Predicting geomorphically-induced flood risk for the Nepalese Terai communities

Science.gov (United States)

Dingle, Elizabeth; Creed, Maggie; Attal, Mikael; Sinclair, Hugh; Mudd, Simon; Borthwick, Alistair; Dugar, Sumit; Brown, Sarah

2017-04-01

Rivers sourced from the Himalaya irrigate the Indo-Gangetic Plain via major river networks that support 10% of the global population. However, many of these rivers are also the source of devastating floods. During the 2014 Karnali River floods in west Nepal, the Karnali rose to around 16 m at Chisapani (where it enters the Indo-Gangetic Plain), 1 m higher than the previous record in 1983; the return interval for this event was estimated to be 1000 years. Flood risk may currently be underestimated in this region, primarily because changes to the channel bed are not included when identifying areas at risk of flooding from events of varying recurrence intervals. Our observations in the field, corroborated by satellite imagery, show that river beds are highly mobile and constantly evolve through each monsoon. Increased bed levels due to sediment aggradation decreases the capacity of the river, increasing significantly the risk of devastating flood events; we refer to these as 'geomorphically-induced floods'. Major, short-lived episodes of sediment accumulation in channels are caused by stochastic variability in sediment flux generated by storms, earthquakes and glacial outburst floods from upstream parts of the catchment. Here, we generate a field-calibrated, geomorphic flood risk model for varying upstream scenarios, and predict changing flood risk for the Karnali River. A numerical model is used to carry out a sensitivity analysis of changes in channel geometry (particularly aggradation or degradation) based on realistic flood scenarios. In these scenarios, water and sediment discharge are varied within a range of plausible values, up to extreme sediment and water fluxes caused by widespread landsliding and/or intense monsoon precipitation based on existing records. The results of this sensitivity analysis will be used to inform flood hazard maps of the Karnali River floodplain and assess the vulnerability of the populations in the region.

Modeling flood events for long-term stability

International Nuclear Information System (INIS)

Schruben, T.; Portillo, R.

1985-01-01

The primary objective for the disposal of uranium mill tailings in the Uranium Mill Tailings Remedial Action (UMTRA) Project is isolation and stabilization to prevent their misuse by man and dispersal by natural forces such as wind, rain, and flood waters (40 CFR-192). Stabilization of sites that are located in or near flood plains presents unique problems in design for long-term performance. This paper discusses the process involved with the selection and hydrologic modeling of the design flood event; and hydraulic modeling with geomorphic considerations of the design flood event. The Gunnison, Colorado, and Riverton, Wyoming, sites will be used as examples in describing the process

Decision Support for Flood Event Prediction and Monitoring

DEFF Research Database (Denmark)

Mioc, Darka; Anton, François; Liang, Gengsheng

2007-01-01

In this paper the development of Web GIS based decision support system for flood events is presented. To improve flood prediction we developed the decision support system for flood prediction and monitoring that integrates hydrological modelling and CARIS GIS. We present the methodology for data...... integration, floodplain delineation, and online map interfaces. Our Web-based GIS model can dynamically display observed and predicted flood extents for decision makers and the general public. The users can access Web-based GIS that models current flood events and displays satellite imagery and digital...... elevation model integrated with flood plain area. The system can show how the flooding prediction based on the output from hydrological modeling for the next 48 hours along the lower Saint John River Valley....

Reforecasting the 1972-73 ENSO Event and the Monsoon Drought Over India

Science.gov (United States)

Shukla, J.; Huang, B.; Shin, C. S.

2016-12-01

This paper presents the results of reforcasting the 1972-73 ENSO event and the Indian summer monsoon drought using the National Centers for Environmental Prediction (NCEP) Climate Forecast System, version 2 (CFSv2), initialized with the Eu­ropean Centre for Medium-Range Weather Forecasts (ECMWF) global ocean reanalysis version 4, and observation-based land and atmosphere reanalyses. The results of this paper demonstrate that if the modern day climate models were available during the 1970's, even with the limited observations at that time, it should have been possible to predict the 1972-73 ENSO event and the associated monsoon drought. These results further suggest the necessity of continuing to develop realistic models of the climate system for accurate and reliable seasonal predictions. This paper also presents a comparison of the 1972-73 El Niño reforecast with the 1997-98 case. As the strongest event during 1958-78, the 1972-73 El Niño is distinguished from the 1997-98 one by its early termination. Initialized in the spring season, the forecast system predicted the onset and development of both events reasonably well, although the reforecasts underestimate the ENSO peaking magnitudes. On the other hand, the reforecasts initialized in spring and fall of 1972 persistently predicted lingering wind and SST anomalies in the eastern equatorial Pacific during the spring of 1973. Initialized in fall of 1997, the reforecast also grossly overestimates the peaking westerly wind and warm SST anomalies in the 1997-98 El Niño.In 1972-73, both the Eastern Pacific SST anomalies (for example Nino 3 Index) and the summer monsoon drought over India and the adjoining areas were predicted remarkably well. In contrast, the Eastern Pacific SST anomalies for the 1997-98 event were predicted well, but the normal summer monsoon rainfall over India of 1997 was not predicted by the model. This case study of the 1972-73 event is part of a larger, comprehensive reforecast project

Spectral characteristics of the nearshore waves off Paradip, India during monsoon and extreme events

Digital Repository Service at National Institute of Oceanography (India)

Aboobacker, V.M.; Vethamony, P.; Sudheesh, K.; Rupali, S.P.

and directional wave energy spectra distinctly separate out the wave conditions that prevailed off Paradip in the monsoon, fair weather and extreme weather events during the above period. Frequency-energy spectra during extreme events are single peaked...

Teleconnections associated with the intensification of the Australian monsoon during El Nino Modoki events

International Nuclear Information System (INIS)

Taschetto, A S; Gupta, A Sen; Ummenhofer, C C; England, M H; Haarsma, R J

2010-01-01

In this study we investigate the teleconnection between the central-western Pacific sea surface temperature (SST) warming, characteristic of El Nino Modoki events, and Australian rainfall using observations and atmospheric general circulation model experiments. During Modoki events, wet conditions are generally observed over northwestern Australia at the peak of the monsoon season (i.e. January and February) while dry conditions occur in the shoulder-months (i.e. December and March). This results in a shorter but more intense monsoon season over northwestern Australia relative to the climatology. We show that, apart from the well-known displacement of the Walker circulation, the anomalous warming in the central-western equatorial Pacific also induces a westward-propagating disturbance associated with a Gill-type mechanism. This in turn generates an anomalous cyclonic circulation over northwestern Australia that reinforces the climatological mean conditions during the peak of the monsoon season. The anomalous circulation leads to convergence of moisture and increased precipitation over northern Australia. This response, however, only occurs persistently during austral summer when the South Pacific Convergence Zone is climatologically strengthened, phase-locking the Gill-type response to the seasonal cycle. The interaction between the interannual SST variability during El Nino Modoki events and the evolution of the seasonal cycle intensifies deep convection in the central-west Pacific, driving a Gill-type response to diabatic heating. The intensified monsoonal rainfall occurs strongly in February due to the climatological wind conditions that are normally cyclonic over northwestern Australia.

Assessment of flood Response Characteristics to Urbanization and extreme flood events-Typhoons at Cheongju, Chungbuk

Science.gov (United States)

Chang, HyungJoon; Lee, Hyosang; Hwang, Myunggyu; Jang, Sukhwan

2016-04-01

The changes of land use influence on the flood characteristics, which depend on rainfall runoff procedures in the catchment. This study assesses the changes of flood characteristics due to land use changes between 1997 and 2012. The catchment model (HEC-HMS) is calibrated with flood events of 1990's and 2000's respectively, then the design rainfall of 100, 200, 500year return period are applied to this model, which represent the catchment in 1990's and 2000's, to assess the flood peaks. Then the extreme flood events (i.e., 6 typhoon events) are applied to assess the flood responses. The results of comparison between 1990's and 2000's show that the flood peak and level of 2000's are increasing and time to peak of 2000's is decreasing comparing to those of 1990's :3% to 78% increase in flood peak, 3% in flood level and 10.2% to 16% decrease in time to peak in 100year return period flood. It is due to decreasing of the farmland area (2.18%), mountainous area (8.88%), and increasing of the urbanization of the area (5.86%). This study also estimates the responses to extreme flood events. The results of 2000's show that the increasing of the flood peak and time to peak comparing to 1990's. It indicates that the extreme rainfall is more responsible at unurbanized catchment ( 2000's), which resulting with a 11% increasing of the peak volume. Acknowledgement This research was supported by a grant (11-TI-C06) from Advanced Water Management Research Program funded by Ministry of Land, Infrastructure and Transport of Korean government.

Estimation of initiating event frequency for external flood events by extreme value theorem

International Nuclear Information System (INIS)

Chowdhury, Sourajyoti; Ganguly, Rimpi; Hari, Vibha

2017-01-01

External flood is an important common cause initiating event in nuclear power plants (NPPs). It may potentially lead to severe core damage (SCD) by first causing the failure of the systems required for maintaining the heat sinks and then by contributing to failures of engineered systems designed to mitigate such failures. The sample NPP taken here is twin 220 MWe Indian standard pressurized heavy water reactor (PHWR) situated inland. A comprehensive in-house Level-1 internal event PSA for full power had already been performed. External flood assessment was further conducted in area of external hazard risk assessment in response to post-Fukushima measures taken in nuclear industries. The present paper describes the methodology to calculate initiating event (IE) frequency for external flood events for the sample inland Indian NPP. General extreme value (GEV) theory based on maximum likelihood method (MLM) and order statistics approach (OSA) is used to analyse the rainfall data for the site. Thousand-year return level and necessary return periods for extreme rainfall are evaluated. These results along with plant-specific topographical calculations quantitatively establish that external flooding resulting from upstream dam break, river flooding and heavy rainfall (flash flood) would be unlikely for the sample NPP in consideration.

Holocene extreme hydrological events and their climatic implications: evidence from the middle Satluj valley, western Himalaya, India

Science.gov (United States)

Sharma, Shubhra; Shukla, Anil; Marh, Bhupinder; Bartarya, Sukesh; Juyal, Navin

2016-04-01

Extreme hydrological events and associated climatic processes are investigated and inferred through palaeoflood deposits preserved in the middle Satluj valley, India. Satluj River is the largest tributary of the Indus River having third largest catchment area in the Himalaya. Both Indian summer monsoon (ISM) and the mid-latitude westerlies contribute to the hydrological budget of the river. The steep southern orographic front prevents the northward penetration of ISM, while the mid-latitude westerlies bring moisture in form of winter snow to the orogenic interiors. It has been observed that the floods in the Himalaya are intimately associated with the variability in the above climate systems. The optical chronology indicates that floods were clustered around three time domains. The oldest flood phase-1 is dated to ˜14-12 ka which climatically occurred during the initiation of the ISM after the Last Glacial Maximum. The second phase-2 is dated between 8-5 ka and is attributed to the moderate ISM. Whereas, the youngest phase-3 is assigned the Little Ice Age (LIA) and were associated with the variability in the mid-latitude westerlies. Geochemical analyses suggest that floods were generated in higher Himalayan crystalline (HHC) zone, as the extreme precipitation destabilised the precipitous slopes creating Landslide induced Lake Outbursts Floods (LLOFs). Further, the average interval between floods has decreased since 14 ka from 500 years, to 250 years and 100 years during respective flood phases. The southern slopes of Himalaya are influenced by both the monsoon and mid-latitude westerlies and any abrupt changes in the circulation pattern were found to associate with heavy rainfall events in this region. Although an interaction between the westerlies and the monsoon is implicated for extreme floods in the western Himalaya. However, exact mechanism of these interactions is still illusive except for the observational based studies which state that extreme floods

Drivers of flood damage on event level

DEFF Research Database (Denmark)

Kreibich, H.; Aerts, J. C. J. H.; Apel, H.

2016-01-01

example are the 2002 and 2013 floods in the Elbe and Danube catchments in Germany. The 2002 flood caused the highest economic damage (EUR 11600 million) due to a natural hazard event in Germany. Damage was so high due to extreme flood hazard triggered by extreme precipitation and a high number......-level mitigation measures, 3) more effective early warning and improved coordination of disaster response and 4) a more targeted maintenance of flood defence systems and their deliberate relocation. Thus, despite higher hydrological severity damage due to the 2013 flood was significantly lower than in 2002. In our...

Impacts of Floods Events on Food Security

Science.gov (United States)

Caporali, E.; Pacetti, T.; Rulli, M. C.

2017-12-01

The analysis of the interactions among natural disasters and food security is particularly significant for developing countries where food availability (one of the four pillars of food security together with access, utilization and stability) can be highly jeopardize by extreme events that damage the primary access to food, i.e. the agriculture. The main objective of this study is to analyze the impact of flood events on food security for two disastrous flood events in Bangladesh on 2007 and in Pakistan on 2010, selected here as case studies based on the existing literature related to extreme floods.The adopted methodology integrates remote sensing data, agricultural statistics, and water footprint values in order to (i) evaluating the potentially affected agricultural areas; (ii) converting the affected areas into crop loss; (iii) estimating the associated calories and water footprint losses. In Bangladesh, the estimated lost rice is around 12.5% of the total potential production, which implies a 5.3% calories loss with respect to the total potential energy provided by rice and 4.4% of total WF associated to national food supply. In Pakistan, the results show a crops loss of 19% for sugarcane and 40% for rice, with a related calories loss of 8.5% and a WF loss of 13.5%.The results highlight the countries vulnerability to flood, being both countries strongly dependent on local agricultural production. The 2007 flood event reflected critically upon Bangladeshi food security, almost doubling the existing food deficit. The same happened in Pakistan where an already scarce food supply has been worsened by the 2010 flood.Method results are fully repeatable; whereas, for remote sensed data the sources of data are valid worldwide and the data regarding land use and crops characteristics are strongly site specific, which need to be carefully evaluated.These case studies stress the importance of integrating different analysis approaches to carry out an assessment of the

A Global Geospatial Database of 5000+ Historic Flood Event Extents

Science.gov (United States)

Tellman, B.; Sullivan, J.; Doyle, C.; Kettner, A.; Brakenridge, G. R.; Erickson, T.; Slayback, D. A.

2017-12-01

A key dataset that is missing for global flood model validation and understanding historic spatial flood vulnerability is a global historical geo-database of flood event extents. Decades of earth observing satellites and cloud computing now make it possible to not only detect floods in near real time, but to run these water detection algorithms back in time to capture the spatial extent of large numbers of specific events. This talk will show results from the largest global historical flood database developed to date. We use the Dartmouth Flood Observatory flood catalogue to map over 5000 floods (from 1985-2017) using MODIS, Landsat, and Sentinel-1 Satellites. All events are available for public download via the Earth Engine Catalogue and via a website that allows the user to query floods by area or date, assess population exposure trends over time, and download flood extents in geospatial format.In this talk, we will highlight major trends in global flood exposure per continent, land use type, and eco-region. We will also make suggestions how to use this dataset in conjunction with other global sets to i) validate global flood models, ii) assess the potential role of climatic change in flood exposure iii) understand how urbanization and other land change processes may influence spatial flood exposure iv) assess how innovative flood interventions (e.g. wetland restoration) influence flood patterns v) control for event magnitude to assess the role of social vulnerability and damage assessment vi) aid in rapid probabilistic risk assessment to enable microinsurance markets. Authors on this paper are already using the database for the later three applications and will show examples of wetland intervention analysis in Argentina, social vulnerability analysis in the USA, and micro insurance in India.

Unusual rainfall shift during monsoon period of 2010 in Pakistan ...

African Journals Online (AJOL)

Floods due to “blocking event” in the jet stream during 2010 caused intense rainfall and flash floods in northern Pakistan which resulted to riverine flooding in southern Pakistan. In the beginning of July 2010, changes in summer monsoon rainfall patterns caused the most severe flooding in Pakistan history. Process control ...

An abrupt centennial-scale drought event and mid-holocene climate change patterns in monsoon marginal zones of East Asia.

Directory of Open Access Journals (Sweden)

Yu Li

Full Text Available The mid-latitudes of East Asia are characterized by the interaction between the Asian summer monsoon and the westerly winds. Understanding long-term climate change in the marginal regions of the Asian monsoon is critical for understanding the millennial-scale interactions between the Asian monsoon and the westerly winds. Abrupt climate events are always associated with changes in large-scale circulation patterns; therefore, investigations into abrupt climate changes provide clues for responses of circulation patterns to extreme climate events. In this paper, we examined the time scale and mid-Holocene climatic background of an abrupt dry mid-Holocene event in the Shiyang River drainage basin in the northwest margin of the Asian monsoon. Mid-Holocene lacustrine records were collected from the middle reaches and the terminal lake of the basin. Using radiocarbon and OSL ages, a centennial-scale drought event, which is characterized by a sand layer in lacustrine sediments both from the middle and lower reaches of the basin, was absolutely dated between 8.0-7.0 cal kyr BP. Grain size data suggest an abrupt decline in lake level and a dry environment in the middle reaches of the basin during the dry interval. Previous studies have shown mid-Holocene drought events in other places of monsoon marginal zones; however, their chronologies are not strong enough to study the mechanism. According to the absolutely dated records, we proposed a new hypothesis that the mid-Holocene dry interval can be related to the weakening Asian summer monsoon and the relatively arid environment in arid Central Asia. Furthermore, abrupt dry climatic events are directly linked to the basin-wide effective moisture change in semi-arid and arid regions. Effective moisture is affected by basin-wide precipitation, evapotranspiration, lake surface evaporation and other geographical settings. As a result, the time scales of the dry interval could vary according to locations due to

Regional flood reconstruction in Kullu District (Himachal Pradesh, India): implication for Disaster Risk Management

Science.gov (United States)

Ballesteros-Cánovas, Juan Antonio; Stoffel, Markus; Trappmann, Daniel; Shekhar, Mayank; Bhattacharyya, Amalava

2016-04-01

Floods are a common natural hazard in the Western Indian Himalayas. They usually occur when humid monsoon airs are lifted along the Himalayan relief, thereby creating intense orographic rainfall and runoff, a process which is often enhanced by simultaneous snowmelt. Monsoon floods are considered a major threat in the region and frequently affect inhabited valleys, disturbing the status quo of communities, stressing the future welfare and condition of their economic development. Given the assumption that ongoing and future climatic changes may impact on monsoon patterns and extreme precipitation, the implementation of adaptation policies in this region is critically needed in order to improve local resilience of Himalayan communities. However, its success implementation is highly dependent on system knowledge and hence reliable baseline data of past disasters. In this communication, we demonstrate how newly gained knowledge on past flood incidents may improve flood hazard and risk assessments. Based on growth-ring analysis of trees growing in the floodplains and other, more classical paleo-hydrology techniques, we reconstruct the regional flood activity for the last decades. This information is then included as non-systematic data into the regional flood frequency by using Bayesian Markov Monte Carlo Chain algorithms, so as to analyse the impact of the additional data on flood hazard assessments. Moreover, through a detailed analysis of three flood risk hotspots, we demonstrate how the newly gained knowledge on past flood disasters derived from indirect proxies can explain failures in the implementation of disaster risk management (DRM). Our methodology allowed identification of thirty-four unrecorded flood events at the study sites located in the upper reaches since the early 20th century, and thus completion of the existing flood history in the region based on flow measurements in the lower part of the catchment. We observe that 56% of the floods occurred

After the flood is before the next flood - post event review of the Central European Floods of June 2013. Insights, recommendations and next steps for future flood prevention

Science.gov (United States)

Szoenyi, Michael; Mechler, Reinhard; McCallum, Ian

2015-04-01

In early June 2013, severe flooding hit Central and Eastern Europe, causing extensive damage, in particular along the Danube and Elbe main watersheds. The situation was particularly severe in Eastern Germany, Austria, Hungary and the Czech Republic. Based on the Post Event Review Capability (PERC) approach, developed by Zurich Insurance's Flood Resilience Program to provide independent review of large flood events, we examine what has worked well (best practice) and opportunities for further improvement. The PERC overall aims to thoroughly examine aspects of flood resilience, flood risk management and catastrophe intervention in order to help build back better after events and learn for future events. As our research from post event analyses shows a lot of losses are in fact avoidable by taking the right measures pre-event and these measures are economically - efficient with a return of 4 Euro on losses saved for every Euro invested in prevention on average (Wharton/IIASA flood resilience alliance paper on cost benefit analysis, Mechler et al. 2014) and up to 10 Euros for certain countries. For the 2013 flood events we provide analysis on the following aspects and in general identify a number of factors that worked in terms of reducing the loss and risk burden. 1. Understanding risk factors of the Central European Floods 2013 We review the precursors leading up to the floods in June, with an extremely wet May 2013 and an atypical V-b weather pattern that brought immense precipitation in a very short period to the watersheds of Elbe, Donau and partially the Rhine in the D-A-CH countries and researched what happened during the flood and why. Key questions we asked revolve around which protection and risk reduction approaches worked well and which did not, and why. 2. Insights and recommendations from the post event review The PERC identified a number of risk factors, which need attention if risk is to be reduced over time. • Yet another "100-year flood" - risk

Shock events and flood risk management: a media analysis of the institutional long-term effects of flood events in the Netherlands and Poland

Directory of Open Access Journals (Sweden)

Maria Kaufmann

2016-12-01

Full Text Available Flood events that have proven to create shock waves in society, which we will call shock events, can open windows of opportunity that allow different actor groups to introduce new ideas. Shock events, however, can also strengthen the status quo. We will take flood events as our object of study. Whereas others focus mainly on the immediate impact and disaster management, we will focus on the long-term impact on and resilience of flood risk governance arrangements. Over the last 25 years, both the Netherlands and Poland have suffered several flood-related events. These triggered strategic and institutional changes, but to different degrees. In a comparative analysis these endogenous processes, i.e., the importance of framing of the flood event, its exploitation by different actor groups, and the extent to which arrangements are actually changing, are examined. In line with previous research, our analysis revealed that shock events test the capacity to resist and bounce back and provide opportunities for adapting and learning. They "open up" institutional arrangements and make them more susceptible to change, increasing the opportunity for adaptation. In this way they can facilitate a shift toward different degrees of resilience, i.e., by adjusting the current strategic approach or by moving toward another strategic approach. The direction of change is influenced by the actors and the frames they introduce, and their ability to increase the resonance of the frame. The persistence of change seems to be influenced by the evolution of the initial management approach, the availability of resources, or the willingness to allocate resources.

