ISSN 1000-3665 CN 11-2202/P

    秃尾河流域河流-地下水转化与生态效应

    River-groundwater transformation and ecological effects in the Tuwei River watershed

    • 摘要: 秃尾河是黄河“几”字弯东翼一个重要的支流,流域大气降水、地下水和河湖水水力联系密切,控制着流域生态格局的演化、稳定和安全。基于秃尾河流域地质地貌、水文地质条件和降水、地下水与河湖水(以下简称“三水”)转化关系,通过野外调查、动态观测、遥感解译、基流解析和统计分析等手段,分析了三水转化特征及其生态效应,得到如下认识:(1)在地质地貌条件和三水转化的控制下,空间上可将流域生态系统划分为湖群-灌-草-乔湿环境生态系统、草-灌-乔-沙干环境生态系统、矮化疏林-草干环境生态系统、农田-乔湿环境生态系统和河滨带湿环境生态系统;(2)时间上,自20世纪90年代以来,流域呈现植被覆盖度增加、地下水位下降、河流基流量减少、湖淖湿地减少的趋势;(3)流域生态格局的形成和演化是自然因素和人类活动共同作用的结果,其中地质地貌条件控制流域生态系统的基本格局,水循环特征控制流域生态格局演化方向和时空变异趋势,人类活动极大地改变了原生生态格局,主导着现代生态格局演化的方向与强度;(4)流域生态格局的安全与稳定对水分有强依赖性,保持水系连通、增强三水转化强度、维持沙区地下水位埋深在1.5~5 m范围内对区内生态系统的健康至关重要。基于秃尾河流域三水转化单向水循环特征,提出了河滨带概念,指出河滨带是流域水流、物流、能流和信息流的源和汇,起生态廊道的作用,河滨带生态功能对流域生态环境质量具有指示作用,可作为流域生态环境质量评价的重要指标之一。研究成果对于黄河“几”字弯以及其他类似地区流域的生态环境保护与治理有重要的指导作用。

       

      Abstract: The Tuwei River, an important tributary of the Yellow River, located in the eastern Jiziwan region exhibits a close hydraulic connection between atmospheric precipitation, groundwater, and river-lake water in the watershed. This connection influences the evolution, stability and safety of the watershed ecological pattern. Based on the geological, geomorphological and hydrogeological conditions, and the water transformation between atmospheric precipitation, groundwater, and river-lake water (hereinafter referred to as three-water) in the Tuwei River, this study examined the characteristics of the three-water transformation and their ecological effects using field investigation, dynamic observation, sensing interpretation, base flow analysis, and statistical analysis. Under the control of geological and geomorphological conditions and the three-water transformation, the watershed can be spatially divided into lakes-shrub-grass-tree wet environment ecosystem, grass-shrub-tree-sand dry environment ecosystem, dwarf sparse forest-grass dry environment ecosystem, farmland-tree wet environment ecosystem, and riparian wet environment ecosystem. Since the 1990s, the vegetation coverage of the watershed has increased, while the groundwater levels have dropped, the river base flow has decreased, and the lake wetland has shown a decreasing trend. The formation and evolution of the watershed ecological pattern is the result of a combination of natural factors and human activities. The geological and geomorphological conditions control the watershed ecological pattern, and the hydrological cycle characteristics control the evolution direction and spatiotemporal variation trend of the watershed ecological pattern. Human activities have greatly changed the original ecological pattern and dominated the direction and intensity of the contemporary ecological pattern evolution. The safety and stability of the watershed ecological pattern are highly dependent on water resources. Maintaining hydrological connectivity, enhancing the intensity of three-water transformation, and ensuring the groundwater level in the desert area within the range of 1.5~5 m are crucial to the health of the ecosystem in the area. Based on the one-way three-water transformation characteristics in the Tuwei River, the definition of the riparian zone was proposed. The riparian zone is the source and sink of water flow, material flow, energy flow, and information flow in the watershed, and plays the role of an ecological corridor. The ecological function of the riparian zone has an indicative effect on the status of the watershed ecological environment and can be used as one of the important indicators for the assessment of the watershed ecological system. These findings support the protection and governance of ecological environments for the Jiziwan region of the Yellow River and similar watersheds.

       

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