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1.
Regional flood frequency analysis (RFFA) is often used in hydrology to estimate flood quantiles when there is a limitation
of at-site recorded flood data. One of the commonly used RFFA methods is the index flood method, which is based on the assumptions
that a region satisfies criterion of simple scaling and it can be treated homogeneous. Another RFFA method is quantile regression
technique where prediction equations are developed for flood quantiles of interest as function of catchment characteristics.
In this paper, the scaling property of regional floods in New South Wales (NSW) State in Australia is investigated. The results
indicate that the annual maximum floods in NSW satisfy a simple scaling assumption. The application of a heterogeneity test,
however, reveals that NSW flood data set does not satisfy the criteria for a homogeneous region. Finally, a set of prediction
equations are developed for NSW using quantile regression technique; an independent test shows that these equations can provide
reasonably accurate design flood estimates with a median relative error of about 27%. 相似文献
2.
现行分期设计洪水模式估算的分期设计洪水值均小于或等于年最大设计值,达不到规定的防洪标准。采用Gumbel-Hougaard Copula函数描述两个分期的分期最大洪水之间的相关性结构,并构造边缘分布为P-Ⅲ分布的分期最大洪水联合分布,建立分期最大洪水与年最大洪水的关系式,讨论分期设计洪水频率与防洪标准应满足的关系,探讨能够满足防洪标准的新的分期设计洪水模式。应用示例表明,新模式主汛期设计值相对年最大设计值小幅度增加,而非主汛期设计值则小于年最大设计值,既满足不降低防洪标准的要求又能够起到优化设计洪水的作用,为分期设计洪水研究提供了一条新的思路。 相似文献
3.
Application of bivariate extreme value distribution to flood frequency analysis: a case study of Northwestern Mexico 总被引：1，自引：0，他引：1
Carlos Escalante-Sandoval 《Natural Hazards》2007,42(1):37-46
In Mexico, poverty has forced people to live almost on the water of rivers. This situation along with the occurrence of floods
is a serious problem for the local governments. In order to protect their lives and goods, it is very important to account
with a mathematical tool that may reduce the uncertainties in computing the design events for different return periods.
In this paper, the Logistic model for bivariate extreme value distribution with Weibull-2 and Mixed Weibull marginals is proposed
for the case of flood frequency analysis. A procedure to estimate their parameters based on the maximum likelihood method
is developed. A region in Northwestern Mexico with 16 gauging stations has been selected to apply the model and regional at-site
quantiles were estimated. A significant improvement occurs, measured through the use of a goodness-of-fit test, when parameters
are estimated using the bivariate distribution instead of its univariate counterpart. Results suggest that it is very important
to consider the Mixed Weibull distribution and its bivariate option when analyzing floods generated by a␣mixture of two populations. 相似文献
4.
Flood frequency analysis based on simulated peak discharges 总被引：2，自引：0，他引：2
Flood frequency approaches vary from statistical methods, directly applied on the observed annual maximum flood series, to adopting rainfall–runoff simulation models that transform design rainfalls to flood discharges. Reliance on statistical flood frequency analysis depends on several factors such as the selected probability distribution function, estimation of the function parameters, possible outliers, and length of the observed flood series. Through adopting the simulation approach in this paper, watershed-average rainfalls of various occurrence probabilities were transformed into the corresponding peak discharges using a calibrated hydrological model. A Monte Carlo scheme was employed to consider the uncertainties involved in rainfall spatial patterns and antecedent soil moisture condition (AMC). For any given rainfall depth, realizations of rainfall spatial distribution and AMC conditions were entered as inputs to the model. Then, floods of different return periods were simulated by transforming rainfall to runoff. The approach was applied to Tangrah watershed in northeastern Iran. It was deduced that the spatial rainfall distribution and the AMCs exerted a varying influence on the peak discharge of different return periods. Comparing the results of the simulation approach with those of the statistical frequency analysis revealed that, for a given return period, flood quantiles based on the observed series were greater than the corresponding simulated discharges. It is also worthy to note that existence of outliers and the selection of the statistical distribution function has a major effect in increasing the differences between the results of the two approaches. 相似文献
5.
6.
