Investigation of the Influence of Reed Vegetation on the Hydraulic Characteristics of the Huai River Inflow Channel

Abstract

When there is vegetation on the beach or main channel bed, it will have a significant impact on the river channel. This study was based on physical model experiments to investigate the flow conditions of the Jinhu section of the Huaihe River estuary, revealing the influence of reed vegetation on water flow resistance. A new comprehensive roughness formula was proposed, and the predictive effectiveness of the formula was verified. The theoretical results indicate that under the condition of vegetation not being submerged, the comprehensive roughness is directly proportional to the square root of vegetation density in areas with vegetation coverage, the square root of water surface vegetation coverage, and the 2/3 power of the hydraulic radius. The bottom slope does not affect it. Under the condition of vegetation inundation, the comprehensive roughness is smaller than that under the condition of no inundation. The experimental prediction results of the influence of reeds on roughness indicate that the measured roughness values and theoretical roughness calculation values are in good agreement. Under the same operating conditions, the roughness gradually decreases with an increase in flow rate. Under the full-reed working condition, the calculated roughness value and the measured roughness value have the same trend of change, both decreasing with the increase in flow rate. The experimental prediction results of the influence of reeds on the relationship between water level and flow rate show that the roughness value of 0 increases with the increase in reed grass surface coverage rate Ki, and an increase in Ki can lead to an increase in comprehensive roughness.