小浪底大坝对黄河下游农业景观生态系统服务的影响研究

Owing to the sediments accumulation, the lower reaches of the Yellow River has formed a unique characteristic of suspended river. The key function of the Xiaolangdi Dam is to regulate water and sediments. The dam significantly affects the channel of the Yellow River after its operation, and also the surface and ground hydrographical features of the influencing area. Thus, the variation of structure and dynamic process of agricultural landscapes in this area influences the provision of regional ecosystem services. This project selects Henan Province section of the Yellow River, which is the representative of the suspended river, and its influencing area as the researching object, and investigates the responses of regional ecosystem services to agricultural landscape patterns and dynamic process, to reveal the formation and maintaining mechanism of the key regional ecosystem services (include regulating services and supporting services). 3D laser scanning system, miniature UVA low attitude measuring system and GIS cloud platform are used in this project. Combining with the field investigation of typical transects of different profiles that intersect with the Yellow River channel and laboratory analysis, the hydrologic dynamic change that before and after the operation of the dam in the lower reaches of the Yellow River can be treated as the breakthrough in this research. In addition, the variation of surface runoffs of agricultural landscapes in researching area, which is caused by lateral seepage effect of the suspended river and surrounding topographic changes, can be seen as the driving force. This study can not only further deepen the research paradigm of “landscape pattern--dynamic process--mechanisms--regulation” and optimize the composition and structure of regional landscape, but also provide a theoretical basis for the provisioning services of agricultural production, and then improving and maintaining ecological environment of the lower reaches of the Yellow River.

黄河下游因泥沙淤积形成地上悬河而独具特色。小浪底大坝的主要功能为调水调沙。其运行前后对黄河河道及其影响区的地表和地下水文过程影响巨大，进而通过影响该地区农业景观的格局和动态过程而影响区域生态系统服务的发挥。本项目以黄河地上悬河最具代表性的河南段及其影响区为对象，借助三维激光扫描系统、微型无人机低空测量系统和云地理信息系统平台，结合相交黄河河道不同剖面上典型样带的野外观测和实验室分析，以小浪底大坝运行前后黄河下游水文动态变化特征为突破口，以研究区农业景观受黄河悬河侧渗作用及其周边因地形变化而引起的地表径流变化为驱动力，探讨区域生态系统服务对农业景观格局和动态过程的响应，揭示区域主要生态系统服务（包括调节服务和支持服务）的形成和维持机制。本研究既可进一步深化景观格局--过程--机理--调控的研究范式，优化区域景观的组成和结构，也可为黄河下游农业生产供给服务和生态环境的改善和维持提供理论支撑。

小浪底大坝的建成和运行对其黄河河道及其影响区的地表和地下水文过程影响巨大，进而驱动着该地区农业景观的格局和动态过程发生变化，最终影响区域生态系统服务的发挥。本项目系统地研究了小浪底大坝对其下游水文过程的影响、小浪底大坝引起的水文变化背景下农业景观格局及其生态环境和生态系统服务的变化过程以及农业景观的调控途径。取得的重要成果如下：（1）揭示了小浪底大坝对其下游水文过程的时空动态的影响，量化了小浪底大坝对黄河下游径流变化的贡献；（2）基于悬河段地下水成因和补排关系的特点，探讨了小浪底大坝通过调节地表水所引起的地下水的动态变化特征；（3）阐明了黄河下游农业景观格局的动态变化特征及其对小浪底大坝水文调节的响应；（4）揭示了小浪底大坝运行前后其下游农业生产环境的变化差异及水文影响机理；（5）阐明了小浪底大坝调水调沙背景下沿黄湿地水质的时空变化，明确了黄河对湿地植物功能性状及水体补给来源和动态的影响；（6）基于农业景观格局的异质性变化，探讨了小浪底大坝运行前后农业景观生态系统服务变化特征及其机理的水利影响；（7）模拟了自然发展、生态保护、耕地保护三种情景下农业景观的发展趋势，提出了黄河下游农业景观的发展方向。本项目成果可为全面深入地了解小浪底大坝的建成运行及水沙调节的水文影响，优化区域景观的组成和结构以及提高黄河下游农业景观生态系统服务提供理论支撑。