Simulation of Infiltration and Surface Runoff: A Windows-Based Hydrologic Modeling System HYDROL-INF

Simulation of infiltration and surface runoff, two closely-correlated processes during rainfall events (wet time periods), is critical to water quantity and quality studies for both surface and subsurface systems. Partitioning rainfall into these two primary water pathways is fundamental to any hydrologic modeling. In a continuous hydrologic model, it is also essential to simulate drainage and redistribution of soil water between two rainfall events (dry time period). A new algorithm is proposed to simulate infiltration into a layered soil profile of arbitrary initial water distributions under unsteady rainfall and the resultant surface runoff. Two distinct periods, pre-ponding and post-ponding, are taken into account. The model tracks the movement of the wetting front along the soil profile, checks the ponding status, and handles the shift between ponding and non-ponding conditions. The model is further extended to complex rainfall patterns that include both wet time periods with unsteady rainfall and dry time periods without rainfall by incorporating a compartmental model that accounts for drainage and redistribution in the soil profile. Furthermore, a Windows-based modeling system, HYDROL-INF, is developed, which integrates pre-processing of data, model run, and post-processing in a user-friendly Windows interface. To facilitate parameter estimation, a parameter database is developed and incorporated. Additionally, the HYDROL-INF system also includes some useful hydrologic tools/calculators that can be used in applied hydrologic investigations.