Hydrodynamic modelling of extreme flood events in the Kashmir valley in India

Science.gov (United States)

Jain, Manoj; Parvaze, Sabah

2017-04-01

Floods are one of the most predominant, costly and deadly hazards of all natural vulnerabilities. Every year, floods exert a heavy toll on human life and property in many parts of the world. The prediction of river stages and discharge during flood extremes plays a vital role in planning structural and non-structural measures of flood management. The predictions are also valuable to prepare the flood inundation maps and river floodplain zoning. In the Kashmir Valley, floods occur mainly and very often in the Jhelum Basin mostly due to extreme precipitation events and rugged mountainous topography of the basin. These floods cause extreme damage to life and property in the valley from time to time. Excessive rainfall, particularly in higher sub-catchments causes the snow to melt resulting in excessive runoff downhill to the streams causing floods in the Kashmir Valley where Srinagar city is located. However, very few hydrological studies have been undertaken for the Jhelum Basin mainly due to non-availability of hydrological data due to very complex mountainous terrain. Therefore, the present study has been conducted to model the extreme flood events in the Jhelum Basin in Kashmir Valley. An integrated NAM and MIKE 11 HD model has been setup for Jhelum basin up to Ram Munshi Bagh gauging site and then four most extreme historical flood events in the time series has been analyzed separately including the most recent and most extreme flood event of 2014. In September 2014, the Kashmir Valley witnessed the most severe flood in the past 60 years due to catastrophic rainfall from 1st to 6th September wherein the valley received unprecedented rainfall of more than 650 mm in just 3 days breaking record of many decades. The MIKE 11 HD and NAM model has been calibrated using 21 years (1985-2005) data and validated using 9 years (2006-2014) data. The efficiency indices of the model for calibration and validation period is 0.749 and 0.792 respectively. The model simulated

Assessment of Flood Disaster Impacts in Cambodia: Implications for Rapid Disaster Response

Science.gov (United States)

Ahamed, Aakash; Bolten, John; Doyle, Colin

2016-04-01

Disaster monitoring systems can provide near real time estimates of population and infrastructure affected by sudden onset natural hazards. This information is useful to decision makers allocating lifesaving resources following disaster events. Floods are the world's most common and devastating disasters (UN, 2004; Doocy et al., 2013), and are particularly frequent and severe in the developing countries of Southeast Asia (Long and Trong, 2001; Jonkman, 2005; Kahn, 2005; Stromberg, 2007; Kirsch et al., 2012). Climate change, a strong regional monsoon, and widespread hydropower construction contribute to a complex and unpredictable regional hydrodynamic regime. As such, there is a critical need for novel techniques to assess flood impacts to population and infrastructure with haste during and following flood events in order to enable governments and agencies to optimize response efforts following disasters. Here, we build on methods to determine regional flood extent in near real time and develop systems that automatically quantify the socioeconomic impacts of flooding in Cambodia. Software developed on cloud based, distributed processing Geographic Information Systems (GIS) is used to demonstrate spatial and numerical estimates of population, households, roadways, schools, hospitals, airports, agriculture and fish catch affected by severe monsoon flooding occurring in the Cambodian portion of Lower Mekong River Basin in 2011. Results show modest agreement with government and agency estimates. Maps and statistics generated from the system are intended to complement on the ground efforts and bridge information gaps to decision makers. The system is open source, flexible, and can be applied to other disasters (e.g. earthquakes, droughts, landslides) in various geographic regions.

Error Analysis of Satellite Precipitation-Driven Modeling of Flood Events in Complex Alpine Terrain

Directory of Open Access Journals (Sweden)

Yiwen Mei

2016-03-01

Full Text Available The error in satellite precipitation-driven complex terrain flood simulations is characterized in this study for eight different global satellite products and 128 flood events over the Eastern Italian Alps. The flood events are grouped according to two flood types: rain floods and flash floods. The satellite precipitation products and runoff simulations are evaluated based on systematic and random error metrics applied on the matched event pairs and basin-scale event properties (i.e., rainfall and runoff cumulative depth and time series shape. Overall, error characteristics exhibit dependency on the flood type. Generally, timing of the event precipitation mass center and dispersion of the time series derived from satellite precipitation exhibits good agreement with the reference; the cumulative depth is mostly underestimated. The study shows a dampening effect in both systematic and random error components of the satellite-driven hydrograph relative to the satellite-retrieved hyetograph. The systematic error in shape of the time series shows a significant dampening effect. The random error dampening effect is less pronounced for the flash flood events and the rain flood events with a high runoff coefficient. This event-based analysis of the satellite precipitation error propagation in flood modeling sheds light on the application of satellite precipitation in mountain flood hydrology.

Prediction of a thermodynamic wave train from the monsoon to the Arctic following extreme rainfall events

Science.gov (United States)

Krishnamurti, T. N.; Kumar, Vinay

2017-04-01

This study addresses numerical prediction of atmospheric wave trains that provide a monsoonal link to the Arctic ice melt. The monsoonal link is one of several ways that heat is conveyed to the Arctic region. This study follows a detailed observational study on thermodynamic wave trains that are initiated by extreme rain events of the northern summer south Asian monsoon. These wave trains carry large values of heat content anomalies, heat transports and convergence of flux of heat. These features seem to be important candidates for the rapid melt scenario. This present study addresses numerical simulation of the extreme rains, over India and Pakistan, and the generation of thermodynamic wave trains, simulations of large heat content anomalies, heat transports along pathways and heat flux convergences, potential vorticity and the diabatic generation of potential vorticity. We compare model based simulation of many features such as precipitation, divergence and the divergent wind with those evaluated from the reanalysis fields. We have also examined the snow and ice cover data sets during and after these events. This modeling study supports our recent observational findings on the monsoonal link to the rapid Arctic ice melt of the Canadian Arctic. This numerical modeling suggests ways to interpret some recent episodes of rapid ice melts that may require a well-coordinated field experiment among atmosphere, ocean, ice and snow cover scientists. Such a well-coordinated study would sharpen our understanding of this one component of the ice melt, i.e. the monsoonal link, which appears to be fairly robust.

Developing a Global Database of Historic Flood Events to Support Machine Learning Flood Prediction in Google Earth Engine

Science.gov (United States)

Tellman, B.; Sullivan, J.; Kettner, A.; Brakenridge, G. R.; Slayback, D. A.; Kuhn, C.; Doyle, C.

2016-12-01

There is an increasing need to understand flood vulnerability as the societal and economic effects of flooding increases. Risk models from insurance companies and flood models from hydrologists must be calibrated based on flood observations in order to make future predictions that can improve planning and help societies reduce future disasters. Specifically, to improve these models both traditional methods of flood prediction from physically based models as well as data-driven techniques, such as machine learning, require spatial flood observation to validate model outputs and quantify uncertainty. A key dataset that is missing for flood model validation is a global historical geo-database of flood event extents. Currently, the most advanced database of historical flood extent is hosted and maintained at the Dartmouth Flood Observatory (DFO) that has catalogued 4320 floods (1985-2015) but has only mapped 5% of these floods. We are addressing this data gap by mapping the inventory of floods in the DFO database to create a first-of- its-kind, comprehensive, global and historical geospatial database of flood events. To do so, we combine water detection algorithms on MODIS and Landsat 5,7 and 8 imagery in Google Earth Engine to map discrete flood events. The created database will be available in the Earth Engine Catalogue for download by country, region, or time period. This dataset can be leveraged for new data-driven hydrologic modeling using machine learning algorithms in Earth Engine's highly parallelized computing environment, and we will show examples for New York and Senegal.

The Generation of a Stochastic Flood Event Catalogue for Continental USA

Science.gov (United States)

Quinn, N.; Wing, O.; Smith, A.; Sampson, C. C.; Neal, J. C.; Bates, P. D.

2017-12-01

Recent advances in the acquisition of spatiotemporal environmental data and improvements in computational capabilities has enabled the generation of large scale, even global, flood hazard layers which serve as a critical decision-making tool for a range of end users. However, these datasets are designed to indicate only the probability and depth of inundation at a given location and are unable to describe the likelihood of concurrent flooding across multiple sites.Recent research has highlighted that although the estimation of large, widespread flood events is of great value to flood mitigation and insurance industries, to date it has been difficult to deal with this spatial dependence structure in flood risk over relatively large scales. Many existing approaches have been restricted to empirical estimates of risk based on historic events, limiting their capability of assessing risk over the full range of plausible scenarios. Therefore, this research utilises a recently developed model-based approach to describe the multisite joint distribution of extreme river flows across continental USA river gauges. Given an extreme event at a site, the model characterises the likelihood neighbouring sites are also impacted. This information is used to simulate an ensemble of plausible synthetic extreme event footprints from which flood depths are extracted from an existing global flood hazard catalogue. Expected economic losses are then estimated by overlaying flood depths with national datasets defining asset locations, characteristics and depth damage functions. The ability of this approach to quantify probabilistic economic risk and rare threshold exceeding events is expected to be of value to those interested in the flood mitigation and insurance sectors.This work describes the methodological steps taken to create the flood loss catalogue over a national scale; highlights the uncertainty in the expected annual economic vulnerability within the USA from extreme river flows

Gauging Flash-Floods: Automated Measurement of Flood Events in Mountain Torrents

Science.gov (United States)

Liechti, Katharina; Boss, Stefan; Fritschi, Bruno; Zappa, Massimiliano

2017-04-01

Rating curves contain uncertainties, especially in their upper range of higher discharge. This is due to more uncertainties in the measurements and also the typically lower number of measurements of high discharge events. However, it is the upper part of a rating curve that is of interest if it comes to dimensioning protection measures against floods and flash floods. For small municipalities who plan mitigation measures like a dam for protection against flash floods of small mountain torrent a rating curve as accurate as possible can be of great interest. It helps to reduce costs that can be caused by both under- and overdimensioning of a protective structure. We therefore invented a mobile discharge measurement station that is set up to construct a rating curve for small turbulent mountain torrents. It operates with salt dilution method and works in its current setup up to about 10 m3/s. The salt is injected automatically to the torrent when an event of desired magnitude takes place. Further downstream a conductivity measuring sensor records the change in salt concentration of the stream water. This mechanism is guided by automatic continuous observation of radar quantitative precipitation estimates (QPE) and a water pressure sensor. Measurements at a first test site gave promising results. The system does event measurements independent of the time of day and day of the week. The measuring equipment at the field site is only activated in case of an event. Therefore it has a low power consumption and can be run by only two solar panels.

The crucial role of ocean-atmosphere coupling on the Indian monsoon anomalous response during dipole events

Energy Technology Data Exchange (ETDEWEB)

Krishnan, R.; Swapna, P.; Ayantika, D.C.; Mujumdar, M. [Indian Institute of Tropical Meteorology, Climate and Global Modelling Division, Pune (India); Sundaram, Suchithra [Indian Institute of Tropical Meteorology, Climate and Global Modelling Division, Pune (India); Universite Catholique de Louvain, Institut d' Astronomie de Geophysique G. Lemaitre, Louvain-La-Neuve (Belgium); Kumar, Vinay [Indian Institute of Tropical Meteorology, Climate and Global Modelling Division, Pune (India); Florida State University, Department of Meteorology, Tallahassee, FL (United States)

2011-07-15

This paper examines an issue concerning the simulation of anomalously wet Indian summer monsoons like 1994 which co-occurred with strong positive Indian Ocean Dipole (IOD) conditions in the tropical Indian Ocean. Contrary to observations it has been noticed that standalone atmospheric general circulation models (AGCM) forced with observed SST boundary condition, consistently depicted a decrease of the summer monsoon rainfall during 1994 over the Indian region. Given the ocean-atmosphere coupling during IOD events, we have examined whether the failure of standalone AGCM simulations in capturing wet Indian monsoons like 1994 can be remedied by including a simple form of coupling that allows the monsoon circulation to dynamically interact with the IOD anomalies. With this view, we have performed a suite of simulations by coupling an AGCM to a slab-ocean model with spatially varying mixed-layer-depth (MLD) specified from observations for the 1994 IOD; as well as four other cases (1983, 1997, 2006, 2007). The specification of spatially varying MLD from observations allows us to constrain the model to observed IOD conditions. It is seen that the inclusion of coupling significantly improves the large-scale circulation response by strengthening the monsoon cross-equatorial flow; leading to precipitation enhancement over the subcontinent and rainfall decrease over south-eastern tropical Indian Ocean - in a manner broadly consistent with observations. A plausible physical mechanism is suggested to explain the monsoonal response in the coupled frame-work. These results warrant the need for improved monsoon simulations with fully coupled models to be able to better capture the observed monsoon interannual variability. (orig.)

Linking events, science and media for flood and drought management

Science.gov (United States)

Ding, M.; Wei, Y.; Zheng, H.; Zhao, Y.

2017-12-01

Throughout history, floods and droughts have been closely related to the development of human riparian civilization. The socio-economic damage caused by floods/droughts appears to be on the rise and the frequency of floods/droughts increases due to global climate change. In this paper, we take a fresh perspective to examine the (dis)connection between events (floods and droughts), research papers and media reports in globally 42 river basins between 1990 and 2012 for better solutions in floods and droughts management. We collected hydrological data from NOAA/ESPL Physical Sciences Division (PSD) and CPC Merged Analysis of Precipitation (CMAP), all relevant scientific papers from Web of Science (WOS) and media records from Emergency Events Database (EM-DAT) during the study period, presented the temporal variability at annual level of these three groups of data, and analysed the (connection) among these three groups of data in typical river basins. We found that 1) the number of flood related reports on both media and research is much more than those on droughts; 2) the concerns of media reports just focused on partial topics (death, severity and damage) and partial catchments (Mediterranean Sea and Nile River); 3) the scientific contribution on floods and droughts were limited within some river basins such as Nile River Basin, Parana River Basin, Savannah River Basin and Murray-Darling River Basin; 4) the scientific contribution on floods and droughts were limited within only a few of disciplines such as Geology, Environmental Sciences & Ecology, Agriculture, Engineering and Forestry. It is recommended that multiple disciplinary contribution and collaboration should be promoted to achieve comprehensive flood/drought management, and science and media should interactively play their valuable roles and in flood/drought issues. Keywords: Floods, droughts, events, science, media, flood and drought management

Investigation of flood pattern using ANOVA statistic and remote sensing in Malaysia

International Nuclear Information System (INIS)

Ya'acob, Norsuzila; Ismail, Nor Syazwani; Mustafa, Norfazira; Yusof, Azita Laily

2014-01-01

Flood is an overflow or inundation that comes from river or other body of water and causes or threatens damages. In Malaysia, there are no formal categorization of flood but often broadly categorized as monsoonal, flash or tidal floods. This project will be focus on flood causes by monsoon. For the last few years, the number of extreme flood was occurred and brings great economic impact. The extreme weather pattern is the main sector contributes for this phenomenon. In 2010, several districts in the states of Kedah neighbour-hoods state have been hit by floods and it is caused by tremendous weather pattern. During this tragedy, the ratio of the rainfalls volume was not fixed for every region, and the flood happened when the amount of water increase rapidly and start to overflow. This is the main objective why this project has been carried out, and the analysis data has been done from August until October in 2010. The investigation was done to find the possibility correlation pattern parameters related to the flood. ANOVA statistic was used to calculate the percentage of parameters was involved and Regression and correlation calculate the strength of coefficient among parameters related to the flood while remote sensing image was used for validation between the calculation accuracy. According to the results, the prediction is successful as the coefficient of relation in flood event is 0.912 and proved by Terra-SAR image on 4th November 2010. The rates of change in weather pattern give the impact to the flood

Bangladesh floods, cyclones and ENSO

International Nuclear Information System (INIS)

Choudhury, A.M.

1994-04-01

It has been found that in general there is a reduction of rainfall in all the regions of Bangladesh in all the seasons - premonsoon, monsoon and post monsoon during El Nino years. It has also been observed that in strong El Nino year Bangladesh is not hit by a catastrophic flood or a catastrophic cyclone. In the past, occurrence of famines in this region of the world coincided with El Nino years. The years of weak El Nino or when the El Nino index is positive seem to be favourable for the occurrence of floods and cyclones in Bangladesh. A theory of the modulation of the monsoon in Bangladesh by the Walker circulation has been described in the paper. (author). 14 refs, 7 figs, 1 tab

Analysis of external flooding events occurred in foreign nuclear power plant sites

International Nuclear Information System (INIS)

Li Dan; Cai Hankun; Xiao Zhi; An Hongzhen; Mao Huan

2013-01-01

This paper screens and studies 17 external flooding events occurred in foreign NPP sites, analysis the characteristic of external flooding events based on the source of the flooding, the impact on the building, systems and equipment, as well as the threat to nuclear safety. Furthermore, based on the experiences and lessons learned from Fukushima nuclear accident relating to external flooding and countermeasures carried out in the world, some suggestions are proposed in order to improve external flooding response capacity for Chinese NPPs. (authors)

A Synoptic Climatology of Combined Severe/Weather/Flash Flood Events

Science.gov (United States)

Pallozzi, Kyle J.

Classical forms of severe weather such as tornadoes, damaging convective wind gusts, and large hail, as well as flash flooding events, all have potentially large societal impacts. This impact is further magnified when these hazards occur simultaneously in time and space. A major challenge for operational forecasters is how to accurately predict the occurrence of combined storm hazards, and how to communicate the associated multiple threat hazards to the public. A seven-year climatology (2009-2015) of combined severe weather/flash flooding (SVR/FF) events across the contiguous United States was developed in attempt to study the combined SVR/FF event hazards further. A total of 211 total cases were identified and sub-divided into seven subcategories based on their convective morphology and meteorological characteristics. Heatmaps of event report frequency were created to extract spatial, seasonal and interannual patterns in SVR/FF event activity. Diurnal trends were examined from time series plots of tornado, hail, wind and flash flood/flood reports. Event-centered composites of environmental variables were created for each subcategory from 13 km RUC/RAP analyses. Representative cases studies were conducted for each subcategory. A "ring of fire" with the highest levels of SVR/FF event activity was noted across the central United States. SVR/FF events were least common in the Southeast, High Plains, and Northern Plains. Enhanced SVR/FF activity reflected contributions from synoptic events during the cool and shoulder seasons over the Lower Mississippi, Arkansas and Tennessee Valleys, and MCS activity during the warm season over the lower Great Plains, and the Upper Mississippi, Missouri and Ohio River Valleys. Results from the composite analyses indicated that relatively high values of CAPE, surface-500 hPa shear and precipitable water were observed for all subcategories. Case studies show that many high-end SVR/FF events featured slow-moving, or quasi

Extensive spatio-temporal assessment of flood events by application of pair-copulas

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M. Schulte

2015-06-01

Full Text Available Although the consequences of floods are strongly related to their peak discharges, a statistical classification of flood events that only depends on these peaks may not be sufficient for flood risk assessments. In many cases, the flood risk depends on a number of event characteristics. In case of an extreme flood, the whole river basin may be affected instead of a single watershed, and there will be superposition of peak discharges from adjoining catchments. These peaks differ in size and timing according to the spatial distribution of precipitation and watershed-specific processes of flood formation. Thus, the spatial characteristics of flood events should be considered as stochastic processes. Hence, there is a need for a multivariate statistical approach that represents the spatial interdependencies between floods from different watersheds and their coincidences. This paper addresses the question how these spatial interdependencies can be quantified. Each flood event is not only assessed with regard to its local conditions but also according to its spatio-temporal pattern within the river basin. In this paper we characterise the coincidence of floods by trivariate Joe-copula and pair-copulas. Their ability to link the marginal distributions of the variates while maintaining their dependence structure characterizes them as an adequate method. The results indicate that the trivariate copula model is able to represent the multivariate probabilities of the occurrence of simultaneous flood peaks well. It is suggested that the approach of this paper is very useful for the risk-based design of retention basins as it accounts for the complex spatio-temporal interactions of floods.

Effects of a flooding event on a threatened black bear population in Louisiana

Science.gov (United States)

O'Connell-Goode, Kaitlin C.; Lowe, Carrie L.; Clark, Joseph D.

2014-01-01

The Louisiana black bear, Ursus americanus luteolus, is listed as threatened under the Endangered Species Act as a result of habitat loss and human-related mortality. Information on population-level responses of large mammals to flooding events is scarce, and we had a unique opportunity to evaluate the viability of the Upper Atchafalaya River Basin (UARB) black bear population before and after a significant flooding event. We began collecting black bear hair samples in 2007 for a DNA mark-recapture study to estimate abundance (N) and apparent survival (φ). In 2011, the Morganza Spillway was opened to divert floodwaters from the Mississippi River through the UARB, inundating > 50% of our study area, potentially impacting recovery of this important bear population. To evaluate the effects of this flooding event on bear population dynamics, we used a robust design multistate model to estimate changes in transition rates from the flooded area to non-flooded area (ψF→NF) before (2007–2010), during (2010–2011) and after (2011–2012) the flood. Average N across all years of study was 63.2 (SE = 5.2), excluding the year of the flooding event. Estimates of ψF→NF increased from 0.014 (SE = 0.010; meaning that 1.4% of the bears moved from the flooded area to non-flooded areas) before flooding to 0.113 (SE = 0.045) during the flood year, and then decreased to 0.028 (SE= 0.035) after the flood. Although we demonstrated a flood effect on transition rates as hypothesized, the effect was small (88.7% of the bears remained in the flooded area during flooding) and φ was unchanged, suggesting that the 2011 flooding event had minimal impact on survival and site fidelity.

Estimation of Damage Costs Associated with Flood Events

Science.gov (United States)

Andrews, T. A.; Wauthier, C.; Zipp, K.

2017-12-01

This study investigates the possibility of creating a mathematical function that enables the estimation of flood-damage costs. We begin by examining the costs associated with past flood events in the United States. The data on these tropical storms and hurricanes are provided by the National Oceanic and Atmospheric Administration. With the location, extent of flooding, and damage reparation costs identified, we analyze variables such as: number of inches rained, land elevation, type of landscape, region development in regards to building density and infrastructure, and population concentration. We seek to identify the leading drivers of high flood-damage costs and understand which variables play a large role in the costliness of these weather events. Upon completion of our mathematical analysis, we turn out attention to the 2017 natural disaster of Texas. We divide the region, as we did above, by land elevation, type of landscape, region development in regards to building density and infrastructure, and population concentration. Then, we overlay the number of inches rained in those regions onto the divided landscape and apply our function. We hope to use these findings to estimate the potential flood-damage costs of Hurricane Harvey. This information is then transformed into a hazard map that could provide citizens and businesses of flood-stricken zones additional resources for their insurance selection process.

Combining geomorphic and documentary flood evidence to reconstruct extreme events in Mediterranean basins

Science.gov (United States)

Thorndycraft, V. R.; Benito, G.; Barriendos, M.; Rico, M.; Sánchez-Moya, Y.; Sopeña, A.; Casas, A.

2009-09-01

Palaeoflood hydrology is the reconstruction of flood magnitude and frequency using geomorphological flood evidence and is particularly valuable for extending the record of extreme floods prior to the availability of instrumental data series. This paper will provide a review of recent developments in palaeoflood hydrology and will be presented in three parts: 1) an overview of the key methodological approaches used in palaeoflood hydrology and the use of historical documentary evidence for reconstructing extreme events; 2) a summary of the Llobregat River palaeoflood case study (Catalonia, NE Spain); and 3) analysis of the AD 1617 flood and its impacts across Catalonia (including the rivers Llobregat, Ter and Segre). The key findings of the Llobregat case study were that at least eight floods occurred with discharges significantly larger than events recorded in the instrumental record, for example at the Pont de Vilomara study reach the palaeodischarges of these events were 3700-4300 m3/s compared to the 1971 flood, the largest on record, of 2300 m3/s. Five of these floods were dated to the last 3000 years and the three events directly dated by radiocarbon all occurred during cold phases of global climate. Comparison of the palaeoflood record with documentary evidence indicated that one flood, radiocarbon dated to cal. AD 1540-1670, was likely to be the AD 1617 event, the largest flood of the last 700 years. Historical records indicate that this event was caused by rainfall occurring from the 2nd to 6th November and the resultant flooding caused widespread socio-economic impacts including the destruction of at least 389 houses, 22 bridges and 17 water mills. Discharges estimated from palaeoflood records and historical flood marks indicate that the Llobregat (4680 m3/s) and Ter (2700-4500 m3/s) rivers witnessed extreme discharges in comparison to observed floods in the instrumental record (2300 and 2350 m3/s, respectively); whilst further east in the Segre River

Pan-European stochastic flood event set

Science.gov (United States)

Kadlec, Martin; Pinto, Joaquim G.; He, Yi; Punčochář, Petr; Kelemen, Fanni D.; Manful, Desmond; Palán, Ladislav

2017-04-01

Impact Forecasting (IF), the model development center of Aon Benfield, has been developing a large suite of catastrophe flood models on probabilistic bases for individual countries in Europe. Such natural catastrophes do not follow national boundaries: for example, the major flood in 2016 was responsible for the Europe's largest insured loss of USD3.4bn and affected Germany, France, Belgium, Austria and parts of several other countries. Reflecting such needs, IF initiated a pan-European flood event set development which combines cross-country exposures with country based loss distributions to provide more insightful data to re/insurers. Because the observed discharge data are not available across the whole Europe in sufficient quantity and quality to permit a detailed loss evaluation purposes, a top-down approach was chosen. This approach is based on simulating precipitation from a GCM/RCM model chain followed by a calculation of discharges using rainfall-runoff modelling. IF set up this project in a close collaboration with Karlsruhe Institute of Technology (KIT) regarding the precipitation estimates and with University of East Anglia (UEA) in terms of the rainfall-runoff modelling. KIT's main objective is to provide high resolution daily historical and stochastic time series of key meteorological variables. A purely dynamical downscaling approach with the regional climate model COSMO-CLM (CCLM) is used to generate the historical time series, using re-analysis data as boundary conditions. The resulting time series are validated against the gridded observational dataset E-OBS, and different bias-correction methods are employed. The generation of the stochastic time series requires transfer functions between large-scale atmospheric variables and regional temperature and precipitation fields. These transfer functions are developed for the historical time series using reanalysis data as predictors and bias-corrected CCLM simulated precipitation and temperature as

The 9.2 ka event in Asian summer monsoon area: the strongest millennial scale collapse of the monsoon during the Holocene

Science.gov (United States)

Zhang, Wenchao; Yan, Hong; Dodson, John; Cheng, Peng; Liu, Chengcheng; Li, Jianyong; Lu, Fengyan; Zhou, Weijian; An, Zhisheng

2018-04-01

Numerous Holocene paleo-proxy records exhibit a series of centennial-millennial scale rapid climatic events. Unlike the widely acknowledged 8.2 ka climate anomaly, the likelihood of a significant climate excursion at around 9.2 cal ka BP, which has been notably recognized in some studies, remains to be fully clarified in terms of its magnitude and intensity, as well as its characteristics and spatial distributions in a range of paleoclimatic records. In this study, a peat sediment profile from the Dajiuhu Basin in central China was collected with several geochemical proxies and a pollen analysis carried out to help improve understanding of the climate changes around 9.2 cal ka BP. The results show that the peat development was interrupted abruptly at around 9.2 cal ka BP, when the chemical weathering strength decreased and the tree-pollen declined. This suggests that a strong drier regional climatic event occurred at around 9.2 cal ka BP in central China, which was, in turn, probably connected to the rapid 9.2 ka climate event co-developing worldwide. In addition, based on the synthesis of our peat records and the other Holocene hydrological records from Asian summer monsoon (ASM) region, we further found that the 9.2 ka event probably constituted the strongest abrupt collapse of the Asian monsoon system during the full Holocene interval. The correlations between ASM and the atmospheric 14C production rate, the North Atlantic drift ice records and Greenland temperature indicated that the weakened ASM event at around 9.2 cal ka BP could be interpreted by the co-influence of external and internal factors, related to the changes of the solar activity and the Atlantic Meridional Overturning Circulation (AMOC).

