Influence Of Wire Engineering Measures On Physical Habitat

Qinghu segment of GuanLan River in Shenzhen was the experimental reach of this study, we selected the two weir project measures:flap gates and dam that have been completed in the river as research object. By studying the key factors of the physical habitat and river physical habitat conditions and use benthic fauna and physical habitat suitability index (K value) to comprehensively evaluate the quality of physical habitat shaped by weir measures. We explore whether the presence of flap gates and dam in GuanLan River (a typical subtropical river) played an active role, and proposed improve suggestion. The main conclusions were as follows:(1) Flap gate and dam could change the key factor of physical habitat significantly Velocity and flow changed significantly when flowed through upstream and downstream of weir measures.Velocity and flow all fluctuated regularly of rise and fall. Velocity and flow upstream and downstream of the dam fluctuated intensely.(2) A3and A4sections, particle size of substrate>2mm accounted for a larger proportion, over60%, significantly higher than the control area. Particle size of>2mm was slightly larger than the control area in other sample points. Particle size of substrate>2mm of each sample point upstream and downstream of the dam accounted for a smaller proportion, significantly smaller than that of the control area. While the particle size of substrate<2mm accounted for more than70%. To sum up:Flap gates and dam caused different effects on sediment particle size. The proportion of large particles upstream and downstream flap gates increased. The proportion of small and medium-sized particles upstream and downstream the dam increased.(3) Through analyzing sandbars’dynamic upstream and downstream two weir measures changes:the weir measures could change the morphology and distribution of the sandbars by changing flow.(4) Changes in the composition and diversity of zoobenthos made us evaluate physical habitat quality upstream and downstream weir measures from a biological point of view. The results showed that:the overall quality of physical habitat upstream and downstream the flap gate was significantly better than the control area. While, the overall quality of physical habitat upstream and downstream the dam was lower than the control area. At the same time, the quality of physical habitat among sample sites upstream and downstream the flap gate was different. The quality of physical habitat among the sample sites upstream and downstream the dam had little differences.(5) Finally, we used physical habitat suitability index (K value) and existing mathematical model to re-evaluated physical habitat quality upstream and downstream the weir measures. The evaluation results:the average K value of all sample points upstream and downstream the flap gate was significantly higher than that of the control area. The average K value of all sample points upstream and downstream the dam was lower than that of the control area. The results showed that:the quality of physical habitat shaped by flap gate was high. The quality of physical habitat by the dam was low. Comparison of each sample point upstream and downstream the weir measures we know that the quality of the physical habitat downstream of the flap gate is higher than that upstream. The quality of the physical habitat did not show significant differences between the points of the dam.