Calibration of an evergy water balance model using satellite data of land surface temperature for the Upper Yangtze River basin

This study has been carried out among the project “Application of remote sensing and other space technology to hydrology and water resources (ID 5281)”. This poster presents a new methodology for the calibration of distributed hydrological models at basin scale by constraining an internal model variable, the pixel-scale equilibrium temperature. Soil hydraulic and vegetation parameters are then calibrated in each pixel of the domain according to the comparison between observed and simulated land surface temperature minimizing the differences. The model algorithm solves the system of energy and mass balances in terms of a representative equilibrium temperature (RET) that is the land surface temperature that closes the energy balance equation and so governs the fluxes of energy and mass over the basin domain. This equilibrium surface temperature, which is a critical model state variable, is comparable to LST as retrieved from operational remote sensing data (MODIS and AATSR). A traditional “trial and error” calibration procedure is also applied by comparing only discharge measurements in the available cross section. The distributed hydrological energy water balance model (FEST-EWB - Flash–flood Event–based Spatially–distributed rainfall–runoff Transformation- Energy Water Balance) has been implemented for the Upper Yangtze River basin with an extent of about 1,000,000 Km2 at spatial resolution of 5km and temporal resolution of 1 hour. Results are provided in terms of hourly evapotranspiration, soil moisture and land surface temperature maps for the period between 2000 to 2004 where ground and satellite data are available for engineering and environmental applications as parsimonious irrigation, real time flood forecast, and quantitative water resources availability. The model accuracy was controlled from the comparison with traditional discharge daily data series and also from the comparison between model and satellite land surface temperature used as a proxy of evapotranspiration fluxes.