Remote Sensing of Watershed Characteristics and Rainfall Input

Abstract

Modern hydrologic modeling techniques require information on the hydrological system as well as on the hydrologic process with high resolution in space and time. Conventional point measurements are not very suitable for this purpose, while various remote sensing (RS) techniques are of great advantage in many cases. After a brief discussion of RS platforms and sensors relevant for hydrological applications, techniques are discussed which can estimate catchment characteristics with the aid of satellite data. Landsat TM and SPOT satellites provide relevant information in various spectral bands which allows the estimation of soil type, land use, vegetation canopy, soil moisture conditions etc. which may form the basis for the estimation of hydrologic model parameters.

Besides the use of RS data for model parameter estimation RS data can also be used for the quantification of model input variables such as rainfall, snowmelt, evapotranspiration et al. In this chapter two RS techniques for rainfall estimation are presented, i.e. radar rainfall measurement (active microwave) and rainfall estimation by data from satellite imagery (infrared and visible). While the use of weather radar provides a high resolution in time and space and is already operational in real time, the satellite imagery produces rainfall estimates of lesser accuracy. It will, however, be improved during the 1990’s and provides a promising perspective for the future.