Abstract: There are several theoretical models existed for describing the relationship between the moisture migration and the temperature in the unsaturated soils. However, most of them are developed based on specific assumptions and boundary conditions and none of them are verified with the data collected from the in-situ conditions in unsaturated red clay soil slopes. An insitu moisture migrationtemperature monitoring system was established at a red slope in Linyanshan, Guilin City.  This monitoring system not only real time monitored the moisture content and temperature change in the red clay slope, it also collected the site weather conditions, moisture content as well as the temperature in the unsaturated soils under the tropical and humid conditions. The monitoring results indicate that, the moisture content and the temperature in the red clay slope changes with ambient weather conditions. The moisture content and temperature in the shallow depth vary significantly with the ambient weather. Under the precipitation conditions, the ambient temperature decreases, the moisture content in soil increases and temperature decreases and vice versa. The moisture content in soil has connected with the temperature in the soil. The increase of the moisture content reduces the influence depth of the ambient temperature and the range of the soil temperature change. With the increase of the depth, the ambient temperature has less influence on the moisture content and temperature variations.

Key words: Unsaturated Red Clay, In-Situ Tests, Moisture Contents, Temperature