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1.
A review of the assessment and mitigation of floods in Sindh, Pakistan   总被引：1，自引：0，他引：1  
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2.
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   

3.
The Indus flood in 2010 was one of the greatest river disasters in recent history, which affected more than 14 million people in Pakistan. Although excessive rainfall between July and September 2010 has been cited as the major causative factor for this disaster, the human interventions in the river system over the years made this disaster a catastrophe. Geomorphic analysis suggests that the Indus River has had a very dynamic regime in the past. However, the river has now been constrained by embankments on both sides, and several barrages have been constructed along the river. As a result, the river has been aggrading rapidly during the last few decades due to its exceptionally high sediment load particularly in reaches upstream of the barrages. This in turn has caused significant increase in cross-valley gradient leading to breaches upstream of the barrages and inundation of large areas. Our flow accumulation analysis using SRTM data not only supports this interpretation but also points out that there are several reaches along the Indus River, which are still vulnerable to such breaches and flooding. Even though the Indus flood in 2010 was characterized by exceptionally high discharges, our experience in working on Himalayan rivers and similar recent events in rivers in Nepal and India suggest that such events can occur at relatively low discharges. It is therefore of utmost importance to identify such areas and plan mitigation measures as soon as possible. We emphasize the role of geomorphology in flood analysis and management and urge the river managers to take urgent steps to incorporate the geomorphic understanding of Himalayan rivers in river management plans.  相似文献   

4.
The Indus basin—one of the largest fluvial-controlled landscapes of the world, provides a major agro-economic resource base while showcasing unique morphometry along its course. However, despite its large socio-economic relevance in South Asia, a distinct account of morphometric variations down its course still remains elusive. Here, for the first time a quantitative demarcation of the Indus basin into—upper, middle, and lower basin is proposed based on analyses of critical morphometric parameters (viz. gradient/river length ratio, elevation-relief ratio, channel width, sinuosity, and slope). Geostatistical and hydrological operations performed on digital elevation models, suggest that the highest and lowest relief sectors are tectonically more stable than the middle relief sector, inferred from a convex hypsometric curve. Elevation-relief ratio for the basin indicates tectonic stability with ~?31% of remnant rock still in place. Cross-sectional transects also demonstrate anomalous patterns that deviate from predictive characteristics of youthful, mature, and senile stages of river development. All parameters are spatially coalesced to provide a first-ever holistic morphometric account of the Indus basin while describing fine-scale planform variations of the spectacular dynamics of this enormous river basin.  相似文献   

5.
Mahmood  Shakeel  Hamayon  Kiran 《Natural Hazards》2021,106(3):2825-2844
Natural Hazards - Pakistan is exposed to hydro-meteorological and geological hazards. Flood is one of the hydro-meteorological hazards, and so far 25 major floods have occurred in Indus River...  相似文献   

6.
Pakistan is exposed to numerous hazards, but the problem of recurrent floods has been causing massive losses to lives and other properties. Swat valley is no exception to it. In this paper, an attempt has been made to analyse the causes and associated socio-economic impacts of floods on the Swat valley, Pakistan. Swat valley falls in the Hindukush region, North-west-Pakistan. The valley has been studied with special reference to its physical and socio-economic environment. Similarly, three-sample villages were also randomly selected from the active floodplain for micro-level analysis. The sample villages include Ningolai, Delay and Ghureijo. All the three-sample communities are located on the right bank of river Swat. This area is located in the active flood zone of Swat valley. The analysis revealed that in the study area, floods occur during summer season, which is mainly caused by heavy rainfall as well as rapid melting of snow and glacier. Besides these, there are some floods intensifying factors, which accelerate intensity of floods and enhance resultant damages in the valley. It was found that during flood season, water overflows the natural levees and trigger tremendous loses to housing, agricultural land, standing crops and other properties. The flood-related Government Departments have only implemented limited structural mitigation measures. However, in addition to structural measure, land-use zoning and flood abatement strategies would largely help in reducing the adverse consequences of this recurrent phenomenon.  相似文献   

7.
Hydrological parameters are among the widely used parameters in assessing flood risk. On the other hand, anticipated flood damages, in case of flooding, are estimated with the help of expected losses in areas nearer to the watercourse. The major source of almost every-year flooding in Pakistan is the Indus River system that comprises the major rivers of Pakistan. We first use observed data to construct simulated data models based on various probability distributions namely normal, lognormal, Weibull, largest extreme value, gamma-3, and log-Pearson type-3 distributions and thereby compute probable maximum flood. Secondly, we perform log-Pearson type-3 analysis with and without historic adjustment on the observed data series of 17 years to forecast floods with return periods T of 2, 5, 10, 25, 50, 100, and 200 years. We also categorize the river structures based on the risk of flooding. Lastly, we estimate risk of flood damages in terms of expected losses based on observed data. The present study reveals that the log-Pearson type-3 distribution is relatively better for estimating probable maximum flood. We use exceedence probability to assess the risk of flooding in the various structures of the said rivers. The analysis shows that flood damages in Pakistan may be reduced by increasing the design capacity of the structures and also by giving awareness to people about the flood-generating factors.  相似文献   

