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1.
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
2.
Flood is among the deadliest disasters in India, and the frequency of floods and extreme precipitation events is projected to increase under the warming climate. The frequency of floods in India varies geographically as some regions are more prone to floods than the others. The Kerala flood of 2018 caused enormous economic damage, affected millions of people, and resulted in the death of more than 400 people. Here we provide a hydroclimatological perspective on the Kerala flood of 2018. Using the observations and model simulations from the Variable Infiltration Capacity (VIC) model, we show that the 2018 extreme precipitation and runoff conditions that caused flooding were unprecedented in the record of the past 66 years (1951–2017). Our results show that mean monsoon precipitation has significantly declined while air temperature has significantly increased during 1951–2017 in Kerala. The drying and warming trends during the monsoon season resulted in a declined total runoff in large part of the state in the last 66 years. Apart from the mean hydroclimatic conditions, extreme precipitation, and extreme total runoff have also declined from 1951 to 2017. However, 1 and 2-day extreme precipitation and extreme runoff conditions in August 2018 exceeded substantially from the long-term 95th percentiles recorded during 1951–2017. Since there is no increase in mean and extreme precipitation in Kerala over the last six decades, the extreme event during August 2018 is likely to be driven by anomalous atmospheric conditions due to climate variability rather anthropogenic climate warming. The severity of the Kerala flood of 2018 and the damage caused might be affected by several factors including land use/land cover change, antecedent hydrologic conditions, reservoir storage and operations, encroachment of flood plains, and other natural factors. The impacts of key drivers (anthropogenic and natural) on flood severity need to be established to improve our understanding of floods and associated damage. 相似文献
3.
This paper presents a synthesis of the main characteristics of precipitation in the State of Rio de Janeiro (Brazil) based on extreme rainfall indicators. Daily precipitation data are derived from 56 rainfall stations during the second half of the twentieth century and the 2000s. Eight indices related to extreme precipitation were analyzed. The Mann–Kendall nonparametric test and the Sen's Curvature were employed to evaluate the significance and magnitude of trends. The primary climatological aspects and identified trends throughout the last decades are discussed, besides the hydrometeorological impacts associated with them. Lower values of annual total precipitation are recorded in northern Rio de Janeiro (around 800 mm) and higher in the southern State (up to 2,200 mm). The Serra do Mar affects the frequency of heavy precipitation, and the areas near the sea and high relief present the highest values of consecutive days with expressive rainfall (more than 150 mm in 5 days). These areas also showed a high concentration of flood and landslides events. Most of Rio de Janeiro exhibits precipitation intensity of about 13 mm/day. The maximum number of consecutive dry days shows a gradient from the coast (about 30 days) to the State's interior (around 50 days). Regarding trends, there is a growth of accumulated extreme precipitation in various stations near the ocean. The extreme rainfall in 24 h displays an increase in most Rio de Janeiro (+?1 to?+?5 mm/decade). The consecutive dry and rainy days present similar signs of decreasing trends, suggesting irregularly distributed precipitation in the State. This study is especially relevant for decision-makers who need detailed information in the short and long term to prevent natural hazards like floods and landslides and the related impacts in the environmental and socioeconomic sectors of the Rio de Janeiro.
相似文献4.
In August 2001, the worst flash flooding event of the Caspian Sea regions in over two centuries claimed over 300 lives after
a weekend of heavy rainfall and brought about a devastating disaster in the Mother-Soo catchment, province of Golestan, Iran.
As a result of this event, a series of site investigation were carried out to identify the pertinent factors that led to a
flood of this magnitude. This paper identifies the fundamental causes of the frequent floods and debris flow occurrence in
the area prone to flooding and analyzes the main runoff mechanism of these events. The maximum observed 24-h rainfall depths
and maximum peak discharges at the existing gauges were compared with the depths of rainfall and the peak values corresponding
to the August 2001 flood respectively. For the majority of the rain gauges, the rainfall depth exceeded those of historical
recorded events. In Golestan dam, an increase of 7.5 times the maximum value observed in the past 20 years was noted. The
flood height was 10–15 m while passing through the middle subcatchment area of Golestan National Park. The preliminary evaluation
indicates the existence of bare soil in the catchment, movable material, steep slopes, high rainfall intensity, deterioration
of pasture and forest land, and inappropriate agriculture and development practices as well as climate change were the main
factors for the occurrence and the extent of the August 2001 disaster. Finally, due to the likelihood of flooding and debris
flow events in future, some countermeasures are proposed. 相似文献
5.