分析洪峰、洪量和历时三变量联合分布与风险概率及其设计分位数,为水利工程规划设计和风险评估提供参考依据。以珠江流域西江高要站52年洪水数据为例,采用非对称阿基米德M6 Copula函数与Kendall分布函数计算三变量洪水联合分布的“或”重现期、“且”重现期和二次重现期及其最可能的设计分位数。结果表明:“或”重现期的风险率偏高,“且”重现期的风险率偏低,二次重现期更准确地反映了特定设计频率情况下三变量洪水要素遭遇的风险率;按三变量“或”重现期或三变量同频率设计值推算的洪水设计值偏高,以最大可能概率推算的三变量洪水要素的二次重现期设计值可为防洪工程安全与风险管理提供新的选择。 相似文献
7.
Several small reservoirs and a large number of check dams had been constructed in the Wangkuai reservoir watershed after 1970s, and flood time series lacked stationarity, which affected the original design flood hydrographs for the Wangkuai reservoir. Since the location, storage capacity and drainage area of the large number of check dams were unknown, we present a method to estimate their total storage capacities (TSC) and total drainage areas (TDA) by using the recorded rainstorm and flood data. On the basis of TSC and TDA, the flood events which occurred in an undisturbed period were reconstructed under current conditions to obtain a stationary flood series. A frequency analysis was subsequently performed to assess the design flood peak and volume for both small and medium design floods with a 10–200 year return period. For large and catastrophic floods, it was assumed that the upstream check dams and small reservoirs would be destroyed, and water stored in these hydraulic structures were re-routed to the Wangkuai reservoir by unit hydrograph. The modified flood peak and volume decreased for floods with a 10–200 year return period when compared to the current design flood. But for large design floods with a return period exceeding 500 years, peak discharge increased. This study provides a new method for design flood calculation or modification of the original design flood in watersheds with a large number of check dams. 相似文献
8.
为分析西江流域灾害性洪水的风险,采用水文学分析法从洪水组成、遭遇时间以及洪峰重现期等方面,重点分析了梧州站干支流洪水遭遇规律。研究表明:梧州15场洪水中红水河、柳江、郁江及桂江的日平均流量平均比重分别为32.31%、40.57%、13.19%及9.13%;其中西江干流洪水发生时间集中在6～8月,柳江洪水发生时间集中在6～7月,桂江洪水发生时间集中在5～7月,郁江洪水发生时间集中在7～9月;西江上游红水河与柳江洪水遭遇频繁,而郁江、桂江遭遇洪水量级较小,其中全流域洪水、红水河—柳江—桂江洪水、柳江—郁江—桂江洪水三种遭遇类型所构成的梧州大洪水重现期依次约为100年、50年、20年一遇,揭示了西江干支流洪水遭遇后致使梧州站洪水重现期显著增大。研究结果可为西江流域防洪减灾提供水文分析参考。 相似文献
9.
当前洪水风险分析按照典型设计标准洪水进行计算的模式难以满足实际防洪管理需要,为了提高洪水风险分析的实时性以及适应洪水演进的动态性,设计了动态实时洪水风险分析框架。在本框架中,先采用一维和二维动态耦合水动力学数值方法耦合溃堤模型,然后在樵桑联围防洪保护区建立洪水演进模拟模型,通过灵活处理模型计算边界条件以及动态设置溃堤功能,计算不同设计标准洪水发生时,堤防出现单一溃口或者组合溃口后保护区内洪水演进过程。按照上述框架开发了樵桑联围动态实时洪水风险图编制与管理应用系统,并利用历史洪水资料开展模型验证,验证结果表明,2008-06洪水马口站、三水站、大熬站、甘竹（一）站的实测最高水位和模型计算最高水位的绝对误差分别为-0.10、0.10、0.09、0.04 m,均满足洪水模拟精度要求。利用模型计算了西江发生200年一遇的洪水情况下,江根堤防出现溃口后的洪水流量及溃口内外洪水水位变化过程,模拟溃口宽度168 m,最大溃口洪水流量达到5 190 m3,分析了堤防溃决后3、6和24 h洪水漫延导致村落淹没情况,结果表明其满足合理性分析。 相似文献
10.
