水库运行对下游岸边带植被和鱼类的影响

Impacts of reservoir regulations on the downstream riparian vegetation and fish dynamics

本研究选取了漓江下游的一段复式河道为例,建立了一维全河流和二维局部河段的水环境模型,并与基于元胞自动机的岸边带植被模型和基于个体的鱼类模型耦合,从岸边带植被变化和鱼类种群动态角度研究水库运行对河流水生态系统的作用。研究以优势种植物水蓼、刺果酸模和益母草为对象,模拟了自然条件和水库调节作用下三种植物空间格局的演变,并选取草鱼和鲫鱼为研究对象,研究水库运行对鱼类生长和分布的影响。通过模拟结果的对比分析,发现水库运行有利于益母草的生长与扩张,而不利于水蓼的生长,水位波动对水蓼生长以及维持岸边植物多样性有正面作用。此外,假设仅考虑水库运行造成的下游水流变化的作用,枯水期水库向河道补水对草鱼有一定的正面影响,对鲫鱼有轻微的负面影响;而在在4-5月,水库运行对两种鱼类都存在比较明显的负面影响。本文建立的模型方法可为河流优化管理及水库生态友好运行提供支持。

The impacts of reservoir operations on the riparian vegetation and fish dynamics in a compound channel of the downstream reach of the Lijiang River was investigated in this paper.The research developed a 1D and 2D water quality model in the reach and the local region respectively,and integrated it with a cellular automata based vegetation module and an individual-based fish module.Basing on field survey,it was found that Polygonum hydropipe,Leonurus heterophyllus and Rumex maritimus are dominant riparian plants,and Ctenopharyngodon idellus and Carassius aumtus are dominant fish species.Under natural flow conditions and reservoir operations the vegetation pattern dynamics was simulated.Meanwhile,the impacts of flow regulations on fish population as well as distribution were primarily analyzed.The results indicated that the flow regulations have positive effects on the Leonurus heterophyllus growth and colonization,while have adverse effects on Polygonum hydropipe.Frequent fluctuations of water level are positive to Leonurus heterophyllus growth and biodiversity maintenance.In addition,if only flow factor is concerned,the reservoir operations in dry season have positive effects on Ctenopharyngodon idellus,but are slightly negative on Carassius aumtus.During April and May,the flow regulations have obvious adverse impacts on the two types of fishes.Although,the ongoing research is still at the early stage and there is a large space for improvement,the methods developed in present study can be used to support reservoir operation optimization for ecological concerns.