A Run off/on Method for Infiltration Capability of Sloped Soil Surface

摘要

The transient infiltration capability process of sloped soil surface under rainfall, runoff, erosion impacts is of great significance in scientific researches such as hydrology, crop water use, irrigation system design and management as well as soil erosion, and etc. A new method, which involves rainwater run-off and run-on on hill slope, was advanced in this paper for the determination of the transient soil infiltrability under rainfall, runoff and erosion conditions. Mathematic models were derived to compute the transient infiltration rates with data from the advance process of runoff water on soil surface and depth of water ponded on the soil surface. Laboratory experiments of two cases under 30 mm/hr rain intensity and 5 degree slope and 60 mm/hr rain intensity and 20 degree slope were conducted to collect data for illustrating the experimental and computational procedures to determine the transient infiltrability curve under lower rainfall intensity with no water ponding and under higher rainfall intensity with water ponding. The rationale of the measurement and the related algorithm was validated with data from other sources. The measured infiltrability curves well explain the transient process of soil infiltration capability. The data also indicate that slope gradient, rainfall intensity and/or soil erosion have their influences on the infiltration capability of soil. The newly suggested method overcomes the shortcomings of the traditional rain simulator and double ring methods. This method has the capability of measuring the complete process of the transient soil infiltration capability under sloped surface as influenced by rainfall splash, runoff, and soil erosion. This method will supply the researchers in related fields a convenient yet useful tool.