Remote sensing study of soil hazards for Odendaalsrus in the Free State Province

Abstract

Expansive soils are some of the most widely distributed and costly of geological hazards. This study examined ASTER satellite data, combined with standard remote sensing techniques, namely band ratios, in identifying these soils. Ratios designed to detect various clay minerals were calculated and possible expansive soils were detected, especially in the pans. It was also possible to delineate the mudrock that may act as a source for expansive soils. Moisture content clearly affected the ratios and it shows that remote sensing can detect where wetness leads to the development of problem soils. The fact that the area has relatively dry climatic conditions may explain why large areas of the mudrock have not yet weathered to clays. Because the ratios are not unique, results can be ambiguous, so care must be taken in the interpretation phase.