基于土地利用变化情景的城市暴雨洪涝灾害风险评估——以深圳市茅洲河流域为例

近年来频发的暴雨洪涝成为威胁城市可持续发展的主要灾害类型,而土地利用变化改变了区域原有的景观结构和水文过程,是城市暴雨洪涝灾害风险加剧的重要诱因,定量探讨土地利用变化对暴雨洪涝灾害及其风险影响具有重要意义。以深圳市茅洲河流域为例,基于CLUE-S模型、SCS模型及等体积淹没算法等,对12种暴雨洪涝致灾-土地利用承灾情景下的城市暴雨洪涝灾害风险进行定量模拟。研究结果显示,相同土地利用空间格局下城市暴雨洪涝灾害随暴雨致灾危险性增加风险加剧显著;在同等致灾危险性水平下随建设用地面积增加,中等风险和高风险区面积均呈现较为明显的增加趋势,中、高风险区面积与建设用地面积的增加率表现出较高的协同变化特征;以50年遇危险性水平为例,随着建设用地面积由基期的15368.85hm~2增加至近期16076.07hm~2和远期16750.89hm~2,高风险区面积由254.07hm~2增加至276.48hm~2和286.2hm~2。由此可见,尽管暴雨强度的增加是城市暴雨洪涝灾害风险加剧的根本诱因,但是以建设用地面积增加为表征的土地利用变化对暴雨洪涝灾害风险的影响不容忽视。

Storm flood disaster risk assessment in urban area based on the simulation of land use scenarios: A case of Maozhou Watershed in Shenzhen City

Recently, the frequent storm flood has become the main hazard in the coastal cities, which treats to the regional sustainable development. Land use change has transformed the original landscape structure and hydrological processes, and also becomes the significant factor to the increase of urban storm flood disaster risk. It is significant to discuss on the relationship between the land use change and the storm flood hazard risk. Based on the CLUE-S model, the SCS model and the equal volume submerged algorithm, this article took the Maozhou Watershed as the study area and quantitatively evaluated the storm flood disaster risk in the twelve interactional scenarios of the storm hazard and the hazard affected land use. Results showed that the urban storm flood hazard risk increased remarkably with the increased storm magnitude on a certain pattern of land use. While at the same level of the storm hazard, the areas of medium and high risk patches showed an obvious increasing trend with the increased construction land. The area increasing rates of high or medium level risk patches and the construction land were highly-related with the form of synergy. Take the recurrence interval of 50years as an example, the area of high risk patches grew from 254.07hm² to 276.48hm² and 286.2hm² when the construction land area increased from the base scenario to short-term and long-term scenario, respectively. Therefore, even though the significant factor to the storm flood disaster risk is the storm magnitude, the influence of land use change characterized by the increasing of construction land on the storm flood disaster risk cannot be ignored.