Ultrasound-based control of water hyacinth proliferation in tropical reservoirs: experimental design and acoustic attenuation modeling.

The proliferation of floating macrophytes such as Eichhornia crassipes, driven by eutrophication, compromises the ecological and operational quality of hydroelectric reservoirs. This study developed and evaluated an ultrasonic (US) system for controlling this species. Controlled experiments tested frequencies of 40, 80, and 120 kHz, identifying 40 kHz as the most effective. E. crassipes seedlings were exposed daily to US in pure and eutrophic water. Growth and seed production were assessed through physical, visual, and photographic analyses. US exposure reduced growth rates, inhibited flowering, and decreased seed production compared to the control group. Acoustic modeling indicated an average attenuation coefficient of 1.00 × 10⁻⁴ dB/cm in eutrophic water. Based on simulated acoustic signal decay derived from experimentally obtained attenuation coefficients, the system using piezoelectric transducers operating at 40 kHz showed a theoretically estimated effective operational range of up to approximately 50 m per transducer, not validated by field tests. The system features an adaptable design and consistent performance across different water compositions, offering a scalable approach for macrophyte control. Continuous environmental monitoring is recommended to ensure efficiency and ecological safety. Overall, US represents a promising and sustainable alternative for macrophyte management, considering potential effects on non-target organisms and environmental variability.