水库报废生态环境影响及其修复

为研究水库报废对生态环境的影响,将水库报废拆坝影响划分为三个层次:以水沙过程为初始影响,视社会和经济影响为最终效应,两者之间为次生影响,并揭示了拆坝影响的综合性、矛盾性、时空延续性及不确定性等特点。从物理、化学、生态三方面明晰了拆坝生态环境影响:物理影响体现对水文、泥沙和地形地貌的影响,拆坝可完全逆转建坝带来的水文影响,淤积的泥沙将重新运移,通过溯源侵蚀使大坝上下游河段逐渐达到相对稳定的坡降;化学影响主要表现为对河流水质的影响;生态影响即可能使水生生物的生境质量得以改善,也可能由于水质退化、物种入侵对水生生境产生负面影响。针对性地提出了拆坝生态修复对策和措施:应通过重新引入乡土植物群落、控制外来物种及顺应植被演替规律修复库区及下游河道濒水植被;清除或降低污染物对生态环境的不利影响;重建河流近岸水文、地貌环境,保护和恢复水生生物;通过生态环境监测,应适时对修复措施进行调整。研究所得成果为报废水库的生态修复提供参考。

Impact from reservoir retirement on eco-environment and its restoration

In order to study the impact from reservoir retirement on eco-environment， the impact from reservoir retirement is divided into three levels， i.e. by taking the water-sediment process as the initial impact， the social and economic impacts are regarded as the final impacts， while the secondary impact is there between both of them， and then the characteristics of the comprehensiveness， contradictoriness， spatio-temporal continuity， uncertainty， etc. of the impact from dam removal are revealed as well. The impact from dam removal on eco-environment is distinguished from physical， chemical and ecological aspects： the physical impact embodies the impact on hydrology， sedimentation and topography， for which the hydrological impact from dam construction can be fully reversed by dam removal， the silted sediment is to be re-transported again and both the upstream and downstream river reaches are gradually reach to relatively stable gradient through the relevant headward erosion； the chemical impact mainly represents an impact on the water quality of river， while the ecological impact can not only improve the habitat quality of the relevant hydrobiontes， but also can generate negative impact on the acuatic habitat therein due to the degradation of water quality and th invasion of exotic species. The relevant countermeasures and methods are pertinently proposed herein that the waterfront vegetation in reservoir area and along the downstream river channel must be restored through re-introducing the indigenous plant groups， controlling the exotic species and accommodating the succession law of vegetation as well as eliminating and reducing the adverse impact from pollutant on the eco-environment， thus re-construct the riverain hydrological and topographical environment， protect and restore the hydrobiontes concerned， while the restoration measures must be duly adjusted through the relevant monitoring on the eco-environment. The study result can provide references for the eco-restoration of retired reservoir.