杭州主城区暴雨水淹灾害模拟与影响因子分析

【目的】近年中国多个大中城市突发极端暴雨灾害并导致严重内涝,探究城市暴雨水淹灾害的影响因子并对其进行模拟评估,以探讨城市对暴雨水淹灾害的承载能力。【方法】以杭州主城区为例,利用Arc GIS 10.2重分类中的手动分类法,结合地理探测器模型研究杭州主城区暴雨水淹灾害与高程、坡度、植被覆盖度、非渗透表面丰度、天然水体保持率和距河流距离6个影响因子的相关关系。通过地理加权回归预测6个影响因子作用下杭州主城区水淹灾害的空间分布。【结果】研究结果显示,杭州主城区水淹灾害与城市空间的高程、坡度、植被覆盖度、距河流距离呈负相关关系,与非渗透表面丰度呈正相关关系。杭州主城区暴雨水淹灾害的6个影响因子按影响程度排序为:植被覆盖度>坡度>高程>距河流距离>非渗透表面丰度>天然水体保持率。所有影响因子的交互作用均增强了单因子对水淹灾害的影响,并呈现出两两相互增强或非线性增强的关系。从空间分布上看,杭州主城区暴雨水淹灾害呈现多核心分布状态,整体上主城区中部主要为高风险和次高风险区域,其余区域主要为中风险、次低风险和低风险区域。【结论】结合模拟成果和实践应用发现,当城市空间的高程大于40 m,坡度大于10°,植被覆盖度大于60%,非渗透表面丰度小于40%,距河流距离大于500 m时,能够对高风险与次高风险区域严重的水淹灾害起到有效的缓解作用。

在GIS技术支持下建立暴雨水调蓄模型

在城市GIS技术平台支持下建立暴雨水调蓄模型,经过大量的实测资料分析验证,首次提出城市暴雨水浅蓄模型的新概念,实现对处于城市地区积水灾害的实时分析预报,并分析GIS在水动力学模型中的应用。

川西特大暴雨后公路山洪泥石流灾损分析

为分析山洪泥石流对公路的灾损特征,基于2019年8月雅安特大暴雨后国道351调查,结合区域工程地质条件,针对63处公路损毁段,从泥石流堆积物、支挡结构损毁、路基损毁和总损失4个方面研究灾损特征,并提出应急措施。结果表明:泥石流堆积物超2×10^(4)m^(3)的工点占81.28%,堆积多呈扇形,且泥石流冲出物粒径差异较大,其成分因物源形成而存在差异;支挡结构损毁超1500 m3的工点占56.82%,损毁主要为河道侧蚀、块石撞击等导致;路基损毁超300 m的工点占26.67%,主要为河流冲刷侧蚀掏空路基、靠山侧崩塌、滑坡掩埋路基等导致;总损失超700万元的工点占26.55%。山区公路勘察设计应充分评估公路沿线易损区段和承灾脆弱区段,分阶段实施不同粒径填料搭建临时保通道路。

法国里尔污水厂Actiflo~ Turbo工艺处理大流量暴雨水

Actiflo~ Turbo工艺是在原Actiflo~微砂加重絮凝高效沉淀工艺的基础上改进更新的,具有抗冲击负荷能力强、快速启动、SS去除率高、运行灵活、占地面积小等特点。介绍了工艺原理、核心设备、工艺特点和适用性。该工艺实际应用于法国里尔市Marquette-Lez-Lille污水厂大流量暴雨水处理,出水指标达到设计要求,可用于湿地灌溉。

香港SSDS以及对南京城市暴雨淹水整治的思考

本文针对近年来南京城市暴雨淹水问题，介绍了香港在这方面的管理经验，重点分析了香港的策略性污水排放计划（ＳＳＤＳ）。在对两地排水情况进行了分析对比之后，对南京城市暴雨淹水整治提出若干建议。

基于SWMM的不同降水量对城市降雨径流TSS的影响分析

受物理、化学、生物等多重因素的影响,城市降雨径流水质的模拟研究比较模糊。以TSS(总悬浮固体量)为例,利用SWMM的污染物模块及其土地利用模块、污染物累积模块和污染物冲刷模块进行城市雨水径流水质模拟;考虑了不同土地利用情况对污染物的累积及冲刷的影响,针对不同的降水量,利用EMC法(平均浓度法)以及指数方程法进行污染物的冲刷模拟,指数方程法的模拟精度大于EMC法的模拟精度,与监测值更接近。指数方程法的模拟结果表明:当降水量小于2.5mm时,其TSS冲刷量增长幅度较缓;而当降水量大于3.5mm时,其TSS冲刷量呈显著线性增加关系,从而表明,降水量较大的降水事件对于TSS的冲刷量影响更为显著。