Loss of life in flood events

Science.gov (United States)

Špitalar, Maruša

2013-04-01

Natural disasters per se give a negative connotation. They are destructive to material elements in a space, nature itself and represent a threat to peoples' lives and health. Floods, especially flash floods due to its power and happening suddenly cause extensive damage. Hence, they are hard to predict and are characterized with violent movement, lots of lives are lost. Floods are among natural hazards the one causing the highest number of fatalities. Having said that very important aspects are humans' vulnerability, risk perception, their behavior when confronted with hazardous situations and on the other hand issues related to adequate warning signs and canals of communication. It is very important to take into consideration this segments also and not mainly just structural measures. However the aim of this paper is to emphasis mainly the social aspects of floods. It consists of two main parts. First one refers to mans' vulnerability, risk perception when it comes to danger caused by rising waters and how does culture influences peoples' response and reaction to flood causalities. The second part consists of data about detailed information on circumstances of death that have been collected from several different sources from several EU countries. There has been also available information on the age and gender of people who lost lives in flood events. With gender males dominated among death people since tend to risk more in risky situations. There has been also defined a vulnerable age group among flood fatalities. Analysis of circumstance of death enabled us to define risky groups that are very important for flood managers. Further on this is very beneficial also for risk prevention, early warning systems and creating the best canals in order to information about upcoming danger would successfully reach people at hazardous areas and also for the others to avoid them.

Floods of the Lower Tisza from the late 17th century onwards: frequency, magnitude, seasonality and great flood events

Science.gov (United States)

Kiss, Andrea

2016-04-01

The present paper is based on a recently developed database including contemporary original, administrative, legal and private source materials (published and archival) as well as media reports related to the floods occurred on the lower sections of the Tisza river in Hungary, with special emphasis on the area of Szeged town. The study area is well-represented by contemporary source evidence from the late 17th century onwards, when the town and its broader area was reoccupied from the Ottoman Turkish Empire. Concerning the applied source materials, the main bases of investigation are the administrative (archival) sources such as town council protocols of Szeged and county meeting protocols of Csanád and Csongrád Counties. In these (legal-)administrative documents damaging events (natural/environmental hazards) were systematically recorded. Moreover, other source types such as taxation-related damage accounts as well as private and official reports, letters and correspondence (published, unpublished) were also included. Concerning published evidence, a most important source is flood reports in contemporary newspapers as well as town chronicles and other contemporary narratives. In the presentation the main focus is on the analysis of flood-rich flood-poor periods of the last ca. 330 years; moreover, the seasonality distribution as well as the magnitude of Tisza flood events are also discussed. Another important aim of the poster is to provide a short overview, in the form of case studies, on the greatest flood events (e.g. duration, magnitude, damages, multi-annual consequences), and their further impacts on the urban and countryside development as well as on (changes in) flood defence strategies. In this respect, especially two flood events, the great (1815-)1816 and the catastrophic 1879 flood (shortly with causes and consequences) - that practically erased Szeged town from the ground - are presented in more detail.

Extreme flood events in the Bolivian Amazon wetlands

Directory of Open Access Journals (Sweden)

A. Ovando

2016-03-01

Full Text Available Study region: The Amazonian wetlands of Bolivia, known as the Llanos de Moxos, are believed to play a crucial role in regulating the upper Madeira hydrological cycle, the most important southern tributary of the Amazon River. Because the area is vast and sparsely populated, the hydrological functioning of the wetlands is poorly known. Study focus: We analyzed the hydrometeorological configurations that led to the major floods of 2007, 2008 and 2014. These data, together with flood mapping derived from remote sensing images, were used to understand the dynamics of the Llanos during the three flood events. New hydrological insights for the region: The results showed that large floods are the result of the superimposition of flood waves from major sub-basins of the region. As a previous study suggested, the dynamics of the floods are controlled by an exogenous process, created by the flood wave originating in the Andes piedmont that travels through the Mamoré River; and by an endogenous process, which is the runoff originating in the Llanos. Our study showed that the first process is evident only at the initial phase of the floods, and although important for attenuating the rising flood wave, it is of lesser importance compared to the endogenous process. We conclude that the endogenous process controls the magnitude and duration of major floods. Keywords: Flood dynamics, Wetlands, Remote sensing, Llanos de Moxos

An Assessment of Monsoon Triggered Landslides in Western Nepal

Science.gov (United States)

Sudan Acharya, Madhu

2010-05-01

Due to heavy monsoon rain, rugged topography and very young mountains, frequent slope failures and soil erosion are very common in Nepal but in most of cases the natural slopes are disturbed by men to construct a road through it and the situation further aggravated by the Monsoon rain. Summer usually tests the disaster response capacity of Nepal, when the monsoons trigger water induced disasters. This year Nepal's Western regions were most severely affected by floods and landslides. Every year, sadly, it is the same story of mostly poor people living in remote villages succumbing to landslides and flooding and those who survive facing hardships brought on by the disaster. The tail end of the monsoon in October has triggered flood and landslides in Nepal which affected a total of 14 districts in the mid and far-west regions, of which Kailali, Bardiya, Banke, Dadeldhura, Accham and Kanchapur district are most affected. The affected areas are geographically scattered and remote, and are therefore difficult to access. In this year (2009), flood and landslides have claimed 62 lives, affecting more than 152,000 individuals from 27,000 families. More than 4,000 families are displaced and are taking shelter in schools, open space and forest areas with no protection from the external elements. In the above context the prevention and mitigation measures for landslides is a great challenge for Nepal. Nepal has been investing its huge amount of resources to stabilize landslides and roadside slope failures, still then it has become unmanageable during Monsoon time. Considering the above facts, an assessment of landslides which were occurred during the Monsoon (July-October 2009), along Khodpe - Jhota - Chainpur road in far western region of Nepal has been carried out based on the field observation of various landslides. The paper presents the causes and mechanisms of failures of different landslides which are mostly triggered by Monsoon rain. It also suggests some low cost

Modelling the interaction between flooding events and economic growth

Science.gov (United States)

Grames, Johanna; Fürnkranz-Prskawetz, Alexia; Grass, Dieter; Viglione, Alberto; Blöschl, Günter

2016-04-01

Recently socio-hydrology models have been proposed to analyze the interplay of community risk-coping culture, flooding damage and economic growth. These models descriptively explain the feedbacks between socio-economic development and natural disasters such as floods. Complementary to these descriptive models, we develop a dynamic optimization model, where the inter-temporal decision of an economic agent interacts with the hydrological system. This interdisciplinary approach matches with the goals of Panta Rhei i.e. to understand feedbacks between hydrology and society. It enables new perspectives but also shows limitations of each discipline. Young scientists need mentors from various scientific backgrounds to learn their different research approaches and how to best combine them such that interdisciplinary scientific work is also accepted by different science communities. In our socio-hydrology model we apply a macro-economic decision framework to a long-term flood-scenario. We assume a standard macro-economic growth model where agents derive utility from consumption and output depends on physical capital that can be accumulated through investment. To this framework we add the occurrence of flooding events which will destroy part of the capital. We identify two specific periodic long term solutions and denote them rich and poor economies. Whereas rich economies can afford to invest in flood defense and therefore avoid flood damage and develop high living standards, poor economies prefer consumption instead of investing in flood defense capital and end up facing flood damages every time the water level rises. Nevertheless, they manage to sustain at least a low level of physical capital. We identify optimal investment strategies and compare simulations with more frequent and more intense high water level events.

Reproducing an extreme flood with uncertain post-event information

Directory of Open Access Journals (Sweden)

D. Fuentes-Andino

2017-07-01

Full Text Available Studies for the prevention and mitigation of floods require information on discharge and extent of inundation, commonly unavailable or uncertain, especially during extreme events. This study was initiated by the devastating flood in Tegucigalpa, the capital of Honduras, when Hurricane Mitch struck the city. In this study we hypothesized that it is possible to estimate, in a trustworthy way considering large data uncertainties, this extreme 1998 flood discharge and the extent of the inundations that followed from a combination of models and post-event measured data. Post-event data collected in 2000 and 2001 were used to estimate discharge peaks, times of peak, and high-water marks. These data were used in combination with rain data from two gauges to drive and constrain a combination of well-known modelling tools: TOPMODEL, Muskingum–Cunge–Todini routing, and the LISFLOOD-FP hydraulic model. Simulations were performed within the generalized likelihood uncertainty estimation (GLUE uncertainty-analysis framework. The model combination predicted peak discharge, times of peaks, and more than 90 % of the observed high-water marks within the uncertainty bounds of the evaluation data. This allowed an inundation likelihood map to be produced. Observed high-water marks could not be reproduced at a few locations on the floodplain. Identifications of these locations are useful to improve model set-up, model structure, or post-event data-estimation methods. Rainfall data were of central importance in simulating the times of peak and results would be improved by a better spatial assessment of rainfall, e.g. from radar data or a denser rain-gauge network. Our study demonstrated that it was possible, considering the uncertainty in the post-event data, to reasonably reproduce the extreme Mitch flood in Tegucigalpa in spite of no hydrometric gauging during the event. The method proposed here can be part of a Bayesian framework in which more events

Event-based rainfall-runoff modelling of the Kelantan River Basin

Science.gov (United States)

Basarudin, Z.; Adnan, N. A.; Latif, A. R. A.; Tahir, W.; Syafiqah, N.

2014-02-01

Flood is one of the most common natural disasters in Malaysia. According to hydrologists there are many causes that contribute to flood events. The two most dominant factors are the meteorology factor (i.e climate change) and change in land use. These two factors contributed to floods in recent decade especially in the monsoonal catchment such as Malaysia. This paper intends to quantify the influence of rainfall during extreme rainfall events on the hydrological model in the Kelantan River catchment. Therefore, two dynamic inputs were used in the study: rainfall and river discharge. The extreme flood events in 2008 and 2004 were compared based on rainfall data for both years. The events were modeled via a semi-distributed HEC-HMS hydrological model. Land use change was not incorporated in the study because the study only tries to quantify rainfall changes during these two events to simulate the discharge and runoff value. Therefore, the land use data representing the year 2004 were used as inputs in the 2008 runoff model. The study managed to demonstrate that rainfall change has a significant impact to determine the peak discharge and runoff depth for the study area.

Event-based rainfall-runoff modelling of the Kelantan River Basin

International Nuclear Information System (INIS)

Basarudin, Z; Adnan, N A; Latif, A R A; Syafiqah, N; Tahir, W

2014-01-01

Flood is one of the most common natural disasters in Malaysia. According to hydrologists there are many causes that contribute to flood events. The two most dominant factors are the meteorology factor (i.e climate change) and change in land use. These two factors contributed to floods in recent decade especially in the monsoonal catchment such as Malaysia. This paper intends to quantify the influence of rainfall during extreme rainfall events on the hydrological model in the Kelantan River catchment. Therefore, two dynamic inputs were used in the study: rainfall and river discharge. The extreme flood events in 2008 and 2004 were compared based on rainfall data for both years. The events were modeled via a semi-distributed HEC-HMS hydrological model. Land use change was not incorporated in the study because the study only tries to quantify rainfall changes during these two events to simulate the discharge and runoff value. Therefore, the land use data representing the year 2004 were used as inputs in the 2008 runoff model. The study managed to demonstrate that rainfall change has a significant impact to determine the peak discharge and runoff depth for the study area

3D Simulation of External Flooding Events for the RISMC Pathway

International Nuclear Information System (INIS)

Prescott, Steven; Mandelli, Diego; Sampath, Ramprasad; Smith, Curtis; Lin, Linyu

2015-01-01

Incorporating 3D simulations as part of the Risk-Informed Safety Margins Characterization (RISMIC) Toolkit allows analysts to obtain a more complete picture of complex system behavior for events including external plant hazards. External events such as flooding have become more important recently – however these can be analyzed with existing and validated simulated physics toolkits. In this report, we describe these approaches specific to flooding-based analysis using an approach called Smoothed Particle Hydrodynamics. The theory, validation, and example applications of the 3D flooding simulation are described. Integrating these 3D simulation methods into computational risk analysis provides a spatial/visual aspect to the design, improves the realism of results, and can prove visual understanding to validate the analysis of flooding.

3D Simulation of External Flooding Events for the RISMC Pathway

Energy Technology Data Exchange (ETDEWEB)

Prescott, Steven [Idaho National Lab. (INL), Idaho Falls, ID (United States); Mandelli, Diego [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sampath, Ramprasad [Idaho National Lab. (INL), Idaho Falls, ID (United States); Smith, Curtis [Idaho National Lab. (INL), Idaho Falls, ID (United States); Lin, Linyu [Idaho National Lab. (INL), Idaho Falls, ID (United States)

2015-09-01

Incorporating 3D simulations as part of the Risk-Informed Safety Margins Characterization (RISMIC) Toolkit allows analysts to obtain a more complete picture of complex system behavior for events including external plant hazards. External events such as flooding have become more important recently – however these can be analyzed with existing and validated simulated physics toolkits. In this report, we describe these approaches specific to flooding-based analysis using an approach called Smoothed Particle Hydrodynamics. The theory, validation, and example applications of the 3D flooding simulation are described. Integrating these 3D simulation methods into computational risk analysis provides a spatial/visual aspect to the design, improves the realism of results, and can prove visual understanding to validate the analysis of flooding.

When surging seas meet stronger rain: Nuclear techniques in flood management

International Nuclear Information System (INIS)

Quevenco, Rodolfo

2015-01-01

Unusually high rainfall in many parts of the world is a result of climate change, scientists say. Since warmer air can hold more water, the rationale goes, increased temperatures will increase the chances of stronger rainfall events. And when surging seas combine with stronger rain, the outcome is almost certain: floods. Floods are the most frequently occurring natural disasters, and south-east Asia is particularly vulnerable. Climate change and variability are expected to bring about increased typhoon activities, rising sea levels and off-season monsoon rains in southeast Asia and other regions. These can cause devastating floods in countries like Cambodia, Laos, Pakistan, the Philippines, Thailand and Viet Nam. For the residents of these countries who have survived the ravages of major floods, the road to recovery can be long and arduous. As the flood water recedes, they have to contend with new forms of flood: floods of concern and worries as to how to rebuild their houses, their lives and their cities. Governments, too, face huge challenges in rebuilding roads, public buildings, infrastructure and natural resources destroyed or polluted by the flood.

Spatiotemporal hazard mapping of a flood event "migration" in a transboundary river basin as an operational tool in flood risk management

Science.gov (United States)

Perrou, Theodora; Papastergios, Asterios; Parcharidis, Issaak; Chini, Marco

2017-10-01

Flood disaster is one of the heaviest disasters in the world. It is necessary to monitor and evaluate the flood disaster in order to mitigate the consequences. As floods do not recognize borders, transboundary flood risk management is imperative in shared river basins. Disaster management is highly dependent on early information and requires data from the whole river basin. Based on the hypothesis that the flood events over the same area with same magnitude have almost identical evolution, it is crucial to develop a repository database of historical flood events. This tool, in the case of extended transboundary river basins, could constitute an operational warning system for the downstream area. The utility of SAR images for flood mapping, was demonstrated by previous studies but the SAR systems in orbit were not characterized by high operational capacity. Copernicus system will fill this gap in operational service for risk management, especially during emergency phase. The operational capabilities have been significantly improved by newly available satellite constellation, such as the Sentinel-1A AB mission, which is able to provide systematic acquisitions with a very high temporal resolution in a wide swath coverage. The present study deals with the monitoring of a transboundary flood event in Evros basin. The objective of the study is to create the "migration story" of the flooded areas on the basis of the evolution in time for the event occurred from October 2014 till May 2015. Flood hazard maps will be created, using SAR-based semi-automatic algorithms and then through the synthesis of the related maps in a GIS-system, a spatiotemporal thematic map of the event will be produced. The thematic map combined with TanDEM-X DEM, 12m/pixel spatial resolution, will define the non- affected areas which is a very useful information for the emergency planning and emergency response phases. The Sentinels meet the main requirements to be an effective and suitable

Early forecasting of Indian Summer Monsoon: case study 2016

Science.gov (United States)

Surovyatkina, Elena; Stolbova, Veronika; Kurths, Jurgen

2017-04-01

The prior knowledge of dates of onset and withdrawal of monsoon is of vital importance for the population of the Indian subcontinent. In May 2016 before monsoon season, India recorded its highest-ever temperature of 51C. Hot waves have decimated crops, killed livestock and left 330 million people without enough water. At the end of monsoon season the floods in Indian this year have also broken previous records. Severe and devastating rainfall poured down, triggering dams spilling and floods. Such extreme conditions pose the vital questions such as: When will the monsoon come? When will the monsoon withdraw? More lead time in monsoon forecast warning is crucial for taking appropriate decisions at various levels - from the farmer's field (e.g. plowing day, seeding) to the central government (e.g. managing water and energy resources, food procurement policies). The Indian Meteorological Department issues forecasts of onset of monsoon for Kerala state in South India on May 15-th. It does not give such predictions for the other 28 states of the country. Our study concerns the central part of India. We made the monsoon forecast using our recently developed method which focuses on Tipping elements of the Indian monsoon [1]. Our prediction relies on observations of near-surface air temperature and relative humidity from both the ERA-40 and NCEP/NCAR reanalyses. We performed both of our forecasts for the onset and withdrawal of monsoon for the central part of India, the Eastern Ghats (20N,80E). We predicted the monsoon arrival to the Eastern Ghats (20N,80E) on the 13th of June with a deviation of +/-4 days. The prediction was made on May 6-th, 2016 [2], that is 40 days in advance of the date of the forecast. The actual monsoon arrival was June 17-th. In this day near-surface air temperature and relative humidity overcame the critical values and the monsoon season started, that was confirmed by observations of meteorological stations located around the EG-region. We

Satellite images of the September 2013 flood event in Lyons, Colorado

Science.gov (United States)

Cole, Christopher J.; Friesen, Beverly A.; Wilds, Stanley; Noble, Suzanne; Warner, Harumi; Wilson, Earl M.

2013-01-01

The U.S. Geological Survey (USGS) Special Applications Science Center (SASC) produced an image base map showing high-resolution remotely sensed data over Lyons, Colorado—a city that was severely affected by the flood event that occurred throughout much of the Colorado Front Range in September of 2013. The 0.5-meter WorldView-2 data products were created from imagery collected by DigitalGlobe on September 13 and September 24, 2013, during and following the flood event. The images shown on this map were created to support flood response efforts, specifically for use in determining damage assessment and mitigation decisions. The raw, unprocessed imagery were orthorectified and pan-sharpened to enhance mapping accuracy and spatial resolution, and reproduced onto a cartographic base map. These maps are intended to provide a snapshot representation of post-flood ground conditions, which may be useful to decisionmakers and the general public. The SASC also provided data processing and analysis support for other Colorado flood-affected areas by creating cartographic products, geo-corrected electro-optical and radar image mosaics, and GIS water cover files for use by the Colorado National Guard, the National Park Service, the U.S. Forest Service, and the flood response community. All products for this International Charter event were uploaded to the USGS Hazards Data Distribution System (HDDS) website (http://hdds.usgs.gov/hdds2/) for distribution.

Impact of climate change on extreme rainfall events and flood risk in ...

Indian Academy of Sciences (India)

events and flood risk in India. P Guhathakurta∗. , O P Sreejith and P A Menon. India Meteorological Department, Shivajinagar, Pune 411 005, India. ∗ e-mail: pguhathakurta@rediffmail.com. The occurrence of exceptionally heavy rainfall events and associated flash floods in many areas during recent years motivate us to ...

Centennial- to decadal-scale monsoon precipitation variations in the upper Hanjiang River region, China over the past 6650 years

Science.gov (United States)

Tan, Liangcheng; Cai, Yanjun; Cheng, Hai; Edwards, Lawrence R.; Gao, Yongli; Xu, Hai; Zhang, Haiwei; An, Zhisheng

2018-01-01

The upper Hanjiang River region is the recharge area of the middle route of South-to-North Water Transfer Project. The region is under construction of the Hanjiang-Weihe River Water Transfer Project in China. Monsoon precipitation variations in this region are critical to water resource and security of China. In this study, high-resolution monsoon precipitation variations were reconstructed in the upper Hanjiang River region over the past 6650 years from δ18O and δ13C records of four stalagmites in Xianglong cave. The long term increasing trend of stalagmite δ18O record since the middle Holocene is consistent with other speleothem records from monsoonal China. This trend follows the gradually decreasing Northern Hemisphere summer insolation, which indicates that solar insolation may control the orbital-scale East Asian summer monsoon (EASM) variations. Despite the declined EASM intensity since the middle Holocene, local precipitation may not have decreased remarkably, as revealed by the δ13C records. A series of centennial- to decadal-scale cyclicity was observed, with quasi-millennium-, quasi-century-, 57-, 36- and 22-year cycles by removing the long-term trend of stalagmite δ18O record. Increased monsoon precipitation during periods of 4390-3800 a BP, 3590-2960 a BP, 2050-1670 a BP and 1110-790 a BP had caused four super-floods in the upper reach of Hanjiang River. Dramatically dry climate existed in this region during the 5.0 ka and 2.8 ka events, coinciding with notable droughts in other regions of monsoonal China. Remarkably intensified and southward Westerly jet, together with weakened summer monsoon, may delay the onset of rainy seasons, resulting in synchronous decreasing of monsoon precipitation in China during the two events. During the 4.2 ka event and the Little Ice Age, the upper Hanjiang River region was wet, which was similar to the climate conditions in central and southern China, but was the opposite of drought observed in northern China. We

Cascading Events, Technology and the Floods Directive: future challenges

Directory of Open Access Journals (Sweden)

Pescaroli Gianluca

2016-01-01

Full Text Available Cascading events can be referred to multidimensional disasters, where a primary trigger generates a nonlinear series of secondary emergencies that escalate in time, becoming eventually the priority to tackle. In this process, critical infrastructure can be handled as roots of vulnerabilities, because they accumulate both physical attributes and functional nodes. When compromised, they produce widespread breakdowns of society, but also orient emergency responses and long-term recovery. Although floods have been widely associated to the failure of vulnerable equipments or to the disruption of strategic sectors such as energy, communication and transportation, their integration with the emerging concept of cascading has been limited. This open topic presents many challenges for scholars, researchers and practitioners, in particular when the implementation of the EU Floods Directive is considered. The paper presents an overview of the Floods Directive and its relation with the cascading events, using case studies and examples from the existing literature to point out missing links and gaps in the legislation. Conclusions argue that the Directive considers only local geographical scales and limited temporal horizons, which can be result inadequate to limit the escalation of events.

