Assessment of the impact of soil hydraulic parameters based on various Microwave datasets on estimation of hydrological fluxes

Soil Moisture (SM) is a key variable in the quantification of the water and the energy-balance fluxes occurring within the atmosphere and the surface. Recent advances in microwave remote sensing provide an unprecedented opportunity to monitor surface soil moisture globally but at a coarse (~25-40 km) spatial resolution. Although hydrological models based on water and energy fluxes are also used for estimation of the high spatial resolution soil moisture at regional scale to understand the surface hydrological processes, agricultural applications, and the water resource management remains a challenge as it depends upon hydraulic parameters. Therefore, the study focuses on the assessment of the impact of the downscaled SM derived from different microwave datasets on optimized soil hydraulic parameters and eventually its effect on discharge at the basin scale. The aim is achieved in two steps: firstly, the coarse scaled SM products from different microwave datasets (Advanced Microwave Scanning Radiometer 2 (AMSR-2) and Soil Moisture Active Passive (SMAP)) are downscaled to 1km spatial resolution using a disaggregation algorithm. Secondly, effective soil hydraulic parameters are optimized with dual input of downscaled SM and the discharge for the Kosi Basin. The results show that there is a significant impact of the optimization of soil hydraulic parameters on the hydrological fluxes and discharge. The effective soil hydraulic parameter derived from the downscaled product of SMAP L3 shows a promising result in simulation of SM from hydrological model in addition to that the optimization technique using GA in the hydrological models ensures a better process representation and spatial prediction.