1999年夏季中昆仑山北坡诸河冰雪大洪水及其成因分析

1999年盛夏中昆仑山北坡大多数河流出现了有正式水文记录以来的最大洪峰,各河流最大洪峰出现时间存在不一致性,洪峰变化复杂.应用主要河流出山口水文站的逐日流量和降水量,和田气象站的逐日0℃层高度,500 hPa气温以及NCEP/NCAR 500 hPa高度场资料,分析了1999年夏季中昆仑山北坡诸河出现的历史特大洪水特性及其气象成因.这次特大洪水是高空持续高温引起的冰雪融水与产流区出现的暴雨共同作用下的混合型洪水.洪水前期春季到初夏该区域山区降水偏多,高空气温和0℃层高度持续偏低,对高山区的积雪积累极为有利;7月底至8月初和田高空气温和0℃层高度迅速上升并维持数日,使冰雪快速消融,同时山区出现大降水是引发洪水的直接气象成因.在青藏高原东部柴达木盆地上空存在有500 hPa稳定高压,使中亚副热带大槽东移中昆仑山北坡是这次特大洪水发生的环流系统特点.

加拿大第一届国家废水问题讨论会

2005年4月3—5日由加拿大水与废水问题联合会组织召开了加拿大第一届国家废水问题讨论会，会议涉及水环境卫生、商业用水、废水循环使用、排污管理、暴雨水控制管理、雨洪管理、中水再利用等废水在园林中的使用及中水灌溉等问题的讨论。

基于数值模拟的风景园林工程地表径流调蓄虚拟仿真实验探索

为突破地表径流调蓄实验在传统教学中的局限,提升大量运算类风景园林工程课程教学质量,文章基于数值模拟构建应对暴雨水环境的地表径流调蓄虚拟仿真实验,探究由简单场景式模拟转向深度关联的数值式模拟过程。通过地形分析模块、地表径流调蓄模块以及水位确定和综合模拟3大模块,打造“基础-核心-应用”层层递进的思维训练和“常规-内涝-超标”3种降雨层级下的数值关联,提升学生分析和解决复杂问题的能力。

GIS及SWMM模型在防洪保护区内涝模拟中的应用

为了研究防洪保护区暴雨内涝积水风险,减少淹没灾害损失,基于GIS技术与SWMM产汇流模型,计算暴雨内涝积水域面积及积水深度值,以此开展积涝风险分析。将该方法应用于茨南淝左片防洪保护区的暴雨内涝计算,利用永幸河闸上、架河闸上、青年闸上2007年实测降水水位验证产汇流模型。结果表明:3个位置计算水位绝对误差分别为0.02、0.10和0.14 m,计算结果较合理,将该模型应用于防洪保护区20年一遇设计暴雨内涝积水风险分析,研究成果对该地区风险管理及决策起着至关重要的作用。

快速城市化下的武汉城市暴雨渍水空间特征及发生机制

随着城市化进程的加快和社会经济的发展,城市内涝已成为继人口拥挤、交通拥堵、环境污染等问题之后的又一大城市病。武汉是我国内涝频发的城市之一,尤其是2016年夏季发生的城市内涝造成了巨大的社会经济损失。文章以武汉中心城区汤逊湖水系为研究范围,利用最邻近指数法、核密度强度分析法、湖泊变化强度指数等方法,探讨2016年6月30日-7月6日期间城市内涝灾害发生最严重时段的渍水特征,并揭示其形成原因和发生机制。研究发现:①城市暴雨渍水类型多样,主要包括居住区渍水、道路渍水和产业园区渍水三类。②渍水点呈现明显的空间集聚特征:渍水点以湖泊为中心集中分布,围湖造地区域是渍水发生的重灾区,城市新开发区和在建施工区也是渍水发生的集中区域,水系中下游比上游渍水严重。③湖泊容量萎缩、水系结构简化、水利建设滞后、汇水强度增大、异常气候突发等共同导致暴雨渍水灾害的发生。

东北西斯基尤绿色大道

2007年ASLA专业奖评委 评语：“这个项目风格简约而让人惬意,它是住宅区暴雨水管理项目的范例。它在短距离内创造了很好的环境效益,为设计师,政策制定者和居民树立了典型。它带来很多效益，甚至有助于减缓交通堵塞。它跟原有景观看起来也很协调。”

