Non-Metalic Material Sand, Gravel and Stone on Ongkag River : Method of Mining

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