SOIL MOISTURE RETRIEVAL USING MICROWAVE REMOTE SENSING

Abstract

The moisture content which a soil can hold is termed as soil moisture. It is an important parameter that plays a vital role in various hydrological and geotechnical applications. It can be categorized into various types namely gravitational, hygroscopic and capillary water. There are various ways in which soil moisture can be estimated. Soil moisture retrieval with the help of remote sensing is one such emerging technique of soil moisture estimation. Scope of remote sensing in soil moisture retrieval is growing day by day. This study presents measurement of soil moisture with the help of active microwave remote sensing using RISAT-1 (5.35GHz) data. With the help of active microwave remote sensing, soil moisture can be measured up to the depth of 5-10cm. The behaviour of RISAT-1 signals are analysed for two polarisation i.e. RH and RV with the incidence angle of 42.1300. A theoretical study of all the models is done for soil moisture retrieval using active microwave remote sensing and the Dubois model has been preferred in this work. The relationship between radar backscattering coefficient (σ0) and various soil parameters like dielectric constant (ε) and soil moisture are studied with the help of linear regression equations and coefficient of determination. For analysing satellite images ERDAS IMAGINE and ENVI software have been used. The results thus obtained with remote sensing data are cross examined using ‘truth data’ obtained from the relevant sites. For accuracy assessment between the soil moisture estimated model obtained and field calculated soil moisture, various parameters like mean absolute error, root mean square error and index of agreement are calculated. Finally, the conclusions are derived based on the results obtained from two methods of soil moisture retrieval.