Study on the Dynamic Variation Law of Highway Slope's Soil Moisture

Abstract

[Objective] Soil moisture is the key factor of highway greening. To maintain the steady and sustainable development of highway greening, the problem of soil moisture should be primarily solved. [Method] In this paper, the dynamic variation law of highway slope’s soil moisture was studied by the continuous observation of the soil moisture (0~40cm) and rainfall in all points (sunny slope, shade slope, ground, and the central partition belt) of China’s Langfang—Zhuozhou Highway from April to November 2009. [Result] From April to May, the soil moisture content declined continuously. From May to August, the soil moisture content increased rapidly and also was kept at a higher level. From August to October, the soil moisture content declined gradually. From October to November, the soil moisture content increased steadily. The soil moisture in the surface (0~10cm) and the lower layer (10cm~20cm) fluctuated greatly, and the variation coefficient was 28.39% and 24.85% respectively; the change of the soil moisture content in the deep layer (20cm~40 cm) decreased significantly, and the variation coefficient was 19.41%. [Conclusion] The seasonal dynamic variation law of highway slope’s soil moisture is significant, and also keeps consistent with the dynamic rainfall, plant transpiration, and soil evaporation laws. The soil moisture conditions from May to August are the best. The spatial variation of the soil moisture can be divided into two layers: the rapid-variation layer (0~20 cm) and the active layer (20cm~40 cm). In each observation point, the soil moisture conditions are the best in the central partition belt, secondary in the sunny and shade slopes, and the worst in ground.