Abstract
Abstract The present study was conducted to examine the accuracy and applicability of the hydrological models Soil and Water Assessment Tool (SWAT) and Hydrologic Engineering Center (HEC)- Hydrologic Modeling System (HMS) to simulate streamflows. Models combined with the ArcGIS interface have been used for hydrological study in the humid tropical Hemavathi catchment (5,427 square kilometer). The critical focus of the streamflow analysis was to determine the efficiency of the models when the models were calibrated and optimized using observed flows in the simulation of streamflows. Daily weather gauge stations data were used as inputs for the models from the 2014–2020 period. Other data inputs required to run the models included land use/land cover (LU/LC) classes resulting from remote sensing satellite imagery, soil map and digital elevation model (DEM). For evaluating the model performance and calibration, daily stream discharge from the catchment outlet data were used. For the SWAT model calibration, available water holding capacity by soil (SOL_AWC), curve number (CN) and soil evaporation compensation factor (ESCO) are identified as the sensitive parameters. Initial abstraction (Ia) and lag time (Tlag) are the significant parameters identified for the HEC-HMS model calibration. The models were subsequently adjusted by autocalibration for 2014–2017 to minimize the variations in simulated and observed streamflow values at the catchment outlet (Akkihebbal). The hydrological models were validated for the 2018–2020 period by using the calibrated models. For evaluating the simulating daily streamflows during calibration and validation phases, performances of the models were conducted by using the Nash-Sutcliffe model efficiency (NSE) and coefficient of determination (R2). The SWAT model yielded high R2 and NSE values of 0.85 and 0.82 for daily streamflow comparisons for the catchment outlet at the validation time, suggesting that the SWAT model showed relatively good results compared to the HEC-HMS model. Also, under modified LU/LC and ungauged streamflow conditions, the calibrated models can be later used to simulate streamflows for future predictions. Overall, the SWAT model seems to have done well in streamflow analysis for hydrological studies.
Highlights
Water demand increases with the rising population; water management is essential through watershed models by better understanding and handling water budget equations
The Soil and Water Assessment Tool (SWAT) and Hydrologic Engineering Center (HEC)-Hydrologic Modeling System (HMS) hydrological models were applied to the sub-humid tropical Hemavathi river basin using the procedures defined in the literature review and described workflow diagrams (Figures 5 and 6)
For the period year 2014–2020, associated data required as the input variables is observed streamflow availability; 2014–2017 was considered the calibration period and 2018–2020 data was considered for the validation period of models
Summary
Water demand increases with the rising population; water management is essential through watershed models by better understanding and handling water budget equations. Streamflow simulations are necessary to produce hydropower, consumptive use and irrigation, etc. The depth of rainfall converted into streamflow is to be estimated effectively. Researchers have undertaken numerous studies for many decades to simulate streamflow using hydrological models on the catchment scale (Gosling et al 2011). The estimation of the streamflow on a basin-scale by executing water budget equations in the hydrological models was necessary (Vijverberg et al 2009). LU/LC affects the streamflow pattern in hydrological modeling due to the infiltration variations (Yamamoto et al 2020). To capture the spatial diversity of the catchment, hydrological models require data inputs such as DEM, soil map, weather gauge stations data and LU/LC, and are subdivided into
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