Study on Soil Moisture Content in Valleys of Semiarid Region of Loess

Based on the measured soil moisture content data in the Sunjiacha basin of Lanzhou,Gansu from 2009 to 2011,the variation characteristics of the soil moisture content in the valley protection zone were analyzed.The results showed different soil moisture contents in different geomorphologic areas in the Loess Hilly Region.The soil moisture content was about 17.3% at the bottom of the ditch,12.4% at the agricultural area of the ditch side,11.1% at the barren land of the ditch side,and 10.1% at the forest land of the ditch slope,and the soil moisture content had a positive correlation with the precipitation.In view of importance of planting the appropriate vegetations in relation to the corresponding soil moisture content for the healthy developments of the agricultural production and the adaptation of water-soil system the following suggestions were proposed in this paper: the vegetations with higher water consumption coefficients should be planted at the bottom of the ditch,the vegetations with lower water consumption coefficients should be planted at the ditch side,and the vegetations with the highest drought tolerance should be planted at the ditch slope.Meanwhile,the trees and grasses in the suitable places can maintain the natural ecological balance of the modern valleys.