Integrating remote sensing-derived evapotranspiration and
ground-monitored discharge data for the improvement of hydrological
modelling: A case study of the Sekong River Basin
Abstract
This study analyses the efficiency of integrating remotely sensed
evapotranspiration into the process of hydrological model calibration. A
joint calibration approach, employing both remote sensing-derived
evapotranspiration and ground-monitored streamflow data was compared
with a conventional ground-monitored streamflow calibration approach
through physically-based hydrological, Soil and Water Assessment Tool
(SWAT) model setups. The efficacy of the two calibration schemes was
investigated in two modelling setups: 1) a physically-based model with
only the outlet gauge available for calibration, and 2) a
physically-based model with multiple gauges available for calibration.
Joint calibration was found to enhance the skill of hydrological models
in streamflow simulation compared to ground-monitored streamflow-only
calibration at the unsaturated zone in the upstream area, where
essential information on evapotranspiration is also required.
Additionally, the use of remote sensing-derived evapotranspiration can
significantly improve high flow compared to low flow simulation. A more
consistent model performance improvement, obtained from using remote
sensing-derived evapotranspiration data was found at gauged sites not
used in the calibration, due to additional information on spatial
evapotranspiration in internal locations being enhanced into a
process-based model. Eventually, satellite-based evapotranspiration with
fine resolution was found to be competent for calibrating and validating
the hydrological model for streamflow simulation in the absence of
measured streamflow data for model calibration. Furthermore, the impact
of using evapotranspiration for hydrologic model calibration tended to
be stronger at the upstream and tributary sub-basins than at downstream
sub-basins.