Projections of hepatitis A virus infection associated with flood events by 2020 and 2030 in Anhui Province, China

Science.gov (United States)

Gao, Lu; Zhang, Ying; Ding, Guoyong; Liu, Qiyong; Wang, Changke; Jiang, Baofa

2016-12-01

Assessing and responding to health risk of climate change is important because of its impact on the natural and societal ecosystems. More frequent and severe flood events will occur in China due to climate change. Given that population is projected to increase, more people will be vulnerable to flood events, which may lead to an increased incidence of HAV infection in the future. This population-based study is going to project the future health burden of HAV infection associated with flood events in Huai River Basin of China. The study area covered four cities of Anhui province in China, where flood events were frequent. Time-series adjusted Poisson regression model was developed to quantify the risks of flood events on HAV infection based on the number of daily cases during summer seasons from 2005 to 2010, controlling for other meteorological variables. Projections of HAV infection in 2020 and 2030 were estimated based on the scenarios of flood events and demographic data. Poisson regression model suggested that compared with the periods without flood events, the risks of severe flood events for HAV infection were significant (OR = 1.28, 95 % CI 1.05-1.55), while risks were not significant from moderate flood events (OR = 1.16, 95 % CI 0.72-1.87) and mild flood events (OR = 1.14, 95 % CI 0.87-1.48). Using the 2010 baseline data and the flood event scenarios (one severe flood event), increased incidence of HAV infection were estimated to be between 0.126/105 and 0.127/105 for 2020. Similarly, the increased HAV infection incidence for 2030 was projected to be between 0.382/105 and 0.399/105. Our study has, for the first time, quantified the increased incidence of HAV infection that will result from flood events in Anhui, China, in 2020 and 2030. The results have implications for public health preparation for developing public health responses to reduce HAV infection during future flood events.

Flood forecasting and warning systems in Pakistan

International Nuclear Information System (INIS)

Ali Awan, Shaukat

2004-01-01

Meteorologically, there are two situations which may cause three types of floods in Indus Basin in Pakistan: i) Meteorological Situation for Category-I Floods when the seasonal low is a semi permanent weather system situated over south eastern Balochistan, south western Punjab, adjoining parts of Sindh get intensified and causes the moisture from the Arabian Sea to be brought up to upper catchments of Chenab and Jhelum rivers. (ii) Meteorological Situation for Category-11 and Category-111 Floods, which is linked with monsoon low/depression. Such monsoon systems originate in Bay of Bengal region and then move across India in general west/north westerly direction arrive over Rajasthan or any of adjoining states of India. Flood management in Pakistan is multi-functional process involving a number of different organizations. The first step in the process is issuance of flood forecast/warning, which is performed by Pakistan Meteorological Department (PMD) utilizing satellite cloud pictures and quantitative precipitation measurement radar data, in addition to the conventional weather forecasting facilities. For quantitative flood forecasting, hydrological data is obtained through the Provincial Irrigation Department and WAPDA. Furthermore, improved rainfall/runoff and flood routing models have been developed to provide more reliable and explicit flood information to a flood prone population.(Author)

FLCNDEMF: An Event Metamodel for Flood Process Information Management under the Sensor Web Environment

Directory of Open Access Journals (Sweden)

Nengcheng Chen

2015-06-01

Full Text Available Significant economic losses, large affected populations, and serious environmental damage caused by recurrent natural disaster events (NDE worldwide indicate insufficiency in emergency preparedness and response. The barrier of full life cycle data preparation and information support is one of the main reasons. This paper adopts the method of integrated environmental modeling, incorporates information from existing event protocols, languages, and models, analyzes observation demands from different event stages, and forms the abstract full life cycle natural disaster event metamodel (FLCNDEM based on meta-object facility. Then task library and knowledge base for floods are built to instantiate FLCNDEM, forming the FLCNDEM for floods (FLCNDEMF. FLCNDEMF is formalized according to Event Pattern Markup Language, and a prototype system, Natural Disaster Event Manager, is developed to assist in the template-based modeling and management. The flood in Liangzi (LZ Lake of Hubei, China on 16 July 2010 is adopted to illustrate how to apply FLCNDEM in real scenarios. FLCNDEM-based modeling is realized, and the candidate remote sensing (RS dataset for different observing missions are provided for LZ Lake flood. Taking the mission of flood area extraction as an example, the appropriate RS data are selected via the model of simplified general perturbation version 4, and the flood area in different phases are calculated and displayed on the map. The phase-based modeling and visualization intuitively display the spatial-temporal distribution and the evolution process of the LZ Lake flood, and it is of great significance for flood responding. In addition, through the extension mechanism, FLCNDEM can also be applied in other environmental applications, providing important support for full life cycle information sharing and rapid responding.

Modelling the interaction between flooding events and economic growth

Directory of Open Access Journals (Sweden)

J. Grames

2015-06-01

Full Text Available Socio-hydrology describes the interaction between the socio-economy and water. Recent models analyze the interplay of community risk-coping culture, flooding damage and economic growth (Di Baldassarre et al., 2013; Viglione et al., 2014. These models descriptively explain the feedbacks between socio-economic development and natural disasters like floods. Contrary to these descriptive models, our approach develops an optimization model, where the intertemporal decision of an economic agent interacts with the hydrological system. In order to build this first economic growth model describing the interaction between the consumption and investment decisions of an economic agent and the occurrence of flooding events, we transform an existing descriptive stochastic model into an optimal deterministic model. The intermediate step is to formulate and simulate a descriptive deterministic model. We develop a periodic water function to approximate the former discrete stochastic time series of rainfall events. Due to the non-autonomous exogenous periodic rainfall function the long-term path of consumption and investment will be periodic.

Characteristics and Future Changes of Great Mississippi Flood Events in a Global Coupled Climate Model

Science.gov (United States)

van der Wiel, K.; Kapnick, S. B.; Vecchi, G.; Smith, J. A.

2017-12-01

The Mississippi-Missouri river catchment houses millions of people and much of the U.S. national agricultural production. Severe flooding events can therefore have large negative societal, natural and economic impacts. GFDL FLOR, a global coupled climate model (atmosphere, ocean, land, sea ice with integrated river routing module) is used to investigate the characteristics of great Mississippi floods with an average return period of 100 years. Model experiments under pre-industrial greenhouse gas forcing were conducted for 3400 years, such that the most extreme flooding events were explicitly modeled and the land and/or atmospheric causes could be investigated. It is shown that melt of snow pack and frozen sub-surface water in the Missouri and Upper Mississippi basins prime the river system, subsequently sensitizing it to above average precipitation in the Ohio and Tennessee basins. The months preceding the greatest flooding events are above average wet, leading to moist sub-surface conditions. Anomalous melt depends on the availability of frozen water in the catchment, therefore anomalous amounts of sub-surface frozen water and anomalous large snow pack in winter (Nov-Feb) make the river system susceptible for these great flooding events in spring (Feb-Apr). An additional experiment of 1200 years under transient greenhouse gas forcing (RCP4.5, 5 members) was done to investigate potential future change in flood risk. Based on a peak-over-threshold method, it is found that the number of great flooding events decreases in a warmer future. This decrease coincides with decreasing occurrence of large melt events, but is despite increasing numbers of large precipitation events. Though the model results indicate a decreasing risk for the greatest flooding events, the predictability of events might decrease in a warmer future given the changing characters of melt and precipitation.

Near-Bed Monitoring of Suspended Sediment during a Major Flood Event Highlights Deficiencies in Existing Event-Loading Estimates

Directory of Open Access Journals (Sweden)

Alistair Grinham

2018-01-01

Full Text Available Rates of fluvial sediment discharge are notoriously difficult to quantify, particularly during major flood events. Measurements are typically undertaken using event stations requiring large capital investment, and the high cost tends to reduce the spatial coverage of monitoring sites. This study aimed to characterise the near-bed suspended sediment dynamics during a major flood event using a low-cost approach. Monitoring nodes consisted of a total suspended sediment (TSS logger, a single stage sampler, and a time-lapse camera for a total cost of less than US$420. Seven nodes were deployed across an elevation gradient on the stream bank of Laidley Creek, Queensland, Australia, and two of these nodes successfully characterised the near-bed suspended sediment dynamics across a major flood event. Near-bed TSS concentrations were closely related to stream flow, with the contribution of suspended bed material dominating the total suspended load during peak flows. Observed TSS concentrations were orders of magnitude higher than historical monitoring data for this site collected using the State government event station. This difference was attributed to the event station pump inlet screening the suspended bed material prior to sample collection. The ‘first flush’ phenomenon was detected and attributed to a local resuspension of muddy crusts immediately upstream of the study site. This low-cost approach will provide an important addition to the existing monitoring of fluvial sediment discharge during flood events.

Management of a Complex Open Channel Network During Flood Events

Science.gov (United States)

Franchini, M.; Valiani, A.; Schippa, L.; Mascellani, G.

2003-04-01

Most part of the area around Ferrara (Italy) is below the mean sea level and an extensive drainage system combined with several pump stations allows the use of this area for both urban development and industrial and agricultural activities. The three main channels of this hydraulic system constitute the Ferrara Inland Waterway (total length approximately 70 km), which connects the Po river near Ferrara to the sea. Because of the level difference between the upstream and dowstream ends of the waterway, three locks are located along it, each of them combined with a set of gates to control the water levels. During rainfall events, most of the water of the basin flows into the waterway and heavy precipitations sometimes cause flooding in several areas. This is due to the insufficiency of the channel network dimensions and an inadequate manual operation of the gates. This study presents a hydrological-hydraulic model for the entire Ferrara basin and a system of rules in order to operate the gates. In particular, their opening is designed to be regulated in real time by monitoring the water level in several sections along the channels. Besides flood peak attenuation, this operation strategy contributes also to the maintenance of a constant water level for irrigation and fluvial navigation during the dry periods. With reference to the flood event of May 1996, it is shown that this floodgate operation policy, unlike that which was actually adopted during that event, would lead to a significant flood peak attenuation, avoiding flooding in the area upstream of Ferrara.

National water summary 1988-89: Hydrologic events and floods and droughts

Science.gov (United States)

Paulson, Richard W.; Chase, Edith B.; Roberts, Robert S.; Moody, David W.

1991-01-01

National Water Summary 1988-89 - Hydrologic Events and Floods and Droughts documents the occurrence in the United States, Puerto Rico, and the U.S. Virgin Islands of two types of extreme hydrologic events floods and droughts on the basis of analysis of stream-discharge data. This report details, for the first time, the areal extent of the most notable floods and droughts in each State, portrays their severity in terms of annual peak discharge for floods and annual departure from long-term discharge for droughts for selected stream-gaging stations, and estimates how frequently floods and droughts of such severity can be expected to recur. These two types of extreme hydrologic events are very different in their duration, cause, areal extent, and effect on human activities. Floods are short-term phenomena that typically last only a few hours to a few days and are associated with weather systems that produce unusually large amounts of rain or that cause snow to melt quickly. The large amount of runoff produced causes rivers to overflow their banks and, thus, is highly dangerous to human life and property. In contrast, droughts are long-term phenomena that typically persist for months to a decade or more and are associated with the absence of precipitation producing weather. They affect large geographic areas that can be statewide, regional, or even nationwide in extent. Droughts can cause great economic hardship and even loss of life in developing countries, although the loss of life results almost wholly from diminished water supplies and catastrophic crop failures rather than from the direct and obvious peril to human life that is common to floods. The following discussion is an overview of the three parts of this 1988-89 National Water Summary "Hydrologic Conditions and Water-Related Events, Water Years 1988-89," "Hydrologic Perspectives on Water Issues," and "State Summaries of Floods and Droughts." Background information on sources of atmospheric moisture to the

Flood Induced Disasters and Stakeholder Involvement to Implement Integrated Food Management in Nepal

Science.gov (United States)

Gautam, N. P.

2016-12-01

Nepal, a landlocked country in South Asia covers an area of 147, 181 square kilometers. Its elevation ranges from 61m as the lowest to 8848m, the highest peak Everest in the world. More than 80% of the annual rainfall occurs in the monsoon season from June to September. Thus, due to the intense rainfall that occurs within a short period, monsoon acts as the biggest cause for the occurrence of different disastrous events including flood. Beyond it, Nepal lies at the center and southern edge of Hindu-Kush Himalayan (HKH) region, which is the youngest geological formation in the world. Hence, floods and landslides are common in this region. In Nepal, from the records of 1971-2010, floods and landslides are the second biggest cause for casualties after epidemics. Hawaii based Center of Excellence in disaster management and humanitarian assistance in 2015 has declared Nepal as 30th vulnerable country from the aspect of floods. According to WMO definition, integrated flood management (IFM) is a process of promoting an integrated rather than a fragmented approach to flood management, integrating land and water resource development in a river basin within the context of integrated water resources management (IWRM), with the aim of maximizing the net benefits from flood plains while minimizing loss of life from flooding. That is the reason why the IFM is one of the important countermeasures to be implemented in Nepal to reduce the adverse effects of floods. This study emphasizes on the existing conditions along with the challenges of IFM with respect to stakeholder involvement in the context of Nepal. It can be assured that all the highlighted issues coming out from this study will be highly valuable to policy makers, implementing agencies along with scientific and local communities to enhance IFM works in the nation for the benefits of societies.

Unusual rainfall shift during monsoon period of 2010 in Pakistan ...

African Journals Online (AJOL)

Arslan

2013-09-04

Sep 4, 2013 ... Key words: Indus River, monsoon, flooding in 2010, rainfall pattern, Climate ... data was plotted in excel sheet with upper and lower limits defined .... Houze Jr, Rasmussen R, Medina K, Brodzik S, Romatschke SU (2011).

Erosion during extreme flood events dominates Holocene canyon evolution in northeast Iceland.

Science.gov (United States)

Baynes, Edwin R C; Attal, Mikaël; Niedermann, Samuel; Kirstein, Linda A; Dugmore, Andrew J; Naylor, Mark

2015-02-24

Extreme flood events have the potential to cause catastrophic landscape change in short periods of time (10(0) to 10(3) h). However, their impacts are rarely considered in studies of long-term landscape evolution (>10(3) y), because the mechanisms of erosion during such floods are poorly constrained. Here we use topographic analysis and cosmogenic (3)He surface exposure dating of fluvially sculpted surfaces to determine the impact of extreme flood events within the Jökulsárgljúfur canyon (northeast Iceland) and to constrain the mechanisms of bedrock erosion during these events. Surface exposure ages allow identification of three periods of intense canyon cutting about 9 ka ago, 5 ka ago, and 2 ka ago during which multiple large knickpoints retreated large distances (>2 km). During these events, a threshold flow depth was exceeded, leading to the toppling and transportation of basalt lava columns. Despite continuing and comparatively large-scale (500 m(3)/s) discharge of sediment-rich glacial meltwater, there is no evidence for a transition to an abrasion-dominated erosion regime since the last erosive event because the vertical knickpoints have not diffused over time. We provide a model for the evolution of the Jökulsárgljúfur canyon through the reconstruction of the river profile and canyon morphology at different stages over the last 9 ka and highlight the dominant role played by extreme flood events in the shaping of this landscape during the Holocene.

The Aerosol-Monsoon Climate System of Asia

Science.gov (United States)

Lau, William K. M.; Kyu-Myong, Kim

2012-01-01

In Asian monsoon countries such as China and India, human health and safety problems caused by air-pollution are worsening due to the increased loading of atmospheric pollutants stemming from rising energy demand associated with the rapid pace of industrialization and modernization. Meanwhile, uneven distribution of monsoon rain associated with flash flood or prolonged drought, has caused major loss of human lives, and damages in crop and properties with devastating societal impacts on Asian countries. Historically, air-pollution and monsoon research are treated as separate problems. However a growing number of recent studies have suggested that the two problems may be intrinsically intertwined and need to be studied jointly. Because of complexity of the dynamics of the monsoon systems, aerosol impacts on monsoons and vice versa must be studied and understood in the context of aerosol forcing in relationship to changes in fundamental driving forces of the monsoon climate system (e.g. sea surface temperature, land-sea contrast etc.) on time scales from intraseasonal variability (weeks) to climate change ( multi-decades). Indeed, because of the large contributions of aerosols to the global and regional energy balance of the atmosphere and earth surface, and possible effects of the microphysics of clouds and precipitation, a better understanding of the response to climate change in Asian monsoon regions requires that aerosols be considered as an integral component of a fully coupled aerosol-monsoon system on all time scales. In this paper, using observations and results from climate modeling, we will discuss the coherent variability of the coupled aerosol-monsoon climate system in South Asia and East Asia, including aerosol distribution and types, with respect to rainfall, moisture, winds, land-sea thermal contrast, heat sources and sink distributions in the atmosphere in seasonal, interannual to climate change time scales. We will show examples of how elevated

Trends in flash flood events versus convective precipitation in the Mediterranean region: The case of Catalonia

Science.gov (United States)

Llasat, Maria Carmen; Marcos, Raul; Turco, Marco; Gilabert, Joan; Llasat-Botija, Montserrat

2016-10-01

The aim of this paper is to analyse the potential relationship between flash flood events and convective precipitation in Catalonia, as well as any related trends. The paper starts with an overview of flash floods and their trends in the Mediterranean region, along with their associated factors, followed by the definition of, identification of, and trends in convective precipitation. After this introduction the paper focuses on the north-eastern Iberian Peninsula, for which there is a long-term precipitation series (since 1928) of 1-min precipitation from the Fabra Observatory, as well as a shorter (1996-2011) but more extensive precipitation series (43 rain gauges) of 5-min precipitation. Both series have been used to characterise the degree of convective contribution to rainfall, introducing the β parameter as the ratio between convective precipitation versus total precipitation in any period. Information about flood events was obtained from the INUNGAMA database (a flood database created by the GAMA team), with the aim of finding any potential links to convective precipitation. These flood data were gathered using information on damage where flood is treated as a multifactorial risk, and where any trend or anomaly might have been caused by one or more factors affecting hazard, vulnerability or exposure. Trend analysis has shown an increase in flash flood events. The fact that no trends were detected in terms of extreme values of precipitation on a daily scale, nor on the associated ETCCDI (Expert Team on Climate Change Detection and Indices) extreme index, could point to an increase in vulnerability, an increase in exposure, or changes in land use. However, the summer increase in convective precipitation was concentrated in less torrential events, which could partially explain this positive trend in flash flood events. The β parameter has been also used to characterise the type of flood event according to the features of the precipitation. The highest values

Impacts of the 2016 outburst flood on the Bhote Koshi River valley, central Nepal

Science.gov (United States)

Cook, Kristen; Andermann, Christoff; Gimbert, Florent; Hovius, Niels; Adhikari, Basanta

2017-04-01

The central Nepal Himalaya is a region of rapid erosion where fluvial processes are largely driven by the annual Indian Summer Monsoon, which delivers up to several meters of precipitation each year. However, the rivers in this region are also subject to rare catastrophic floods caused by the sudden failure of landslide or moraine dams. Because these floods happen rarely, it has been difficult to isolate their impact on the rivers and adjacent hillslopes, and their importance for the long-term evolution of Himalayan rivers is poorly constrained. On the 5th of July, 2016, the Bhote Koshi River in central Nepal was hit by a glacial lake outburst flood (GLOF). The flood passed through a seismic and hydrological observatory installed along the river in June 2015, and we have used the resulting data to constrain the timing, duration, and bedload transport properties of the outburst flood. The impact of the flood on the river can be further observed with hourly time-lapse photographs, daily measurements of suspended sediment load, repeat lidar surveys, and satellite imagery. Overall, our observatory data span two monsoon seasons, allowing us to evaluate the impacts of the outburst flood relative to the annual monsoon flood. The outburst flood affected the river on several timescales. In the short term, it transported large amounts of coarse sediment and restructured the river bed during the hours of the flood pulse itself. Over intermediate timescales it resulted in elevated bedload and suspended load transport for several weeks following the flood. Over longer timescales the flood undercut and destabilized the river banks and hillslopes in a number of locations, leading to bank collapses, slumps, and landslides. We map changes in the channel and associated mass wasting using rapidEye imagery from Oct. 2015 and Oct. 2016. We also use repeat terrestrial lidar scans to quantify the magnitude of change in multiple locations along the river channel and to measure bank

Nonstationarities in the occurrence rates of flood events in Portuguese watersheds

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A. T. Silva

2012-01-01

Full Text Available An exploratory analysis on the variability of flood occurrence rates in 10 Portuguese watersheds is made, to ascertain if that variability is concurrent with the principle of stationarity. A peaks-over-threshold (POT sampling technique is applied to 10 long series of mean daily streamflows and to 4 long series of daily rainfall in order to sample the times of occurrence (POT time data of the peak values of those series. The kernel occurrence rate estimator, coupled with a bootstrap approach, was applied to the POT time data to obtain the time dependent estimated occurrence rate curves, λˆ(t, of floods and extreme rainfall events. The results of the analysis show that the occurrence of those events constitutes an inhomogeneous Poisson process, hence the occurrence rates are nonstationary. An attempt was made to assess whether the North Atlantic Oscillation (NAO casted any influence on the occurrence rate of floods in the study area. Although further research is warranted, it was found that years with a less-than-average occurrence of floods tend to occur when the winter NAO is in the positive phase, and years with a higher occurrence of floods (more than twice the average tend to occur when the winter NAO is in the negative phase. Although the number of analyzed watersheds and their uneven spatial distribution hinders the generalization of the findings to the country scale, the authors conclude that the mathematical formulation of the flood frequency models relying on stationarity commonly employed in Portugal should be revised in order to account for possible nonstationarities in the occurrence rates of such events.

Flood-risk mapping: contributions towards an enhanced assessment of extreme events and associated risks

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B. Büchele

2006-01-01

Full Text Available Currently, a shift from classical flood protection as engineering task towards integrated flood risk management concepts can be observed. In this context, a more consequent consideration of extreme events which exceed the design event of flood protection structures and failure scenarios such as dike breaches have to be investigated. Therefore, this study aims to enhance existing methods for hazard and risk assessment for extreme events and is divided into three parts. In the first part, a regionalization approach for flood peak discharges was further developed and substantiated, especially regarding recurrence intervals of 200 to 10 000 years and a large number of small ungauged catchments. Model comparisons show that more confidence in such flood estimates for ungauged areas and very long recurrence intervals may be given as implied by statistical analysis alone. The hydraulic simulation in the second part is oriented towards hazard mapping and risk analyses covering the whole spectrum of relevant flood events. As the hydrodynamic simulation is directly coupled with a GIS, the results can be easily processed as local inundation depths for spatial risk analyses. For this, a new GIS-based software tool was developed, being presented in the third part, which enables estimations of the direct flood damage to single buildings or areas based on different established stage-damage functions. Furthermore, a new multifactorial approach for damage estimation is presented, aiming at the improvement of damage estimation on local scale by considering factors like building quality, contamination and precautionary measures. The methods and results from this study form the base for comprehensive risk analyses and flood management strategies.

