| Knowledge of soil moisture helps to derive parameters, such as evaporation, transpiration, infiltration, runoff and drainage classes, which are very useful in several agricultural and hydrological applications. Active and passive remote sensing sensors have shown the capability to estimate soil moisture based on the large contrast between the dielectric properties of wet and dry soil. However, the retrieval of soil moisture from microwaves system is mostly influenced by the characteristics of the vegetation cover. Indeed, having accurate information of the spatial distribution of vegetation (i.e. NDVI and vegetation optical depth) improves the soil moisture retrieval from microwave data. The major objective of this research is to develop an algorithm to produce spatial retrieval of soil moisture using active microwave data. The algorithm will be developed using a combination of parametric and non-parametric tools such as neural networks, fuzzy logic, maximum likelihood etc. The study area is located in Oklahoma (97d35'W, 36d15'N). The active microwave data from RADARSAT-1 acquired in SCANSAR mode were used in combination with the soil moisture data generated from passive Electronically Scanned Thinned Array Radiometer (ESTAR) during the SGP97 campaign operated by NASA.; This study will evaluate the contribution of vegetation in minimizing its effect on the accuracy of soil moisture retrieval. Based on our research, we found that the presence of higher vegetation cover reduces the accuracy of soil moisture retrieval. The empirical model to limit the effect of vegetation cover to maximize the accuracy of soil moisture retrieval has been proposed. The final product of this study, which has been produced, is a soil moisture map using active microwave data with different level of accuracy. This research also highlights the impact of spatial heterogeneity in land surface conditions on soil moisture retrieval from microwave data. Sensitivity of soil moisture retrieval in spatial heterogeneous area is positively correlated with the type of land-cover. |
