Effects of forest on water circle on the Loess Plateau
摘要
From the research results on soil hydrology， the effects of forest hydrology on the total runoff and the surface water transferred into ground water were analyzed．It was found out that there exits an underlying drying layer of soil underneath forestland at a depth of more than 1 to 3 m from the soil surface．The distribution of the drying layer and causes why it exits are expounded， as related to ecological attributes of the Loess Plateau． It was believed that the drying layer is in great water deficit caused by evapotranspiration，which prevents gravitational infiltration of water and the replenishment of ground water．It is determined that a forestland on the Loess Plateau reduces the total runoff as the results of the increased retention of runoff and of the reduced recharged into ground water．