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1.
Flash floods are the most common type of natural hazards that cause loss of life and massive damage to economic activities. During the last few decades, their impact increased due to rapid urbanization and settlement in downstream areas, which are desirable place for development. Wadi Asyuti, much like other wadis in the Eastern Desert of Egypt, is prone to flash flood problems. Analysis and interpretation of microwave remotely sensed data obtained from the Shuttle Radar Topography Mission (SRTM) and Tropical Rainfall Measuring Mission (TRMM) data using GIS techniques provided information on physical characteristics of catchments and rainfall zones. These data play a crucial role in mapping flash flood potentials and predicting hydrologic conditions in space and time. In order to delineate flash flood potentials in Wadi Asyuti basin, several morphometric parameters that tend to promote higher flood peak and runoff, including drainage characteristics, basin relief, texture, and geometry were computed, ranked, and combined using several approaches. The resulting flash flood potential maps, categorized the sub-basins into five classes, ranging from very low to very high flood potentials. In addition, integrating the spatially distributed drainage density, rainfall intensity, and slope gradient further highlighted areas of potential flooding within the Wadi Asyuti basin. Processing of recent Landsat-8 imagery acquired on March 15, 2014, validated the flood potential maps and offered an opportunity to measure the extent (200–900 m in width) of the flooding zone within the flash flood event on March 9, 2014, as well as revealed vulnerable areas of social and economic activities. These results demonstrated that excessive rainfall intensity in areas of higher topographic relief, steep slope, and drainage density are the major causes of flash floods. Furthermore, integration of remote sensing data and GIS techniques allowed mapping flood-prone areas in a fast and cost-effective to help decision makers in preventing flood hazards in the future.  相似文献   

2.
TRMM3B42降雨数据在渭河流域的应用分析   总被引：3，自引：0，他引：3       下载免费PDF全文
运用渭河流域24个气象站点日降雨数据对2001~2012年热带测雨卫星(TRMM)3B42数据在不同子流域、不同降雨强度以及不同时间尺度的精度进行了对比验证,并对比分析了基于TRMM和站点数据的渭河流域降雨时空分布特征。结果显示:在不同子流域的日TRMM数据比站点观测数据对低值降雨更为敏感,而在极大值降雨数据观测上两者差距较大,月尺度TRMM站点观测数据确定性系数在0.89到0.96之间;两种数据在流域降雨的时空分布上表现一致性,在年内6月中旬~10月初为湿润多雨期,其余月份降雨较少,空间分布呈东南部大,西北部小的格局。  相似文献   

3.
Satellite precipitation products offer an opportunity to evaluate extreme events (flood and drought) for areas where rainfall data are not available or rain gauge stations are sparse. In this study, daily precipitation amount and frequency of TRMM 3B42V.7 and CMORPH products have been validated against daily rain gauge precipitation for the monsoon months (June–September or JJAS) from 2005–2010 in the trans-boundary Gandak River basin. The analysis shows that the both TRMM and CMORPH can detect rain and no-rain events, but they fail to capture the intensity of rainfall.  相似文献   

4.
通过评估GPM计划三种日降水产品（IMERG-E、 IMERG-L和IMERG-F）和TRMM卫星、 两种日降水产品（TMPA 3B42和TMPA 3B42RT）在黄河源及其周边区域38个台站的适用性, 探究了五种产品探测精度和海拔高度及雨强的相关关系, 结果表明： 在与实测资料的一致性和偏差方面, GPM卫星产品要全面优于TMPA产品。在TRMM卫星产品中, 3B42产品明显优于3B42RT。五种产品的相关系数均表现出明显的从东南到西北递减的趋势, 均方根误差北部普遍低于南部。IMERG产品的探测率（POD）和探测成功率（CSI）都要普遍高于TMPA产品, 而误报率（FAR）则是TMPA 产品更低, 表现更好。五种产品均在个别台站出现了严重误报的情况, 这些台站主要分布在研究区的西北部。IMERG三种产品对于海拔高度的依赖程度具有很强的一致性, 而3B42RT产品对海拔高度几乎没有依赖。除3B42RT产品外, 其余四种产品的偏差均随雨强的增加而增大。在探测率方面, IMERG产品对小雨、 中雨和大雨的探测能力均优于TMPA产品。  相似文献   

