水电开发对河流生态系统服务的效应评估与时空变化特征分析——以武江干流为例

水电开发对河流生态系统的影响不容忽视,科学评估其影响有助于建立更可持续的水电开发模式。以武江干流为例,利用当量因子法和功能价值评估法,分析了武江干流梯级水电开发对受淹没影响的河岸带陆地生态系统和河流生态系统服务的效益及损失,并就其对河流生态系统服务的综合效应进行了评估。结果显示：武江干流水电开发使受淹没影响的河岸带生态系统和河流生态系统本身的服务价值均出现增加,价值增量主要体现在水文调节、水资源供给等服务方面;武江干流水电开发对河流生态系统服务的正效应大于负效应,正效应主要体现在发电、水文调节、气体调节等方面,负效应主要体现在维持生物多样性、土壤保持等支持服务方面。研究认为不同规模水电站的正负效应侧重点不同,不同流域单位电能的生态损失难以直接横向比较。结合多年来武江鱼类资源跟踪调查数据,分析了鱼类生物损失指数的变化趋势,探讨了水电开发在时间上的累积生态效应及水电服务的空间格局差异。由于生物多样性等服务的影响难以用货币直接衡量,加上水域的单位面积服务价值远高于其他生态用地类型,导致负效应的价值评估偏保守,武江干流水电开发的正负效应之比偏大。

Evaluating the cumulative impacts of the hydropower development on the river ecosystem services in terms of spatial and temporal aspects: A case study in the mainstream of the Wujiang River

The impact of hydropower development on river ecosystems cannot be ignored, and scientific evaluation of its impact will contribute to the establishment of a more sustainable hydropower development patterns. In this paper, we analyzed the benefits and losses of the cascade hydropower development in the mainstream of the Wujiang River on the riparian terrestrial ecosystems and river ecosystems by using both equivalent factor and functional value evaluation methods. Based on the benefits and losses, we made a comprehensive evaluation of the cascade hydropower development on the river ecosystem services. The results show that the hydropower development in the mainstream of the Wujiang River increased the values of the riparian terrestrial ecosystem and river ecosystem services, particularly in the hydrological regulating and water supply functions. In addition, positive effects of the development were found on the power generation, hydrological and air regulating functions, while negative effects were observed on biodiversity maintaining and soil conservation. And the positive effects on river ecosystem service are greater than the negative effects. It was difficult to compare directly the ecological losses of unit electrical energy with other basins as different hydropower stations had their own emphasis regarding the positive and negative effects. Based on the long-term survey data of fish resources in the Wujiang River, the trend of fish biological loss index was analyzed to understand temporal cumulative ecological effects of hydropower development. The differences in the spatial pattern of hydropower generation were discussed by using InVEST model. The impact of ecosystem services such as biodiversity was hard to evaluate directly in terms of currency, and the service value per unit area of the water body was considerably higher than that of any other land-use types, which resulted in a conservative, e.g. a low value of negative effects of the hydropower development in the mainstream of the Wujiang River, and a high ratio of positive to negative values.