MODIFIED GREEN AND AMPT MODELS FOR LAYERED SOIL INFILTRATION AND MUDDY WATER INFILTRATION

Soil water infiltration is an important hydrological process at the earth's surface. It is connected with both soil water recharge and surface runoff and erosion. While most soil water infiltration models are designed for clean water entering uniform soil profiles, many actual soil profiles consist of layers. Existing models do not account for surface deposition during muddy water infiltration. The objectives of this study are to measure soil water infiltration into layered soil columns, to measure infiltration with various muddied waters, and to develop simple models describing layered soil infiltration and muddy water infiltration. Experimental results show clear effects of layering and muddy water on soil water infiltration. Layered soil infiltration can be divided into two time frames: (i) when infiltration is controlled by the top soil layer and (ii) when infiltration is controlled by a subsurface layer. A simple modification to the Green-Ampt model is shown to provide a good description of two-layer infiltration. Muddy water infiltration is related to the sediment concentration of the infiltrating water. The larger the sediment concentration, the slower the infiltration. A modified Green-Ampt model is also shown to be useful for describing muddy water infiltration.