Enhanced Water Temperature Calculation Model Incorporating the Effects of Aqueduct Orientation and Water Surface Shading

Abstract Solar radiation is a key factor influencing the water temperature of aqueducts and constitutes a critical component in calculating water temperatures, yet current one-dimensional models conventionally neglect the shadow effect created by sidewall structures and aqueduct orientation. This omission leads to inaccurate estimations of solar radiation absorption and considerable predictive deviations. To address this limitation, this study proposes an enhanced one-dimensional aqueduct water temperature calculation model, which is developed through theoretical derivation based on fundamental heat transfer equations, including the energy equation, continuity equation, and momentum equation. This proposed model incorporates the relative motion between the Sun and the Earth, and quantitatively evaluates the impact of aqueduct orientation and water surface shading on aqueduct water temperature variations. The results of calculations and analyses based on field-measured data from the Caohe Aqueduct of the South-to-North Water Diversion Project demonstrates that, compared with conventional models, the improved model achieves better agreement with observed water temperatures, reducing the mean squared error (MSE) by 65%. These improvements have effectively enhanced the applicability and reliability of the model in engineering practice.