Influence of Land Use/Cover Change on Storm Runoff—A Case Study of Xitiaoxi River Basin in Upstream of Taihu Lake Watershed

Land use/cover change (LUCC) is one of the main boundary conditions which influence many hydrologic processes. In view of the importance of Taihu Lake Watershed in China and the urgency of discovering the impacts of LUCC on storm runoff, two flood events under five land cover scenarios in the Xitiaoxi River Basin of the upstream of Taihu Lake watershed were simulated by distributed hydrologic modeling system HEC-HMS. The influences of each land cover on storm runoff were discussed. It was concluded that under the same rainstorm the ascending order of runoff coefficient and peak flow produced by the 5 different land covers were woodland, shrub, grassland, arable land, and built-up land; the descending order of swelling time were woodland, shrub, grassland, arable land, and built-up land. Scenario of built-up land was the first to reach peak flow, then arable land, grassland, shrub, and woodland. There were close relationships between the runoff coefficients produced by the 5 different land covers. The degrees of impacts on runoff coefficient of land cover change modes were sorted by descending: woodland to built-up land, shrub to built-up land, grassland to built-up land, arable land to built-up land, woodland to arable land, shrub to arable land, arable land to grassland, shrub to grassland, grassland to arable land, and woodland to shrub. Urbanization will contribute to flood disaster, while forestation will mitigate flood disaster.

Mountain Effect and Differences in Storm Floods between Northern and Southern Sources of the Songhua River Basin

In this study, the differences in annual rainstorm changes in the Second Songhua River Basin and the Nenjiang River basin and their causes were compared from the perspective of mountain effects. The following results were drawn: (1) Altitude effect is the primary factor leading to increased rainstorms in the southern source; (2) Slope effect primarily leads to differences of the weather systems in the two sources, and thus cause the difference of the rainstorms; (3) Slope effect is responsible for the greater fluctuation in the observed floods in the southern source. These landform differences eventually lead to the differences in the characteristics of floods in the southern and northern sources. Commensurability method was used to identify the period of rainstorms in the southern and northern sources. The results showed that although rainstorms do not appear at the same time in the two sources they are characteristic of a 10 years' period in both areas. These results can serve as hydrological references for flood control and long-term flood disaster predictions.

Analyses of Dry Intrusion and Instability during a Heavy Rainfall Event that Occurred in Northern China

The 1°×1° National Center for Environmental Prediction/National Center for Atmospheric Research （NCEP/NCAR） data and mesoscale numerical simulation data are analyzed to reveal a mechanism for the formation of heavy rainfall in Northern China; this mechanism is the non-uniformly saturated instability induced by a dry intrusion. The dry intrusion and the accompanying downward transport of air with a high value of potential vorticity （PV） are maintained during the precipitation event. As the dry air intrudes down into the warm and moist sector in the lower troposphere, the cold, dry air and the warm, moist air mix with each other, and, as a result, the atmosphere becomes non-uniformly saturated. On the basis of this non-uniform saturation, a new Brunt-Vaisaila frequency （BVF） formula is derived and applied to the precipitation event. It is shown that, compared to the conditions of either a dry or a saturated atmosphere, the BVF in a non-uniformly saturated, moist atmosphere （BVF） may be more appropriate for depicting the atmospheric instability in rainy regions.

A Spatial Cluster Analysis of Heavy Rains in China

Clustered heavy rains （CHRs） defined using hierarchical cluster analysis based on daily observations of precipitation in China during 1960-2008 are investi- gated in this paper. The geographical pattern of CHRs in China shows three high-frequency centers--South China, the Yangtze River basin, and part of North China around the Bohai Sea. CHRs occur most frequently in South China with a mean annual frequency of 6.8 （a total of 334 times during 1960-2008）. June has the highest monthly frequency （2.2 times/month with a total of 108 times dur- ing 1960-2008）, partly in association with the Meiyu phenomenon in the Yangtze River basin. Within the past 50 years, the frequency of CHRs in China has increased significantly from 13.5 to 17.3 times per year, which is approximately 28%. In the 1990s, the frequency of CHRs often reached 19.1 times per year. The geographical extent of CHR has expanded slightly by 0.5 stations, and its average daily rainfall intensity has increased by 3.7 mm d-1. The contribution of CHRs to total rainfall amount and the frequency of daily precipitation have increased by 63.1% and 22.7%, respectively, partly due to a significant decrease in light rains. In drying regions of North and Northeast China, the amounts of minimal CHRs have had no significant trend in recent years, probably due to warming in these arid regions enhancing atmospheric conveetivity at individual stations.

