三峡库区河流生境质量评价

三峡水库建成蓄水后,库区流水生境的大幅度减少及垂直落差最高可达30 m的消落带的形成,使库区支流生境发生了剧烈变化,因此对库区河流生境质量评价十分必要。基于水文情势、河流形态和河岸带生境3个方面18个指标的河流生境评价指标体系,对三峡库区36条重要支流254个样点河段进行河流生境质量评价。结果表明,4.72%的样点河流生境质量处于优等,30.31%为良好等级,49.61%为一般等级,15.35%为较差等级,没有最差等级的样点。对于表征河流生境状况的水文情势、河流形态和河岸带生境3个类别,254个河段总体上河岸带生境状况最好,其次为水文情势,河流形态最差。从总体上来看,三峡库区支流生境质量是自然环境和人类活动相互作用的结果,其中河岸带植被状况、消落带宽度、人为干扰、河床底质状况、水文情势自然性等为主要的驱动因子。

Assessment of river habitat quality in the Three Gorges Reservoir Region

After the completion of the Three Gorges Reservoir, tributaries of the reservoir habitat changed dramatically because of the greatly reduced flow of water and formation of a 30 m deep water-level fluctuation zone, so it is very necessary to evaluate reservoir river habitat quality. Based on the river habitat assessment index system, including 18 indicators that relate to river hydrology, river morphology, and riparian habitat, we evaluated the quality of the river habitat at 254 sampling points in the 36 important tributaries of the Three Gorges Reservoir area. The quality of the habitat scored within the range of "excellent" at 4.72 percent of the sampling sites and 30.31 percent received a score within the range of "very good." On the other hand, 49.61 percent received a score within the range of "average", while the remaining 15.35 percent received a score of "poor". There was no site within this catchment that received a score of "very poor". For the river habitat conditions, the riparian zone was the best out of the whole 254 sites, followed by the hydrological regime, and the river morphology was the worst. Overall, the habitat quality of tributaries of the Three Gorges Reservoir is due to the interaction between the natural environment and human interaction, and the riparian vegetation condition, riparian zone width, human disturbance, riverbed sediment conditions, and hydrological nature are the main driving factors.