MAPPING SATURATED AREAS WITH A HELICOPTER-BORNE C BAND SCATTEROMETER

The “contributing area” concept is one of several basic concepts in modeling hydrologic processes used to explain storm runoff production. The main difficulty in using this concept of variable source areas is the identification and characterization of saturated areas according to the temporal and spatial variability during a storm event. In this experiment a helicopter‐borne C band scatterometer has been used to locate the saturated areas within a small watershed. In contrast to the general results, where radar cross section increases with soil moisture, calibration shows a backscatter coefficient decreasing for the high gravimetric water contents of the saturated areas, which may be due to the increasing importance of specular reflection processes. It appears that a threshold on the backscatter coefficient may be determined which would allow the location of saturated areas, independent of the nature of the field surface (vegetation cover or slope). These experiments, which were intended partly as ERS 1 satellite simulations, show that active microwaves may be a good tool for partial hydrology. Copyright 1990 by the American Geophysical Union.