Temporal distribution of southwest monsoon (June –September) rainfall is very useful for the country’s agriculture and food
grain production. It contributes more than 75% of India’s annual rainfall. In view of this, an attempt has been made here
to understand the performance of the monthly rainfall for June, July, August and September when the seasonal rainfall is reported
as excess, deficient or normal. To know the dependence of seasonal rainfall on monthly rainfall, the probabilities of occurrence
of excess, deficient and normal monsoon when June, July, August and also June + July and August + September rainfall is reported
to be excess or deficient, are worked out using the long homogenous series of 124 years (1871-–1994) data of monthly and seasonal
rainfall of 29 meteorological sub-divisions of the plain regions of India.
In excess monsoon years, the average percentage contribution of each monsoon month to the long term mean (1871–1994) seasonal
rainfall (June –September) is more than that of the normal while in the deficient years it is less than normal. This is noticed
in all 29 meteorological sub-divisions. From the probability analysis, it is seen that there is a rare possibility of occurrence
of seasonal rainfall to be excess/deficient when the monthly rainfall of any month is deficient/excess. 相似文献
6.
Amrit Kumar Pandey Rajendra P. Mishra Surendra K. Daradur Mihail 《Natural Hazards》2018,92(2):1199-1210
The frequency and severity of occurrence of meteorological droughts in different climatic regions depend on regional climatic factors. This study has made an effort to explore the relationship of range of annual temperature variation at a given place with the frequency of occurrence of drought and the maximum magnitude of seasonal rainfall deficit (i.e., severity). The seasonal rainfall refers to sum of monsoon season (rainy season) rainfall in India. The monthly precipitation data of 113 years (1901–2013) for 256 stations in different parts of India have been used to estimate the return period of meteorological drought at different stations. The daily normal values of observed maximum and minimum temperatures from 40 years of records have been utilized to estimate range of temperature variation (θR) during the year at each stations. In various parts of India, the θR ranges from 10 °C in humid regions to 40 °C in arid regions. The various climatic regions have been experiencing maximum deficiency of annual rainfall ranging from 30% (humid) to 90% (arid). The results reveal that places exhibiting θR values between 40 to 30 °C face more frequent droughts with average frequency of once in 3 to once in 6 years. The occurrence of extreme and severe drought events is more frequent in the regions with higher values of θR compare to that in lesser values of θR. The regions with θR values between 30 to 25 °C mostly face severe and moderate events having the average drought return period of 6–9 years, and the occurrence of extreme droughts in these regions is rare. Furthermore, regions with θR?<?20 °C face moderate droughts only with an average return period of 14 years. This study divulges that the average return period and magnitude of deficiency of drought events have notable relationship with the range of temperature variation during the year at a given place.
相似文献7.
Most urban agglomerations located in the Mumbai coastal region in India are vulnerable to flooding due to increasing frequency of the short-duration heavy rainfall, by virtue of their location at foothills on one side and tidal variations on the other side. Steep slopes in the catchment ensure fast runoff and tidal variation adds to backwater effect in the drainage system, which together are favorable for flooding. The present study simulates the flood inundation due to heavy rainfall and high-tide conditions in a coastal urban catchment within Mumbai region with detention pond. Overland flow is modeled using a mass balance approach, which can adapt to hilly slopes and smoothly accommodate detention pond hydraulics. Dynamic wave channel routing based on finite element method captures the backwater effects due to tidal variation, and raster-based flood inundation model enables direct use of digital elevation model. The integrated model is capable of simulating detention pond hydraulics within the raster flood model for heavy rainfall events. The database required for the model is obtained from the geographical information system (GIS) and remote sensing techniques. Application of the integrated model to literature problems and the catchment of the study area for two non-flooding events gave satisfactory results. Further, the model is applied to an extreme rainfall event of July 26, 2005, coinciding with high-tide conditions, which revealed vulnerability of the area to flooding despite of an existing detention pond. A sensitivity analysis on the location of detention pond indicated that catchment response can be better governed by relocating the detention pond to upstream of existing detention pond especially when heavy rainfall events are becoming frequent. 相似文献
8.
