Separating and analyzing wind- and boat-induced waves: a filtering framework for hydraulic lake monitoring

Scherbaum S, Mirbach S, Hübl F, Fuchs Y, Haun S, Schneider J. 2026. Separating and analyzing wind- and boat-induced waves: a filtering framework for hydraulic lake monitoring. Lake Reserv Manag. XXX–XXX.Separating artificially induced waves by motorboats from natural wind waves on lakes is essential to assess their damage potential for lake ecosystems and to implement effective protective measures. A novel filtering framework, combining a classification of wave packet by peak period with high- and low-pass filter and wavelet denoising methods, enabled a reliable classification of small motorboat-induced and wind-induced waves. Wind waves were determined using a calibrated numerical SWAN model, while waves induced by motorboats were identified using synchronized drone footage in a field campaign at an Austrian lake. Thereby, motorboat-induced waves accounted for 83% of the total wave energy, and wind‑generated waves accounted for 3%. The remaining 14% could not be classified, likely due to low signal strength or disturbances caused by other vehicles and reflections that were not identifiable as boat-induced. The framework was subsequently applied to 7 wave recordings obtained along shorelines characterized by contrasting hydraulic conditions. Results consistently indicated that motorboat-induced waves dominated the wave energy budget, and increased wind exposure resulted in a higher contribution of wind-generated waves. Pronounced buffering effects of wave-protection fences and sheltered bays were observed, whereas wave energy increased substantially near reflective shore structures compared to dissipative shorelines. Filtered boat-induced waves were characterized by higher wave heights, longer periods, and greater energy flux, with clear distinctions between planing and semi-planing modes visible in the wavelet spectrograms. The developed framework enhances the evaluation of wave recordings, enabling robust monitoring and assessment of anthropogenic wave exposure, which supports evidence-based management of lake ecosystems.