Distribution and Characteristic Sediment Material of Watershed Deli River-Sumatera, Indonesia

<jats:title>Abstract</jats:title> <jats:p>Rivers are a source of surface water and bring benefits to human life. River water quality changes along with the development of the river environment which is influenced by various activities and human life. Deli River is one of the rivers used by the people of Medan-North Sumatra as a provider of clean water and various other daily activities and is also used as a transportation route for fishermen. This study aims to determine the flooding conditions that often occur in the Deli River, this is caused by the shallowness and narrowness of the river body. In this study, the quantitative method was taking sediment samples at several points along the river starting from upstream, middle, and downstream with research time on 7 July 2023. The results obtained from this study were river sediment material along the Deli River from upstream to downstream generally has a grain size of 65% sand, a grain size of 26% clay, a grain size of silt 6.3%, and a grain size of gravel 3.7%. The upstream sediments are dominated by sand-sized sediments and in the middle (between the upstream and downstream) the sediments are dominated by clay-sand-sized sediments, while the downstream sediments are predominantly sandy loam. The flooding of the Deli River is caused by the reduced capacity of the river, high intensity of rainfall in the upper reaches, and narrowing of the river and high sediment deposits in the middle to lower reaches so flooding often occurs along the Deli River.</jats:p>