A Basis Function Approach to Simulate Storm Surge Events for Coastal Flood Risk Assessment

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Wu, Wenyan; Westra, Seth; Leonard, Michael

2017-04-01

Storm surge is a significant contributor to flooding in coastal and estuarine regions, especially when it coincides with other flood producing mechanisms, such as extreme rainfall. Therefore, storm surge has always been a research focus in coastal flood risk assessment. Often numerical models have been developed to understand storm surge events for risk assessment (Kumagai et al. 2016; Li et al. 2016; Zhang et al. 2016) (Bastidas et al. 2016; Bilskie et al. 2016; Dalledonne and Mayerle 2016; Haigh et al. 2014; Kodaira et al. 2016; Lapetina and Sheng 2015), and assess how these events may change or evolve in the future (Izuru et al. 2015; Oey and Chou 2016). However, numeric models often require a lot of input information and difficulties arise when there are not sufficient data available (Madsen et al. 2015). Alternative, statistical methods have been used to forecast storm surge based on historical data (Hashemi et al. 2016; Kim et al. 2016) or to examine the long term trend in the change of storm surge events, especially under climate change (Balaguru et al. 2016; Oh et al. 2016; Rueda et al. 2016). In these studies, often the peak of surge events is used, which result in the loss of dynamic information within a tidal cycle or surge event (i.e. a time series of storm surge values). In this study, we propose an alternative basis function (BF) based approach to examine the different attributes (e.g. peak and durations) of storm surge events using historical data. Two simple two-parameter BFs were used: the exponential function and the triangular function. High quality hourly storm surge record from 15 tide gauges around Australia were examined. It was found that there are significantly location and seasonal variability in the peak and duration of storm surge events, which provides additional insights in coastal flood risk. In addition, the simple form of these BFs allows fast simulation of storm surge events and minimises the complexity of joint probability

Reconstructing the 2015 Flash Flood event of Salgar Colombia, The Case of a Poor Gauged Basin

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Velasquez, N.; Zapata, E.; Hoyos Ortiz, C. D.; Velez, J. I.

2017-12-01

Flash floods events associated with severe precipitation events are highly destructive, often resulting in significant human and economic losses. Due to their nature, flash floods trend to occur in medium to small basins located within complex high mountainous regions. In the Colombian Andean region these basins are very common, with the aggravating factor that the vulnerability is considerably high as some important human settlements are located within these basins, frequently occupating flood plains and other flash-flood prone areas. During the dawn of May 18 of 2015 two severe rainfall events generated a flash flood event in the municipality ofSalgar, La Liboriana basin, locatedin the northwestern Colombian Andes, resulting in more than 100 human casualties and significant economic losses. The present work is a reconstruction of the hydrological processes that took place before and during the Liboriana flash flood event, analyzed as a case of poorly gauged basin.The event conditions where recreated based on radar retrievals and a hydrological distributed model, linked with a proposed 1D hydraulic model and simple shallow landslide model. Results suggest that the flash flood event was caused by the occurrence of two successive severe convective events over the same basin, with an important modulation associated with soil characteristics and water storage.Despite of its simplicity, the proposed hydraulic model achieves a good representation of the flooded area during the event, with limitations due to the adopted spatial scale (12.7 meters, from ALOS PALSAR images). Observed landslides were obtained from satellite images; for this case the model simulates skillfully the landslide occurrence regions with small differences in the exact locations.To understand this case, radar data shows to be key due to specific convective cores location and rainfall intensity estimation.In mountainous regions, there exists a significant number of settlements with similar

Effect of climate change on seasonal monsoon in Asia and its impact on the variability of monsoon rainfall in Southeast Asia

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Yen Yi Loo

2015-11-01

Full Text Available Global warming and climate change is one of the most extensively researched and discussed topical issues affecting the environment. Although there are enough historical evidence to support the theory that climate change is a natural phenomenon, many research scientists are widely in agreement that the increase in temperature in the 20th century is anthropologically related. The associated effects are the variability of rainfall and cyclonic patterns that are being observed globally. In Southeast Asia the link between global warming and the seasonal atmospheric flow during the monsoon seasons shows varying degree of fuzziness. This study investigates the impact of climate change on the seasonality of monsoon Asia and its effect on the variability of monsoon rainfall in Southeast Asia. The comparison of decadal variation of precipitation and temperature anomalies before the 1970s found general increases which were mostly varying. But beyond the 1970s, global precipitation anomalous showed increases that almost corresponded with increases in global temperature anomalies for the same period. There are frequent changes and a shift westward of the Indian summer monsoon. Although precipitation is observed to be 70% below normal levels, in some areas the topography affects the intensity of rainfall. These shifting phenomenon of other monsoon season in the region are impacting on the variability of rainfall and the onset of monsoons in Southeast Asia and is predicted to delay for 15 days the onset of the monsoon in the future. The variability of monsoon rainfall in the SEA region is observed to be decadal and the frequency and intensity of intermittent flooding of some areas during the monsoon season have serious consequences on the human, financial, infrastructure and food security of the region.

Rapid formation of a modern bedrock canyon by a single flood event

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Lamb, Michael P.; Fonstad, Mark A.

2010-07-01

Deep river canyons are thought to form slowly over geological time (see, for example, ref. 1), cut by moderate flows that reoccur every few years. In contrast, some of the most spectacular canyons on Earth and Mars were probably carved rapidly during ancient megaflood events. Quantification of the flood discharge, duration and erosion mechanics that operated during such events is hampered because we lack modern analogues. Canyon Lake Gorge, Texas, was carved in 2002 during a single catastrophic flood. The event offers a rare opportunity to analyse canyon formation and test palaeo-hydraulic-reconstruction techniques under known topographic and hydraulic conditions. Here we use digital topographic models and visible/near-infrared aerial images from before and after the flood, discharge measured during the event, field measurements and sediment-transport modelling to show that the flood moved metre-sized boulders, excavated ~7m of limestone and transformed a soil-mantled valley into a bedrock canyon in just ~3days. We find that canyon morphology is strongly dependent on rock type: plucking of limestone blocks produced waterfalls, inner channels and bedrock strath terraces, whereas abrasion of cemented alluvium sculpted walls, plunge pools and streamlined islands. Canyon formation was so rapid that erosion might have been limited by the ability of the flow to transport sediment. We suggest that our results might improve hydraulic reconstructions of similar megafloods on Earth and Mars.

Hydrological simulation of flood transformations in the upper Danube River: Case study of large flood events

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Mitková Veronika Bačová

2016-12-01

Full Text Available The problem of understand natural processes as factors that restrict, limit or even jeopardize the interests of human society is currently of great concern. The natural transformation of flood waves is increasingly affected and disturbed by artificial interventions in river basins. The Danube River basin is an area of high economic and water management importance. Channel training can result in changes in the transformation of flood waves and different hydrographic shapes of flood waves compared with the past. The estimation and evolution of the transformation of historical flood waves under recent river conditions is only possible by model simulations. For this purpose a nonlinear reservoir cascade model was constructed. The NLN-Danube nonlinear reservoir river model was used to simulate the transformation of flood waves in four sections of the Danube River from Kienstock (Austria to Štúrovo (Slovakia under relatively recent river reach conditions. The model was individually calibrated for two extreme events in August 2002 and June 2013. Some floods that occurred on the Danube during the period of 1991–2002 were used for the validation of the model. The model was used to identify changes in the transformational properties of the Danube channel in the selected river reach for some historical summer floods (1899, 1954 1965 and 1975. Finally, a simulation of flood wave propagation of the most destructive Danube flood of the last millennium (August 1501 is discussed.

Flood characteristics of the Haor area in Bangladesh

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Suman, Asadusjjaman; Bhattacharya, Biswa

2013-04-01

In recent years the world has experienced deaths, large-scale displacement of people, billions of Euros of economic damage, mental stress and ecosystem impacts due to flooding. Global changes (climate change, population and economic growth, and urbanisation) are exacerbating the severity of flooding. The 2010 floods in Pakistan and the 2011 floods in Australia and Thailand demonstrate the need for concerted action in the face of global societal and environmental changes to strengthen resilience against flooding. Bangladesh is a country, which is frequently suffering from flooding. The current research is conducted in the framework of a project, which focuses on the flooding issues in the Haor region in the north-east of Bangladesh. A haor is a saucer-shaped depression, which is used during the dry period (December to mid-May) for agriculture and as a fishery during the wet period (June-November), and thereby presents a very interesting socio-economic perspective of flood risk management. Pre-monsoon flooding till mid-May causes agricultural loss and lot of distress whereas monsoon flooding brings benefits. The area is bordering India, thereby presenting trans-boundary issues as well, and is fed by some flashy Indian catchments. The area is drained mainly through the Surma-Kushiyara river system. The terrain generally is flat and the flashy characteristics die out within a short distance from the border. Limited studies on the region, particularly with the help of numerical models, have been carried out in the past. Therefore, an objective of the current research was to set up numerical models capable of reasonably emulating the physical system. Such models could, for example, associate different gauges to the spatio-temporal variation of hydrodynamic variables and help in carrying out a systemic study on the impact of climate changes. A 1D2D model, with one-dimensional model for the rivers (based on MIKE 11 modelling tool from Danish Hydraulic Institute) and a two

Fluvial hydrology and geomorphology of Monsoon-dominated Indian rivers

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Vishwas S. Kale

2005-11-01

Full Text Available The Indian rivers are dominantly monsoon rainfed. As a result, their regime characteristics are dictated by the spatio-temporal variations in the monsoon rainfall. Although the rivers carry out most of the geomorphic work during 4-5 months of the monsoon season, the nature and magnitude of response to variations in the discharge and sediment load varies with the basin size and relief characteristics. Large monsoon floods play a role of great importance on all the rivers. This paper describes the hydrological and geomorphological characteristics of the two major fluvial systems of the Indian region, namely the Himalayan fluvial system and the Peninsular fluvial system. Large number of studies published so far indicate that there are noteworthy differences between the two river systems, with respect to river hydrology, channel morphology, sediment load and behaviour. The nature of alterations in the fluvial system due to increased human interference is also briefly mentioned. This short review demonstrates that there is immense variety of rivers in India. This makes India one of the best places to study rivers and their forms and processes.

Physical and economic impacts of sea-level rise and low probability flooding events on coastal communities.

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Thomas Prime

Full Text Available Conventionally flood mapping typically includes only a static water level (e.g. peak of a storm tide in coastal flood inundation events. Additional factors become increasingly important when increased water-level thresholds are met during the combination of a storm tide and increased mean sea level. This research incorporates factors such as wave overtopping and river flow in a range of flood inundation scenarios of future sea-level projections for a UK case study of Fleetwood, northwest England. With increasing mean sea level it is shown that wave overtopping and river forcing have an important bearing on the cost of coastal flood events. The method presented converts inundation maps into monetary cost. This research demonstrates that under scenarios of joint extreme surge-wave-river events the cost of flooding can be increased by up to a factor of 8 compared with an increase in extent of up to a factor of 3 relative to "surge alone" event. This is due to different areas being exposed to different flood hazards and areas with common hazard where flood waters combine non-linearly. This shows that relying simply on flood extent and volume can under-predict the actual economic impact felt by a coastal community. Additionally, the scenario inundation depths have been presented as "brick course" maps, which represent a new way of interpreting flood maps. This is primarily aimed at stakeholders to increase levels of engagement within the coastal community.

Physical and economic impacts of sea-level rise and low probability flooding events on coastal communities.

Science.gov (United States)

Prime, Thomas; Brown, Jennifer M; Plater, Andrew J

2015-01-01

Conventionally flood mapping typically includes only a static water level (e.g. peak of a storm tide) in coastal flood inundation events. Additional factors become increasingly important when increased water-level thresholds are met during the combination of a storm tide and increased mean sea level. This research incorporates factors such as wave overtopping and river flow in a range of flood inundation scenarios of future sea-level projections for a UK case study of Fleetwood, northwest England. With increasing mean sea level it is shown that wave overtopping and river forcing have an important bearing on the cost of coastal flood events. The method presented converts inundation maps into monetary cost. This research demonstrates that under scenarios of joint extreme surge-wave-river events the cost of flooding can be increased by up to a factor of 8 compared with an increase in extent of up to a factor of 3 relative to "surge alone" event. This is due to different areas being exposed to different flood hazards and areas with common hazard where flood waters combine non-linearly. This shows that relying simply on flood extent and volume can under-predict the actual economic impact felt by a coastal community. Additionally, the scenario inundation depths have been presented as "brick course" maps, which represent a new way of interpreting flood maps. This is primarily aimed at stakeholders to increase levels of engagement within the coastal community.

Multi-decadal modulation of the El Nino-Indian monsoon relationship by Indian Ocean variability

International Nuclear Information System (INIS)

Ummenhofer, Caroline C; Sen Gupta, Alexander; Li Yue; Taschetto, Andrea S; England, Matthew H

2011-01-01

The role of leading modes of Indo-Pacific climate variability is investigated for modulation of the strength of the Indian summer monsoon during the period 1877-2006. In particular, the effect of Indian Ocean conditions on the relationship between the El Nino-Southern Oscillation (ENSO) and the Indian monsoon is explored. Using an extended classification for ENSO and Indian Ocean dipole (IOD) events for the past 130 years and reanalyses, we have expanded previous interannual work to show that variations in Indian Ocean conditions modulate the ENSO-Indian monsoon relationship also on decadal timescales. El Nino events are frequently accompanied by a significantly reduced Indian monsoon and widespread drought conditions due to anomalous subsidence associated with a shift in the descending branch of the zonal Walker circulation. However, for El Nino events that co-occur with positive IOD (pIOD) events, Indian Ocean conditions act to counter El Nino's drought-inducing subsidence by enhancing moisture convergence over the Indian subcontinent, with an average monsoon season resulting. Decadal modulations of the frequency of independent and combined El Nino and pIOD events are consistent with a strengthened El Nino-Indian monsoon relationship observed at the start of the 20th century and the apparent recent weakening of the El Nino-Indian monsoon relationship.

Multi-decadal modulation of the El Nino-Indian monsoon relationship by Indian Ocean variability

Energy Technology Data Exchange (ETDEWEB)

Ummenhofer, Caroline C; Sen Gupta, Alexander; Li Yue; Taschetto, Andrea S; England, Matthew H, E-mail: c.ummenhofer@unsw.edu.au [Climate Change Research Centre, University of New South Wales, Sydney (Australia)

2011-07-15

The role of leading modes of Indo-Pacific climate variability is investigated for modulation of the strength of the Indian summer monsoon during the period 1877-2006. In particular, the effect of Indian Ocean conditions on the relationship between the El Nino-Southern Oscillation (ENSO) and the Indian monsoon is explored. Using an extended classification for ENSO and Indian Ocean dipole (IOD) events for the past 130 years and reanalyses, we have expanded previous interannual work to show that variations in Indian Ocean conditions modulate the ENSO-Indian monsoon relationship also on decadal timescales. El Nino events are frequently accompanied by a significantly reduced Indian monsoon and widespread drought conditions due to anomalous subsidence associated with a shift in the descending branch of the zonal Walker circulation. However, for El Nino events that co-occur with positive IOD (pIOD) events, Indian Ocean conditions act to counter El Nino's drought-inducing subsidence by enhancing moisture convergence over the Indian subcontinent, with an average monsoon season resulting. Decadal modulations of the frequency of independent and combined El Nino and pIOD events are consistent with a strengthened El Nino-Indian monsoon relationship observed at the start of the 20th century and the apparent recent weakening of the El Nino-Indian monsoon relationship.

Monsoonal influence on variation of hydrochemistry and isotopic signatures: Implications for associated arsenic release in groundwater

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Majumder, Santanu; Datta, Saugata; Nath, Bibhash; Neidhardt, Harald; Sarkar, Simita; Roman-Ross, Gabriela; Berner, Zsolt; Hidalgo, Manuela; Chatterjee, Debankur; Chatterjee, Debashis

2016-04-01

The present study examines the groundwater and surface water geochemistry of two different geomorphic domains within the Chakdaha block, West Bengal, in an attempt to decipher potential influences of groundwater abstraction on the hydrochemical evolution of the aquifer, the effect of different water inputs (monsoon rain, irrigation and downward percolation from surface water impoundments) to the groundwater system and concomitant As release. A low-land flood plain and a natural levee have been selected for this purpose. Although the stable isotopic signatures of oxygen (δ18O) and hydrogen (δ2H) are largely controlled by local precipitation, the isotopic composition falls sub-parallel to the Global Meteoric Water Line (GMWL). The Cl/Br molar ratio indicates vertical recharge into the wells within the flood plain area, especially during the post-monsoon season, while influences of both evaporation and vertical mixing are visible within the natural levee wells. Increase in mean DOC concentrations (from 1.33 to 6.29 mg/L), from pre- to post-monsoon season, indicates possible inflow of organic carbon to the aquifer during the monsoonal recharge. Concomitant increase in AsT, Fe(II) and HCO3- highlights a possible initial episode of reductive dissolution of As-rich Fe-oxyhydroxides. The subsequent sharp increase in the mean As(III) proportions (by 223%), particularly in the flood plain samples during the post-monsoon season, which is accompanied by a slight increase in mean AsT (7%) may refer to anaerobic microbial degradation of DOC coupled with the reduction of As(V) to As(III) without triggering additional As release from the aquifer sediments.

Multiscale Aspects of the Storm Producing the June 2013 Flooding in Uttarakhand, India

Energy Technology Data Exchange (ETDEWEB)

Houze, R. A. [Department of Atmospheric Sciences, University of Washington, Seattle, and Pacific Northwest National Laboratory, Richland, Washington; McMurdie, L. A. [Department of Atmospheric Sciences, University of Washington, Seattle, Washington; Rasmussen, K. L. [Department of Atmospheric Science, Colorado State University, Fort Collins, Colorado; Kumar, A. [NASA Goddard Space Flight Center, Greenbelt, and Earth System Science Interdisciplinary Center, University of Maryland, College Park, College Park, Maryland; Chaplin, M. M. [Department of Atmospheric Sciences, University of Washington, Seattle, Washington

2017-11-01

Conditions producing disastrous flooding in Uttarakhand, India, in June 2013 differed from conditions that produced other notorious floods in the Himalayan region in recent years. During the week preceding the Uttarakhand flood, deep convection moistened the mountainsides, making them vulnerable to flooding. However, the precipitation producing the flood was not associated with a deep convective event. Rather, an eastward-propagating upper-level trough in the westerlies extended abnormally far southward, with the jet reaching the Himalayas. The south end of the trough merged with a monsoon low moving westward across India. The merged system produced persistent moist low-level flow oriented normal to the Himalayas that advected large amounts of water vapor into the Uttarakhand region. The flow was moist neutral when it passed over the Himalayan barrier, and orographic lifting produced heavy continuous rain over the region for 2–3 days. The precipitation was largely stratiform in nature although embedded convection of moderate depth occurred along the foothills, where some mild instability was being released. The Uttarakhand flood had characteristics in common with major 2013 floods in the Rocky Mountains in Colorado and Alberta, Canada.

Hydraulic description of a flood event with optical remote sensors: a constructive constraint on modelling uncertainties

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Battiston, Stéphanie; Allenbach, Bernard

2010-05-01

The exceptional characteristics of the December 2003 Rhône flood event (particularly high water flows, extent of the affected area, important damages especially in the region of Arles) make it be considered as a reference flood episode of this French river and a very well-known event. During the crisis, the International Charter "Space and Major Disasters" was triggered by the French Civil Protection for the rapid mapping of the flooding using Earth Observation imagery in order to facilitate crisis operations. As a result, more than 60 satellite images covering the flood were acquired over a 10 days period following the peak flow. Using the opportunity provided by this incomparable data coverage, the French Ministry of the Environment ordered a study on the evaluation of remote sensing's potential benefits for flood management. One of the questions asked by the risk managers was: what type of flood information can be provided by the different remote sensing platforms? Elements of response were delivered mainly in the form of a comprehensive compilation of maps and illustrations, displaying the main hydraulic elements (static ones as well as dynamic ones), initially listed and requested by hydrologists (more precisely, by a regional engineering society specialised in hydraulics and hydrology and in charge of a field campaign during the event), observed on different optical images of the flood event having affected the plain between Tarascon (upstream) and Arles (downstream). It is seen that a careful mapping of all flood traces visible on remote sensing event imagery - apparent water, moisture traces, breaches, overflows, stream directions, impermeable boundaries … - delivers a valuable vision of the flood's occurrence combining accuracy and comprehensiveness. In fact, optical imagery offers a detailed vision of the event : moisture traces complete flood traces extent; the observation of draw-off directions through waterproof barriers reveals hydraulic

Changing frequency of flooding in Bangladesh: Is the wettest place on Earth getting wetter?

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Haustein, K.; Uhe, P.; Rimi, R.; Islam, A. S.; Otto, F. E. L.

2017-12-01

Human influence on the Asian monsoon is exerted by two counteracting forces, (1) anthropogenic warming due to the influence of increasing Greenhouse Gas (GHG) emissions and (2) radiative cooling due to increased amounts of anthropogenic aerosols. GHG emissions tend to intensify the water cycle and increase monsoon precipitation, whereas aerosols are considered to have the opposite effect. On larger scales, aerosols may be responsible for meridional circulation anomalies as well as direct cooling effects, with an associated tendency for drier monsoon seasons that compensate a change towards wetter conditions in a purely GHG-driven scenario. On regional scales, aerosols weaken the thermal contrast between land and ocean which acts to inhibit the monsoon too. As a result, neither observations nor model simulations that consider all human influences suggest clear changes in extreme precipitation at present. In actual reality we are essentially committed to more rainfall extremes already as aerosol pollution will eventually be reduced regardless of future GHG emissions. Thus we argue that it is crucial to assess the risk related to removing anthropogenic aerosols from the current world as opposed to standard experiments that use projected climate scenarios. We present results from on analysis of extreme precipitation that led to the Bangladesh floods in summer 2016. Since the Meghalaya Hills are the major contributor to flood waters in Bangladesh, we focus on this region, despite slightly higher rainfall anomalies further west. More specifically, we primarily analyze the grid point representing Cherrapunji, also known to be the wettest place on Earth (situated on the southern flank of Meghalaya Hills). We use the weather@home HadAM3P model at 50km spatial resolution. Our model results generally support the notion that rainfall extremes in Cherrapunji might have become more likely already. Mean rainfall is slightly lowered, but 21-day maximum rainfall under current

Variable partitioning of flow and sediment transfer through a large river diffluence-confluence unit across a monsoonal flood pulse

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Hackney, C. R.; Aalto, R. E.; Darby, S. E.; Parsons, D. R.; Leyland, J.; Nicholas, A. P.; Best, J.

2016-12-01

Bifurcations represent key morphological nodes within the channel networks of anabranching and braided fluvial channels, playing an important role in controlling local bed morphology, the routing of sediment and water, and defining the stability of the downstream reaches. Herein, we detail field observations of the three-dimensional flow structure, bed morphological changes and partitioning of both flow discharge and suspended sediment through a large diffluence-confluence unit on the Mekong River, Cambodia, across a range of flow stages (from 13,500 m3 s-1 to 27,000 m3 s-1) over the monsoonal flood-pulse cycle. We show that the discharge asymmetry (a measure of the disparity between discharges distributed down the left and right branches of the bifurcation) varies with flow discharge and that the influence of upstream curvature-induced cross-stream water surface slope and bed morphological changes are first-order controls in modulating the asymmetry in bifurcation discharge. Flow discharge is shown to play a key role in defining the morphodynamics of the diffluence-confluence unit downstream of the bifurcation. Our data show that during peak flows (Q 27,000 m3 s-1), the downstream island complex acts as a net sink of suspended sediment (with 2600 kg s-1 being deposited between the diffluence and confluence), whereas during lower flows, on both the rising and falling limbs of the flood wave, the sediment balance is in quasi-equilibrium. We propose a new conceptual model of bifurcation stability that incorporates varying flood discharge and in which the long term stability of the bifurcation, as well as the larger channel planform and morphology of the diffluence-confluence unit, are controlled by the variations in flood discharge.