Pradeep Adhikari Yang Hong Kimberly R. Douglas Dalia Bach Kirschbaum Jonathan Gourley Robert Adler G. Robert Brakenridge 《Natural Hazards》2010,55(2):405-422
Floods have profound impacts on populations worldwide in terms of both loss of life and property. A global inventory of floods
is an important tool for quantifying the spatial and temporal distribution of floods and for evaluating global flood prediction
models. Several global hazard inventories currently exist; however, their utility for spatiotemporal analysis of global floods
is limited. The existing flood catalogs either fail to record the geospatial area over which the flood impacted or restrict
the types of flood events included in the database according to a set of criteria, limiting the scope of the inventory. To
improve upon existing databases, and make it more comprehensive, we have compiled a digitized Global Flood Inventory (GFI)
for the period 1998–2008 which also geo-references each flood event by latitude and longitude. This technical report presents
the methodology used to compile the GFI and preliminary findings on the spatial and temporal distributions of the flooding
events that are contained in the inventory. 相似文献
11.
The evolution of flood activity with global warming remains uncertain. To better assess flood–climate relationships, lake sediments are increasingly being investigated because they could provide regional flood histories long enough to cover past climate changes. However, site‐specific sedimentary processes may bias flood reconstructions. The aim of this article is to investigate these effects through the reconstruction of two distinct flood records from independent, neighbouring sedimentary basins of the same lake (Lake Allos in the Mediterranean French Alps), i.e. under the same climate conditions. Understanding of sedimentary processes is crucial in order to adapt the sampling strategy and the flood‐intensity proxy to each sedimentary system and, thereby, reconstruct a complete and reliable flood history. Thanks to this detailed approach, the main trends of the regional flood variability can be reproduced; i.e. periods of high flood‐frequency, ranges of flood‐frequency values and timing of the most intense events. In detail, some differences appeared associated to the various stream capacities to erode and transport flood sediments to the lake system, implying variable sensitivity of sedimentary systems in recording floods. Comparing regional flood records based on independent sedimentary systems from similar environments could thus be a complementary approach to assessing past flood intensity. Such an approach could open particularly interesting perspectives because reconstructing the long‐term evolution of flood intensity is a key challenge in the geosciences. 相似文献
12.
Flood quantiles are routinely used in hydrologic engineering to design hydraulic structures, optimize erosion control structure
and map the extent of floodplains. As an increasing number of papers are pointing out cycles and trends in hydrologic time
series, the use of stationary flood distributions leads to the overestimation or underestimation of the hydrologic risk at
a given time. Several authors tried to address this problem by using probability distributions with time-varying parameters.
The parameters of these distributions were assumed to follow a linear or quadratic trend in time, which may be valid for the
short term but may lead to unrealistic long-term projections. On the other hand, deterministic rainfall-runoff models are
able to successfully reproduce trends and cycles in stream flow data but can perform poorly in reproducing daily flows and
flood peaks. Rainfall-runoff models typically have a better performance when simulation results are aggregated at a larger
time scale (e.g. at a monthly time scale vs. at a daily time scale). The strengths of these two approaches are combined in
this paper where the annual maximum of the time-averaged outputs of a hydrologic model are used to modulate the parameters
of a non-stationary GEV model of the daily maximum flow. The method was applied to the Kemptville Creek located in Ontario,
Canada, using the SWAT (Soil and Water Assessment Tool) model as rainfall-runoff model. The parameters of the non-stationary
GEV model are then estimated using Monte Carlo Markov Chain, and the optimal span of the time windows over which the SWAT
outputs were averaged was selected using Bayes factors. Results show that using the non-stationary GEV distribution with a
location parameter linked to the maximum 9-day average flow provides a much better estimation of flood quantiles than applying
a stationary frequency analysis to the simulated peak flows. 相似文献
13.
介绍了基于水文气象途径的地区线性矩法的概念,通过基于次序统计量的线性矩进行参数估计与基于水文气象一致区的地区分析法相结合,以太湖流域1d时段的年极值降雨资料为例,进行暴雨频率分析。应用水文气象一致区的判别准则,将太湖流域划分为8个水文气象一致区;综合考虑三种拟合优度检测方法,选择1~8区的最优分布线型分别为:GEV、GLO、GEV、GEV、GNO、GNO、GEV、GNO;根据地区分析法原理,估算各雨量站的暴雨频率设计值。分析表明:太湖流域各重现期下的年极值降雨空间分布形态基本一致,西南山区是太湖流域的暴雨高风险区,应该在地区防洪规划中引起重视。结果表明:地区线性矩法具有很高的学术和实用价值,建议在全国范围内推广,作为防洪规划的顶层设计和基础工作,以满足工程防洪设计、地区防洪规划、山洪预警和城市防涝防洪规划等方面的需求。 相似文献
14.
