Experimental investigation into flow resistance of large benthic crab burrows in the Yellow River Delta, China

The current study investigates the impact of burrowing activities by crab species in the tidal flats of the Yellow River Delta in China on the hydraulic resistance characteristics of water flow, particularly the regulatory effect of biological activity on hydraulic parameters. Although there are many models that attempt to describe the resistance to water flow, these models tend to ignore the influence of such things as biological structures, geomorphological features, and artificial constructs in complex natural water bodies, resulting in insufficient predictive accuracy of the resistance coefficients and Manning's roughness coefficients. In this paper, a new theoretical model is developed to achieve the construction of a model for predicting the hydrodynamic resistance characteristics of crab-hole regions affected by water flow by introducing a cross-sectional area correction coefficient to improve the accuracy of the calculation. The experimental results show that there is a significant positive correlation between the drag coefficient, and the hydraulic radius, and cave density, and a negative correlation with the Reynolds number, and the modification for the sidewall and bed effect greatly improves the representativeness of the measured data. In addition, a new theoretical model is proposed to improve the prediction of drag and Manning's roughness coefficient, and the prediction results are in good agreement with the measured data. The improved drag coefficient calculation model proposed in this paper improves the applicability to the research object and helps to establish a more accurate hydrodynamic model.