Variation of water level in Dongting Lake over a 50-year period: Implications for the impacts of anthropogenic and climatic factors

Abstract

Understanding the variation regularity of water level and the potential drivers can provide insights into lake conservation and management. In this study, inter- and inner-annual variations of water level in Dongting Lake during the period of 1961–2010 were analyzed to determine whether anthropogenic or climatic factor should be responsible for the variations. The results showed that water level decreased significantly during the period of 1961–1980, while increased significantly during the period of 1981–2002 at the 5% significance level. However, the variation trend of water level after 2002 did not reach a significant level. The variation in the dry season was more obviously than that in the wet season. The date when water level was firstly below 24 m during the period of 2003–2010 appeared about 27 days earlier than usual, and the date was even advanced to mid-September in 2006. As for the duration, water level was below 24 m for about 185 days in the period of 2003–2010 and 20–30 days longer than the other two periods. In conclusion, water level might be influenced by a combination of anthropogenic and climatic factors, with rainfall probably as the main driver responsible for hydrological alteration during the period of 1961–1980 and 1981–2002 while dam construction as the main driver during the period of 2003–2010. Under the circumstance of uncontrollable climate change, effective measures for reservoir operation should be put forward to maintain the ecological integrity and ensure water release and storage capacity of aquatic ecosystems.