Sand mining and increasing Poyang Lake's discharge ability: A reassessment of causes for lake decline in China

- Declining Poyang Lake level is closely related to extensive sand mining.
- Larger outflow channel increases Poyang Lake discharge ability into the Yangtze River.
- Prohibition of sand mining should have a priority over lake damming.

SummaryA recent dramatic decline in China's largest freshwater lake, Poyang Lake, has caused particular concerns because of its significant influence on water availability and lake ecology. To better understand the causes of lake decline, especially the abnormal low water levels in the dry season, we investigated channel changes using surveyed and remote sensing data and hence the increasing lake discharge ability and the resulting drop of water level of the lake. The results show that intensive sand mining resulted in a wider and deeper outflow channel for Poyang Lake. The discharge ability of Poyang Lake into the Yangtze River at low water levels has increased to 1.5-2 times the values before the initiation of extensive sand mining. This allows the lake to drain quickly and reach a lower water level than would otherwise have occurred. Higher discharge potential increases drought risk in Poyang Lake, particularly under the superimposed effects of regional rainfall anomalies and the water storage of dams. In response to potential low lake levels, the prohibition of sand mining should be given priority in lake management planning as opposed to damming the lake.