基于重力空间熵的城市湿地压力模型构建研究——以武汉南湖湿地为例

城市化进程中人口和建设用地需求增加引发的湿地退化压力日益凸显，熵理论为城市扩张、土地利用结构变化和城市湿地退化压力建模研究提供了新思路。已有研究表明，城市湿地损失、湿地区域建设用地的增加会导致土地利用结构空间熵的数值不断下降，但仅依靠空间熵理论难以定量湿地退化压力。因此依据城市地理学中的重力递减理论，引入距离因素，从湿地区域土地利用空间熵、湿地本身面积、距湿地中心的距离、距商业中心的距离4个要素构建重力空间熵的城市湿地压力模型。研究以1988年武汉南湖湿地遥感影像为基础，制作矢量图，从南湖湿地周边众多湖泊湿地中，随机选取40个样本湿地，分别计算了1988年、1992年、1996年、2000年、2004年5个时期的样本湿地压力值，并利用Kriging空间插值对南湖湿地所受的压力值分布进行可视化处理。结果表明：（1）湿地所在区域土地利用空间熵越小，湿地所承受压力越大；距中心湿地越远越靠近城市商业中心且面积越小的城市湿地更容易发生消亡；（2）根据城市湿地压力模型计算的压力值大的湿地更容易在下一阶段发生显著的损失或消亡；（3）随着城市化的推进，建设用地的扩张，城市湿地承受的压力值逐年增加，当压力值到达0.7左右，湿地存在极大消亡风险。遥感影像解译的结果与按照重力空间熵的城市湿地压力模型计算结果一致，说明该模型能较好地预测城市湿地在城市扩张压力下的演化过程。模型的建成对于城市湿地动态变化和保护规划具有重要意义，了解并把握这一湿地损失过程和趋势，预测城市湿地在城市扩张压力下的演化过程能为城市管理者对城市湿地的具体保护提供方向和指导。 关键词： 城市湿地； 重力空间熵； 压力模型； 城市扩张划具有重要意义，了解并把握这一湿地损失过程和趋势，预测城市湿地在城市扩张压力下的演化过程能为城市管理者对城市湿地的具体保护提供方向和指导。 关键词： 城市湿地； 重力空间熵； 压力模型； 城市扩张

Construction of Urban Wetland Pressure Model Based on Gravity Spatial Entropy:A Case of Wuhan South Lake Wetlands

It becomes increasingly evident that wetland degradation pressure caused by Population and construction land demand increasing in the process of urbanization. Entropy theory provides new ideas for urban expansion, land structure transformation and the research of urban wetland degradation pressure model. There are studies showing that, urban wetland shrinkage and the increase of wetland construction land will lead to the continuous decrease of land use structure spatial entropy, while it is not fair to quantify the degradation pressure of the wetland only by the spatial entropy theory. Based on the gravity declining theory in urban geography, this research will introduce the distance factors to construct the urban wetland pressure model of gravity space entropy from the land use space entropy in the area where the wetland is located, wetland area, distance from the central wetland, distance from business center. Based on the remote sensing images of Wuhan South Lake Wetlands in 1988, a vector diagram was made according to 40 sample wetlands from the lakes and wetlands around theWuhan South Lake Wetlands. The sample wetland pressure values in five periods of 1988, 1992, 1996, 2000 and 2004 were calculated and visualized with Kriging space interpolation. The results show that: (1) with the development of urbanization and the expansion of construction land, the pressure of urban wetlands is increasing year by year. (2) the smaller the spatial entropy of land use is in the wetland area and the greater the pressure is on the wetland, the faster the wetland will disappear. (3) the wetlands farther away from the Wetland Center, closer to the urban commercial center and smaller areas are more likely to die out. (4) the results of model validation based on remote sensing data indicate that urban wetlands with high pressure are more likely to suffer significant losses or die out in the next stage. The results interpreted by remote sensing images are in agreement with the results of the urban wetland pressure model calculated according to the gravity space entropy, which shows that the model can predict the evolution process of urban wetland under the urban expansion pressure. The construction of the model is of great significance to the dynamic change and protection planning of urban wetland. Understand and grasping the loss process and trend of wetland, and predicting the evolution process of urban wetland under the pressure of urban expansion can provide direction and guidance for city manager protecting the urban wetland. Key words：urban wetland; gravity-spatial entropy; pressure model; urban expansion