研究探讨梯级水库运行期设计洪水计算理论和方法,实现防洪和发电效益最大化。采用t-Copula函数建立各分区洪水的联合分布,通过蒙特卡罗法和遗传算法(GA)推求金沙江下游梯级水库的最可能地区组成;分析计算各水库运行期的设计洪水及汛控水位。结果表明:①最可能地区组成结果合理可靠,可为梯级水库运行期设计洪水的分析计算提供依据;②金沙江下游梯级水库受上游水库调蓄影响显著,向家坝水库1000年一遇设计洪峰15400m^3/s(35%),3d、7d和30d洪量的削减量(削减率)分别为35.6亿m^3(33%)、70.2亿m^3(30%)和85.0亿m^3(11%);③在不降低防洪标准的前提下,下游各水库在运行期汛控水位相比汛限水位可适当抬高,白鹤滩、溪洛渡和向家坝水库的汛控水位(汛限水位)分别为788.82m(785m)、570.67m(560m)和371.36m(370m),汛期年均发电量分别增加2.1%、6.1%和1.4%,年增发电量17.1亿kW·h。 相似文献
15.
Flooding in urban area is a major natural hazard causing loss of life and damage to property and infrastructure. The major causes of urban floods include increase in precipitation due to climate change effect, drastic change in land use–land cover (LULC) and related hydrological impacts. In this study, the change in LULC between the years 1966 and 2009 is estimated from the toposheets and satellite images for the catchment of Poisar River in Mumbai, India. The delineated catchment area of the Poisar River is 20.19 km2. For the study area, there is an increase in built-up area from 16.64 to 44.08% and reduction in open space from 43.09 to 7.38% with reference to total catchment area between the years 1966 and 2009. For the flood assessment, an integrated approach of Hydrological Engineering Centre-Hydrological Modeling System (HEC-HMS), HEC-GeoHMS and HEC-River analysis system (HEC-RAS) with HEC-GeoRAS has been used. These models are integrated with geographic information system (GIS) and remote sensing data to develop a regional model for the estimation of flood plain extent and flood hazard analysis. The impact of LULC change and effects of detention ponds on surface runoff as well as flood plain extent for different return periods have been analyzed, and flood plain maps are developed. From the analysis, it is observed that there is an increase in peak discharge from 2.6 to 20.9% for LULC change between the years 1966 and 2009 for the return periods of 200, 100, 50, 25, 10 and 2 years. For the LULC of year 2009, there is a decrease in peak discharge from 10.7% for 2-year return period to 34.5% for 200-year return period due to provision of detention ponds. There is also an increase in flood plain extent from 14.22 to 42.5% for return periods of 10, 25, 50 and 100 years for LULC change between the year 1966 and year 2009. There is decrease in flood extent from 4.5% for 25-year return period to 7.7% for 100-year return period and decrease in total flood hazard area by 14.9% due to provisions of detention pond for LULC of year 2009. The results indicate that for low return period rainfall events, the hydrological impacts are higher due to geographic characteristics of the region. The provision of detention ponds reduces the peak discharge as well as the extent of the flooded area, flood depth and flood hazard considerably. The flood plain maps and flood hazard maps generated in this study can be used by the Municipal Corporation for flood disaster and mitigation planning. The integration of available software models with GIS and remote sensing proves to be very effective for flood disaster and mitigation management planning and measures. 相似文献
16.
Péter Hegedüs Szabolcs Czigány László Balatonyi Ervin Pirkhoffer 《Central European Journal of Geosciences》2013,5(1):97-111
Flash floods are one of the most significant natural hazards of today. Due to the complexity of flash flood triggering factors, to prevent or mitigate flood triggered losses, numeric model based flood forecasting models are capable tools to predict stream water levels. The main goal of the current research was to reproduce two flow peaks with the HEC-HMS rainfall-runoff model and test the model sensitivity for various input parameters. To obtain sufficient input data, we monitored soil depth, maximum infiltration rate, soil moisture content, rainfall, time of concentration and flow. To obtain input data, parameters were calculated, measured in the Sás Valley experimental watershed (SW Hungary) or optimized with the built in function of the HEC-HMS. Soil moisture was monitored in the 1.7 km2 pilot catchment over the period between September 2008 and September 2009. HEC-HMS had a good performance reproducing the two events, however simulated flow time series are highly influenced by the antecedent soil moisture, infiltration rate and canopy storage. Outflow modeled data were verified for two flood events (June 4, 2008 and July 9, 2009). The HEC-HMS was over-sensitive for input soil moisture and with increasing input rainfall and increasing outflow, larger simulation errors were observed. 相似文献
17.
