THE USE OF AIRBORNE THERMAL REMOTE-SENSING FOR SOIL MAPPING - A CASE-STUDY IN THE LIMOUSIN REGION (FRANCE)

We applied airborne thermal remote sensing to a wet soil test area in the French region of Limousin for which a 1:10 000 scale soil map alre ady exists. Specific types of soil can be recognized and delimited on the thermographs. The flight took place on 21 February 1985 at 10:00 l ocal time, following a four-day cold period. The radiometer was used w ith a 10.5-12.5 mum channel. Apparent temperatures were higher on shal low soils (developed on gneissic and diorite rocks) and hydromorphic s oils than on well-drained soils on slopes. Measurements of the ground soil thermal properties allow thermal inertia to be calculated for eac h type of soil; in addition they enable the verification that both dee p wet soils with high heat capacities and pebbly soils with high condu ctivities have higher thermal inertias. The differences in thermal ine rtia explain the observed differences in apparent temperature for a fl ux variation corresponding to that which prevail during the days prece ding the flight.