国家黑河流域综合治理工程生态成效科学评估

Scientific Assessment on Ecological Effects of National Integrated Management Project in Heihe River Basin

黑河是我国西北地区第二大内陆河,2001年国家实施了该流域的综合治理工程。文章基于近10年来对黑河流域自然-经济系统水循环、水过程和生态与环境变化研究成果和阶段认识,对生态治理效果及其生态环境影响进行了科学评估。整体上,黑河流域水资源主要受西风带影响,主要产流区为中高山区。近10年和百年是流域器测记录以来和千年尺度上的丰水期,这为流域分水和综合治理提供了有力的水资源保障,而持续增长的社会经济系统水资源需求压力是导致流域中下游和经济发展-生态用水之间矛盾的主要根源。在中游地表水利用量得到有效控制的情况下,中游地区社会经济系统用水结构产生显著变化,但地表水资源限制和中游耕地面积持续增加导致局地地下水水位及储量呈减少趋势,且面临枯水期水资源严重超载问题。进入下游的水量接近规划要求,下游水系统和生态环境恶化趋势得到有效遏制,但还未全面恢复,并存在较大空间异质性;持续增加的由河岸林地开垦而来的耕地,对下游生态与生产用水分配带来更大的压力,下游需要更为精细的水资源时空管理和调控措施。在未来可能面临的枯水期,流域社会-经济-生态可持续发展目标下的水资源管理将面临更大的挑战。

The Heihe River is the second largest inland river in northwest China, where the national integrated management project was executed in 2001. Based on the research results and periodicity understanding on the hydrologic cycle, process of nature-society system, and eco-environmental changes of the Heihe River Basin, the scientific assessment on the ecological and environmental effects is carried out. Generally, the water resources of the river are influenced by the Westerlies, and the alp and sub-alp are the main runoff producing area. The last decade and last century are the high flow periods of the instrumental records and on the millennium scale in the Heihe River. This above normal water resources level provided a powerful guarantee for the water division and the integrated management of watershed. Nevertheless, the pressure from increasing water demand of the local socioeconomic system is the main cause of the conflict between the water use by the middle and the lower reaches of Heihe River, and between the economic development and ecological water utilization. Under the effective control of water utilization volume in the middle reaches, the water utilization structure of the socioeconomic system has changed significantly. Because of the limited water resources and the continued increasing farmland area, the grounder water level and volume reserve presents locally decreased tendency in the middle reaches, and it will face serious overloading of water resources in the future lower runoff period. The quantity of water flowed into the lower reaches closes to the request of the water division, the deteriorated tendency of ecology and water environment got restrained, but it has not recovered and has stronger spatial heterogeneity. More elaborated adjustment measures and space- time administration of the limited water resources are needed, because the increasing farmland from the reclaimed riparian forestland will bring more pressure between the farmland and ecologic water utilization. In the possible lower runoff future, the water resources management of Heihe River Basin will face greater challenge under the sustainable development aim of society-economy-ecology in the whole watershed.