Community Research and Development Information Service - CORDIS


Although soil moisture constitutes only about 0.005 % of the global water resources, it is an important component of the hydrological cycle. It is a limiting factor in agricultural production, puts an important control on ecosystems, influences runoff, affects weather patterns, and is a crucial element in climate change studies. Currently, soil moisture can only be reliably measured on the ground, which is expensive and does not provide a good spatial representation of the soil wetness conditions due to the high variability of soil moisture on a local scale. Remote sensing may resolve these problems since it naturally provides areal measurements and because soil moisture maps of large regions could be produced at relatively low costs. However, the problem is that soil moisture is only one of the many factors that affects the remotely sensed signsl.
The objective of this work was to develop a method to retrieve soil moisture from ERS Scatterometer data. The ERS Scatterometer is a C-band radar with a spatial resolution of about 50 km, and has been flown on board of the European Remote Sensing Satellites ERS-1 and ERS-2. It measures the backscattering coefficient that, over land surfaces, is a function of vegetation, surface roughness, soil moisture content, and incidence angle. To estimate soil moisture the other influencing factors need to be accounted for.How this is achieved is described in this thesis.
The retrieved soil wetness values are a relative measure of the moisture content in the remotely sensed soil surface layer which, in C-band, is in general 0.5-2 cm deep. In most applications, however one is interested in the water content in the soil profile, and therefore an algorithm to estimate the profile soil moisture content from ERS Scatterometer and soil data is developed. A validation of the method based on an extensive data set of gravimetric soil moisture measurements from the Ukraine shows that the soil moisture content in the first meter of the soi

Additional information

Authors: WAGNER W, SAI, Ispra (IT)
Bibliographic Reference: EUR 18670 EN (1998)
Availability: Available free of charge from CCR Ispra
Record Number: 199910578 / Last updated on: 1999-04-01
Original language: en
Available languages: en