Chinese Lakes Behaviours in the Framework of Meteorology and Water Management Practices: EO Based Monitoring Lessons
Yesou, Herve¹; Huang, Shifeng²; Huber, Claire¹; Lai, Xijun³; Cao, Lei⁴; Uribe, Carlos¹; Chen, Xiaoling^5
1SERTIT UdS, FRANCE; ²IWHR, CHINA; ³NIGLAS, CHINA; ⁴University of Science and Technology of China, CHINA; ⁵LIESMARS, CHINA

Yangtze reaches, particularly on the middle and lower ones as the human population, few hundred millions of inhabitants downstream of 3 gorges dam, depend directly on the services that wetlands provide: regulating services such as flood storage; provisioning services such as fishing, and being biodiversity holders. The two largest fresh water lakes, Poyang and Dongting Lakes, which are very valuable ecosystems in term of biodiversity maintain but also threaded by epidemics, are the core of the monitored area since 2000. Similar work has began, within the framework the Dragon 3, downstream of these large lakes, on smaller ones, including Caizi, Wuchang, Baidang and Shengjain lakes in Anhui province. This monitoring based on medium and high resolution at a high temporal frequency, ie ca 10 days has allowed characterizing trends on an intra and interring annual basis. A key result is the apparent increase of years with water default since the mid 2000, ie near one year every two years. Results of the dynamic analysis of water height and water surfaces can be now analyzed in term of climatic variations and human activities (ie the Three Gorges reservoir impact). Obtained results shown that the meteorology, ie rainfall, at Yangtzee's basin scale rather than lakes' basin scale, has a significant impact on water resources.

In addition, and this for the first time, the effects management mode of the 3 Gorges reservoir, ie infilling of the reservoir rapidly in October at the beginning of the dry period followed by a slow release of the stocked water appears to reinforce the drought's trends observed in recent dry years.