Effects of vegetation arrangement pattern on flow resistance in an open channel

Abstract

Vegetation community are often observed to grow in stripe pattern or patches within many stream channel. It is necessary to predict or understand stage-discharge relationships and velocity distributions in partially vegetated channel for enhancements of flood protection and river environment. In this paper, the influence that arrangement patterns of vegetation zones gave to the flow resistance in an open-channel was examined experimentally. The water-surface fluctuations and flow velocity were measured by stage gauge using ultorasonic wave and Particle Image Velocimetry method respectively. Results showed that the relationship between flow depth and discharge significantly depended on the arrangement patterns and the reason could be explained by the difference of momentum transport from the relatively fast flow in non-vegetated zone to the slow flow within the vegetated zone.