8.
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   

9.
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   

10.
Development of a well-calibrated, distributed hydrological model for flood forecasting based on rainfall and snowmelt is quite challenging, especially when in situ data is limited or unavailable. This paper presents the study carried out to parameterise the Integrated Flood Analysis System (IFAS) model for the trans-boundary, scarcely gauged catchments of Jhelum and Chenab rivers in Pakistan. Rainfall-runoff analysis was performed with a two-layered tank configuration, integrating snowmelt and dam and barrage operation from the very upstream in India to Trimmu Barrage in Pakistan. A grid size of 5?×?5 km was considered. Global map topography, land cover and soil data was utilised. The model was tested considering different magnitudes of floods of the years 2014, 2015 and 2017. The results showed that the satellite rainfall product, i.e. Global Satellite Mapping of Precipitation (GSMaP-NRT), underestimated the rainfall volume, compared to the ground-gauged rainfall. The GSMaP-IF correction method showed poor performance owing to the lack of ground observatory rainfall data for correcting the trans-boundary part of the basin. The GSMaP-Type1 correction method showed good results, except for the confluence point where complex flow conditions were not properly reproduced by the model. In addition, the incorporation of dam and barrages in the model improved the simulated flow results. It is concluded that the satellite rainfall estimates must be corrected to improve the results. Snowmelt module estimated the snowmelt contribution as 3 to 7% and 4 to 23% of the average daily discharge during the monsoon season at Mangla Dam and Marala Barrage, respectively, during 2014 and 2015. This study assessed various correction methods and concluded that the model and methodology used in the study functioned well with suitable precipitation.  相似文献   

11.
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   

12.
全球气候变暖将加剧水循环,增大洪水风险。阿克苏河流域位于天山南坡,是北半球中纬度典型的高山流域。本流域不仅有暴雨洪水、冰川和积雪融水造成的洪水,而且还有冰川溃决突发洪水。以阿克苏河的两条支流库玛拉克河和托什干河为研究对象,利用块最大值抽样方法（block maximum）和超定量阈值（peak over threshold,POT）抽样方法提取出1958—2011年的洪水事件,其中基于POT方法在两条支流分别提取106次和112次洪水事件,主要集中在6月、7月和8月份。研究表明：阿克苏河的两条支流库玛拉克河和托什干河的年最大洪水强度分别以8.48 m3?s-1和3.40 m3?s-1的速率增加;在洪水发生时间上,以冰川融水补给为主的库玛拉克河,洪水发生时间有提前的趋势,而以降雨和融雪水补给为主的托什干河,洪水发生时间变得更加分散,表现为春季最大洪水提前、秋季最大洪水推后。  相似文献   

13.
Flood risk assessment of River Indus of Pakistan   总被引：1，自引：1，他引：0  
Annual flood peak discharges is widely used in risk assessment. Major sources of flooding in Pakistan are River Jhelum, River Chenab, River Kabul, and upper and lower parts of River Indus. These rivers are major tributaries of the River Indus System which is one of the most important systems of the world and the greatest system of Pakistan. River Indus is the longest river of Pakistan containing seven gauge stations and several barrages, and it plays a vital role in the irrigation system and power generation for the country. This paper estimates the risk of flood in River Indus using historical data of maximum peak discharges. On the basis of our analysis, we find out which dam/barrage reservoir need to be updated in capacity, and whether there are more dams/barrages needed.  相似文献   

14.
There are serious concerns of rise in temperatures over snowy and glacierized Himalayan region that may eventually affect future river flows of Indus river system. It is therefore necessary to predict snow and glacier melt runoff to manage future water resource of Upper Indus Basin(UIB). The snowmelt runoff model(SRM) coupled with MODIS remote sensing data was employed in this study to predict daily discharges of Gilgit River in the Karakoram Range. The SRM was calibrated successfully and then simulation was made over four years i.e. 2007, 2008, 2009 and 2010 achieving coefficient of model efficiency of 0.96, 0.86, 0.9 and 0.94 respectively. The scenarios of precipitation and mean temperature developed from regional climate model PRECIS were used in SRM model to predict future flows of Gilgit River. The increase of 3 C in mean annual temperature by the end of 21 th century may result in increase of 35-40% in Gilgit River flows. The expected increase in the surface runoff from the snow and glacier melt demands better water conservation and management for irrigation and hydel-power generation in the Indus basin in future.  相似文献   

15.
淮河流域近500年洪旱事件演变特征分析   总被引：1，自引：0，他引：1  
为了认识淮河流域过去500年洪旱事件发生规律并鉴别当前的洪旱情势,收集并对比分析了流域实测降雨资料、重建历史雨季降雨资料、历史旱涝等级资料、历史洪旱文献记录和历史调查洪水资料等多源洪旱灾害数据。以重建历史雨季降雨资料和历史旱涝等级资料为主要依据,通过滑动平均、频率计算、小波分析和突变检验等方法,分析流域过去500年洪水干旱时空分布特征和演变规律。结果表明,17世纪淮河流域洪旱灾害最严重,但20世纪极端洪旱事件发生频次最多。淮河流域洪旱事件存在40年左右的稳定长周期,主周期从18世纪的15~20年逐渐减少到19世纪的5年周期,近20年来出现2~3年的主周期,洪旱灾害事件呈增加趋势,流域社会经济发展面临着严峻的洪旱灾害威胁。  相似文献   

