用水活动影响下的水分能量交换过程观测与模拟研究-以沩水河流域为例

Weihe River, located in southern margin of Dongting Lake, northeast Hunan province, the transition zone of Xuefeng Mountain Reminder to Northeast Binhu Plain, originates from Weishan of Ningxiang, in Hunan province and drains into Xiangjiang River from west to east. The basin has mountains, hilly plains, and Huangcai Reservoir in the upstream which benefits to irrigation, power generation, flood control, aquaculture, and carry-over storage. The humain activities including water transfer, irrigation, crops planting and harvesting, would modify the soil moisture, water and energy exchange between land and atmosphere in the basin, and then affect ecological and hydrological process at land surface, and climate. This project intends to conduct observation and analysis in Weihe River Basin as a case study using a synthetic observation platform for land-atmosphere water cycle, and construct a high resolution land surface model considering human water utilizations, crops planting and irrigation and groundwater lateral flow, and to reveal the effects and mechanisms of anthropogenic water withdrawal to land-atmosphere energy and water exchange, and then to predict the variation of water and energy fluxes under future climate change. It provides a land surface process model platform for development of high resolution earth system models to consider the human water utilizations, and is highly scientific meaningful and application valuable to increase understanding of land-atmosphere water and energy exchange process. Besides, it also improves the ability of hydrological and meteorological prediction of earth system modesl.

地处湘东偏北的洞庭湖南缘地区，雪峰山余脉向东北滨湖平原过渡地带，自西向东流入湘江的沩水河，发源于湖南宁乡沩山。流域内有山地、丘岗、平原，上游有以灌溉为主，兼发电、防洪、养殖等综合效益并进行多年调节的黄材水库，用水活动频繁。流域调水灌溉、作物种植收割等人类活动，引起土壤湿度以及陆面和大气之间水分和能量交换的改变，从而影响陆面生态水文过程与气候。本项目拟以沩水河流域作为典型区，利用流域内地气水循环综合观测平台开展观测与模拟研究，构建考虑人类取水用水、灌溉与作物种植、地下水侧向流动影响的陆面过程模型，研究并揭示人类用水活动对水分能量交换过程的影响并探讨其机理，预估未来变化环境下水分能量交换特征及变化。这为高分辨率地球系统模式的发展提供了考虑人类用水影响的陆面过程模型平台，对于增加水分能量交换过程与陆气相互作用的理解、提高地球系统模式对水文气象的模拟和预测水平具有重要的科学意义和应用价值。

沩水河地处湘东偏北的洞庭湖南缘地区，雪峰山余脉向东北滨湖平原过渡地带，自西向东流入湘江，发源于湖南宁乡沩山。流域内有山地、丘岗、平原，上游有以灌溉为主，兼发电、防洪、养殖等综合效益并进行多年调节的黄材水库，用水活动频繁。流域调水灌溉、作物种植收割等人类活动，引起土壤湿度以及陆面和大气之间水分和能量交换的改变，从而影响陆面生态水文过程与气候。本项目针对沩水河流域这一典型区，研究用水活动影响下的水分能量交换过程，其主要科学目标是：研发针对流域考虑水土资源开发影响的高分辨率陆面过程模式平台，揭示人类用水影响下水分能量交换过程时空演变特征及驱动机制。项目执行四年来，围绕上述科学目标，在观测与模式研发方面开展研究，完成了预期目标。取得如下主要成果：利用沩水河流域“地气水循环综合观测平台”，开展水分能量交换综合观测研究，建立了气象、土壤水、地下水及二氧化碳通量高时间分辨率数据集，研究揭示了夏季极端干旱对亚热带森林生态系统碳水通量的影响；针对沩水河流域建立了综合考虑作物种植、地下水开采及灌溉等人类活动的陆面过程模型CAS-LSM，为定量评估人类用水影响下流域水分能量交换过程时空演变特征提供模拟平台，研究并揭示了多种人类活动共同作用对陆气水分能量交换的影响。本项目为高分辨率地球系统模式的发展提供了考虑人类用水影响的陆面过程模型平台，对于增加水分能量交换过程与陆气相互作用的理解、提高地球系统模式对水文气象的模拟和预测水平具有重要的科学意义和应用价值。