防洪效益评估对防洪工程投资决策与减灾对策制定具有重要意义。建立集成了与太湖流域防洪效益评估相关的系列模型和方法,包括含降雨产流与平原净雨计算的水文分析方法、由河网水动力学模型和平原区域洪水分析模型组成的大尺度水力学模型、综合流域社会经济和淹没因素的洪灾损失评估模型。模拟了太湖流域遇特大洪水的灾害损失,开展了不同防洪工程应对流域性特大洪水减灾效益的预测分析。结果表明:1999年型200年一遇降雨将会给太湖流域造成高达568.29亿元的直接经济损失,外排动力增强30%至100%的防洪效益介于26.69亿元到45.70亿元之间,新建圩区、太浦河拓宽的防洪效益依次减小,而圩区泵排能力增加30%的防洪效益仅为0.65亿元。基于研究成果提出了增设外排泵站、加强圩区科学调度、通过保险分担风险等应对特大洪水的对策措施建议,为太湖流域特大洪水的防治提供支撑和参考。 相似文献
18.
Geomorphic Effects of Monsoon Floods on Indian Rivers 总被引：1，自引：0，他引：1
The southwest summer monsoon contributesthe bulk of India's rainfall. Consequently,almost all the geomorphic work by the rivers is carried out during the monsoonseason in general and the monsoon floods in particular. Indian rivers arecharacterized by high average flood discharges and large temporal variability. Thereis also significant spatial variation in the magnitude, frequency and power of floods, on account of regional variations in monsoon rainfall, basin characteristics andchannel geometry. As a result, the channel responses and the geomorphic effects also varyspatially. This paper describes the hydrological and geomorphological aspects, as well asthe geomorphic effects of monsoon floods in the Indian rivers. The geomorphic effects of floods are most impressive only in certainareas – the Himalaya, the Thar Desert, and the Indus-Ganga-Brahmaputra Plains. There are numerous instances of flood-induced changes in the channel dimension,position and pattern in these areas. In the Ganga-Brahmaputra Plains, the annualfloods appear to be geomorphologically more effective than the occasional large floods.In comparison, the rivers of the Indian Peninsula are, by and large, stable and thegeomorphic effects of floods are modest. Only large-magnitude floods that occur at aninterval of several years to decades are competent to modify the channel morphology in asignificant way. A synthesis of the various case studies available from the Indianregion indicates that often the absolute magnitude of a flood is not as important withrespect to the geomorphic effects as the flow stress and competence. 相似文献
19.
新疆河流洪水与洪灾的变化趋势 总被引：32，自引：11，他引：21
在西北气候由暖干转向暖湿的过程中,新疆河流的洪水和洪灾反映明显.对新疆29条河流选取年最大洪水,统计出超标准洪水、20a一遇、50a一遇洪水的出现频次进行分析,结果显示1987年后洪水量级、洪水频次呈增加的变化趋势.通过20世纪90年代以来灾害性洪水出现的频次、灾害损失的变化比较分析,90年代以来灾害性洪水尤其是灾害性暴雨洪水和突发性洪水呈现增加的态势,1987—2000年的灾害损失与1950—1986年相比增加了30倍. 相似文献
20.
防洪效益评估对防洪工程投资决策与减灾对策制定具有重要意义。建立集成了与太湖流域防洪效益评估相关的系列模型和方法,包括含降雨产流与平原净雨计算的水文分析方法、由河网水动力学模型和平原区域洪水分析模型组成的大尺度水力学模型、综合流域社会经济和淹没因素的洪灾损失评估模型。模拟了太湖流域遇特大洪水的灾害损失,开展了不同防洪工程应对流域性特大洪水减灾效益的预测分析。结果表明：1999年型200年一遇降雨将会给太湖流域造成高达568.29亿元的直接经济损失,外排动力增强30%至100%的防洪效益介于26.69亿元到45.70亿元之间,新建圩区、太浦河拓宽的防洪效益依次减小,而圩区泵排能力增加30%的防洪效益仅为0.65亿元。基于研究成果提出了增设外排泵站、加强圩区科学调度、通过保险分担风险等应对特大洪水的对策措施建议,为太湖流域特大洪水的防治提供支撑和参考。 相似文献