Determination of Soil Water Regime Based on Ground-Based Microwave Radiometry Measurements
Abstract
The primary objective of this project is to link remotely sensed surface water contents to the soil water regime, in particular to the regime of structured soils. We attempt to use the dynamics of spatially averaged surface water contents measured with microwave radiometry to predict preferential infiltration and drainage. Under field conditions the so-called macropore flow plays an important role in the infiltration and drainage behavior of a soil, as well as in the mass transfer of all sorts of solutes. These rapid processes are only detectable during the first few hours after a rainfall event, when most of the larger pores are still water filled. The main focus of our project lies in an areal integration of such processes on a field scale. For this reason, we depend on areal data with a high temporal resolution that allow to characterize the soil water dynamics. We present a field experiment with two different ground-based radiometers (1.4 GHz and 11.4 GHz, respectively) centered at a 5 m x 10 m bare soil plot. The brightness temperature measured with passive microwave sensors contains information on surface water content that is already spatially averaged. Furthermore the water content was measured in-situ with time domain reflectometry probes (TDR) assembled at five depths. In the same depths we measured matric potential (pressure head of soil water) and soil temperature. These data were recorded every 30 min from May to July 2002. We illustrate the implications of the results from this field campaign on the determination of the soil water regime. Based on the van Genuchten-Mualem model for the soil hydraulic functions we investigate how the hydraulic properties affect the dynamics of the topsoil water content and in how far we can estimate the hydraulic properties with inverse modeling.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2002
- Bibcode:
- 2002AGUFM.H71E..10S
- Keywords:
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- 1866 Soil moisture;
- 1894 Instruments and techniques;
- 6969 Remote sensing