Abstract
ABSTRACT To tackle the eutrophication of Lake Erie, USA and Canada agreed to reduce phosphorus levels by 40% by 2025. An accurate simulation of water quality and quantity is essential to achieve this goal. Various hydrological and water quality models have been applied in the Lake Erie Basin for this purpose. However, uncertainty in channel geometry parameters leads to uncertainty in sediment and nutrient loadings. Besides, the presence of reservoirs significantly affects the sediment and nutrient loads as they are transported through the streams. Thus, improving how these models calculate channel geometry parameters and reservoir processes can minimize the uncertainty and improve the estimation of these loads. So, this study tested the applicability of regional regression equations for in-stream and reservoir processes in the SWAT model which currently uses a single nationwide curve to derive channel geometry parameters, and a simplistic mass-balance approach to simulate sediment and nutrients in water bodies such as reservoirs. Their impact on water quantity and quality was investigated for two Canadian watersheds- Guelph and Pittock. Results showed that calibrating and validating the model at reservoir inlets and outlets, modifications to channel geometry parameters and sediment transport methods significantly improved predictions. The inclusion of reservoir routines enhanced the accuracy of streamflow simulations, while the modified Vollenweider equations outperformed SWAT in simulating reservoir nutrient loadings.
Published Version
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