5.
TRMM卫星降水数据在洣水流域径流模拟中的应用   总被引：3，自引：0，他引：3       下载免费PDF全文
采用地面雨量站点观测降水作为基准数据,评估热带降雨观测计划（TRMM）最新一代卫星降水产品3B42V7的精度;利用站点和卫星两种降水数据驱动栅格新安江模型,采用SCEM-UA算法考虑模型参数不确定性,进行流量过程模拟,评估TRMM 3B42V7在流域水文模拟和预报中的应用能力。数据精度评估显示:在平均意义上,TRMM 3B42V7日降水精度较高,较站点观测低估了6.68%;但在绝对值意义上,TRMM 3B42V7日降水精度较低,绝对偏差达到57.76%;TRMM 3B42V7经过了地面月降水量偏差校准,其精度在月尺度上有较大提高。径流模拟结果表明:TRMM 3B42V7模拟的日径流过程精度较低,有部分洪峰没有捕捉到,但仍能表征径流的日变化特征;月尺度上模拟径流与实测径流吻合较好,能表征径流的季节性和年内变化特征;计算的日尺度和月尺度95%置信区间包含大部分实测流量过程。  相似文献   

6.
赣江流域TRMM降水数据的误差特征与成因   总被引：1，自引：0，他引：1       下载免费PDF全文
阐明TRMM 3B42V6（Tropical rainfall measuring mission 3B42 version 6）的误差特征及成因,对于合理使用该卫星降水数据,并完善其降水反演算法具有重要意义。在赣江流域0.25°×0.25°空间尺度上,对比了TRMM 3B42V6、TRMM 3B42RTV6和CMORPH的精度特征。结果表明,3B42V6的系统偏差远低于3B42RTV6、CMORPH,但平均绝对值偏差、效率系数和探测率均明显劣于CMORPH。TRMM 3B42V6的系统偏差较低的原因主要在于该数据采用地面月降水量进行了校准,而其绝对值偏差、效率系数和探测率明显劣于CMORPH的主要原因在于所采用的热红外/被动微波降水联合反演算法不及后者有效。今后有必要对TRMM 3B42的精度进行全面评估,并改进该数据的热红外/微波降水反演算法及与地面降水信息的融合算法。  相似文献   

7.
分析研究了2001年5月15日～8月15日3个月GMS卫星资料在湖南资水流域实时数值预报中的应用以及将TRMM(Tropical Rainfall Measuring Mission)卫星上的TMI(Microwave Imager)雨水资料适时融入数值模式改变当时模式中雨水分布场,数值模拟还研究了发生在淮河流域的10次暴雨过程。结果表明:资水流域3个月的实时预报效果良好,准确预报出其中出现的3次致洪暴雨和1次特大暴雨;对淮河流域暴雨,由于TMI资料空间分辨率较高,能够很好地反映中小尺度系统的空间结构,加入模式后使得模拟出来的降雨强度,雨量中心时空分布更接近实际情况,10次暴雨过程的TS评分较不使用TMI资料更好。  相似文献   

8.
The January 2010 earthquake that devastated Haiti left its population ever more vulnerable to rainfall-induced flash floods. A flash flood guidance system has been implemented to provide real-time information on the potential of small (~70 km2) basins for flash flooding throughout Haiti. This system has components for satellite rainfall ingest and adjustment on the basis of rain gauge information, dynamic soil water deficit estimation, ingest of operational mesoscale model quantitative precipitation forecasts, and estimation of the times of channel flow at bankfull. The result of the system integration is the estimation of the flash flood guidance (FFG) for a given basin and for a given duration. FFG is the amount of rain of a given duration over a small basin that causes minor flooding in the outlet of the basin. Amounts predicted or nowcasted that are higher than the FFG indicate basins with potential for flash flooding. In preparation for Hurricane Tomas’ landfall in early November 2010, the FFG system was used to generate 36-h forecasts of flash flood occurrence based on rainfall forecasts of the nested high-resolution North American Model of the National Centers for Environmental Prediction. Assessment of the forecast flood maps and forecast precipitation indicates the utility and value of the forecasts in understanding the spatial distribution of the expected flooding for mitigation and disaster management. It also highlights the need for explicit uncertainty characterization of forecast risk products due to large uncertainties in quantitative precipitation forecasts on hydrologic basin scales.  相似文献   