Flood events, fatalities and damages in India from 1978 to 2006 总被引：1，自引：1，他引：0
High temporal and spatial variability of rainfall qualifies India to be highly vulnerable to floods. Recurring floods of various magnitudes play havoc with the lives and property of the people, leading to unplanned development and unchecked environmental degradation, thwarting and retarding the overall development of the country. Therefore, the purpose of the present study is to analyze the types and trends in terms of flood events, frequency, number of people killed, injured, missing and economic damage both in space and time on the basis of a nationwide database published by India Meteorological Department, Pune, from 1978 to 2006. Analysis of these long-term data has revealed that 2,443 flood events claimed about 44,991 lives with the average of 1,551 lives each year. In terms of population size, these figures translate into a loss of 1.5 human lives per million of the population. A majority (56 %) of flood fatalities were caused during severe flood events. However, the frequency of these events was just 19 % in comparison with heavy rainfall events (65 %). In spatial context, flood-related fatalities are distributed all over the country with highest fatalities in Uttar Pradesh (17 %), Maharashtra (13 %), and Bihar and Gujarat (10 % each). Most fatalities occurred during the summer season monsoon months of August (30 %) followed by July (29 %) and September (20 %). The country suffered a cumulative flood-related economic loss of about 16 billion US$ between 1978 and 2006 and a maximum economic loss of 1.6 billion US$ in the year 2000 alone. The study further suggests that both flood events and fatalities have increased in India over a period of time. 相似文献
9.
Numerical simulation of cloud burst event on August 05, 2010, over Leh using WRF mesoscale model 总被引：1，自引：1，他引：0
M. Sravana Kumar M. S. Shekhar S. S. V. S. Rama Krishna M. R. Bhutiyani A. Ganju 《Natural Hazards》2012,62(3):1261-1271
Localized deep cumulus convective clouds have a capability of giving enormous amount of rainfall over a limited horizontal area, within a short span of time. Such types of extreme rainfall events are most common over the high elevated areas of Northern India during the Southwest monsoon season which causes widespread damage to the property and lives. Therefore, it is necessary to predict such extreme events accurately to avoid damage associated with them. The numerical mesoscale model Weather Research and Forecasting has been used to simulate the cloud burst event of Leh on August 05, 2010, so as to capture the main characteristics of the various parameters associated with this localized mesoscale phenomenon. The model has been integrated with four nested domains keeping Leh and its adjoining area as center. Two cloud microphysics parameterization schemes namely WSM3 and WSM6 have been used for the sensitivity experiments and results have been analyzed to examine the performance of both the schemes in capturing such extreme localized heavy rainfall events. Results show that the WSM6 microphysics was able to simulate the precipitation near to the observation. WSM3 microphysics simulated the location of the circulation near to the observation. In addition, the results also show that the maximum magnitudes of meridional and vertical wind as simulated with WSM3 microphysics are 12 and 4 m/s, respectively. 相似文献
10.
Some characteristics of very heavy rainfall over Orissa during summer monsoon season 总被引：1，自引：0，他引：1
Orissa is one of the most flood prone states of India. The floods in Orissa mostly occur during monsoon season due to very
heavy rainfall caused by synoptic scale monsoon disturbances. Hence a study is undertaken to find out the characteristic features
of very heavy rainfall (24 hours rainfall ≥125 mm) over Orissa during summer monsoon season (June–September) by analysing
20 years (1980–1999) daily rainfall data of different stations in Orissa. The principal objective of this study is to find
out the role of synoptic scale monsoon disturbances in spatial and temporal variability of very heavy rainfall over Orissa.
Most of the very heavy rainfall events occur in July and August. The region, extending from central part of coastal Orissa
in the southeast towards Sambalpur district in the northwest, experiences higher frequency and higher intensity of very heavy
rainfall with less interannual variability. It is due to the fact that most of the causative synoptic disturbances like low
pressure systems (LPS) develop over northwest (NW) Bay of Bengal with minimum interannual variation and the monsoon trough
extends in west-northwesterly direction from the centre of the system. The very heavy rainfall occurs more frequently with
less interannual variability on the western side of Eastern Ghat during all the months and the season except September. It
occurs more frequently with less interannual variability on the eastern side of Eastern Ghat during September. The NW Bay
followed by Gangetic West Bengal/Orissa is the most favourable region of LPS to cause very heavy rainfall over different parts
of Orissa except eastern side of Eastern Ghat. The NW Bay and west central (WC) Bay are equally favourable regions of LPS
to cause very heavy rainfall over eastern side of Eastern Ghat. The frequency of very heavy rainfall does not show any significant
trend in recent years over Orissa except some places in north-east Orissa which exhibit significant rising trend in all the
monsoon months and the season as a whole. 相似文献
11.
