English

Abstract

Mining nonmetallic sand, gravel, and river stones in a river channel has previously caused damage to the river channel itself and the surrounding environment. Technical studies are needed to minimize the damage in mining in the river channel. Ongkag Dumoga River channel is planned to be the location of mining non-metal material for sand, gravel and river stone. The research method was carried out by geodesic mapping to determine the profile of the river cross-section, hydrological analysis with a return period of 25, 50, and 100 years and hydraulic analysis on the river flow along the 600 m. The design of the post-mining river technical profile is carried out to improve the capacity of the existing river cross-section. Changes in river profile are the potential volume of nonmetallic material in the form of sand, gravel and river stones that become river sediment. The results of the analysis of flood discharge HSS-Snyder method get a discharge of 1249.1692 m³ / s at the 100-year return, 1178.8064 m³ / s at the 50-year return period, 1104.2372 m³ / s at the 25-year return period. The simulated flood discharge shows a flood overflow in the existing river during the 25, 50 and 100-year floods. The new technical river cross-section will use the economic cross-section of the trapezium cross-section. Changes in river profiles are calculated to get a potential excavation volume of 88,347.42 m³.