HYDROLOGICAL APPLICATIONS OF SCATTEROMETER DATA

Abstract

Microwave remote sensing sensors (scatterometers and radiometers) offer emerging capabilities to monitor global soil moisture at high temporal resolution. This information is highly valuable for modelling hydrological processes in large river basins. In recent years, a number of studies have geared towards the use of space-borne soil moisture estimates for the hydrological applications at the catchment scale. However, concepts of how to integrate macroscale soil moisture data in hydrologic models are still vague. Reliable real-time discharge forecasts provide valuable information for managing watershed systems, for ecological releases discharge prediction with moderate accuracy. An important parameter in hydrological systems is soil moisture, which has recently been characterized by satellite-based measurements. In the present study, a discharge prediction forecast framework was set up and applied to different sub-areas of the Four Indian River Basin. The model is based entirely on remote sensing data and provides estimates of soil moisture. The soil moisture product used is based on the radar signal back-amplitude as measured by a radar scatterometer. In this study, high resolution ASCAT backscatter data developed in the framework of NASA Scatterometer Climate Record Pathfinder (SCP) have been utilized for the estimation of soil moisture for the years 2007–2016. Further, the derived soil moisture products were compared to the observed runoff of the four river basins ( Narmada, Krishna, Kavery and Mahanadi) of India. Results depicted high correlations between basin-averaged soil moisture and runoff time series (R2= 0.8) and exhibit that the seasonal changes in the discharge from dry to wet season is well captured by the ASCAT Scatterometer. The results showed that differences in runoff from year to year could, to some extent, be explained by soil moisture anomalies. The result reveals that there is hydrologic relevant information in high temporal resolution of scatterometer data.