长江流域典型支流生境健康评价

Habitat Health Assessment of Typical Tributaries of the Yangtze River

调查评估长江流域典型支流雅砻江、赤水河、乌江以及汉江的生境状况,探索影响不同支流生境状况的主要因子,为长江流域河流生境保护和修复提供支撑。从河流物理生境形态、河流岸边带生境和水环境特征3个方面选取了10个指标,借鉴栖息地评估指数(QHEI)和快速生物评估草案(RBPs)构建河流生境评价的指标体系。2017年8-9月对4条支流的162个断面进行了调查并对河流生境进行了综合评估。评价结果表明,雅砻江、赤水河、乌江、汉江的河流生境综合指数(RHI)分别为124.7、158.5、137.8、135.5,其中赤水河评价等级为“优”,其他河流评价等级均为“良”。影响雅砻江、赤水河、乌江和汉江生境状况的最主要指标有河岸植被覆盖、河岸植被带宽、河道硬化渠化度、人类活动干扰度和河道蜿蜒度。建议强化支流国土空间管控,建立自然保护区,对具有重要生态服务功能的支流河段开展生态修复。

In recent years,river ecosystem degradation is increasingly manifested in the Yangtze River basin,caused by global climate change and human activities.Aquatic habitat is an important component of river ecosystems and plays an important role in maintaining river health.An accurate assessment of river habitat status provides important guidance for the protection and restoration of degraded river ecosystems.In this study,four rivers,the Yalong,Wu Jiang,Chishui and Hanjiang,all typical tributaries of the middle and lower Yangtze River were selected for assessment.The habitat status of the four rivers were evaluated based on an established habitat evaluation index system and the primary factors affecting the habitat of each river were explored,aiming to support conservation and restoration of river habitat in the Yangtze River basin.The habitat evaluation index system included ten indices covering three aspects of river morphology,riparian habitat and water quality.Based on the index score,habitat status was ranked into five categories:excellent(RHI>150),good(120<RHI≤15),moderate(90<RHI≤120),poor(60<RHI≤90),very poor(RHI≤60).From August to September 2017,monitoring and investigation at 162 sampling sections in the four rivers were carried out,and the river health index(RHI)of each river was calculated based on the evaluation system.The RHI of the Yalong River,Chishui River,Wujiang River,and Hanjiang River were 124.7,158.5,137.8 and 135.5,respectively.The habitat status of the Chishui River was excellent,and status of the other three rivers was good.Human activities,vegetation cover in the riparian zone,river harden and canalization,riparian plant width and the degree of river meandering were the primary factors affecting habitat quality.Based on the evaluation results,we recommend strengthening territorial control of tributaries,establishing nature reserves,and protecting and restorating tributary reaches that provide important ecological services.