Impact of the water-sediment regulation and a rainstorm on nutrient transport in the Huanghe River

Dissolved nutrient concentration in the Huanghe （Yellow） River at Lijin was monitored during a water-sediment regulation period and a subsequent rainstorm from 14 June to 19 July, 2005. This study provides detailed information on nutrient concentrations in the Huanghe River during the water-sediment regulation and rainstorm periods, and is of significance for the downstream area of the Huanghe River and the Bohai Sea. The average concentrations of nitrate, nitrite and ammonia were 304.7 μmol/L, 0.19 μmol/L, and 1.10 μmol/L, respectively, while the average concentrations of dissolved inorganic phosphorus （DIP） and dissolved silicate （DSi） were 0.23 gmol/L and 122.9 ktmol/L, respectively. Nutrient concentrations during the water-sediment regulation period were mainly influenced by the dilution effect, floodplain effect and sediment resuspension while dilution and erosion effects were the main factors during the rainstorm. The fluxes of dissolved inorganic nitrogen （DIN）, DIP and DSi during the water-sediment regulation and rainstorm periods accounted for 20.4%, 19.5%, 16.7% and 4.97%, 6.45%, 5.47% of the annual nutrient fluxes, respectively. Discharge was the main factor influencing the fluxes of nutrients during both the water- sediment regulation and the rainstorm periods.

Case study of debris flow disaster scenario caused by torrential rain on Kiyomizu-dera, Kyoto, Japan - using Hyper KANAKO system

This paper presents debris-flow numerical simulations using the Hyper KANAKO system,developed by the authors.The system uses the debris flow simulator KANAKO 2D equipped with a graphical user interface(GUI);hence,a user can easily produce appropriate landform data for simulations using standard laser profiler data,and visualize the results using a GIS.Hyper KANAKO was applied to the streams around Kiyomizu-dera in Kyoto,Japan.Kiyomizu-dera is a famous temple in Japan which is visited by numerous tourists throughout the year.We simulated a disaster scenario of debris flow caused by torrential rain.We set the hydrograph using rainfall intensity data,and set the landform data using information from the Geospatial Information Authority of Japan(GSI) and a digital elevation model(DEM).We evaluated different mesh sizes and also used a digital surface model(DSM) to consider the building heights.The simulation results showed that with small mesh size,the debris flowmoved through the roads,which seems realistic for a disaster situation.When buildings were considered,the flow direction changed,and a 1-m flow depth,which was deeper than in other cases,appeared in the flow path.This may pose a dangerous situation for evacuations.

SPATIOTEMPORAL DISTRIBUTION CHARACTERISTICS AND VARIATION TRENDS OF HIERARCHICAL PRECIPITATION IN GUANGDONG PROVINCE OVER THE PAST 50 YEARS

The climatic characteristics of the precipitation in Guangdong province over the past 50 years were analyzed based on the daily rainfall datasets of 86 stations from 1961 to 2010. The rainfall was divided into five categories according to its intensity, and their spatiotemporal characteristics and variation trends were investigated. The annual rainfall amount was within 1,500 to 2,000 mm over most parts of Guangdong, but substantial differences of rainfall amount and rainy days were found among different parts of the province. There were many rainy days in the dry seasons （October to March）, but the daily rainfall amounts are small. The rainy seasons （April to September） have not only many rainy days but also heavy daily rainfall amounts. The spatial distributions of light rainy days （1 mm〈P〈 10 mm） and moderate rainy days （10 mm〈P〈 25 mm） resemble each other. The heavy rainy days （25 mm〈P〈 50 mm）, rainstorm days （50 ram〈P〈 100 mm） and downpour days （P〉 100 mm） are generally concentrated in three regions, Qingyuan, Yangjiang, and Haifeng/Lufeng. The average rainfall amount for rainy days increases form the north to the south of Guangdong, while decreasing as the rainfall intensity increases. The contributions from light, moderate and heavy rain to the total rainfall decreases form the north to the south. The annual rainy days show a decreasing trend in the past 50 years. The light rainy days decreased significantly while the heavy, rainstorm and downpour rainy days increased slightly. The annual total rainfall amount increased over the past 50 years, which was contributed by heavy, rainstorm and downpour rains, while the contribution from light and moderate rains decreased. Key words： spatiotemporal distribution; rainfall amount; rainy days; rainfall contribution rate