Catchment Classification-Based Comparison of Hydrological Models to Inform Water Systems Analysis

Choosing a suitable model and determining the best calibration method are complex processes. These can be simplified by comparing uncalibrated models and analyzing modeling results based on catchment characteristics. The amalgamation of these two stages forms "informing water systems analysis." This study examines the application of the Water Systems Integrated Modelling framework (WSIMOD), which is a comprehensive water systems model applied previously for catchments in the UK, and the Soil and Water Assessment Tool (SWAT), a commonly used hydrological model in India. The comparison is conducted using a catchment classification scheme based on physiography. This approach establishes a connection between the catchment characteristics and the model performances, providing valuable insights for the analysis of water systems. WSIMOD demonstrates superior performance compared to SWAT in its out-of-the-box configuration, particularly when simulating average flows. WSIMOD necessitates a greater amount of data preparation compared to SWAT, but it involves a less complex calibration process. The performance of SWAT is highly dependent on the characteristics of each catchment, necessitating the use of multi-site calibration. WSIMOD's performance is not significantly influenced by catchment characteristics, enabling regions within the same agro-ecological zone to share identical parameter values. The catchment classification analysis indicated that to enhance the accuracy of the SWAT model, it is necessary to select topography, precipitation, and soil parameters for calibration. Additionally, the infiltration rate and residence times of water should be further refined to improve the WSIMOD model. This proposed methodology facilitates and simplifies the processes of model selection and calibration.