基于水动力模拟的湿地阻水围堤围埝判定——以白洋淀为例

为识别并拆除影响较大的围堤围埝,以利于湿地恢复,本文提出了包括4个步骤的湿地关键阻水围堤围埝的判定方法,首先利用水动力模型模拟结果提取流线分布图;然后计算流线分布密度、均匀度、平均蜿蜒度指标;接下来初步判定关键阻水围堤围埝;最后利用地形、土地利用校核判定结果,确定关键阻水围堤围埝。以白洋淀为例,进行淀区关键阻水围堤围埝的判定,并模拟了围堤围埝拆除后淀区水动力的变化情况。结果表明,淀区内存在8处关键阻水围堤围埝,总面积约9.93 km²。关键阻水围堤围埝拆除后,流线丰富且分布更均匀,水面面积占比由90.42%增加到94.70%,滞水区面积占比降低约4.20%。

Determination of wetland water-blocking cofferdams based on hydrodynamic simulation:A case study of Baiyangdian wetland

Owing to the requirements of aquaculture and other social and economic activities, many cofferdams have been built in wetlands, which hinder the connection of the water system and affect the hydrodynamics and self-purification of wetlands. In order to facilitate the restoration of the wetland, it is necessary to determine and remove cofferdams. This study introduces the determination method of key water-blocking cofferdams in wetlands, which includes the following four steps:(1) the distribution diagram of streamlines is extracted using the simulation results of a hydrodynamic model; (2) the indexes of distribution density, distribution uniformity, and mean meandering of streamlines are calculated;(3) the key cofferdams are preliminarily determined; and(4) the key cofferdams are determined according to the topography and land use results. Taking the Baiyangdian wetland as an example, we used this method to determine the key water-blocking cofferdams and to simulate the hydrodynamic changes after their demolition. The results showed that there were eight key water-blocking cofferdams with a total area of approximately 9.93 km². After their demolition, the streamlines were abundant and more evenly distributed. The proportion of water surface area increased from 90.42% to 94.70%, whereas the proportion of stagnant water area decreased by approximately 4.20%.