汉江桥闸工程下游河段典型鱼种栖息地模拟研究

探究水利工程干扰下的鱼类生境变化特征是维护河流生态健康的基础性研究。以汉中平川段内汉江三桥桥闸下游10 km为研究河段,利用水文学法和栖息地模拟法计算了生态流量。建立了河段二维水动力学模型,选用宽鳍鱲为目标鱼种,依据其对水深和流速的适宜性曲线确定了流量变化下的生境面积,并采用生境质量分级分析了不同流量响应鱼类生境的变化特征。研究结果表明:两种方法计算出河流生态流量相近,分别为54.3和53.1m~3/s,最终适宜流量为47.8～54.3 m~3/s;在流量8.8～212.7 m~3/s时,相比中等和低质量生境,高质量生境面积随流量的波动更为显著,呈现先升后降的趋势,212.7 m~3/s以上流量的各级生境面积随流量变化较小;高质量生境多分布于两岸和冷水河交汇口,中等质量生境主要分布在河段下游;低质量生境位置相对不固定;研究成果可为桥闸运行和河流鱼类保护提供重要参考依据。

Simulation of typical fish habitats in the downstream reach of Hanjiang River Bridge Sluice Project

The research of the characteristics of fish habitat changes under the impact of water conservancy projects is essential for preserving the ecological health of rivers. Taking a reach of 10 km in the downstream of the third bridge sluice of the Pingchuan section, Hanjiang River in Hanzhong as the research object, the ecological flow was calculated using the hydrological method and the habitat simulation method. A two-dimensional hydrodynamic model of the river section was established, and the targeted fish species was selected, which is Zacco Platypus. The habitat area of this species under the flow change was determined according to its suitability curve for water depth and flow velocity, and the classification of habitat quality was used to analyze the response of fish habitats to different flow patterns. It is found that the calculated river ecological flow of these two methods are very close, which are 54.3 m³/s and 53.1 m³/s respectively, and the final suitable flow is in the range of 47.8-54.3 m³/s. When the flow rate is in the range of 8.8-212.7 m³/s, the high-quality habitat area fluctuates more significantly with the flow compared with the medium-quality and low-quality habitats, showing a trend of rising first and then decreasing. However, when the flow rate exceeds 212.7 m³/s, all habitats varies little with the flow. Most of the high-quality habitats are distributed at the two banks of Hanjiang River and the intersection of Lengshui River and Hanjiang River, the medium-quality habitats are mainly located in the lower reaches of the river, whereas the low-quality habitats are relatively unstable. The research results can provide a technical support for the safe operation of bridges and sluices and the preservation of river fish.