南水北调中线水源地陡坡型库岸生态屏障构建

Ecological barrier constructing of steep slope reservoir bank in the water source of Middle Route of South-to-North Water Diversion Project

丹江口水库陡坡型库岸曲折,沟谷深切,大坝加高后消落区面临植被消亡、生态退化等问题。恢复消落区植被,拦截阻滞沟谷径流,以及强化库湾净化能力是构建库岸生态屏障的基本途径。消落区植被恢复应根据淹水时间配置不同群落类型:高位区(165~170 m)构建乔木-灌木-草本植物混交群落;在中位区(163.5~165 m)构建灌木-草本植物混交群落;在低位区(160~163.5 m)构建草本植物群落。沟谷径流拦截阻滞的目的在于减少冲刷,主要技术措施有生态拦截坝、生态溪沟和微地形改造等。库湾水体通过风车驱动的水循环系统增强流动性,同时配套生态塘等净化措施,防控富营养化风险。技术方法的实施包括基础资料收集、现场勘察、问题分析、工程措施布局、工程设计和运行监测等步骤。羊山库岸的应用案例表明,构建的措施体系对TSS去除率大于90.4%,对TN去除率大于46.8%,对TP去除率大于55.3%,能够减少TSS输出量112 t·a^−1,减少TN输出量19 kg·a^−1,减少TP输出量11 kg·a^−1。上述研究结果可为南水北调中线水源地生态屏障构建提供依据,亦可为我国其它水库库岸生态建设提供借鉴和参考。

The bank of the steep bank in Danjiangkou reservoir is zigzag and the gully is deep,and the waterlevel-flucutation zone is faced with vegetation extinction and ecological degradation after the dam was raised.Restoration of vegetation in water-level-flucutation zone,interception of gully runoff and enhancement of reservoir bay purification capacity are basic ways to construct ecological barrier of reservoir bank.Different community types should be configured according to the time of flooding for vegetation restoration in the waterlevel-flucutation zone,of which the mixed community of arbor,shrub and herbaceous plants were constructed at the high location(165~170 m),the mixed community of shrub and herbaceous plants were constructed at the middle location(163.5~165 m),and the herbaceous plants were constructed at the low location(160~163.5 m).The purpose of gully runoff interception and block is to reduce erosion,and the main technical measures include ecological interception dam,ecological gully and micro-terrain reconstruction.Water was lifted by windmill to enhance water flow in reservoir bay,and purification measures such as ecological pond were also taken to reflux the extracted water back to reservoir bay after purification,so as to prevent and control eutrophication risk.The technical implementation includes basic data collection,site investigation,problem analysis,engineering measure layout,engineering design and operation monitoring.The application practice case in Yangshan reservoir bank indicated that the removal rates of TSS,total nitrogen,and total phosphorus were greater than 90.4%,46.8%and 55.3%,respectively.And their outputs were reduced by 112 t·a^−1,19 kg·a^−1 and 11 kg·a^−1,respectively.This study provides a basis for the ecological barrier construction in the middle route of the southto-north water diversion project,and also provides reference for the ecological construction of other reservoirs in China.