Quantifying wind-induced turbulence and wave energy in a shallow lake: Insights from a large-scale indoor physical model of Lake Taihu

Understanding wind-driven hydrodynamic disturbances is critical for evaluating sediment resuspension and ecosystem stability in shallow lake environments. This study investigates the spatiotemporal variability of near-bed turbulence and wave energy under varying wind forcing and water depth conditions using laboratory experiments. Three observation regions (A, B, and C) with water depths of 20, 25, and 30 cm were subjected to different wind speeds. Turbulent kinetic energy (TKE) and significant wave height (H1/3) were calculated based on acoustic doppler velocimeter velocity fluctuations and wave gauge data, respectively. The results show that TKE increases with wind speed but decreases with water depth, while H1/3 increases with both wind speed and depth. Both turbulence energy (ET) and wave energy (EW) exhibit a consistent spatial gradient (A > B > C), reflecting differences in exposure and fetch length. A normalized disturbance index—composite disturbance energy index (CDEI) was proposed to integrate ET and EW, and its linear relationship with wind energy (EWind) input revealed high correlation coefficients (R2 > 0.97) across all regions. Regression analysis indicated that regional variations in CDEI response were primarily governed by effective wind forcing, quantified by a fetch- and angle-based wind index. Furthermore, we propose a refined model for bottom shear stress that incorporates both turbulent and wave-induced components, overcoming limitations of classical turbulence-based formulations. These findings underscore the dominant role of wind energy in shaping benthic hydrodynamics and provide a quantitative framework for assessing sediment disturbance potential in shallow aquatic systems.