conducted by observing the types of land use, as well as, climate and hydrological data. The results of Surveyed data and soil analysis were used to assess land damage. The findings showed that understanding the biophysical flow of the river especially land use, slope, landform, and rainfall in the upstream Deli sub watershed in the Deli river in Medan is very important and sensitive. One of the causes of flooding in Medan City due to the degradation / damage of land both due to erosion, land criticality, and land use that is not in accordance with the ability of land use. The direction of conservation and land use has an impact on the decrease of maximum flood and flood volume of each Sub Watershed with 2, 5 and 10 year re-period. تفاصيل المقالة

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. تفاصيل المقالة