Impact of mixed-height vegetation patches on energy loss in open-channel flow

Abstract

Abstract This study investigates the influence of riparian vegetation on energy losses in open-channel flow, focusing on channels partially covered by mixed-height vegetation patches, a common feature in natural rivers and canals. While previous research has primarily focused on flow resistance in fully vegetated channels, there has been limited attention to channels with unevenly distributed vegetation patches. To address this gap, we developed an innovative experimental approach to evaluate energy loss in channels with mixed-height vegetation patches under different submergence conditions. The experimental setup involved a channel partially covered with vegetation of varying heights, mimicking the natural, uneven distribution of vegetation patches. The results provided key insights into flow velocity distribution and turbulence intensity under these conditions. Furthermore, we introduced a standardized conceptualization method for the submergence ratio, specifically the concept of effective height ( $${h}_{e}$$ ), to standardize the calculation methods for submerged and emergent vegetation.Using this parameter, we derived a theoretical formula for calculating energy loss caused by vegetation patches, which closely matched the experimental data. This method offers a reliable framework for calculating hydraulic resistance in channels with uneven vegetation distribution.