关键词: 天津市滨海新区, 暴雨内涝, 情景模拟, 风险评估

Abstract:

Natural disaster is the hotspot question in international society and academy. Coastal cities are important areas and strategic focus of people convergence, national economy and society development. However, natural disasters occur easily and frequently in these areas. Tianjin Binhai New Area (TBNA) lies in the center of the Bohai Rim Region. Following the Shenzhen Special Economic Zone and Pudong New Area, TBNA becomes a new polarization of economic development which drives regional growth. Affected by physical-geographical conditions and human activities, however, TBNA is one of the areas where the loss from natural disasters is huge and fatal in the coastal areas in China. In view of the main causing factor, the numerical model of land subsidence was established. With three groundwater extraction scenarios, the computer program was compiled to predict the land subsidence in the process of dynamic changes of groundwater level. Based on the complex dynamic multi-hazard risk assessment theory, in accordance with population planning, land use planning and socio-economic development plan of TBNA, and according to prediction of land subsidence and sea level rise, three scenarios were designed, that was the most unfavorable, moderate, and the most ideal scenarios. Pearson-Ⅲ distribution method was used to calculate intensity of the different frequency’s maximum rainstorms in 24 hours by rainstorm data of the past 40 years at 14 hydrological stations in TBNA and its nearby regions. Inverse distance weight and Disjunctive Kriging method were respectively employed to interpolate the different frequency’s maximum rainstorms in 24 hours. The calculation model of flood submerged area was therefore established by GIS. The submerged area and depth were calculated by the module of “non-source flood”. On the basis of the loss rate of different submerged depth, the submerged loss was gained. The results showed that, by 2020, under Scenario 1, the submerged area is 32.73%, 29.34% and 26.01%; inundated population accounts for 338×10⁴, 305×10⁴ and 264×10⁴; and the loss of submerged is 220.89×10⁸yuan, 181.39×10⁸yuan and 139.12×10⁸yuan respectively induced by torrential rain with return period of 1 000, 200, and 50 years. Under Scenario 2, the submerged area is 30.70%, 27.47% and 24.23%; inundated population accounts for 318×10⁴, 289×10⁴ and 248×10⁴; and the loss of submerged is 199.68×10⁸yuan, 150.31×10⁸yuan and 126.03×10⁸yuan respectively induced by torrential rain with return period of 1000, 200, and 50 years. Under Scenario 3, the submerged area is 29.06%, 25.83% and 22.58%; inundated population accounts for 300×10⁴, 268×10⁴ and 224×10⁴; and the loss of submerged is 174.48×10⁸yuan, 135.29×10⁸yuan and 111.53×10⁸yuan respectively induced by torrential rain with return period of 1 000, 200, and 50 years.

Key words: Tianjin Binhai New Area, rainstorm waterlogging, scenario simulation, risk assessment