Recently, the Qinghai-Tibet Plateau Research Institute of the Chinese Academy of Sciences released China’s 50-year lake dataset, and revealed the characteristics and potential driving mechanisms of lake changes in six major regions of China, sharing the data set of lake changes in China over the past 50 years or more larger than 1 square kilometer. The data set is the first long-series lake catalog dataset based on historical topographic maps and more than 3831 remote sensing satellite imagery, which is updated and more complete than the existing data.
Lakes are important freshwater resources and are sensitive indicators of climate change and human response. However, in the past, China’s complete long-scale lake data is relatively scarce, the drivers of lake changes in different regions are difficult to quantitatively assess.
Zhang Guoqing, an associate researcher at the Qinghai-Tibet Plateau Research Institute of the Chinese Academy of Sciences, and his collaborators spent more than 3 years using a semi-automatic water extraction algorithm based on historical topographic maps and long sequences of Landsat remote sensing satellite images, which were manually visually examined and corrected. Completed the change of lake area and quantity of lakes (greater than 1 square kilometer) in China from 1960 to 2015.
China’s 50-year lake dataset divides China’s lakes into six regions: Northeast China, Xinjiang, Qinghai-Tibet Plateau, Inner Mongolia Plateau, Eastern Plains and Yungui Plateau. Overall, from the 1960s to 2015, the total number of lakes in China increased by 20% from 2,127 to 2,554, and the area increased by 9% from 68,537 square kilometers to 74,395 square kilometres.
However, the spatial change of the lake was uneven, and the area of the Lake District of the Qinghai-Tibet Plateau, Xinjiang and the Northeast Plains increased significantly, while the area of the Inner Mongolia Lake District decreased significantly. In terms of quantity, the new lakes are mainly located in the Qinghai-Tibet Plateau and Xinjiang Lake District, while the disappearing lakes are mainly located in the wet eastern China Lake District.
“In the past 50 years, china’s lakes have expanded, with the Qinghai-Tibet Plateau contributing the most, increasing by 5,676 square kilometers, mainly due to increased precipitation and melting water from glaciers. Zhang Guoqing told China Science Daily.
Studies have shown that the increase in precipitation is the main reason for the expansion of lakes in the Qinghai-Tibet Plateau region (about 70%).
Zhang Also reminded that the expansion of the lake is not a good thing, for example, in 2001 the expansion of the Cocoa Sili hinterland, Zhuo Nai Lake caused a burst of embankment, so that its downstream Kusai Lake, Hydinnoll Lake and Salt Lake and other chain response, the Qinghai-Tibet Railway poses a threat.
The researchers also quantified the causes of lake changes in terms of climate and man-made factors. The results show that climate factors play a leading role in the overall change of lakes in China, and human factors contribute higher in the eastern plains and Yungui Plateau (about 35%).
“Complete lake data will help to understand the response of lake changes to climate change, and future lake change simulation spredictions. At present, quantitative assessment of the water balance drivers of lakes is still difficult to study, such as precipitation, the contribution of the frozen circle and other natural factors, human activities to contribute to how much, and more data accumulation. Zhang Guoqing said.
At present, china’s lake data (1960s, 1970s, 1990, 1995, 2000, 2015, 2010, 2015) have been obtained free of charge through the National Qinghai-Tibet Plateau Data Center over the past 50 years, and have been used by water conservancy departments, lake hydrologists and other scholars to improve China’s water resources management strategy. To study the spatial and temporal evolution characteristics of lakes in the region, the trends of ecological resources and environmental changes, and rural surveys.