Abstract
Recent field hydrologic studies revealed that groundwater in weathered bedrock contributes to runoff variabilities. Followed by the findings, distributed runoff models which simulate bedrock groundwater have been also developed. However, efficient modeling of the infiltration processes in unsaturated zone has not been achieved in the distribution runoff models. This study derive an analytical solution of Richards' equation suitable for such modeling. The obtained analytical solution can set arbitrary water content boundary and initial conditions to account for temporal variations of water content on top of the bedrock and groundwater in unsaturated zone. In addition, we applied the derived solution to a one-dimensional vertical simulation, which connects surface soil layer and bedrock, and analyze the infiltration processes with time varying boundary conditions.
