Yunnan may be landlocked, but it has some of China's most abundant water resources, most notably the upper reaches of the Yangtze, Mekong, Salween, Irawaddy and Pearl rivers.
The province also has more than 40 highland lakes that have traditionally served as important sources of drinking water plus fish and other aquatic edibles for some of Yunnan's most populated areas. In recent years the lakes have also been increasingly important to Yunnan's fast-growing tourism sector.
Today it seems unwise to assume that Yunnan's lakes will continue to provide as they have in the past. Recent studies suggest that the accumulated effects of three successive years of drought are already posing a major threat to the future of Yunnan's lakes.
On average, Yunnan's nine largest lakes have lost 70 centimeters of depth since this time last year, according to recently released government data. It is estimated that the nine lakes have shed a total of 292 million cubic meters of volume during the same period.
Dianchi Lake (滇池), Yunnan's largest lake and China's eighth-largest, is 33 centimeters below its normal level and has lost 83.1 million cubic meters in the last year. It is believed that if no substantial rains come by June, Dianchi will drop another 45 centimeters. This could have a major impact on the shallow lake, which has an average depth of 4.4 meters.
Meanwhile Fuxian Lake (抚仙湖) has dropped to its lowest level in 10 years and adjacent Xingyun Lake (星云湖) is already at its lowest-ever recorded level. The two lakes have dropped below official government warning levels and are 1.8 meters lower than they were four years ago.
Every day Fuxian Lake is reportedly losing an average of 0.5 centimeters of depth, or roughly 1.4 million cubic meters of volume, to evaporation. Xingyun Lake – one of the smaller of Yunnan's nine major lakes – has lost more than 20 million cubic meters since last year's drought.
One official responsible for managing Fuxian Lake said the dropping water levels are affecting lakes' ability to naturally clean themselves, increasing the threat of worsening water quality.
Erhai Lake (洱海) in Dali has dropped 95 centimeters in the last 12 months. Substantial water loss has also been reported at Yunnan's five other major lakes - Lugu Lake (泸沽湖), Yilong Lake (异龙湖), Chenghai Lake (程海), Yangzonghai Lake (阳宗海) and Qilu Lake (杞麓湖).
In addition to water loss via evaporation, Yunnan's lakes are also receiving less water from the rivers that feed them. According to official data, 273 small- to medium-sized rivers in the province have already run dry.