India experienced a heavy rainfall event in the year 2013 over Uttarakhand and its adjoining areas, which was exceptional as it witnessed the fastest monsoon progression. This study aims to explore the causative factors of this heavy rainfall event leading to flood and landslides which claimed huge loss of lives and property. The catastrophic event occurred from 14th to 17th June, 2013 during which the state received 375% more rainfall than the highest rainfall recorded during a normal monsoon season. Using the high resolution precipitation data and complementary parameters, we found that the mid-latitude westerlies shifted southward from its normal position during the intense flooding event. The southward extension of subtropical jet (STJ) over the northern part of India was observed only during the event days and its intensity was found to be increasing from 14th to 16th June. The classical theory of westward tilt of mid-latitude trough with height, which acts to intensify the system through the transfer of potential energy of the mean flow, is evident from analysis of relative vorticity at multiple pressure levels. On analysing the North Atlantic Oscillation (NAO), negative values were observed during the event days. Thus, the decrease in pressure gradient resulted in decrease of the intensity of westerlies which caused the cold air to move southward. During the event, as the cold air moved south, it pushed the mid-latitude westerlies south of its normal position during summer monsoon and created a conducive atmosphere for the intensification of the system. 相似文献
12.
为分析城镇化发展程度与极端降雨变化之间的关系,选取珠江三角洲地区22个雨量站1973—2012年的小时降雨资料,利用空间分析、线性回归、滑动平均和Mann-Kendall趋势检验等方法,分析高度城镇化背景下珠三角地区极端降雨时空分布规律和变化特性,并解析暴雨雨型变化特征。结果表明:①珠江三角洲高度城镇化地区极端降雨量上升了44.3 mm/（10 a）,呈显著增加趋势,相邻其他地区则无明显变化,高度城镇化地区的前汛期极端降雨量显著增多是造成其年极端降雨量增加的主要原因。②珠三角地区暴雨雨型以单峰型为主,其中以雨峰在前的Ⅰ型暴雨占比最高,约为33.7%,高度城镇化地区Ⅰ型暴雨发生频率明显增加,易导致暴雨内涝事件增加,需加强高度城镇化地区防洪排涝工作。 相似文献
13.
Anthony Foucher Olivier Evrard Olivier Cerdan Clément Chabert François Lecompte Irène Lefèvre Rosalie Vandromme Sébastien Salvador-Blanes 《Sedimentology》2020,67(1):486-501
Long-term records are needed to investigate the impact of extreme events in the current framework of global change. Sedimentary reconstruction with a high resolution remains difficult without conducting expensive, destructive and/or time-consuming analyses. In this study, high resolution CT-scan profiles (0·6 mm resolution) were used to investigate their potential for detecting flood deposits induced by heavy rainfall events. This method was applied to a sediment core dated with fallout radionuclides – covering a 120 year period – collected in a pond draining a small forested catchment (French Massif Central – Central France). Between 1960 and 2017, 28 layers were deposited. Seventy-six percent of these deposits were correlated to the occurrence of heavy rainfall (>50 mm) recorded during one or two consecutive days. The remainder of the deposits detected with the Computer Tomography (CT) scanner (n = 5) were not correlated to weather events. They mainly occurred in response to landscape management operations (for example, afforestation works as a result of the major 1999 storm). This period was indeed characterized by an increase in the delivery of 137Cs-enriched sediment, demonstrating a greater topsoil contribution to sediment during major forest management operations. The intensity of detrital layers has significantly decreased throughout time after a major land use change that took place in 1948 and land abandonment. The frequency of heavy rainfall and associated detrital deposits has nevertheless increased by 60% and 75%, respectively, between the years 1960 and 2017. These results outline the potential of CT-scan for reconstructing long-term flood deposits associated with heavy precipitation. 相似文献
14.
Deepak Jhajharia Brijesh K. Yadav Sunil Maske Surajit Chattopadhyay Anil K. Kar 《Comptes Rendus Geoscience》2012,344(1):1-13
Trends in rainfall, rainy days and 24 h maximum rainfall are investigated using the Mann-Kendall non-parametric test at twenty-four sites of subtropical Assam located in the northeastern region of India. The trends are statistically confirmed by both the parametric and non-parametric methods and the magnitudes of significant trends are obtained through the linear regression test. In Assam, the average monsoon rainfall (rainy days) during the monsoon months of June to September is about 1606 mm (70), which accounts for about 70% (64%) of the annual rainfall (rainy days). On monthly time scales, sixteen and seventeen sites (twenty-one sites each) witnessed decreasing trends in the total rainfall (rainy days), out of which one and three trends (seven trends each) were found to be statistically significant in June and July, respectively. On the other hand, seventeen sites witnessed increasing trends in rainfall in the month of September, but none were statistically significant. In December (February), eighteen (twenty-two) sites witnessed decreasing (increasing) trends in total rainfall, out of which five (three) trends were statistically significant. For the rainy days during the months of November to January, twenty-two or more sites witnessed decreasing trends in Assam, but for nine (November), twelve (January) and eighteen (December) sites, these trends were statistically significant. These observed changes in rainfall, although most time series are not convincing as they show predominantly no significance, along with the well-reported climatic warming in monsoon and post-monsoon seasons may have implications for human health and water resources management over bio-diversity rich Northeast India. 相似文献
15.