9.
This research compares data from the Tropical Rainfall Measuring Mission 3B42 V6 with data obtained from 19 synoptic rain gauges during the period 1998–2010 over the semiarid climate of Khorasan Razavi, Iran. Validation was performed using three spatial extents, including 1 TRMM grid face from the synoptic station (1PTRM), 3 TRMM points surrounding the synoptic station (3PTRM) and 5 TRMM points surrounding the synoptic station (5PTRM), using ArcGIS 10.2 software. The perfect and poor r were obtained at stations S08 and S19, with values of 0.92 and 0.26, respectively. According to the Nash–Sutcliffe efficiency coefficient, the TRMM satellite can predict the spatial variation of the mean annual rainfall by 0.23, 0.43 and 0.38 for 1PTRM, 3PTRM and 5PTRM, respectively, at 19 stations. The agreement significantly increases by 0.88, 0.83 and 0.80 for 1PTRM, 3PTRM and 5PTRM, respectively, when gauges S05, S07, S11 and S13 are excluded from the dataset, which may be associated with orographic or instrumental error at the stations.  相似文献   

10.
基于TRMM卫星雷达降雨的流域陆面水文过程   总被引：12，自引：2，他引：10       下载免费PDF全文
利用热带降雨观测计划(TRMM)卫星雷达降雨数据驱动分布式陆面水文模型,研究流域尺度陆面水文过程,评估该数据在水文模拟与预报等研究领域的性能。通过与实测雨量资料比较,验证TRMM卫星雷达降雨数据的质量。分别将TRMM卫星雷达降雨与观测降雨作为耦合模型的气象输入,模拟和研究淮河流域1998~2003年的陆面水文过程时空变化。结果表明,TRMM卫星雷达降雨数据能够很好地描述降雨的时空分布,利用TRMM降雨模拟的结果与利用观测降雨模拟的结果精度相当;模拟流量与实测资料基本吻合。卫星雷达降雨数据在陆面水文过程研究中具有广泛的应用前景。  相似文献   

11.
Flash floods are considered to be one of the worst weather-related natural disasters. They are dangerous because they are sudden and are highly unpredictable following brief spells of heavy rain. Several qualitative methods exist in the literature for the estimations of the risk level of flash flood hazard within a watershed. This paper presents the utilization of remote sensing data such as enhanced Thematic Mapper Plus (ETM+), Shuttle Radar Topography Mission (SRTM), coupled with geological, geomorphological, and field data in a GIS environment for the estimation of the flash flood risk along the Feiran–Katherine road, southern Sinai, Egypt. This road is a vital corridor for the tourists visiting here for religious purposes (St. Katherine monastery) and is subjected to frequent flash floods, causing heavy damage to man-made features. In this paper, morphometric analyses have been used to estimate the flash flood risk levels of sub-watersheds within the Wadi Feiran basin. First, drainage characteristics are captured by a set of parameters relevant to the flash flood risk. Further, comparison between the effectiveness of the sub-basins has been performed in order to understand the active ones. A detailed geomorphological map for the most hazardous sub-basins is presented. In addition, a map identifying sensitive sections is constructed for the Feiran–Katherine road. Finally, the most influenced factors for both flash flood hazard and critical sensitive zones have been discussed. The results of this study can initiate appropriate measures to mitigate the probable hazards in the area.  相似文献   

12.
The impacts of floods and droughts are intensified by climate change, lack of preparedness, and coordination. The average rainfall in study area is ranging from 200 to 400 mm per year. Rain gauge generally provides very accurate measurement of point rain rates and the amounts of rainfall but due to scarcity of the gauge locations provides very general information of the area on regional scale. Recognizing these practical limitations, it is essential to use remote sensing techniques for measuring the quantity of rainfall in the Middle Indus. In this research, Tropical Rainfall Measuring Mission (TRMM) estimation can be used as a proxy for the magnitude of rainfall estimates from classical methods (rain gauge), quantity, and its spatial distribution for Middle Indus river basin. In order to use TRMM satellite data for discharge measurement, its accuracy is determined by statistically comparing it with in situ gauged data on daily and monthly bases. The daily R 2 value (0.42) is significantly lower than monthly R 2 value (0.82), probably due to the time of summation of TRMM 3-hourly precipitation data into daily estimates. Daily TRMM data from 2003 to 2012 was used as input forcing in Soil and Water Assessment Tool (SWAT) hydrological model along with other input parameters. The calibration and validation results of SWAT model give R 2 = 0.72 and 0.73 and Nash-Sutcliffe coefficient of efficiency = 0.69 and 0.65, respectively. Daily and monthly comparison graphs are generated on the basis of model discharge output and observed data.  相似文献   

