Spatial and Temporal Changes of Fish Hydraulic Habitat in the Confluence Area of Rivers
The confluence arterial and tributary is an important place for fish growth,reproduction and migration,and the hydrological condi-tions in the confluence area are exceptionally complex,and the spatial and temporal changes in the flow structure will have a direct impact on the distribution of fish hydraulic habitat indicators.The study of the distribution characteristics of fish hydraulic habitat indicators in the con-fluence zone under high-flow pulse conditions is of great significance to the protection of river ecosystems.Taking the confluence of the Yan-gtze River and the Jialing River as an example,the response relationship between the spatial-temporal distribution of hydraulic habitat indices and the high-flow pulse process was analyzed by using a three-dimensional numerical simulation method.The results show that:during the process of rising water,the interaction between the main stream and its tributaries increases,the maximum velocity appears in the concave bank and the deep channel of the river bottom in the confluence,and the width of the circumfluence structure decreases in the separation area of the convex bank,the change trend of falling water is opposite to that of rising water.The habitat suitability index(SH)greater than 0.8 moved between the deep trough and the bank,and moved to the bottom of the river and the bank wall with the process of rising water,with the falling water is compressed to the concave bank deep trough and the edge beach.Under the condition of high flow pulse,the area of mi-crohabitat A in the confluence area increases first and then decreases with the fluctuation of water,and the A peak appears near the peak of high flow pulse.
high flow pulseconfluence zonefish hydraulic habitat indicatorsspatial and temporal distribution characteristics
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