Environmental water demand of Baiyangdian Lake at different times and places
白洋淀湿地不同时空水生植物生态需水规律研究

Water consumption imbalance between human and nature is a key reason for the degradation of the eco-environment in the Haihe River Basin. The wetland ecosystem is one of the most important modules in the Haihe River Basin and the large scale ecosystem. Calculation of the wetland ecosystem environmental-flow demand is needed to keep the water balance of the ecosystem. In this study, based on field monitoring, evapotranspiration (ET) of the hydrophytes in Baiyangdian Lake was calculated at different times and locations. The current water demand of the hydrophyte system is classified, calculated and reported in comparison to different recovery targets. The monthly integrated ETof the hydrophyte system from June to September in Baiyangdian Lake was 3.21,6.24,6.02 and 1.86. The magnitude of ETfor different sites decreased in the order: land surface >transition belt>water area. The minimum water demand of the hydrophyte system from June to September in Baiyangdian Lake is 0.49×108m3, 0.80×108m3, 0.60×108m3, 0.16×108m3, (equal to 44%, 56%, 49% and 50% of the whole water demand of the wetland ecosystem) and the corresponding lake water levels were 7.50 m, 7.50 m, 7.50 m and 6.30 m. According to the recovery targets, the minimum water demand from June to September in Baiyangdian Lake is 0.56×108m3, 0.91×108m3, 0.69×108m3 and 0.19×108m3, which is 30%, 41%, 35% and 21% of the whole water demand of the wetland. The measured value of the hydrophyte system water demand from June to September in Baiyangdian is 5.75, 6.42, 5.00 and 2.29 times the estimated value.