Analisis Infiltrasi Unsteady Tanah Heterogen pada Saluran Rectangular Impermeable menggunakan Dual Reciprocity Boundary Element Method

Abstract

The infiltration problem in this study focuses on time-dependent infiltration in heterogeneous soil with rectangular irrigation channels lined with an impermeable material. The soil types used are yolo light clay in the first layer and chino clay in the second layer. This infiltration problem is modeled using the nonlinear Richard Equation; several transformations will be performed to obtain a linear equation. This study aims to solve the infiltration problem model using a numerical approach. It also examines the effect of time on the infiltration rate in heterogeneous soil. The transformation of the Richard Equation yields the Modified Helmholtz Equation. The numerical solutions use the DRBEM combined with the Stehfest method to restore time dependence. The research data used are the characteristic data of yolo light clay in the first layer (0–50 cm) and chino clay in the second layer (51–100 cm). Simulation experiments were conducted using MATLAB. The results obtained were values of suction potential. The results show that suction potential values at points below and around the channel bottom are smaller than those at points farther from the channel. This is due to the presence of an impermeable layer, causing more water to be absorbed through the side walls, and the suction potential values increase with increasing depth. Analysis regarding the effect of time revealed that at the initial time t, there was a fairly noticeable change in suction potential values. However, as t increased, the suction potential values at each point converged and approached steady-state conditions at t = 5. Sudden jumps in suction potential also occurred at the boundaries between layers due to differences in the soil characteristics and hydraulic conductivity.