16.
This study was carried out to analyze the hydrological characteristics and assess the distinguished hydrological periods of Upper Indus Basin (UIB) Rivers of Pakistan. For this purpose, statistical analysis (variation coefficient, the auto-correlation coefficient, sequential Mann–Kendall’s test) and a proposed method for distinguishing hydrological periods (described in methodology section) were applied. The results revealed that all rivers reflect moderate variability. The results of auto-correlation displayed that the river flow observed at Astore gauging station only indicated independency, while for Gilgit, Hunza and Kachura guaging at Indus River exhibited 2, 2, 4-year lag. The mutation analysis indicated that after 1980, the change point occurred at all UIB rivers. During analysis, it was also observed that river regimes have the same hydrological periods (i.e., 4), but with different dates of occurrence. The Gilgit River showed a low high-flow hydrological period compared to Astore, Hunza and Kachora (Indus). This difference may be due to the river’s own area natural conditions. The current analysis may be helpful for planning and management of water resources, designing of hydraulic structures and to make better policies in response to agricultural water requirement downstream of UIB River.  相似文献   

17.
This paper deals with the presentation of a flood warning system (GFWS) developed for the specific characteristics of the Guadalhorce basin (3,200 km2, SE of Spain), which is poorly gauged and often affected by flash and plain floods. Its complementarity with the European flood alert system (EFAS) has also been studied. At a lower resolution, EFAS is able to provide a flood forecast several days in advance. The GFWS is adapted to the use of distributed rainfall maps (such as radar rainfall estimates), and discharge forecasts are computed using a distributed rainfall–runoff model. Due to the lack of flow measurements, the model parameters calibrated on a small watershed have been transferred in most of the basin area. The system is oriented to provide distributed warnings and fulfills the requirements of ungauged basins. This work reports on the performance of the system on two recent rainfall events that caused several inundations. These results show how the GFWS performed well and was able to forecast the location and timing of flooding. It demonstrates that despite its limitations, a simple rainfall–runoff model and a relatively simple calibration could be useful for event risk management. Moreover, with low resolution and long anticipation, EFAS appears as a good complement tool to improve flood forecasting and compensate for the short lead times of the GFWS.  相似文献   

18.
It is well known that heavy rainfall occurs in the southwestern sector of the monsoon depressions due to strong convergence in that sector. By examining the rainfall distribution associated with the monsoon disturbances (lows and depressions) in one of the central Indian river basins, ‘Godavari’, the author found that when the disturbance-centre is away from the basin, heavy rainfall may also occur in the basin area close to the confluence line and cause severe floods in the river. The confluence line is the zone of convergence between the northeasterlies to the west of the disturbance centre and the monsoon westerlies. This study further reveals the importance of the position and movement of the confluence line with respect to the basin, on which the intensity and the raising period of the resulting flood depend.  相似文献   

19.
1823年(清道光三年)我国发生大范围、多流域的严重雨涝,这是在小冰期寒冷气候背景下的重大气象灾害和极端气候事件.文章依据历史文献记载复原了1823年的气候实况并绘图显示,指出该年我国华北夏季雨期长、多大雨,北京6～8月雨日53天、降水量663mm超过现代(1971～2000年)平均值5成;长江中下游全年多雨,梅雨期长...  相似文献   

20.
Over 1 km thick Mesozoic sedimentary sequence is exposed over a wide area in the Upper Indus basin of north Pakistan along the western margin of the Indian Plate. The Mesozoic sequence is comprised of clastic facies in the lower part, while carbonate facies are dominant in the upper part. About 200 m thick mixed sequence of interbedded sandstone, siltstone, clay, and carbonaceous shale represents the lower Jurassic Datta Formation in the Salt and Trans Indus Ranges in North Pakistan. The Datta Formation constitutes important reservoir horizons in a number of oil fields in the western Himalayan foreland basins where it is encountered at a depth of about 4 km in various wells. The Datta Formation is described from different parts of the range front to understand the internal architecture of various sedimentary facies and their depositional system. The thickness and lithofacies assemblages of the Datta Formation change in different parts of the range front as well as in subsurface of the Upper Indus basin. The Datta Formation represents a coarsening upward deltaic sequence in most parts of the basin. On the basis of lithological variations and sedimentary structures, a number of depositional facies have been recognized which include channel belt facies, floodplain/abandoned channel facies, swamp facies, and lagoonal facies. Further north, in the Kalachitta and Hazara regions, the siliciclastic facies change to more complex assemblages of interbedded bauxite, silcrete, marl, and some limestone. These sediments represent deposition in a delta-plain setting of a fluvial-dominated delta with northwestward flowing channels.  相似文献   

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