海河流域水资源开采利用过程的区域气候效应模拟研究

The processes of water resource exploitation and utilization have disturbed the natural water cycle by regulating the distribution of land water resource, and affected the global climate system. It is a hot topic in climate change research that understanding the climate affecting mechanism of water exploitation and utilization and quantitatively analyzing the climatic effects of these processes. Also, it is related to the strategies of water resource management on climate change risk. However, most current studies on climate simulation only focus on the climate impacts of irrigation supplied by surface water, and lack the overall consideration of groundwater exploitation and other water use processes, which is hard to be adopted directly in this project. Therefore, this project is to choose the Haihe River Basin, which has been affected by human activities seriously, as the study domain. By developing a scheme of water exploitation and utilization in the land model CLM4.5 based on the water balance of supply and demand and realizing the two-way coupling in the regional climate model RegCM4, this project is to establish a regional climate model which considers the exploitation of surface water and groundwater as well as the industrial, domestic and agricultural water use. Then, long-term simulations will be conducted over Haihe River Basin by using the new model, in order to quantitatively evaluate the climate impacts of water exploitation and utilization over the basin and reveal the effecting mechanism of water exploitation and utilization on regional climate. The result of the project will be expected to provided data reference for the basin manager when making adaptive strategies on climate change.

水资源开采利用过程通过人为调节陆地水资源的分布干扰了自然水循环过程，进而影响全球气候系统。正确认识水资源开采利用活动对气候的影响机制，并定量分析该活动引起的气候变化量级，不仅是气候变化研究的热门命题，也与水资源管理如何应对气候变化风险息息相关。然而，目前的气候模拟研究多数仅关注地表水灌溉过程的气候影响，缺乏对地下水开采和各行业用水的综合考虑，难以直接借鉴应用。因此，本项目拟选择人类活动剧烈的海河流域作为典型区，基于水量供需平衡关系在陆面模型CLM4.5内发展一个水资源开采利用方案，并与区域气候模式RegCM4实现耦合，建立综合考虑地下水、地表水供水过程与工业、生活、农业灌溉用水过程的区域气候模式。以该模式为工具，针对海河流域开展长期气候模拟，研究取水用水活动对区域气候的影响反馈机制，评估流域内水资源开采利用活动所引起的气候变化量级，为海河流域制定气候变化适应性对策提供数据参考。

海河流域是中国北方地下水资源严重超采的典型区域，其流域内的水资源开采利用过程对区域气候的影响评估受到了广泛关注。本项目针对海河流域的取用水活动，基于水量供需平衡关系建立了一个水资源开采利用方案，并在陆面模型CLM4.5中耦合应用。随后，利用改进的CLM4.5陆面模型，进一步与区域气候模式RegCM4实现耦合，建立了综合考虑地下水、地表水供水过程与工业、生活、农业灌溉用水过程的区域气候模式。以该模式为工具，针对海河流域高强度水资源开采过程开展长期气候模拟，研究取水用水活动对局地陆面过程及区域气候的影响反馈机制。项目研究发现，海河流域的水资源开采利用活动造成流域陆地水储量的迅速减少及陆表降温增湿的变化，其中流域内降水平均增加0.03mm/天，2m气温平均降低0.35℃。另外，流域东北的渤海、辽河流域等地由于环流改变呈现夏季降水增多的现象，而海河流域内的降温现象也影响到流域以西的太行山、河套地区等。这种冷湿效应与用水强度呈正相关，且随时间逐渐增强。如果不考虑气候反馈，局地陆面冷湿变化与用水强度的线性相关较强，而考虑气候反馈后，大气非线性反馈作用会进一步增强这一冷湿效应，形成一定程度的正反馈机制，使得区域气候变化与用水强度呈高度非线性的正相关关系。本项目定量研究成果能够完善了解人类取水用水活动与区域气候系统的相互作用机制，为合理评估海河流域水资源管理与气候变化应对措施间的关系提供科学依据。