Evaluation of integrating topographic wetness index with backscattering coefficient of TerraSAR-X image for soil moisture estimation in a mountainous region |
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Institution: | 1. Department of Physical Geography and Geoecology, Faculty of Science, University of Ostrava, Chittussiho 10, 710 00 Ostrava, Czech Republic;2. Department of Geography and Geology, Faculty of Natural Sciences, Matej Bel University, Tajovského 40, 974 01 Banská Bystrica, Slovakia;1. Universidad Complutense de Madrid, Geodynamics, Madrid, Spain;2. CEI Campus Moncloa, UCM–UPM, Madrid, Spain;3. IGEO, Instituto de Geociencias, UCM–CSIC, Madrid, Spain;1. Department of Forestry and Environmental Conservation, Clemson University, Clemson, SC 29634, USA;2. Department of Mechanical Engineering, Clemson University, Clemson, SC 29634, USA;3. Department of Environmental Engineering and Earth Sciences, Clemson University, Anderson, SC 29625, USA |
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Abstract: | The estimation of soil moisture by using the backscattering coefficient of radar in a mountainous region is a challenging task due to the complex topography, which impacts the distribution of soil moisture and changes the backscattering coefficient. Complicated terrain can disturb empirical moisture estimation models, thereby, the resulting estimates of soil moisture are very unlikely reliable. This article proposed an innovative way of integration of the topographic wetness index (TWI) and the backscattering coefficient of soil obtained from the TerraSAR-X image, which improves the accuracy of measurement of the soil moisture. The standard estimation error and the coefficient of determination from the model were used to evaluate the performance of TWI. Our results show that the standard estimation error was decreased from: (1) 4.0% to 3.3% cm3 cm?3 at a depth of 5 cm and (2) 4.5% to 3.9% cm3 cm?3 at a depth of 10 cm. The most reliable estimation was observed at a depth of 5 cm, when it was compared with those of 0–5 cm, 10 cm and 15 cm. The TWI from the digital elevation model (DEM) is useful as a constraint condition for modeling work. This article concludes that the integration of the backscattering coefficient of soil with TWI can significantly reduce the uncertainty in the estimation of soil moisture in a mountainous region. |
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Keywords: | Soil water content TerraSAR-X Topographic wetness index Backscattering coefficient |
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