In this paper, hydroclimatic fluctuations of the Upper Narmada catchment (upto Narmadasagar damsite) have been studied by
examining the time series (1901–80) of (i) 1-to 10-day annual extreme rainfall; (ii) seasonal total rainfall between May and
October; (iii) the precipitation concentration index (PCI); (iv) a modified version of PCI(MPCI); and (v) parameters of the
periods contributing specified percentages of rainfall to annual total. Most of these parameters followed the normal distribution
and did not show any significant long-term trend. However, some dominant long period oscillations have been noticed in extreme
rainfall, seasonal rainfall, PCI and MPCI series. Influence of break-monsoon days over India during July and August on the
rainfall activities of the Upper Narmada catchment has also been investigated and salient findings discussed. 相似文献
16.
The summer monsoon season of the year 2006 was highlighted by an unprecedented number of monsoon lows over the central and
the western parts of India, particularly giving widespread rainfall over Gujarat and Rajasthan. Ahmedabad had received 540.2mm
of rainfall in the month of August 2006 against the climatological mean of 219.8mm. The two spells of very heavy rainfall
of 108.4mm and 97.7mm were recorded on 8 and 12 August 2006 respectively. Due to meteorological complexities involved in replicating
the rainfall occurrences over a region, the Weather Research and Forecast (WRF-ARW version) modeling system with two different
cumulus schemes in a nested configuration is chosen for simulating these events. The spatial distributions of large-scale
circulation and moisture fields have been simulated reasonably well in this model, though there are some spatial biases in
the simulated rainfall pattern. The rainfall amount over Ahmedabad has been underestimated by both the cumulus parameterization
schemes. The quantitative validation of the simulated rainfall is done by calculating the categorical skill scores like frequency
bias, threat scores (TS) and equitable threat scores (ETS). In this case the KF scheme has outperformed the GD scheme for
the low precipitation threshold. 相似文献
17.
Coastal hazard mapping in the Cuddalore region, South India 总被引：1，自引：0，他引：1
It is estimated that nearly one-third of India’s population lives on the coast and is dependent on its resources. Shoreline erosion, storm surges and extreme events have resulted in severe loss of human life, damage to ecosystems and to property along the coast of India. Studies carried out in the Cuddalore region of South India reveal that this low-lying coastal zone, which suffered significant erosion during the last century, has been severely affected by the tsunami of 2004, storm floods and cyclones. In response to these impacts, a variety of coastal defense measures and adaptation strategies have been implemented in the region, although with only limited success. In order to inform future coastal planning in this region, the work reported here identifies a composite hazard line, seaward of which coastal flooding events will have a return interval of less than 1 in 100 years. The area landward of the coastal hazard line will be unaffected by 100 years of coastal erosion at present day rates. The study directly supports the Integrated Coastal Zone Management (ICZM) Plan of the Tamil Nadu State through the identification and assessment of coastal hazards and the overall vulnerability to coastal flooding and erosion. The key results from this pilot study will be used directly by the State of Tamil Nadu in the protection of the coastal livelihoods, better conservation measures and sustainable development along the coast. This study is a step toward mapping the hazard line for the entire coast of India that helps protect human lives and property. 相似文献
18.
Active and break spells of the Indian summer monsoon 总被引：6，自引：0，他引：6
In this paper, we suggest criteria for the identification of active and break events of the Indian summer monsoon on the basis
of recently derived high resolution daily gridded rainfall dataset over India (1951–2007). Active and break events are defined
as periods during the peak monsoon months of July and August, in which the normalized anomaly of the rainfall over a critical
area, called the monsoon core zone exceeds 1 or is less than −1.0 respectively, provided the criterion is satisfied for at
least three consecutive days. We elucidate the major features of these events. We consider very briefly the relationship of
the intraseasonal fluctuations between these events and the interannual variation of the summer monsoon rainfall. 相似文献
19.
Natural Hazards - South-west monsoon of 2019 advanced towards northern parts of India during the first week of July. Heavy-to-very-heavy rainfall events during July 05–16 resulted in severe... 相似文献
20.
Liu Jiandong Doan Chi Dung Liong Shie-Yui Sanders Richard Dao Anh Tuan Fewtrell Timothy 《Natural Hazards》2015,75(2):1075-1104
Natural Hazards - Jakarta is vulnerable to flooding and extreme rainfall events are always the main cause of the occurrence of heavy flood events with loss of life and property. The flood in... 相似文献