Lightning activity, rainfall and flash flooding – occasional or interrelated events? A case study in the island of Crete

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A. G. Koutroulis

2012-04-01

Full Text Available The majority of cyclones passing over Crete in late autumn to early winter originate from southwest, west and northwest and are of varying size and intensity. A number of these cyclones cause flash floods. The present study reports the possible relationships between lighting activity and high precipitation related to flash flood events. In this study an attempt was made to correlate the lightning number and location, recorded by the ZEUS lightning detection system, with the rainfall characteristics for sixteen rain events (4 flood and 12 non-flood events on the island of Crete, during the period 2008–2009. Spatiotemporal analysis of rain and rain rate with flash count was performed with respect to distance (radius of flashes from raingauge location at various temporal scales, in order to examine the correlation of accumulated rainfall and lightning activity. The maximum attained statistical significant correlation was obtained within a circular area of an average radius of 15 km around the raingauge, and an average time lag of flash count prior precipitation accumulation of 15 min. The maximum correlation between the lightning and rainfall data is obtained for shorter time lags for the flood events (15 min than the non-flood events (25 min, that could reflect the faster propagation of flood triggering storms due to high convective activity. Results show increased lightning activity occurring during flood triggering storms, by an average of four times higher. Furthermore, there is evidence that the number of flashes that occur during a precipitation event is related to precipitation depth when the latter is adequate to produce a flood event. Differences between flood and non-flood producing storms need to be further assessed by analyzing more independent parameters, including the synoptic conditions and dominant flash flood hydrological generating processes.

Characterization of the Temporal Clustering of Flood Events across the Central United States in terms of Climate States

Science.gov (United States)

Mallakpour, Iman; Villarini, Gabriele; Jones, Michael; Smith, James

2016-04-01

The central United States is a region of the country that has been plagued by frequent catastrophic flooding (e.g., flood events of 1993, 2008, 2013, and 2014), with large economic and social repercussions (e.g., fatalities, agricultural losses, flood losses, water quality issues). The goal of this study is to examine whether it is possible to describe the occurrence of flood events at the sub-seasonal scale in terms of variations in the climate system. Daily streamflow time series from 774 USGS stream gage stations over the central United States (defined here to include North Dakota, South Dakota, Nebraska, Kansas, Missouri, Iowa, Minnesota, Wisconsin, Illinois, West Virginia, Kentucky, Ohio, Indiana, and Michigan) with a record of at least 50 years and ending no earlier than 2011 are used for this study. We use a peak-over-threshold (POT) approach to identify flood peaks so that we have, on average two events per year. We model the occurrence/non-occurrence of a flood event over time using regression models based on Cox processes. Cox processes are widely used in biostatistics and can be viewed as a generalization of Poisson processes. Rather than assuming that flood events occur independently of the occurrence of previous events (as in Poisson processes), Cox processes allow us to account for the potential presence of temporal clustering, which manifests itself in an alternation of quiet and active periods. Here we model the occurrence/non-occurrence of flood events using two climate indices as climate time-varying covariates: the North Atlantic Oscillation (NAO) and the Pacific-North American pattern (PNA). The results of this study show that NAO and/or PNA can explain the temporal clustering in flood occurrences in over 90% of the stream gage stations we considered. Analyses of the sensitivity of the results to different average numbers of flood events per year (from one to five) are also performed and lead to the same conclusions. The findings of this work

A prediction and damage assessment model for snowmelt flood events in middle and high latitudes Region

Science.gov (United States)

Qiao, C.; Huang, Q.; Chen, T.; Zhang, X.

2017-12-01

In the context of global warming, the snowmelt flood events in the mountainous area of the middle and high latitudes are increasingly frequent and create severe casualties and property damages. Carrying out the prediction and risk assessment of the snowmelt flood is of great importance in the water resources management, the flood warning and prevention. Based on the remote sensing and GIS techniques, the relationships of the variables influencing the snowmelt flood such as the snow area, the snow depth, the air temperature, the precipitation, the land topography and land covers are analyzed and a prediction and damage assessment model for snowmelt floods is developed. This model analyzes and predicts the flood submerging area, flood depth, flood grade, and the damages of different underlying surfaces in the study area in a given time period based on the estimation of snowmelt amount, the snowmelt runoff, the direction and velocity of the flood. Then it was used to predict a snowmelt flood event in the Ertis River Basin in northern Xinjiang, China, during March and June, 2005 and to assess its damages including the damages of roads, transmission lines, settlements caused by the floods and the possible landslides using the hydrological and meteorological data, snow parameter data, DEM data and land use data. A comparison was made between the prediction results from this model and observation data including the flood measurement and its disaster loss data, which suggests that this model performs well in predicting the strength and impact area of snowmelt flood and its damage assessment. This model will be helpful for the prediction and damage assessment of snowmelt flood events in the mountainous area in the middle and high latitudes in spring, which has great social and economic significance because it provides a relatively reliable method for snowmelt flood prediction and reduces the possible damages caused by snowmelt floods.

Groundwater hydrochemistry,Variation of Arsenic and Monsoonal influence : An explanation regarding release mechanism assisted by isotopic signatures

Science.gov (United States)

Chatterjee, Debashis

2017-04-01

The investigation examines the groundwater and surface water geochemistry of two different geomorphics in West Bengal. During investigation, several key factors are taken into account e.g. potential influences of groundwater abstraction on the hydrochemical evolution of the aquifer, the effect of different water inputs (monsoon rain, irrigation and downward percolation from surface water impoundments) to the groundwater system and accompanying As release. A natural levee and low-land flood plain have been chosen for said investigation. The results reveal that the stable isotopic signatures of oxygen (d18O) and hydrogen (d2H) are governed by local precipitation, the isotopic composition falls sub-parallel to the Global Meteoric Water Line (GMWL). The Cl/Br molar ratio indicates vertical recharge into the wells within the flood plain area, notably during the post-monsoon season, while influences of both evaporation and vertical mixing are visible within the natural levee wells. The important finding is the increasing mean DOC concentrations (from 1.33 to 6.29 mg/L), from pre- to post-monsoon season, which is indicative of possible inflow of organic carbon to the aquifer during the monsoonal recharge. This suggests the subsequent increase in AsT, Fe(II) and HCO3 highlighting a possible initial episode of reductive dissolution of As-rich Fe-oxyhydroxides. The abrupt increase in the mean As(III) proportions (by 223%), notably in the flood plain samples during the post-monsoon season. This is attended by a slight increase in mean AsT (7%). This may refer to anaerobic microbial degradation of DOC coupled with the reduction of As(V) to As(III) without resulting in additional As release from the aquifer sediments.

Assessing the Impacts of Flooding Caused by Extreme Rainfall Events Through a Combined Geospatial and Numerical Modeling Approach

Science.gov (United States)

Santillan, J. R.; Amora, A. M.; Makinano-Santillan, M.; Marqueso, J. T.; Cutamora, L. C.; Serviano, J. L.; Makinano, R. M.

2016-06-01

In this paper, we present a combined geospatial and two dimensional (2D) flood modeling approach to assess the impacts of flooding due to extreme rainfall events. We developed and implemented this approach to the Tago River Basin in the province of Surigao del Sur in Mindanao, Philippines, an area which suffered great damage due to flooding caused by Tropical Storms Lingling and Jangmi in the year 2014. The geospatial component of the approach involves extraction of several layers of information such as detailed topography/terrain, man-made features (buildings, roads, bridges) from 1-m spatial resolution LiDAR Digital Surface and Terrain Models (DTM/DSMs), and recent land-cover from Landsat 7 ETM+ and Landsat 8 OLI images. We then used these layers as inputs in developing a Hydrologic Engineering Center Hydrologic Modeling System (HEC HMS)-based hydrologic model, and a hydraulic model based on the 2D module of the latest version of HEC River Analysis System (RAS) to dynamically simulate and map the depth and extent of flooding due to extreme rainfall events. The extreme rainfall events used in the simulation represent 6 hypothetical rainfall events with return periods of 2, 5, 10, 25, 50, and 100 years. For each event, maximum flood depth maps were generated from the simulations, and these maps were further transformed into hazard maps by categorizing the flood depth into low, medium and high hazard levels. Using both the flood hazard maps and the layers of information extracted from remotely-sensed datasets in spatial overlay analysis, we were then able to estimate and assess the impacts of these flooding events to buildings, roads, bridges and landcover. Results of the assessments revealed increase in number of buildings, roads and bridges; and increase in areas of land-cover exposed to various flood hazards as rainfall events become more extreme. The wealth of information generated from the flood impact assessment using the approach can be very useful to the

Characterization of a Mediterranean flash flood event using rain gauges, radar, GIS and lightning data

Directory of Open Access Journals (Sweden)

M. Barnolas

2008-06-01

Full Text Available Flash flood events are very common in Catalonia, generating a high impact on society, including losses in life almost every year. They are produced by the overflowing of ephemeral rivers in narrow and steep basins close to the sea. This kind of floods is associated with convective events producing high rainfall intensities. The aim of the present study is to analyse the 12–14 September 2006 flash flood event within the framework of the characteristics of flood events in the Internal Basins of Catalonia (IBC. To achieve this purpose all flood events occurred between 1996 and 2005 have been analysed. Rainfall and radar data have been introduced into a GIS, and a classification of the events has been done. A distinction of episodes has been made considering the spatial coverage of accumulated rainfall in 24 h, and the degree of the convective precipitation registered. The study case can be considered as a highly convective one, with rainfalls covering all the IBC on the 13th of September. In that day 215.9 mm/24 h were recorded with maximum intensities above 130 mm/h. A complete meteorological study of this event is also presented. In addition, as this is an episode with a high lightning activity it has been chosen to be studied into the framework of the FLASH project. In this way, a comparison between this information and raingauge data has been developed. All with the goal in mind of finding a relation between lightning density, radar echoes and amounts of precipitation. Furthermore, these studies improve our knowledge about thunderstorms systems.

External flooding event analysis in a PWR-W with MAAP5

International Nuclear Information System (INIS)

Fernandez-Cosials, Mikel Kevin; Jimenez, Gonzalo; Barreira, Pilar; Queral, Cesar

2015-01-01

Highlights: • External flooding preceded by a SCRAM is simulated with MAAP5.01. • Sensitivities include AFW-TDP, SLOCA and operator preventive actions. • SLOCA flow is the dominant factor in the sequences. • Vessel failure is avoidable with operator preventive actions. - Abstract: The Fukushima accident has drawn attention even more to the importance of external events and loss of energy supply on safety analysis. Since 2011, several Station Blackout (SBO) analyses have been done for all type of reactors. The most post-Fukushima studies analyze a pure and straight SBO transient, but the Fukushima accident was more complex than a standard SBO. At Fukushima accident, the SBO was a consequence of an external flooding from the tsunami and occurred 40 min after an emergency shutdown (SCRAM) caused by the earthquake. The first objective of this paper is to assume the consequences of an external flooding accident in a PWR site caused by a river flood, a dam break or a tsunami, where all the plant is damaged, not only the diesel generators. The second objective is to analyze possible actions to be performed in the time between the earthquake event (that causes a SCRAM) and the external flooding arrival, which could be applicable to accidents such as dam failures or river flooding in order to avoid more severe consequences, delay the core damage and improve the accident management. The results reveal how the actuation of the different systems and equipments affect the core damage time and how some actions could delay the core damage time enough to increase the possibility of AC power recovery

Modelling the interaction between flooding events and economic growth

Science.gov (United States)

Grames, Johanna; Grass, Dieter; Prskawetz, Alexia; Blöschl, Günther

2015-04-01

Socio-hydrology describes the interaction between the socio-economy, water and population dynamics. Recent models analyze the interplay of community risk-coping culture, flooding damage and economic growth (Di Baldassarre, 2013, Viglione, 2014). These models descriptively explain the feedbacks between socio-economic development and natural disasters like floods. Contrary to these descriptive models, our approach develops an optimization model, where the intertemporal decision of an economic agent interacts with the hydrological system. This is the first economic growth model describing the interaction between the consumption and investment decisions of an economic agent and the occurrence of flooding events: Investments in defense capital can avoid floods even when the water level is high, but on the other hand such investment competes with investment in productive capital and hence may reduce the level of consumption. When floods occur, the flood damage therefore depends on the existing defense capital. The aim is to find an optimal tradeoff between investments in productive versus defense capital such as to optimize the stream of consumption in the long-term. We assume a non-autonomous exogenous periodic rainfall function (Yevjevich et.al. 1990, Zakaria 2001) which implies that the long-term equilibrium will be periodic . With our model we aim to derive mechanisms that allow consumption smoothing in the long term, and at the same time allow for optimal investment in flood defense to maximize economic output. We choose an aggregate welfare function that depends on the consumption level of the society as the objective function. I.e. we assume a social planer with perfect foresight that maximizes the aggregate welfare function. Within our model framework we can also study whether the path and level of defense capital (that protects people from floods) is related to the time preference rate of the social planner. Our model also allows to investigate how the frequency

On the dynamics of synoptic scale cyclones associated with flood events in Crete

Science.gov (United States)

Flocas, Helena; Katavoutas, George; Tsanis, Ioannis; Iordanidou, Vasiliki

2015-04-01

Flood events in the Mediterranean are frequently linked to synoptic scale cyclones, although topographical or anthropogenic factors can play important role. The knowledge of the vertical profile and dynamics of these cyclones can serve as a reliable early flood warning system that can further help in hazard mitigation and risk management planning. Crete is the second largest island in the eastern Mediterranean region, being characterized by high precipitation amounts during winter, frequently causing flood events. The objective of this study is to examine the dynamic and thermodynamic mechanisms at the upper and lower levels responsible for the generation of these events, according to their origin domain. The flooding events were recorded for a period of almost 20 years. The surface cyclones are identified with the aid of MS scheme that was appropriately modified and extensively employed in the Mediterranean region in previous studies. Then, the software VTS, specially developed for the Mediterranean cyclones, was employed to investigate the vertical extension, slope and dynamic/kinematic characteristics of the surface cyclones. Composite maps of dynamic/thermodynamic parameters, such as potential vorticity, temperature advection, divergence, surface fluxes were then constructed before and during the time of the flood. The dataset includes 6-hourly surface and isobaric analyses on a 0.5° x 0.5° regular latitude-longitude grid, as derived from the ERA-INTERIM Reanalysis of the ECMWF. It was found that cyclones associated with flood events in Crete mainly generate over northern Africa or southern eastern Mediterranean region and experience their minimum pressure over Crete or southwestern Greece. About 84% of the cyclones extend up to 500hPa, demonstrating that they are well vertically well-organized systems. The vast majority (almost 84%) of the surface cyclones attains their minimum pressure when their 500 hpa counterparts are located in the NW or SW, confirming

Integrating a Typhoon Event Database with an Optimal Flood Operation Model on the Real-Time Flood Control of the Tseng-Wen Reservoir

Science.gov (United States)

Chen, Y. W.; Chang, L. C.

2012-04-01

Typhoons which normally bring a great amount of precipitation are the primary natural hazard in Taiwan during flooding season. Because the plentiful rainfall quantities brought by typhoons are normally stored for the usage of the next draught period, the determination of release strategies for flood operation of reservoirs which is required to simultaneously consider not only the impact of reservoir safety and the flooding damage in plain area but also for the water resource stored in the reservoir after typhoon becomes important. This study proposes a two-steps study process. First, this study develop an optimal flood operation model (OFOM) for the planning of flood control and also applies the OFOM on Tseng-wun reservoir and the downstream plain related to the reservoir. Second, integrating a typhoon event database with the OFOM mentioned above makes the proposed planning model have ability to deal with a real-time flood control problem and names as real-time flood operation model (RTFOM). Three conditions are considered in the proposed models, OFOM and RTFOM, include the safety of the reservoir itself, the reservoir storage after typhoons and the impact of flooding in the plain area. Besides, the flood operation guideline announced by government is also considered in the proposed models. The these conditions and the guideline can be formed as an optimization problem which is solved by the genetic algorithm (GA) in this study. Furthermore, a distributed runoff model, kinematic-wave geomorphic instantaneous unit hydrograph (KW-GIUH), and a river flow simulation model, HEC-RAS, are used to simulate the river water level of Tseng-wun basin in the plain area and the simulated level is shown as an index of the impact of flooding. Because the simulated levels are required to re-calculate iteratively in the optimization model, applying a recursive artificial neural network (recursive ANN) instead of the HEC-RAS model can significantly reduce the computational burden of

Impact of climate change on extreme rainfall events and flood risk

Indian Academy of Sciences (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 ...

Towards a whole-network risk assessment for railway bridge failures caused by scour during flood events

Directory of Open Access Journals (Sweden)

Lamb Rob

2016-01-01

Full Text Available Localised erosion (scour during flood flow conditions can lead to costly damage or catastrophic failure of bridges, and in some cases loss of life or significant disruption to transport networks. Here, we take a broad scale view to assess risk associated with bridge scour during flood events over an entire infrastructure network, illustrating the analysis with data from the British railways. There have been 54 recorded events since 1846 in which scour led to the failure of railway bridges in Britain. These events tended to occur during periods of extremely high river flow, although there is uncertainty about the precise conditions under which failures occur, which motivates a probabilistic analysis of the failure events. We show how data from the historical bridge failures, combined with hydrological analysis, have been used to construct fragility curves that quantify the conditional probability of bridge failure as a function of river flow, accompanied by estimates of the associated uncertainty. The new fragility analysis is tested using flood events simulated from a national, spatial joint probability model for extremes in river flows. The combined models appear robust in comparison with historical observations of the expected number of bridge failures in a flood event, and provide an empirical basis for further broad-scale network risk analysis.

Long range forecasting of summer monsoon rainfall from SST in the central equatorial Indian Ocean

Digital Repository Service at National Institute of Oceanography (India)

Sadhuram, Y; Murthy, T.V.R.

of summer monsoon rainfall from SST in the central equatorial Indian ocean Y. Sadhuram and T. V. Ramana Murthy National Institute of Oceanography, Regional Centre, 176, Lawson's Bay Colony, . Visakhapatnam-530017 ABSTRACT Severalprediction tedmiques have... and droughts associated with strong and weak monsoons greatly influence the economy of the country. Most of the droughts and floods are associated with EI-Nino and La- Nina respectively (Webster andYang3 and krishna Kumar et al\\. The relationship between ENSO...

Telling and measuring urban floods: event reconstruction by means of public-domain media

Science.gov (United States)

Macchia, S.; Gallo, E.; Claps, P.

2012-04-01

In the last decade, the diffusion of mobile telephones and ond of low-cost digital cameras have changed the public approach to catastrophes. As regards floods, it has become widespread the availability of images and videos taken in urban areas. Searching into Youtube or Youreporter, for example, one can understand how often citizen are considering to report even scary events. Nowadays these amateurs videos are often used in news world reports, which often increase or dampen the public perception of flood risk. More importantly, these amateur videos can play a crucial role in a didactic and technical representation of media flooding problems. The question so arise: why don't use the amateur videos for civil protection purposes? This work shows a new way to use flood images and videos to obtain technical data and spread safety information. Specifically, we show how to determine the height and speed of water flow, which have been achieved in some places during Genoa flood - 4th November 2011 - For this event we have downloaded more than 50 videos from different websites, where the authors have provided information about the time of recording, the geographical coordinates and the height above ground of the point of recording. The support by Google tools, such as Google maps and StreetWiew © has allowed us to geographically locate the recording points, so to put together shots and slides necessary to put together a whole reconstruction of the event. Future research will be in the direction of using these videos to generate a tool for the Google platforms, in order to address an easily achievable, yet accurate, information to the public, so to warn people on how to behave in front of imminent floods.

Projected large flood event sensitivity to projection selection and temporal downscaling methodology

Energy Technology Data Exchange (ETDEWEB)

Raff, D. [U.S. Dept. of the Interior, Bureau of Reclamation, Denver, Colorado (United States)

2008-07-01

Large flood events, that influence regulatory guidelines as well as safety of dams decisions, are likely to be affected by climate change. This talk will evaluate the use of climate projections downscaled and run through a rainfall - runoff model and its influence on large flood events. The climate spatial downscaling is performed statistically and a re-sampling and scaling methodology is used to temporally downscale from monthly to daily signals. The signals are run through a National Weather Service operational rainfall-runoff model to produce 6-hour flows. The flows will be evaluated for changes in large events at look-ahead horizons from 2011 - 2040, 2041 - 2070, and 2071 - 2099. The sensitivity of results will be evaluated with respect to projection selection criteria and re-sampling and scaling criteria for the Boise River in Idaho near Lucky Peak Dam. (author)

Projected large flood event sensitivity to projection selection and temporal downscaling methodology

International Nuclear Information System (INIS)

Raff, D.

2008-01-01

Large flood events, that influence regulatory guidelines as well as safety of dams decisions, are likely to be affected by climate change. This talk will evaluate the use of climate projections downscaled and run through a rainfall - runoff model and its influence on large flood events. The climate spatial downscaling is performed statistically and a re-sampling and scaling methodology is used to temporally downscale from monthly to daily signals. The signals are run through a National Weather Service operational rainfall-runoff model to produce 6-hour flows. The flows will be evaluated for changes in large events at look-ahead horizons from 2011 - 2040, 2041 - 2070, and 2071 - 2099. The sensitivity of results will be evaluated with respect to projection selection criteria and re-sampling and scaling criteria for the Boise River in Idaho near Lucky Peak Dam. (author)

Exploring How Changing Monsoonal Dynamics and Human Pressures Challenge Multi-Reservoir Management of Food-Energy-Water Tradeoffs

Science.gov (United States)

Quinn, J.; Reed, P. M.; Giuliani, M.; Castelletti, A.; Oyler, J.; Nicholas, R.

2017-12-01

Multi-reservoir systems require robust and adaptive control policies capable of managing evolving hydroclimatic variability and human demands across a wide range of time scales. This is especially true for systems with high intra-annual and inter-annual variability, such as monsoonal river systems that need to buffer against seasonal droughts while also managing extreme floods. Moreover, the timing, intensity, duration, and frequency of these hydrologic extremes may be affected by deeply uncertain changes in socioeconomic and climatic pressures. This study contributes an innovative method for exploring how possible changes in the timing and magnitude of monsoonal seasonal extremes impact the robustness of reservoir operating policies optimized to historical conditions assuming stationarity. We illustrate this analysis on the Red River basin in Vietnam, where reservoirs and dams serve as important sources of hydropower production, irrigable water supply, and flood protection for the capital city of Hanoi. Applying our scenario discovery approach, we find food-energy-water tradeoffs are exacerbated by potential hydrologic shifts, with wetter worlds threatening the ability of operating strategies to manage flood risk and drier worlds threatening their ability to provide sufficient water supply and hydropower production, especially if demands increase. Most notably, though, amplification of the within-year monsoonal cycle and increased inter-annual variability threaten all of the above. These findings highlight the importance of considering changes in both lower order moments of annual streamflow and intra-annual monsoonal behavior when evaluating the robustness of alternative water systems control strategies for managing deeply uncertain futures.

Impact of floods induced by extreme precipitation events on public health

Science.gov (United States)

Mavroulis, Spyridon; Mavrouli, Maria; Lekkas, Efthymios; Tsakris, Athanassios

2017-04-01

Hydrometeorological disasters comprise the most reported type of natural disaster, and floods account for the majority of disasters in this category in both developed and developing countries. Flooding can lead to extensive morbidity and mortality and pose multiple risks to public health throughout the world. This study involved an extensive and systematic literature review of 124 research publications related to public health impact of 98 floods that occurred globally (Oceania 4, Africa 9, America 22, Europe 24, Asia 39) from 1942 to 2014. The inclusion criteria were literature type comprising journal articles and official reports, natural disaster type including floods induced after extreme precipitation events (accumulation of rainwater in poorly-drained environments, riverine and flash floods), population type including humans, and outcome measure characterized by infectious diseases (ID) incidence increase. The potential post-flood ID are classified into 13 groups including rodent-borne (reported in 38 of the total 98 events, 38.78%), water-borne (33, 33.67%), vector-borne (25, 25.51%), respiratory (19, 19.39%), fecal-oral (14, 14.29%), skin (9, 9.18%), blood-borne (4, 4.08%), eye (3, 3.06%), soil-related (3, 3.06%), ear (2, 2.04%), fungal (1, 1.02%) and wound-borne (1, 1.02%) ID. Based on available age and genre data, it is concluded that the most vulnerable population groups are predominantly young children (age ≤ 5 years) and male. The most fatal post-flood ID are leptospirosis and diarrhea followed by respiratory tract infections. The detected risk factors include (1) poor economic status and living in flood prone areas, (2) destruction of infrastructures, disruption of public utilities and interruption of basic public health services such as vector control programs, (3) direct physical exposure to sewage-polluted flood water, (4) lack of adequate potable water and water-supply from contaminated ponds and tube wells along with lack of distribution of

Spatial analysis of landfills in respect to flood events and sea-level rise using ArcGIS Pro

OpenAIRE

Taylor, Benjamin S; Fei, Songlin

2017-01-01

"Recently in the news, media coverage of flood events has garnered attention due to tropical storms like Hurricane Harvey and the costly damages that resulted. Under climate change, events like sea-level rise (SLR) and flooding are projected to increase which threaten infrastructure, making it necessary for proper planning before, during, and after installation of landfills to mitigate risk. Studies in Austria and the UK have revealed that many landfills are located in flood zones in addition...