13.
The program Simulation of Hydrological Extreme Events provides a set of functionalities that combined together allows constructing, manipulating, analyzing and comparing the hydrological processes involved in flash flood generation. The program makes use of existing databases of interest in hydrology and available in Spain, such as digital terrain models, coverage of rainfall or curve number. Two pilot watersheds from Spain were selected, Arás and Aguilón, where flash flood episodes have taken place. A sensitivity analysis of the flash flood episodes in response to changes in the main hydrological processes involved has been made, such as spatial and temporal distribution of rainfall, soil moisture status and water flow through channel network. In this work, we found that the antecedent moisture condition is the most influential factor in the magnitude of flash floods produced by the same amount of rain. The temporal distribution of the storm represents the second characteristic in order of relevance. In addition, terrain morphology (specially the slope) is found to be decisive in the results differences obtained.  相似文献   

14.
Impact of climate change on extreme rainfall events and flood risk in India   总被引：8，自引：0，他引：8  
The occurrence of exceptionally heavy rainfall events and associated flash floods in many areas during recent years motivate us to study long-term changes in extreme rainfall over India. The analysis of the frequency of rainy days, rain days and heavy rainfall days as well as one-day extreme rainfall and return period has been carried out in this study to observe the impact of climate change on extreme rainfall events and flood risk in India. The frequency of heavy rainfall events are decreasing in major parts of central and north India while they are increasing in peninsular, east and north east India. The study tries to bring out some of the interesting findings which are very useful for hydrological planning and disaster managements. Extreme rainfall and flood risk are increasing significantly in the country except some parts of central India.  相似文献   

15.
洪涝灾害历来是影响中国的主要自然灾害之一。根据历史文献记载及观测资料,从天气过程、水文过程、受灾情况等方面对1917年海河流域洪涝灾害的自然过程作了详细梳理。得出以下结论： (1) 1917年洪涝灾害呈现由台风袭扰→集中降水→山洪暴发/河流决口→积水/淹没→受灾的成灾过程。 (2) 7月份2次台风带来大范围暴雨,集中性降水出现于7月20—28日,沿燕山、太行山分布,而9月份2次台风带来的暴雨则使灾情更加严重。 (3) 1917年海河流域各河于7月中旬开始涨溢、决口,9月中旬上游降雨结束后,中下游水位趋于稳定并下降,10月份以后洪水才迟缓退去,而洪水泛滥引发的涝灾影响一直延续到1918年。 (4) 1917年洪涝灾害在海河南系和北系都有发生,南系尤为严重,共造成156个县受灾。受灾田亩级数在5级以上的区域主要集中于海河干流沿线、南运河沿线以及河北省文安县等低洼地区。  相似文献   

16.
Flash floods are one of the major natural hazards occurring in small streams with a negative effect on the country as well as on human lives. Heavy rainfall occurred on July 20, 2014 and July 21, 2014 and caused severe surface water flooding and a flash flood in the Malá Fatra National Park (Slovakia). The most affected was Vrátna Valley with the Varínka stream. This study presents a reconstruction and post-event analysis of a flash flood on small ungauged basin located in this protected area of Slovakia. The reconstruction included hydraulic terrain measurements on estimating the flood’s culmination and documenting the flood’s development. The measurements were taken at three cross sections of the Varínka stream. This paper is focused mainly on post-event analysis of the Varínka stream in two profiles: Strá?a (gauged profile) and Tiesňavy (ungauged cross section). Subsequently, the extremeness of the flash flood was preliminary evaluated. Results of the post-event analysis showed that the July 2014 flood was not the highest flood in this area despite its catastrophic consequences. By studying historical materials, we came to the conclusion that in the past (e.g. in 1848 or 1939) some devastating floods in this area had occurred, which had disastrous consequences for the population. The second part of the study is focused on comparing this flash flood with three major floods which have occurred in Slovak territory since 1998. The first flood occurred on the 20th of July, 1998 on the Malá Svinka stream, and the two others are floods which occurred on the 7th of June, 2011 in the Small Carpathian Mountains: on the Gidra stream in Píla village and on the Parná stream in Horné Ore?any village. Such comparison of flash floods from different geographical regions and different rainfall events can provide comprehensive information about their regimes, threats and disastrous effects.  相似文献   

