Formation mechanism of instantaneous saturated zone and seepage characteristics in the slope of Taihang Mountain areas

To study the effect of soil-rock's characteristics on the transformation and redistribution of rainwater, a long and continuous monitor of soil-rock moisture was conducted using the time domain reflectometry(TDR) in slope of TaiHang Mountain area, and the spatial-temporal variation of soil-rock moisture was analyzed. Results show that spatial and temporal variations of soil-rock moisture exist in the slope of gneiss region. In the soil-rock layer from surface down to 100 cm, moisture contents distributs from low to high and then to low in vertical profile and the water changs in the same trend in season. In addition, saturated zone instantaneously exists at the soil-gneiss interface in about August. The spatial variation of medium of the soil-rock layer, especially its structure offers the geological condition for the form of instantaneous saturated zone, and the heavy rainfall process offers the hydrological condition. Moreover, soil moisture content of slope before moisture contents and rainfall characteristics such as intensity and duration affects the time that moisture get to or over saturation. Instantaneous saturated zone is good for the formation of preferential flows in lateral and vertical directions. The flows in two directions interacts with each other and prompts the rain infiltration to groundwater.