EPISODIC EVENTS: THE EFFECT OF FLOODS ON NUTRIENT TRANSPORT IN A NORTHWESTERN, USA ESTUARY

Science.gov (United States)

To estimate the effects of storms on nutrient transport, dissolved nutrients and suspended sediment loads were measured relative to stream discharge in the Yaquina River, OR for three storm events. Episodic events, particularly high rainfall or flood events may transport high di...

Tropical and Monsoonal Studies.

Science.gov (United States)

1988-01-01

Duiing the cold surge event the balance of the 200 mb zonal momentum budget is between the zonal advecton of momentum and the coriolis, aceration ...over the South China Sea in the Malaysia ACKNOWLEDGEMENTS region during the winter monsoon, December 1973. Pure AppL Geophys., 115, 1303-1334. We wish

Recent trends in pre-monsoon daily temperature extremes over India

Indian Academy of Sciences (India)

e-mail: kotha@tropmet.res.in. Extreme climate and weather events are increasingly being recognized as key aspects of climate change. Pre-monsoon season ... change in day-to-day magnitude of fluctuations of pre-monsoon maximum and minimum tempera- tures. ... by high exceedence counts during drought periods.

Characterization of flood and precipitation events in Southwestern Germany and stochastic simulation of extreme precipitation (Project FLORIS-SV)

Science.gov (United States)

Florian, Ehmele; Michael, Kunz

2016-04-01

Several major flood events occurred in Germany in the past 15-20 years especially in the eastern parts along the rivers Elbe and Danube. Examples include the major floods of 2002 and 2013 with an estimated loss of about 2 billion Euros each. The last major flood events in the State of Baden-Württemberg in southwest Germany occurred in the years 1978 and 1993/1994 along the rivers Rhine and Neckar with an estimated total loss of about 150 million Euros (converted) each. Flood hazard originates from a combination of different meteorological, hydrological and hydraulic processes. Currently there is no defined methodology available for evaluating and quantifying the flood hazard and related risk for larger areas or whole river catchments instead of single gauges. In order to estimate the probable maximum loss for higher return periods (e.g. 200 years, PML200), a stochastic model approach is designed since observational data are limited in time and space. In our approach, precipitation is linearly composed of three elements: background precipitation, orographically-induces precipitation, and a convectively-driven part. We use linear theory of orographic precipitation formation for the stochastic precipitation model (SPM), which is based on fundamental statistics of relevant atmospheric variables. For an adequate number of historic flood events, the corresponding atmospheric conditions and parameters are determined in order to calculate a probability density function (pdf) for each variable. This method involves all theoretically possible scenarios which may not have happened, yet. This work is part of the FLORIS-SV (FLOod RISk Sparkassen Versicherung) project and establishes the first step of a complete modelling chain of the flood risk. On the basis of the generated stochastic precipitation event set, hydrological and hydraulic simulations will be performed to estimate discharge and water level. The resulting stochastic flood event set will be used to quantify the

Impact of climate change on flood frequency and intensity in the kabul river basin

NARCIS (Netherlands)

Iqbal, Muhammad Shahid; Dahri, Zakir Hussain; Querner, Erik P.; Khan, Asif; Hofstra, Nynke

2018-01-01

Devastating floods adversely affect human life and infrastructure. Various regions of the Hindukush-Karakoram-Himalayas receive intense monsoon rainfall, which, together with snow and glacier melt, produce intense floods. The Kabul river basin originates from the Hindukush Mountains and is

Extreme flood event reconstruction spanning the last century in the El Bibane Lagoon (southeastern Tunisia: a multi-proxy approach

Directory of Open Access Journals (Sweden)

A. Affouri

2017-06-01

Full Text Available Climate models project that rising atmospheric carbon dioxide concentrations will increase the frequency and the severity of some extreme weather events. The flood events represent a major risk for populations and infrastructures settled on coastal lowlands. Recent studies of lagoon sediments have enhanced our knowledge on extreme hydrological events such as palaeo-storms and on their relation with climate change over the last millennium. However, few studies have been undertaken to reconstruct past flood events from lagoon sediments. Here, the past flood activity was investigated using a multi-proxy approach combining sedimentological and geochemical analysis of surfaces sediments from a southeastern Tunisian catchment in order to trace the origin of sediment deposits in the El Bibane Lagoon. Three sediment sources were identified: marine, fluvial and aeolian. When applying this multi-proxy approach on core BL12-10, recovered from the El Bibane Lagoon, we can see that finer material, a high content of the clay and silt, and a high content of the elemental ratios (Fe ∕ Ca and Ti ∕ Ca characterise the sedimentological signature of the palaeo-flood levels identified in the lagoonal sequence. For the last century, which is the period covered by the BL12-10 short core, three palaeo-flood events were identified. The age of these flood events have been determined by 210Pb and 137Cs chronology and give ages of AD 1995 ± 6, 1970 ± 9 and 1945 ± 9. These results show a good temporal correlation with historical flood events recorded in southern Tunisia in the last century (AD 1932, 1969, 1979 and 1995. Our finding suggests that reconstruction of the history of the hydrological extreme events during the upper Holocene is possible in this location through the use of the sedimentary archives.

Seepage patterns of Diuron in a ditch bed during a sequence of flood events

International Nuclear Information System (INIS)

Dages, C.; Samouëlian, A.; Negro, S.; Storck, V.; Huttel, O.; Voltz, M.

2015-01-01

Although ditches limit surface water contamination, groundwater recharge through ditches in Mediterranean catchments may result in groundwater contamination. We analysed the dynamics of pesticide percolation in ditches by conducting an original lab experiment that mimicked the successive percolation processes that occur during a flood season. Nine successive percolation events were operated on an undisturbed soil column collected from a ditch bed. The infiltrating water was doped with 14 C-Diuron at concentrations that were chosen to decrease between the events so as to correspond to values observed during actual flood events. The water and solute fluxes were monitored during each event, and the final extractable and non-extractable Diuron residues in the column were determined. Two main observations were made. First, a high leaching potential was observed through the ditch bed over a succession of infiltrating flood events, with 58.9% of the infiltrated Diuron and its metabolites leaching. Second, compared with the contamination of surface water circulating in the ditches, the contamination of seepage water exhibited smaller peak values and persisted much longer because of the desorption of Diuron residues stored in the ditch bed. Thus, ditches serve as buffering zones between surface and groundwater. However, compared with field plots, ditches appear to be a preferential location for the percolation of pesticides into groundwater at the catchment scale. - Highlights: • Diuron percolation in a ditch bed during flood events was mimicked in a column setup. • Diuron percolation can represent up to 50% of the infiltrated Diuron. • The ditch bed exhibits a high buffering capacity due to its high sorption properties. • Contamination period of percolation water lasts longer than that of infiltrating water. • Diuron residues stored in ditch bed move deeper than in field topsoils.

Seepage patterns of Diuron in a ditch bed during a sequence of flood events

Energy Technology Data Exchange (ETDEWEB)

Dages, C., E-mail: cecile.dages@supagro.inra.fr; Samouëlian, A.; Negro, S.; Storck, V.; Huttel, O.; Voltz, M.

2015-12-15

Although ditches limit surface water contamination, groundwater recharge through ditches in Mediterranean catchments may result in groundwater contamination. We analysed the dynamics of pesticide percolation in ditches by conducting an original lab experiment that mimicked the successive percolation processes that occur during a flood season. Nine successive percolation events were operated on an undisturbed soil column collected from a ditch bed. The infiltrating water was doped with {sup 14}C-Diuron at concentrations that were chosen to decrease between the events so as to correspond to values observed during actual flood events. The water and solute fluxes were monitored during each event, and the final extractable and non-extractable Diuron residues in the column were determined. Two main observations were made. First, a high leaching potential was observed through the ditch bed over a succession of infiltrating flood events, with 58.9% of the infiltrated Diuron and its metabolites leaching. Second, compared with the contamination of surface water circulating in the ditches, the contamination of seepage water exhibited smaller peak values and persisted much longer because of the desorption of Diuron residues stored in the ditch bed. Thus, ditches serve as buffering zones between surface and groundwater. However, compared with field plots, ditches appear to be a preferential location for the percolation of pesticides into groundwater at the catchment scale. - Highlights: • Diuron percolation in a ditch bed during flood events was mimicked in a column setup. • Diuron percolation can represent up to 50% of the infiltrated Diuron. • The ditch bed exhibits a high buffering capacity due to its high sorption properties. • Contamination period of percolation water lasts longer than that of infiltrating water. • Diuron residues stored in ditch bed move deeper than in field topsoils.

Towards a better knowledge of flash flood forecasting at the Three Gorges Region: Progress over the past decade and challenges ahead

Science.gov (United States)

Li, Zhe; Yang, Dawen; Yang, Hanbo; Wu, Tianjiao; Xu, Jijun; Gao, Bing; Xu, Tao

2015-04-01

The study area, the Three Gorges Region (TGR), plays a critical role in predicting the floods drained into the Three Gorges Reservoir, as reported local floods often exceed 10000m3/s during rainstorm events and trigger fast as well as significant impacts on the Three Gorges Reservoir's regulation. Meanwhile, it is one of typical mountainous areas in China, which is located in the transition zone between two monsoon systems: the East Asian monsoon and the South Asian (Indian) monsoon. This climatic feature, combined with local irregular terrains, has shaped complicated rainfall-runoff regimes in this focal region. However, due to the lack of high-resolution hydrometeorological data and physically-based hydrologic modeling framework, there was little knowledge about rainfall variability and flood pattern in this historically ungauged region, which posed great uncertainties to flash flood forecasting in the past. The present study summarize latest progresses of regional flash floods monitoring and prediction, including installation of a ground-based Hydrometeorological Observation Network (TGR-HMON), application of a regional geomorphology-based hydrological model (TGR-GBHM), development of an integrated forecasting and modeling system (TGR-INFORMS), and evaluation of quantitative precipitation estimations (QPE) and quantitative precipitation forecasting (QPF) products in TGR flash flood forecasting. With these continuing efforts to improve the forecasting performance of flash floods in TGR, we have addressed several critical issues: (1) Current observation network is still insufficient to capture localized rainstorms, and weather radar provides valuable information to forecast flash floods induced by localized rainstorms, although current radar QPE products can be improved substantially in future; (2) Long-term evaluation shows that the geomorphology-based distributed hydrologic model (GBHM) is able to simulate flash flooding processes reasonably, while model

Lessons learnt from past Flash Floods and Debris Flow events to propose future strategies on risk management

Science.gov (United States)

Cabello, Angels; Velasco, Marc; Escaler, Isabel

2010-05-01

Floods, including flash floods and debris flow events, are one of the most important hazards in Europe regarding both economic and life loss. Moreover, changes in precipitation patterns and intensity are very likely to increase due to the observed and predicted global warming, rising the risk in areas that are already vulnerable to floods. Therefore, it is very important to carry out new strategies to improve flood protection, but it is also crucial to take into account historical data to identify high risk areas. The main objective of this paper is to show a comparative analysis of the flood risk management information compiled in four test-bed basins (Llobregat, Guadalhorce, Gardon d'Anduze and Linth basins) from three different European countries (Spain, France and Switzerland) and to identify which are the lessons learnt from their past experiences in order to propose future strategies on risk management. This work is part of the EU 7th FP project IMPRINTS which aims at reducing loss of life and economic damage through the improvement of the preparedness and the operational risk management of flash flood and debris flow (FF & DF) events. The methodology followed includes the following steps: o Specific survey on the effectivity of the implemented emergency plans and risk management procedures sent to the test-bed basin authorities that participate in the project o Analysis of the answers from the questionnaire and further research on their methodologies for risk evaluation o Compilation of available follow-up studies carried out after major flood events in the four test-bed basins analyzed o Collection of the lessons learnt through a comparative analysis of the previous information o Recommendations for future strategies on risk management based on lessons learnt and management gaps detected through the process As the Floods Directive (FD) already states, the flood risks associated to FF & DF events should be assessed through the elaboration of Flood Risk

Flood hazard assessment in areas prone to flash flooding

Science.gov (United States)

Kvočka, Davor; Falconer, Roger A.; Bray, Michaela

2016-04-01

Contemporary climate projections suggest that there will be an increase in the occurrence of high-intensity rainfall events in the future. These precipitation extremes are usually the main cause for the emergence of extreme flooding, such as flash flooding. Flash floods are among the most unpredictable, violent and fatal natural hazards in the world. Furthermore, it is expected that flash flooding will occur even more frequently in the future due to more frequent development of extreme weather events, which will greatly increase the danger to people caused by flash flooding. This being the case, there will be a need for high resolution flood hazard maps in areas susceptible to flash flooding. This study investigates what type of flood hazard assessment methods should be used for assessing the flood hazard to people caused by flash flooding. Two different types of flood hazard assessment methods were tested: (i) a widely used method based on an empirical analysis, and (ii) a new, physically based and experimentally calibrated method. Two flash flood events were considered herein, namely: the 2004 Boscastle flash flood and the 2007 Železniki flash flood. The results obtained in this study suggest that in the areas susceptible to extreme flooding, the flood hazard assessment should be conducted using methods based on a mechanics-based analysis. In comparison to standard flood hazard assessment methods, these physically based methods: (i) take into account all of the physical forces, which act on a human body in floodwater, (ii) successfully adapt to abrupt changes in the flow regime, which often occur for flash flood events, and (iii) rapidly assess a flood hazard index in a relatively short period of time.

Study on the association of green house gas (CO2) with monsoon rainfall using AIRS and TRMM satellite observations

Science.gov (United States)

Singh, R. B.; Janmaijaya, M.; Dhaka, S. K.; Kumar, V.

Monsoon water cycle is the lifeline to over 60 per cent of the world's population. Throughout history, the monsoon-related calamities of droughts and floods have determined the life pattern of people. The association of Green House Gases (GHGs) particularly Carbon dioxide (CO2) with monsoon has been greatly debated amongst the scientific community in the past. The effect of CO2 on the monsoon rainfall over the Indian-Indonesian region (8-30°N, 65°-100°E) is being investigated using satellite data. The correlation coefficient (Rxy) between CO2 and monsoon is analysed. The Rxy is not significantly positive over a greater part of the study region, except a few regions. The inter-annual anomalies of CO2 is identified for playing a secondary role to influencing monsoon while other phenomenon like ENSO might be exerting a much greater influence.

The More Extreme Nature of North American Monsoon Precipitation in the Southwestern United States as Revealed by a Historical Climatology of Simulated Severe Weather Events

KAUST Repository

Luong, Thang M.; Castro, Christopher L.; Chang, Hsin-I; Lahmers, Timothy; Adams, David K.; Ochoa-Moya, Carlos A.

2017-01-01

Long-term changes in North American monsoon (NAM) precipitation intensity in the southwestern United States are evaluated through the use of convective-permitting model simulations of objectively identified severe weather events during

The More Extreme Nature of North American Monsoon Precipitation in the Southwestern United States as Revealed by a Historical Climatology of Simulated Severe Weather Events

KAUST Repository

Luong, Thang M.

2017-07-03

Long-term changes in North American monsoon (NAM) precipitation intensity in the southwestern United States are evaluated through the use of convective-permitting model simulations of objectively identified severe weather events during

The Impacts of Episodic Storm and Flood Events on Carbon and Sediment Delivery to Gulf of Mexico Sediments

Science.gov (United States)

Schreiner, K. M.; Carlin, J. A.; Sayers, L.; Swenson, J.

2017-12-01

Marine sediments are an important long-term reservoir for both recently fixed organic carbon (OC) and ancient rock derived OC, much of which is delivered by rivers. The ratio between these two sources of OC in turn regulates atmospheric levels of oxygen and carbon dioxide over geologic time, making this riverine delivery of OC, primarily carried by sediments, an important flux in the global carbon cycle. However, while the overall magnitude of these fluxes are relatively well known, it remains to be determined the importance of episodic events, like storms and floods, in the flux of OC from terrestrial to marine environments. Here, we present data from a 34 cm core collected from the Gulf of Mexico at a mid-shelf distal depocenter for the Brazos River in 2015, during a strong El Nino when that area of the country was experiencing 100-year flood events and anomalously high river flow. Based on analysis of the radioactive isotope 7Be, approximately the top 7-8 cm of the sediment in this core was deposited during this flood event. Both bulk elemental (C, N, and stable carbon isotopes) and chemical biomarker (lignin-phenol) data has been combined to provide information of the origin and chemistry of the OC in this core both before and during flooding. C:N and d13C indicate a mixture of marine-sourced and terrestrially-sourced OC throughout the length of the core with very little variation between the flood layer and deeper sediments. However, lignin-phenol concentrations are higher in flood-deposited sediment, indicating that this sediment is likely terrestrially-sourced. Lignin-phenol indicators of OC degradation state (Acid:Aldehyde ratios) indicate that flood sediment is fresher and less degraded than deeper sediments. Taken together, these results indicate that 1. Bulk analyses are not enough to determine OC source and the importance of flood events in OC cycling and 2. Episodic events like floods could have an oversized impact on OC storage in marine sediments.

Influence of risk factors and past events on flood resilience in coastal megacities: Comparative analysis of NYC and Shanghai.

Science.gov (United States)

Xian, Siyuan; Yin, Jie; Lin, Ning; Oppenheimer, Michael

2018-01-01

Coastal flood protection measures have been widely implemented to improve flood resilience. However, protection levels vary among coastal megacities globally. This study compares the distinct flood protection standards for two coastal megacities, New York City and Shanghai, and investigates potential influences such as risk factors and past flood events. Extreme value analysis reveals that, compared to NYC, Shanghai faces a significantly higher flood hazard. Flood inundation analysis indicates that Shanghai has a higher exposure to extreme flooding. Meanwhile, Shanghai's urban development, population, and economy have increased much faster than NYC's over the last three decades. These risk factors provide part of the explanation for the implementation of a relatively high level of protection (e.g. reinforced concrete sea-wall designed for a 200-year flood return level) in Shanghai and low protection (e.g. vertical brick and stone walls and sand dunes) in NYC. However, individual extreme flood events (typhoons in 1962, 1974, and 1981) seem to have had a greater impact on flood protection decision-making in Shanghai, while NYC responded significantly less to past events (with the exception of Hurricane Sandy). Climate change, sea level rise, and ongoing coastal development are rapidly changing the hazard and risk calculus for both cities and both would benefit from a more systematic and dynamic approach to coastal protection. Copyright © 2017 Elsevier B.V. All rights reserved.

Validating quantitative precipitation forecast for the Flood ...

Indian Academy of Sciences (India)

In order to issue an accurate warning for flood, a better or appropriate quantitative forecasting of precipitationis required. In view of this, the present study intends to validate the quantitative precipitationforecast (QPF) issued during southwest monsoon season for six river catchments (basin) under theflood meteorological ...

Orbital forcing of the late Pleistocene boreal summer monsoon: Links to North Atlantic cold events and El Nino; Southern Oscillation. Geologica Ultraiectina (313)

NARCIS (Netherlands)

Ziegler, M.

2009-01-01

This thesis revolves about the timing of precession-related variations in the boreal summer monsoon and the impact of North Atlantic cold events and the El Nino Southern Oscillation on this timing. Transient climate modelling experiments indicate that the intensity of the Northern Hemisphere summer

Enhanced transfer of terrestrially derived carbon to the atmosphere in a flooding event

Science.gov (United States)

Bianchi, Thomas S.; Garcia-Tigreros, Fenix; Yvon-Lewis, Shari A.; Shields, Michael; Mills, Heath J.; Butman, David; Osburn, Christopher; Raymond, Peter A.; Shank, G. Christopher; DiMarco, Steven F.; Walker, Nan; Kiel Reese, Brandi; Mullins-Perry, Ruth; Quigg, Antonietta; Aiken, George R.; Grossman, Ethan L.

2013-01-01

Rising CO2 concentration in the atmosphere, global climate change, and the sustainability of the Earth's biosphere are great societal concerns for the 21st century. Global climate change has, in part, resulted in a higher frequency of flooding events, which allow for greater exchange between soil/plant litter and aquatic carbon pools. Here we demonstrate that the summer 2011 flood in the Mississippi River basin, caused by extreme precipitation events, resulted in a “flushing” of terrestrially derived dissolved organic carbon (TDOC) to the northern Gulf of Mexico. Data from the lower Atchafalaya and Mississippi rivers showed that the DOC flux to the northern Gulf of Mexico during this flood was significantly higher than in previous years. We also show that consumption of radiocarbon-modern TDOC by bacteria in floodwaters in the lower Atchafalaya River and along the adjacent shelf contributed to northern Gulf shelf waters changing from a net sink to a net source of CO2 to the atmosphere in June and August 2011. This work shows that enhanced flooding, which may or may not be caused by climate change, can result in rapid losses of stored carbon in soils to the atmosphere via processes in aquatic ecosystems.

Long-term changes in flood event patterns due to changes in hydrological distribution parameters in a rural-urban catchment, Shikoku, Japan

Science.gov (United States)

Mouri, Goro; Kanae, Shinjiro; Oki, Taikan

2011-07-01

This article describes the principal control parameters of flood events and precipitation and the relationships between corresponding hydrologic and climatologic parameters. The long-term generation of runoff and associated processes is important in understanding floods and droughts under changes in climate and land use. This study presents detailed analyses of flood events in a coastal amphitheatre catchment with a total area of 445 km 2 in western Japan, followed by analyses of flood events in both urban and forest areas. Using long-term (1962 to 2002) hydrological and climatological data from the Ministry of Land, Infrastructure and Transport, Japan, the contributions of precipitation, river discharge, temperature, and relative humidity to flood events were analysed. Flood events could be divided into three types with respect to hydrologic and climatologic principal control parameters: the long-term tendency; medium-term changes as revealed by hydrographs and hyetographs of high-intensity events such as the relative precipitation, river discharge, and temperature; and large events, as shown by the flow-duration curve, with each cluster having particular characteristics. River discharge showed a decreasing tendency of flow quantity during small rainfall events of less than 100 mm/event from the 1980s to the present. An approximately 7% decrease from 44.8 to 37.3% occurred in the percentage of river water supplied by precipitation in the years after the 1980s. For the medium-term changes, no marked change occurred in the flow quantity of the peak point over time in event hydrographs. However, flow quantities before and after the peak tended to decrease by 1 to 2 m 3/s after the 1980s. Theoretical considerations with regard to the influence of hydrologic and climatologic parameters on flood discharge are discussed and examined in terms of observational data. These findings provide a sound foundation for use in hydrological catchment modelling.

Modelling Inland Flood Events for Hazard Maps in Taiwan

Science.gov (United States)

Ghosh, S.; Nzerem, K.; Sassi, M.; Hilberts, A.; Assteerawatt, A.; Tillmanns, S.; Mathur, P.; Mitas, C.; Rafique, F.

2015-12-01

. Major historical flood events have been successfully simulated along with spatial patterns of flows. Comparison of stochastic discharge statistics w.r.t. observed ones from Hydrological Year Books of Taiwan over all recorded years are also in good agreement.

