The effect of sediment density parameter values on the debris flow velocity parameters

¹ Magister in Civil Engineering, Universitas Muhammadiyah Yogyakarta, Brawijaya St., Bantul, Special Province of Yogyakarta, 55183 Indonesia
² Undergraduate Program, Dept of Civil Engineering, Universitas Muhammadiyah Yogyakarta, Brawijaya St., Bantul, Special Province of Yogyakarta, 55183 Indonesia
³ Dept of Civil Engineering, Universitas Muhammadiyah Yogyakarta, Brawijaya St., Bantul, Special Province of Yogyakarta, 55183 Indonesia

^* Corresponding author: jazaul.ikhsan@umy.ac.id

Abstract

Debris flow is a phenomenon where the material from the eruption is carried away by the flow of water due to rain in the upstream area of the river and usually crashes into watersheds around the volcano. The potential for large debris flows can be caused by high rainfall and sediment deposits that occur during debris flows. Rainfall and sediment carried by water flow can affect the volume and velocity of debris flows. A debris flow simulation was carried out to anticipate casualties and damage using SIMLAR V2.1 by modifying rain intensity and the density of sediment carried by the debris flow. Based on the result, we can obtain the results of the velocity, volume, and area affected by the debris flow. The flow velocity values obtained for testing with rainfall intensity of 162 mm with a density of sediment 1370 kg/m3, 2340 kg/m³, 2635 kg/m³, and 2820 kg/m³, respectively, were 2.72 m/s, 2.16 m/s, 2.50 m/s, and 2.57 m/s. The volume values with the same intensity and density of sediment are 186,381 m³, 311,116 m³, 274,030 m³, and 294,987 m³. Based on the test results, it can be concluded that sediment density significantly affects the velocity and volume of the debris flow. Where sediment density is inversely proportional to the flow velocity, the higher the sediment density, the slower the flow velocity, while the volume is directly proportional to the sediment density. The higher the density of the sediment, the higher the volume.