17.
Pakistan has experienced severe floods over the past decades due to climate variability. Among all the floods, the flood of 2010 was the worst in history. This study focuses on the assessment of (1) riverine flooding in the district Jhang (where Jhelum and Chenab rivers join, and the district was severely flood affected) and (2) south Asiatic summer monsoon rainfall patterns and anomalies considering the case of 2010 flood in Pakistan. The land use/cover change has been analyzed by using Landsat TM 30 m resolution satellite imageries for supervised classification, and three instances have been compared, i.e., pre-flooding, flooding, and post-flooding. The water flow accumulation, drainage density and pattern, and river catchment areas have been calculated by using Shutter Radar Topography Mission digital elevation model 90 m resolution. The standard deviation of south Asiatic summer monsoon rainfall patterns, anomalies and normal (1979–2008) has been calculated for July, August, and September by using rainfall data set of Era interim (0.75° × 0.75° resolution). El Niño Southern Oscillation has also been considered for its role in prevailing rainfall anomalies during the year 2010 over Upper Indus Basin region. Results show the considerable changing of land cover during the three instances in the Jhang district and water content in the rivers. Abnormal rainfall patterns over Upper Indus Basin region prevailed during summer monsoon months in the year 2010 and 2011. The El Niño (2009–2010) and its rapid phase transition to La Niña (2011–2012) may be the cause of severity and disturbances in rainfall patterns during the year 2010. The Geographical Information System techniques and model based simulated climate data sets have been used in this study which can be helpful in developing a monitoring tool for flood management.  相似文献   

18.
The Mediterranean coastal region is prone to high-intensity rainfall events that are frequently associated with devastating flash floods. This paper discusses the role of a karst aquifer system in the flash floods of a Mediterranean river, the Lez river. Most of the Lez river watershed is located on karst terrains where interactions between surface water and groundwater take place. During extreme rainfall events, the presence of fractures and well-developed karst features in carbonate terrains enhances the infiltration processes and involves the concentration of the recharge into highly organized and permeable flow paths. The groundwater, therefore, quickly moves towards the natural outlets of the karst system. The influence of the Lez karst aquifer system on the associated river floods dynamics is analysed while considering the spatially distributed rainfall, as well as the time series of the groundwater level within the aquifer and of the Lez river discharge measured at various gauging stations. Special attention is given to the relative importance of the surface and underground processes involved in flash flood genesis. It is shown that the karst groundwater contributes to flash floods under certain conditions, while high-rate pumping within the karst aquifer, which generates significant drawdown, may mitigate flash floods under other conditions.  相似文献   

19.
Karst flash flooding, identified as one of the hazards in karst terrains, is directly linked to the structure and hydraulic properties of karst aquifers. Due to the characteristics of flow within karst aquifers, characterized by a dual flow – diffuse flow within fissured limestone and conduit flow within karst conduits networks – flash flooding may be important in volume and dynamics. Such phenomenon may cause serious damages including loss of lives, as it occurred on 3rd October 1988 in Nîmes (Gard, South France). Flash floods there have been considered to be the result of very intensive rainfall events conjugated to runoff due to the geomorphologic context of the city located down hill. However, preliminary results of recent studies of the hydrologic behaviour of groundwater and surface water for a specific event (September 2005) show that the karst plays an important role in the flood genesis. The main characteristics of the Nîmes karst system leading to karst flash flooding are presented in this paper. A methodology comprising modelling of the karst system allowed proposing simple warning thresholds for various part of the karst (water level threshold for the karst conduits and cumulative rainfall threshold for the overflowing fissured karst). These thresholds can be included in the flash flood warning system of the Nîmes city.  相似文献   

20.
In arid regions, flash floods often occur as a consequence of excessive rainfall. Occasionally causing major loss of property and life, floods are large events of relatively short duration. Makkah area in western Saudi Arabia is characterized by high rainfall intensity that leads to flash floods. This study quantifies the hydrological characteristics and flood probability of some major wadis in western Saudi Arabia, including Na’man, Fatimah, and Usfan. Flood responses in these wadis vary due to the nature and rainfall distribution within these wadis. Rainfall frequency analysis was performed using selected annual maximums of 24-h rainfall from eight stations located in the area. Two of the most applied methods of statistical distribution, Gumbel’s extreme value distribution and log Pearson type III distribution, were applied to maximum daily rainfall data over 26 to 40 years. The Gumbel’s model was found to be the best fitting model for identifying and predicting future rainfall occurrence. Rainfall estimations from different return periods were identified. Probable maximum floods of the major wadis studied were also estimated for different return periods, which were extrapolated from the probable maximum precipitation.  相似文献   

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