Influence of radiation and low-temperature infiltration on soil moisture and temperature variation

【Objective】This study investigated the variation of soil moisture and temperature affected by radiation and infitration of low-temperature water to support further research on improving downstream ecological environment in the riparian zone.【Method】Using fine sand as the representative soil sample,a self-developed test system device was used to analyze the dynamic characteristics of the soil internal temperature and moisture under infiltration of water at low temperature(water temperature 10℃,infiltration head 25cm)and different radiation temperatures(no radiation,30and 40 ℃).【Result】The vertical distance of sandy soil wetting front and steady infiltration rate increased along with the radiation temperature.As the increase of radiation heat flux,the soil surface temperature and temperature gradient rose,and the surface to the internal heat transfer increased accordingly,leading to increase of soil internal temperature.The internal soil temperature gradient was large when the radiation temperature was 40℃,and the overall average temperature was higher than that of no radiation.The infiltration of water at low temperature had impacts on the soil internal temperature and moisture distribution regardless radiation.And the reduced amplitude of temperature in deep soil was large.Soil surface temperature with radiation was significantlyhigher than the case without radiation.【Conclusion】With low water infiltration,variation of radiation temperature had influence on soil moisture and temperature dynamics,and its scope and impact strength varied with radiation temperature.