USE OF LANDSAT THERMAL-IR DATA AND GIS IN SOIL-MOISTURE ASSESSMENT

Landsat satellite Thematic Mapper (TM) data were explored as an altern ative for monitoring regional soil moisture conditions. The theoretica l method of using single daily temperature data sets to estimate root zone soil moisture was tested with ground-based observations. Results indicated that the percentage gravimetric soil moisture content in the 0-24-cm depth was inversely related to the soil surface temperature. A demonstration of Landsat-TM based soil moisture estimation was perfo rmed for Lee County in southwestern Florida. The thermal-infrared (IR) data from TM band 6 were overlain onto four principal land-use catego ries (agricultural/irrigated, urban/clearings, forest/wetlands, water) using a geographic information system (GIS). The thermal-IR data were used to assess four qualitative soil moisture conditions (water/very wet, wet, moist, and dry) within each land-use category. Integration o f Landsat thermal-IR data with land-use through GIS under certain cond itions may be a useful technique for assessing regional soil moisture conditions, and further research to refine and quantify this technique is recommended.