白洋淀湿地不同时空水生植物生态需水规律研究

在对白洋淀典型水生植物的蒸腾量实地监测的基础上,确定了不同时间和空间下水生植物的蒸散系数,对白洋淀湿地基于现状和恢复目标下的植物生态需水量进行了等级划分和计算.研究结果表明,6～9月综合蒸散系数为3.21、6.24、6.02和1.86.水生植物需水量的时间分布规律为7月>8月>6月>9月,空间分布规律为陆地>水陆过渡带>水中.现状条件下,白洋淀水生植物6～9月的最小需水量分别为0.49×108m3、0.80×108m3、0.60×108m3、0.16×108m3,分别占湿地最小生态需水量的44%、56%、49%、50%(未包含湿地土壤需水量),与湿地最小生态需水量对应的最低生态水位为7.50m、7.50m、7.50m、6.30m.基于生态恢复目标,计算得到6～9月的水生植物最小生态需水量分别为0 56×108m3、0.91×108m3、0.69×108m3、0.19×108m3,为湿地最小生态需水量的30%、41%、35%、21%.对比白洋淀水生植物生态需水量的实际值和计算值发现,白洋淀水生植物的生态需水量在6～9月间分别是计算值的5.75倍、6.42倍、5.00倍和2.29倍.

Environmental water demand of Baiyangdian Lake at different times and places

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.