Importance and main ecological and environmental problems of lakes in China
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Lakes including reservoirs are sensitive to global environmental change and human activities in the basin. They are sensitive sentinels and regulators of global environmental change and regional climate. Meanwhile, lakes are important constituent of “landscape, forest, farmland, lake, grassland and sand” life community. Remote sensing monitoring showed that there were 2670 lakes (≥1 km2) with a total water area of 80662.4 km2, and 5156 reservoirs (≥1 km2) with a total water area of 39697.1 km2 in China in 2020. China Water Statistical Yearbook 2021 showed that the number and storage capacity of completed reservoirs increased from 86822 to 98566, and from 416.9 to 930.6 km3 from 1980 to 2020. Therefore, there is a total lakes and reservoirs area of 120359.5 km2, but only accounting for 1.25% of China’s land area. Although the area of lakes and their proportion of land area are very limited, lakes play a vital role in ensuring the ecological civilization construction and promoting the economic and social development of the basin. Unfortunately, the importance and ecological service values of lakes are seriously underestimated and lack the real quantification. Therefore, this study systematically explores and quantifies the importance and ecological services of lakes in China from seven different perspectives. First, lakes are the most and the best centralized drinking water sources (CDWSs) contributing 40.6% of the CDWSs vs. river (30.8%) and groundwater (28.6%), and act as the backbone of the safety of drinking water in China based on 1093 CDWSs from 340 prefecture-level cities and 55 county-level cities (population ≥1 million). Second, lakes have important regulation and storage functions and play a key role in flood control and drought resistance. Based on the national lake survey data, the total amount of water regulation of natural lakes (≥1 km2) is close to 150 km3. Meanwhile, the joint operation of the Yangtze River Basin in 2021 indicated a total regulation capacity of 106.6 km3 and a total flood control capacity of about 69.5 km3 of 47 control reservoirs. Third, lake basins play an important role in the national economic development and food security. Of China’s nine major commercial grain production areas, seven are located in Jianghuai lakes zone and northeast plain lake zone. Fourth, lakes are one of the richest biodiversity ecosystems on earth. Among the 62 international important wetlands in China, there are 26 lake wetlands including Lake Poyang, Lake Dongting, Lake Qinghai etc accounting for 41.9%. Fifth, lake fishery plays an important role in China’s fishery production evidenced by China Fishery Statistical Yearbook 2021, which showed that the aquaculture area of lakes was 2186662 hectares, accounting for 42.7% of the national freshwater aquaculture area and 30.8% of the national aquaculture area in 2019. Sixth, lakes have important tourism value and contribute to beautiful business cards of many cities. Among the 45 national tourist resorts in China, there are 15 lakes tourist resorts, accounting for one third, highlighting the rich tourism value resources of lakes. Seventh, lakes are an important part of the northern ecological security barrier. Lake Hulunhu, Lake Wuliangsuhai, Lake Daihai, Lake Qinghaihu, Lake Bositenghu, and Lake Aibihu act as the key nodes of northern ecological security barrier. In addition, lakes play a big role in energy storage and power generation, agricultural irrigation, inland navigation, carbon sequestration and pollution reduction and regional climate regulation. Large numbers of lakes with different types are widely distributed throughout China exhibiting obvious regional differentiation. Moreover, lakes are facing many ecological and environmental problems which reduce their value of providing ecological services. Specifically, eutrophication and cyanobacteria bloom have not been fundamentally alleviated, which threats the water quality safety of lake drinking water sources. The aquatic vegetation of the lakes is seriously degraded, which weaken their purification capacity and reduce their biodiversity. The synergistic effects of rapid climate change and intense human activities cause either lake flooding, shrinkage or salinization. Warm and humid climate results in a rapid expansion of the lakes on the Tibetan Plateau, which significantly increase the risk of glacial lake outburst. Aiming the above-mentioned ecological and environmental problems, this study puts forward the strategies and countermeasures for lake protection and management including lake-basin system studies, scientific regulation of water resources, cyanobacteria bloom early warning and control, national lake ecological restoration project, basin industrial structure upgrading, and lake protection legislation, which will promote the improvement of lake environmental and the construction of beautiful lakes.
Yunlin Zhang*, Boqiang Qin, Guangwei Zhu et al.,Importance and main ecological and environmental problems of lakes in China.Chinese Science Bulletin, Volume 67, Issue 30: 3503 - 3519 (2022)