Developing a dynamic semi-distributed hydrological model considering interactions between soil moisture and evapotranspiration: application of bulk transfer method

ABSTRACT

Empirically-derived relationships are mainly used to estimate evapotranspiration (ET) in water balance models. Due to a lack of effective factors and correct conceptual relationships, the resulting ET may be inaccurate. Therefore, a hydrological model was developed by combining water balance and bulk transfer theory, called semi-distributed coupled water balance and bulk transfer (SD-CWBT). According to it, a dynamic interrelationship between ET and soil moisture was correctly established to estimate ET via physical concepts. Global gridded ET retrievals, which provide the spatiotemporal distribution of ET at a global scale, including ECMWF Reanalysis v5-Land (ERA5-Land), TERRA, Global Land Evaporation Amsterdam Model (GLEAM), and Operational Simplified Surface Energy Balance (SSEBop), were employed to evaluate the model. The results indicated the SD-CWBT, with Nash–Sutcliffe Efficiency (NSE), Kling-Gupta Efficiency (KGE), and Root Mean Squared Error (RMSE) of [0.6, 0.95], [0.68, 0.96], and [12.61, 0.99] for the streamflow and groundwater level simulation, respectively, had better performance compared to the alternatives. Furthermore, the estimated spatiotemporal distributions of ET agreed well with the climatic-vegetation conditions.

KEYWORDS:

• Evapotranspiration
• soil moisture
• water balance
• bulk transfer
• SD-CWBT model
• global gridded ET retrievals

Editor A. Fiori Associate Editor M. Rahman

Editor A. Fiori Associate Editor M. Rahman