Search

Suzhou City, located in the Yangtze River Delta in China, is prone to flooding due to a complex combination of natural factors, including its monsoon climate, low elevation, and tidally influenced position, as well as intensive human activities. The Large Encirclement Flood Control Project (LEFCP) was launched to cope with serious floods in the urban area. This project changed the spatiotemporal pattern of flood processes and caused spatial diversion of floods from the urban area to the outskirts of the city. Therefore, this study developed a distributed flood simulation model in order to understand this transition of flood processes. The results revealed that the LEFCP effectively protected the urban areas from floods, but the present scheduling schemes resulted in the spatial diversion of floods to the outskirts of the city. With rainstorm frequencies of 10.0% to 0.5%, the water level differences between two representative water level stations (Miduqiao (MDQ) and Fengqiao (FQ)) located inside and outside the LEFCP area, ranged from 0.75 m to 0.24 m and from 1.80 m to 1.58 m, respectively. In addition, the flood safety margin at MDQ and the duration with the water level exceeding the warning water level at FQ ranged from 0.95 m to 0.43 m and from 4 h to 22 h, respectively. Rational scheduling schemes for the hydraulic facilities of the LEFCP in extreme precipitation cases were developed according to flood simulations under seven scheduling scenarios. This helps to regulate the spatial flood diversion caused by the LEFCP during extreme precipitation.

With global warming, rainstorms and other extreme weather events are occurring frequently, leading to urban waterlogging disasters. A study on spatiotemporal variation characteristics of rainstorms in urban areas can provide scientific support for the design of urban drainage facilities to mitigate the damage of urban flooding disasters. Drawing on daily rainfall data from 20 meteorological stations during 1960-2010, this study analyzed change trends for annual rainstorms in Beijing, using the Mann-Kendall approach and cumulative departure curve as methodology. The results show that annual days of rainstorms in Beijing decreased non-significantly, but the precipitation of rainstorms and annual maximum daily precipitation declined significantly. The frequency of rainstorms generally decreased from southeast to northwest, with the greatest decrease occurring in the southeast plain areas. The results of this study contribute to the understanding of rainstorm risk in Beijing. [ABSTRACT FROM AUTHOR]

The locations (longitudes and latitudes) of the tropical cyclones (TCs) making landfall on the Chinese mainland from 1949 to 2008 are investigated in detail by using ArcGis and FORTRAN routine. The southeast coastline (110 to 122°E) with most landfall TCs was selected as the key region, which was divided into 12 subsections with 1° intervals of longitude. The study period was from July to September in each year. The result showed that the average sustaining time of TCs making landfall on the subsections east of 118°E is longer than those west of 118°E. Before landfall, the averaged TC intensity in the subsections east of 118°E is stronger than that west of it. After landfall, however, the difference between the west and east is not significant. The index of destructive potential for the period before/after landfall was defined as TDP1/TDP2. The maximum of TDP1/TDP2 occurred in the subsection of (119, 120°E)/(110, 111°E). The ENSO impact on the frequency and average location of landfall TC over the whole region at 110 to 122°E is not obvious, but the effect varies with specific subsections. There is little differences of averaged TDP1 in the subsections between different phases of ENSO events, but the averaged TDP2 is larger in the warm events than that in the cold events. The rainstorm days of each station caused by TCs in different subsections were counted respectively. The results suggested that the rainstorm days of the subsections east of 118°E are much more than those west of 118°E. The larger values are primarily distributed at the subsections of [119, 120°E) and [110, 111°E). [ABSTRACT FROM AUTHOR]