Diagnosis and treatment of the swat hydrological response using the Budyko framework

Abstract

The hydrologic response of a river basin pertains to how precipitation is partitioned into streamflow, evapotranspiration, and infiltration. The reliability of all these components is essential for the sustainable use of water resources. This paper seeks to understand if the prediction of the main components of the water balance from the SWAT model can be controlled and interpreted by a simple Darwinian approach: the Budyko framework. The Danube Basin was selected to assess the SWAT model green (evapotranspiration) and blue water fluxes (water yield or water that runs off the landscape into rivers) in a diagnostic approach based on two mono-parametric Budyko curve-type equations. This analysis was conducted comparing the evaporative index (EI) and the base flow index (BFI) predicted by Budyko's equations based on observed data from 418 gauging stations with those simulated by SWAT. The study demonstrated that SWAT evapotranspiration estimations were in good agreement with those of the Budyko curves, whereas SWAT baseflow underestimated the Inn and Austrian Danube regions. The analysis of the Budyko equations in each water management region of the Danube provided a pioneering understanding of the relationship between EI and BFI in the study area, leading to an improvement of the hydrological simulations and providing a more reliable water balance in each water management region.