PEMODELAN ALIRAN DEBRIS 1 DIMENSI DENGAN METODE ELEMEN HINGGA EULERIAN DAN LAGRANGIAN

Debris flow is natural disasters that can cause not only loss of property but also of human lives. This flow is very dangerous because it can destroy anything in its path. To avoid large losses from natural disasters, mitigation of natural disasters is needed. One of mitigation measure is an early warning system and it can be in the form of hazard maps and travel time table of debris flow. This hazard maps and the travel time table of debris flow inform the extent of the affected area, so that it gives early warning for evacuation to residents around the disaster site when indicators gives signals. Debris flow modeling can be conducted for developing the early warning tools. The development of 1D (one-dimensional) model of debris flow uses the Finite Element Method with Eulerian approach and Lagrangian approach. The result of both approaches are compared to determine which one is better in modeling debris flow. The numerical models then are applied to two initial conditions, the staircase-shaped and half-Gaussian form. In order to get better modeling results a smoothing method is used to improve the stability of the numerical model. For the Eulerian approach, it is obtained that the results looks like a diffusive wave propagation to upstream and downstream, but still skewed to downstream. While the Lagrangian approach shows that the flow propagates downstream. The comparison of two methods shows that the model with Lagrangian Galerkin approach is more presenting the debris flow than Eulerian approach 2 Step Taylor Galerkin (2STG)