Derivation of new resistance principle on flow-induced morphological response of flexible vegetation

Water flow under vegetated environments is a noteworthy research topic in environmental hydraulics and restoration ecology, and this research is particularly important for maintaining water transport and streambed stability in water ecosystems. The calculation of the resistance coefficient in vegetated water flow is the core of this research. But there are still problems such as complex expressions and low simulation accuracy in this research field. To solve this scientific problem, this research, based on the theoretical study of environmental hydraulics and genetic algorithm, selected three basic parameters of vegetation submergence, resistance length and curvature degree, and successfully constructed the formula for calculating the resistance coefficient for flexible vegetated flow by using a wide range of data sets. New quantitative relationship between the drag coefficient and the relative roughness of flexible vegetation was established in this study. The formula of drag coefficients for flexible vegetation conditions has a more concise form and can be successfully applied to both flexible and rigid vegetation. As flexible vegetation is deformed under the action of water flow, and the quantitative expressions of Vogel number and relative roughness are given quantitatively through the analysis of its physical properties. Overall, this study improves the basic theoretical study of vegetated flow in environmental fluid dynamics and provides scientific theoretical support for vegetation restoration.