不同补水条件下黄河三角洲湿地恢复情景模拟

针对黄河三角洲湿地退化现状,设计了三种湿地修复水量预案。利用水文模型SOBEK和地下水模型Visual Modflow对不同补水预案下湿地水文过程进行模拟,将水文模拟结果与湿地立地条件、植被条件在景观决策支持模型LEDESS框架下进行集成,对三种补水预案下湿地修复情景进行模拟和评价。研究表明,对黄河三角洲湿地的恢复,根据区域湿地条件差异,其恢复目标及所需要的适宜水量也有所不同。一千二管理区宜采用最大引水预案,提高涉禽鸟类的生境适宜性;黄河口管理区宜采用最小水量预案,同时应降低生境干扰以改善栖息地质量;对于大汶流管理区,中等水量对于涉禽类和游禽类的生境都有较大改善。本研究将水文过程与景观过程进行集成,利用情景模拟方法,为湿地恢复决策提供一种新的尝试。

Scenario simulation of wetlands restoration in the Yellow River Delta

In recent years, a sharp decrease of water quantity and frequent discontinuous flow happened in the lower Yellow River due to the rapid increase of water consumption in the basin area. This leads to deficiency of suitable water demanded by the ecosystem of the estuarine delta. As a result, fresh water wetlands in the delta are diminishing and facing the danger of disappearance. Basic guarantee of water supply to the Yellow River estuary and eco-water demand for wetland restoration has become a key issue in maintaining the ecosystem of the Yellow River Delta. In this paper, landscape ecological and hydrological models were integrated for the Yellow River Delta wetlands restoration. First, three scenarios at different water depths for the degraded wetlands restoration were designed. For each scenario, the spatio-temporal changes of flooding duration and water table were simulated with the model SOBEK, and average groundwater levels were simulated with the finite-difference groundwater flow model Visual MODFLOW. Then the simulation results were integrated with site conditions and current vegetation types into LEDESS model for modeling the landscape development after 5 years of restoration. Finally, each scenario was evaluated based on its consequences for habitat effects. In this way, choices can be made on what kind of nature type is desired and what is the optimal restoration strategy. The results show that all scenarios can significantly improve the wetland conditions of reed marshes, which are used for many rare and endangered birds like red-crowned crane as important habitats. By comparison, scenario B with the medium water discharge is better than scenarios A and C in reed marsh restoration, but scenario C can also create large area of open water bodies which are crucial for the swan's habitat conservation. However, not all kinds of species benefit from the restoration plans. The study also shows that large areas of tidal flats were encroached by the restored reed marshes. As a result, carrying capacity of the estuarine wetlands in shorebirds such as Saunder's Gull would decrease after restoration. This study demonstrates that a spatial decision support framework that integrates hydrological processes modeling with ecological evaluation at a landscape scale is indispensable to evaluate uncertainty about the effects of restoration plans and policies on different wetland types and the quality of waterfowl habitats.