Effect of Floodplain Inundation on River Pollution in Taiwan's Strong Monsoonal Climate

Science.gov (United States)

Hester, E. T.; Lin, A. Y. C.

2017-12-01

River-floodplain interaction provides important benefits such as flood mitigation, provision of ecological habitat, and improved water quality. Human actions have historically reduced such interaction and associated benefits by diking, floodplain fill, and river regulation. In response, floodplain restoration has become popular in North America and Europe, but is less practiced in Asia. In Taiwan, unusually strong monsoons and steep terrain alter floodplain dynamics relative to elsewhere around the world, and provide a unique environment for floodplain management. We used numerical models of flow, transport, and reaction in river channels and floodplains to quantify the effect of river-floodplain interaction on water quality in Taiwan's strong monsoon and high topographic relief. We conducted sensitivity analyses of parameters such as river slope, monsoon severity, reservoir operation mode, degree of floodplain reconnection, contaminant reaction rate, and contaminant reaction type on floodplain connectivity and contaminant mitigation. We found significant differences in floodplain hydraulics and residence times in Taiwan's steep monsoonal environment relative to the shallower non-monsoonal environment typical of the eastern USA, with significant implications for water quality. For example, greater flashiness of floodplain inundation in Taiwan provides greater challenges for reconnecting sufficient floodplain volume to handle monsoonal runoff. Yet longer periods when floodplains are reliably dry means that such lands may have greater value for seasonal use such as parks or agriculture. The potential for floodplain restoration in Taiwan is thus significant, but qualitatively different than in the eastern USA.

Flood Foresight: A near-real time flood monitoring and forecasting tool for rapid and predictive flood impact assessment

Science.gov (United States)

Revilla-Romero, Beatriz; Shelton, Kay; Wood, Elizabeth; Berry, Robert; Bevington, John; Hankin, Barry; Lewis, Gavin; Gubbin, Andrew; Griffiths, Samuel; Barnard, Paul; Pinnell, Marc; Huyck, Charles

2017-04-01

The hours and days immediately after a major flood event are often chaotic and confusing, with first responders rushing to mobilise emergency responders, provide alleviation assistance and assess loss to assets of interest (e.g., population, buildings or utilities). Preparations in advance of a forthcoming event are becoming increasingly important; early warning systems have been demonstrated to be useful tools for decision markers. The extent of damage, human casualties and economic loss estimates can vary greatly during an event, and the timely availability of an accurate flood extent allows emergency response and resources to be optimised, reduces impacts, and helps prioritise recovery. In the insurance sector, for example, insurers are under pressure to respond in a proactive manner to claims rather than waiting for policyholders to report losses. Even though there is a great demand for flood inundation extents and severity information in different sectors, generating flood footprints for large areas from hydraulic models in real time remains a challenge. While such footprints can be produced in real time using remote sensing, weather conditions and sensor availability limit their ability to capture every single flood event across the globe. In this session, we will present Flood Foresight (www.floodforesight.com), an operational tool developed to meet the universal requirement for rapid geographic information, before, during and after major riverine flood events. The tool provides spatial data with which users can measure their current or predicted impact from an event - at building, basin, national or continental scales. Within Flood Foresight, the Screening component uses global rainfall predictions to provide a regional- to continental-scale view of heavy rainfall events up to a week in advance, alerting the user to potentially hazardous situations relevant to them. The Forecasting component enhances the predictive suite of tools by providing a local

Combined fluvial and pluvial urban flood hazard analysis: concept development and application to Can Tho city, Mekong Delta, Vietnam

Science.gov (United States)

Apel, Heiko; Martínez Trepat, Oriol; Nghia Hung, Nguyen; Thi Chinh, Do; Merz, Bruno; Viet Dung, Nguyen

2016-04-01

Many urban areas experience both fluvial and pluvial floods, because locations next to rivers are preferred settlement areas and the predominantly sealed urban surface prevents infiltration and facilitates surface inundation. The latter problem is enhanced in cities with insufficient or non-existent sewer systems. While there are a number of approaches to analyse either a fluvial or pluvial flood hazard, studies of a combined fluvial and pluvial flood hazard are hardly available. Thus this study aims to analyse a fluvial and a pluvial flood hazard individually, but also to develop a method for the analysis of a combined pluvial and fluvial flood hazard. This combined fluvial-pluvial flood hazard analysis is performed taking Can Tho city, the largest city in the Vietnamese part of the Mekong Delta, as an example. In this tropical environment the annual monsoon triggered floods of the Mekong River, which can coincide with heavy local convective precipitation events, causing both fluvial and pluvial flooding at the same time. The fluvial flood hazard was estimated with a copula-based bivariate extreme value statistic for the gauge Kratie at the upper boundary of the Mekong Delta and a large-scale hydrodynamic model of the Mekong Delta. This provided the boundaries for 2-dimensional hydrodynamic inundation simulation for Can Tho city. The pluvial hazard was estimated by a peak-over-threshold frequency estimation based on local rain gauge data and a stochastic rainstorm generator. Inundation for all flood scenarios was simulated by a 2-dimensional hydrodynamic model implemented on a Graphics Processing Unit (GPU) for time-efficient flood propagation modelling. The combined fluvial-pluvial flood scenarios were derived by adding rainstorms to the fluvial flood events during the highest fluvial water levels. The probabilities of occurrence of the combined events were determined assuming independence of the two flood types and taking the seasonality and probability of

A coupled hydrological-hydraulic flood inundation model calibrated using post-event measurements and integrated uncertainty analysis in a poorly gauged Mediterranean basin

Science.gov (United States)

Hdeib, Rouya; Abdallah, Chadi; Moussa, Roger; Colin, Francois

2017-04-01

Developing flood inundation maps of defined exceedance probabilities is required to provide information on the flood hazard and the associated risk. A methodology has been developed to model flood inundation in poorly gauged basins, where reliable information on the hydrological characteristics of floods are uncertain and partially captured by the traditional rain-gauge networks. Flood inundation is performed through coupling a hydrological rainfall-runoff (RR) model (HEC-HMS) with a hydraulic model (HEC-RAS). The RR model is calibrated against the January 2013 flood event in the Awali River basin, Lebanon (300 km2), whose flood peak discharge was estimated by post-event measurements. The resulting flows of the RR model are defined as boundary conditions of the hydraulic model, which is run to generate the corresponding water surface profiles and calibrated against 20 post-event surveyed cross sections after the January-2013 flood event. An uncertainty analysis is performed to assess the results of the models. Consequently, the coupled flood inundation model is simulated with design storms and flood inundation maps are generated of defined exceedance probabilities. The peak discharges estimated by the simulated RR model were in close agreement with the results from different empirical and statistical methods. This methodology can be extended to other poorly gauged basins facing common stage-gauge failure or characterized by floods with a stage exceeding the gauge measurement level, or higher than that defined by the rating curve.

Monsoon onset over Kerala and pre monsoon rainfall peak

Digital Repository Service at National Institute of Oceanography (India)

RameshKumar, M.R.; Shenoi, S.S.C.; Shankar, D.

and the monsoon onset date over Kerala was found to be 0.72, which was statistically significant. Thus, as is felt that the pre monsoon rainfall estimate from the satellite data can be used for predicting the monsoon onset over Kerala coast. The results...

Spatial coherence of flood-rich and flood-poor periods across Germany

Science.gov (United States)

Merz, Bruno; Dung, Nguyen Viet; Apel, Heiko; Gerlitz, Lars; Schröter, Kai; Steirou, Eva; Vorogushyn, Sergiy

2018-04-01

Despite its societal relevance, the question whether fluctuations in flood occurrence or magnitude are coherent in space has hardly been addressed in quantitative terms. We investigate this question for Germany by analysing fluctuations in annual maximum series (AMS) values at 68 discharge gauges for the common time period 1932-2005. We find remarkable spatial coherence across Germany given its different flood regimes. For example, there is a tendency that flood-rich/-poor years in sub-catchments of the Rhine basin, which are dominated by winter floods, coincide with flood-rich/-poor years in the southern sub-catchments of the Danube basin, which have their dominant flood season in summer. Our findings indicate that coherence is caused rather by persistence in catchment wetness than by persistent periods of higher/lower event precipitation. Further, we propose to differentiate between event-type and non-event-type coherence. There are quite a number of hydrological years with considerable non-event-type coherence, i.e. AMS values of the 68 gauges are spread out through the year but in the same magnitude range. Years with extreme flooding tend to be of event-type and non-coherent, i.e. there is at least one precipitation event that affects many catchments to various degree. Although spatial coherence is a remarkable phenomenon, and large-scale flooding across Germany can lead to severe situations, extreme magnitudes across the whole country within one event or within one year were not observed in the investigated period.

Consequences of an unusual flood event: case study of a drainage canal breach on a fluvial plain in NE Slovenia

Science.gov (United States)

Vidmar, Ines; Ambrožič, Bojan; Debeljak, Barbara; Dolžan, Erazem; Gregorin, Špela; Grom, Nina; Herman, Polona; Keršmanc, Teja; Mencin, Eva; Mernik, Natalija; Švara, Astrid; Trobec, Ana; Turnšek, Anita; Vodeb, Petra; Torkar, Anja; Brenčič, Mihael

2013-04-01

On November 4-6 2012 heavy precipitation resulted in floods in the middle and lower course of Drava River in NE Slovenia causing damage to many properties in the flooded area. The meteorological situation that led to consequent floods was characterized by high precipitation, fast snowmelt, SW wind and relatively high air temperature. The weather event was part of a cyclone which was spreading over the area of North, West and Central Europe in the direction of Central Europe and carried with it the passing of a cold front through Slovenia on November 4 and 5. The flood wave travelled on the Drava River from Austria to Slovenia past the 11 hydroelectric power plants after eventually moving over the Slovenian-Croatian border. The river discharge increased in the early morning of November 5 reaching 3165 m3/s. This work focuses on a single event in the Ptujsko polje where among other damage caused by the flooding, the river broke through the drainage canal of the Formin hydroelectric power plant and changed its course. The Ptujsko polje contains two fluvial terraces. In the area of Formin HPP, the lower terrace is 1.5 km wide and the surface as well as the groundwater gradient shift from west to east with the groundwater flowing parallel to the river. These characteristics contributed to the flooding and consequential breach in the embankment of the drainage canal. Several aspects of the recent floods are discussed including a critical reflection of data accessibility, possible causes and mechanisms behind it as well as the possibility of its forecasting. Synthesis of accessible data from open domain sources is performed with emphasis on geological conditions. Discharge and precipitation data from the data base of Slovenian Environment Agency are collected, reviewed and analyzed. The flood event itself is analyzed and described in detail. It is determined that the flood wave was different from the ones regulated by natural processes which points to an anthropogenic

Differential response of vegetation in Hulun Lake region at the northern margin of Asian summer monsoon to extreme cold events of the last deglaciation

Science.gov (United States)

Zhang, Shengrui; Xiao, Jule; Xu, Qinghai; Wen, Ruilin; Fan, Jiawei; Huang, Yun; Yamagata, Hideki

2018-06-01

The response of vegetation to extreme cold events during the last deglaciation is important for assessing the impact of possible extreme climatic events on terrestrial ecosystems under future global warming scenarios. Here, we present a detailed record of the development of regional vegetation in the northern margin of Asian summer monsoon during the last deglaciation (16,500-11,000 cal yr BP) based on a radiocarbon-dated high-resolution pollen record from Hulun Lake, northeast China. The results show that the regional vegetation changed from subalpine meadow-desert steppe to mixed coniferous and deciduous forest-typical steppe during the last deglaciation. However, its responses to the Heinrich event 1 (H1) and the Younger Dryas event (YD) were significantly different: during the H1 event, scattered sparse forest was present in the surrounding mountains, while within the lake catchment the vegetation cover was poor and was dominated by desert steppe. In contrast, during the YD event, deciduous forest developed and the proportion of coniferous forest increased in the mountains, the lake catchment was occupied by typical steppe. We suggest that changes in Northern Hemisphere summer insolation and land surface conditions (ice sheets and sea level) caused temperature and monsoonal precipitation variations that contributed to the contrasting vegetation response during the two cold events. We conclude that under future global warming scenarios, extreme climatic events may cause a deterioration of the ecological environment of the Hulun Lake region, resulting in increased coniferous forest and decreased total forest cover in the surrounding mountains, and a reduction in typical steppe in the lake catchment.

Reconstruction and numerical modelling of a flash flood event: Atrani 2010

Science.gov (United States)

Ciervo, F.; Papa, M. N.; Medina, V.; Bateman, A.

2012-04-01

The work intends to reproduce the flash-flood event that occurred in Atrani (Amalfi Coast - Southern Italy) on the 9 September 2010. In the days leading up to the event, intense low pressure system affected the North Europe attracting hot humid air masses from the Mediterranean areas and pushing them to the southern regions of Italy. These conditions contributed to the development of strong convective storm systems, Mesoscale Convective Systems (MCS) type. The development of intense convective rain cells, over an extremely confined areas, leaded to a cumulative daily rainfall of 129.2 mm; the maximum precipitation in 1hr was 19.4mm. The Dragone river is artificially forced to flow underneath the urban estate of Atrani through a culvert until it finally flows out into the sea. In correspondence of the culvert inlet a minor fraction of the water discharge (5.9m^3/s), skimming over the channel cover, flowed on the street and invaded the village. The channelized flow generated overpressure involving the breaking of the cover of culvert slab and caused a new discharge inlet (20 m^3/s) on the street modifying the downstream flood dynamics. Information acquired, soon after the event, through the local people interviews and the field measurements significantly contributed to the rainfall event reconstruction and to the characterization of the induced effects. In absence of hydrometric data, the support of the amateur videos was of crucial importance for the hydraulic model development and calibration. A geomorphology based rainfall-runoff model, WFIUH type (Instantaneous Unit Hydrograph Width Function), is implemented to extract the hydrograph of the hydrological event. All analysis are performed with GIS support basing on a Digital Terrain System (DTM) 5x5m. Two parameters have been used to calibrate the model: the average watershed velocity (Vmean = 0.08m/s) and hydrodynamic diffusivity (D=10E^-6 m^2/s). The model is calibrated basing on the peak discharge assessed value

Physiologically-based toxicokinetic models help identifying the key factors affecting contaminant uptake during flood events

International Nuclear Information System (INIS)

Brinkmann, Markus; Eichbaum, Kathrin; Kammann, Ulrike; Hudjetz, Sebastian; Cofalla, Catrina; Buchinger, Sebastian; Reifferscheid, Georg; Schüttrumpf, Holger; Preuss, Thomas

2014-01-01

Highlights: • A PBTK model for trout was coupled with a sediment equilibrium partitioning model. • The influence of physical exercise on pollutant uptake was studies using the model. • Physical exercise during flood events can increase the level of biliary metabolites. • Cardiac output and effective respiratory volume were identified as relevant factors. • These confounding factors need to be considered also for bioconcentration studies. - Abstract: As a consequence of global climate change, we will be likely facing an increasing frequency and intensity of flood events. Thus, the ecotoxicological relevance of sediment re-suspension is of growing concern. It is vital to understand contaminant uptake from suspended sediments and relate it to effects in aquatic biota. Here we report on a computational study that utilizes a physiologically based toxicokinetic model to predict uptake, metabolism and excretion of sediment-borne pyrene in rainbow trout (Oncorhynchus mykiss). To this end, data from two experimental studies were compared with the model predictions: (a) batch re-suspension experiments with constant concentration of suspended particulate matter at two different temperatures (12 and 24 °C), and (b) simulated flood events in an annular flume. The model predicted both the final concentrations and the kinetics of 1-hydroxypyrene secretion into the gall bladder of exposed rainbow trout well. We were able to show that exhaustive exercise during exposure in simulated flood events can lead to increased levels of biliary metabolites and identified cardiac output and effective respiratory volume as the two most important factors for contaminant uptake. The results of our study clearly demonstrate the relevance and the necessity to investigate uptake of contaminants from suspended sediments under realistic exposure scenarios

Physiologically-based toxicokinetic models help identifying the key factors affecting contaminant uptake during flood events

Energy Technology Data Exchange (ETDEWEB)

Brinkmann, Markus; Eichbaum, Kathrin [Department of Ecosystem Analysis, Institute for Environmental Research,ABBt – Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen (Germany); Kammann, Ulrike [Thünen-Institute of Fisheries Ecology, Palmaille 9, 22767 Hamburg (Germany); Hudjetz, Sebastian [Department of Ecosystem Analysis, Institute for Environmental Research,ABBt – Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen (Germany); Institute of Hydraulic Engineering and Water Resources Management, RWTH Aachen University, Mies-van-der-Rohe-Straße 1, 52056 Aachen (Germany); Cofalla, Catrina [Institute of Hydraulic Engineering and Water Resources Management, RWTH Aachen University, Mies-van-der-Rohe-Straße 1, 52056 Aachen (Germany); Buchinger, Sebastian; Reifferscheid, Georg [Federal Institute of Hydrology (BFG), Department G3: Biochemistry, Ecotoxicology, Am Mainzer Tor 1, 56068 Koblenz (Germany); Schüttrumpf, Holger [Institute of Hydraulic Engineering and Water Resources Management, RWTH Aachen University, Mies-van-der-Rohe-Straße 1, 52056 Aachen (Germany); Preuss, Thomas [Department of Environmental Biology and Chemodynamics, Institute for Environmental Research,ABBt- Aachen Biology and Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen (Germany); and others

2014-07-01

Highlights: • A PBTK model for trout was coupled with a sediment equilibrium partitioning model. • The influence of physical exercise on pollutant uptake was studies using the model. • Physical exercise during flood events can increase the level of biliary metabolites. • Cardiac output and effective respiratory volume were identified as relevant factors. • These confounding factors need to be considered also for bioconcentration studies. - Abstract: As a consequence of global climate change, we will be likely facing an increasing frequency and intensity of flood events. Thus, the ecotoxicological relevance of sediment re-suspension is of growing concern. It is vital to understand contaminant uptake from suspended sediments and relate it to effects in aquatic biota. Here we report on a computational study that utilizes a physiologically based toxicokinetic model to predict uptake, metabolism and excretion of sediment-borne pyrene in rainbow trout (Oncorhynchus mykiss). To this end, data from two experimental studies were compared with the model predictions: (a) batch re-suspension experiments with constant concentration of suspended particulate matter at two different temperatures (12 and 24 °C), and (b) simulated flood events in an annular flume. The model predicted both the final concentrations and the kinetics of 1-hydroxypyrene secretion into the gall bladder of exposed rainbow trout well. We were able to show that exhaustive exercise during exposure in simulated flood events can lead to increased levels of biliary metabolites and identified cardiac output and effective respiratory volume as the two most important factors for contaminant uptake. The results of our study clearly demonstrate the relevance and the necessity to investigate uptake of contaminants from suspended sediments under realistic exposure scenarios.

Flood Risk Assessment and Forecasting for the Ganges-Brahmaputra-Meghna River Basins

Science.gov (United States)

Hopson, T. M.; Priya, S.; Young, W.; Avasthi, A.; Clayton, T. D.; Brakenridge, G. R.; Birkett, C. M.; Riddle, E. E.; Broman, D.; Boehnert, J.; Sampson, K. M.; Kettner, A.; Singh, D.

2017-12-01

During the 2017 South Asia monsoon, torrential rains and catastrophic floods affected more than 45 million people, including 16 million children, across the Ganges-Brahmaputra-Meghna (GBM) basins. The basin is recognized as one of the world's most disaster-prone regions, with severe floods occurring almost annually causing extreme loss of life and property. In light of this vulnerability, the World Bank and collaborators have contributed toward reducing future flood impacts through recent developments to improve operational preparedness for such events, as well as efforts in more general preparedness and resilience building through planning based on detailed risk assessments. With respect to improved event-specific flood preparedness through operational warnings, we discuss a new forecasting system that provides probability-based flood forecasts developed for more than 85 GBM locations. Forecasts are available online, along with near-real-time data maps of rainfall (predicted and actual) and river levels. The new system uses multiple data sets and multiple models to enhance forecasting skill, and provides improved forecasts up to 16 days in advance of the arrival of high waters. These longer lead times provide the opportunity to save both lives and livelihoods. With sufficient advance notice, for example, farmers can harvest a threatened rice crop or move vulnerable livestock to higher ground. Importantly, the forecasts not only predict future water levels but indicate the level of confidence in each forecast. Knowing whether the probability of a danger-level flood is 10 percent or 90 percent helps people to decide what, if any, action to take. With respect to efforts in general preparedness and resilience building, we also present a recent flood risk assessment, and how it provides, for the first time, a numbers-based view of the impacts of different size floods across the Ganges basin. The findings help identify priority areas for tackling flood risks (for

Monsoon effect simulation on typhoon rainfall potential - Typhoon Morakot (2009

Directory of Open Access Journals (Sweden)

Yi-Ling Chang

2017-01-01

Full Text Available A record breaking extreme precipitation event produced 3000 mm day-1 of accumulated rainfall over southern Taiwan in August 2009. The interactions between Typhoon Morakot and the prevailing southwesterly (SW monsoon are the primary mechanism for this heavy precipitation during 5 - 13 August 2009. This extreme precipitation could be produced by the abundant moisture from the SW monsoon associated with the interaction between typhoon and monsoon wind fields, leading to severe property damage. The accurate mapping of extreme precipitation caused from the interaction between a monsoon and typhoon is critical for early warning in Taiwan. This study simulates the heavy rainfall event is based on the Weather Research and Forecast system model (WRF using the three nested domain configuration. Using data assimilation with a virtual meteorological field using the 3D-Var system, such as wind field to alter the SW monsoon strength in the initial condition, the impacts of intensified convergence and water vapor content on the accumulated rainfall are analyzed to quantize the intensification of typhoon rainfall potential. The results showed a positive correlation between the enhanced precipitation and the intensity of low-level wind speed convergence as well as water vapor content. For the Typhoon Morakot case study the rainfall for could attain approximately 2 × 104 mm at 6 hours interval in the southern Taiwan area when 10 × 10-6 s-1 convergence intensified at 850 hPa level around the southern part of the Taiwan Strait. These results suggest that low-level wind speed, convergence and water vapor content play key roles in the typhoon rainfall potential coupled with the SW monsoon.

The Monsoon Erosion Pump and the Indian Monsoon since Eocene

Science.gov (United States)

Giosan, L.

2017-12-01

Lack of consensus on the Neogene establishment and evolution of the Indian Monsoon is remarkable after half a century of research. Conflicting interpretations point toward the possibility of periodic decoupling between monsoon winds and monsoon precipitation. Here I introduce the concept of a monsoon erosion pump based on terrestrial and oceanic records reconstructed from recent NGHP and IODP drilling and spanning the last 34 million years in the Bay of Bengal, Arabian and Andaman Seas. From millennial to orbital to tectonic timescales, these records suggest that vegetation land cover interacts and modulates the regime of erosion and weathering under perennial but variable monsoonal rain conditions. Under this new proposed paradigm the Indian monsoon exhibits two distinct flavours during the Neogene that can be largely explained by its heartbeat, or astronomical forcing, mediated by the global glacial state and interacting with the paleogeography of South Asia.

AP1000R design robustness against extreme external events - Seismic, flooding, and aircraft crash

International Nuclear Information System (INIS)

Pfister, A.; Goossen, C.; Coogler, K.; Gorgemans, J.

2012-01-01

Both the International Atomic Energy Agency (IAEA) and the U.S. Nuclear Regulatory Commission (NRC) require existing and new nuclear power plants to conduct plant assessments to demonstrate the unit's ability to withstand external hazards. The events that occurred at the Fukushima-Dai-ichi nuclear power station demonstrated the importance of designing a nuclear power plant with the ability to protect the plant against extreme external hazards. The innovative design of the AP1000 R nuclear power plant provides unparalleled protection against catastrophic external events which can lead to extensive infrastructure damage and place the plant in an extended abnormal situation. The AP1000 plant is an 1100-MWe pressurized water reactor with passive safety features and extensive plant simplifications that enhance construction, operation, maintenance and safety. The plant's compact safety related footprint and protection provided by its robust nuclear island structures prevent significant damage to systems, structures, and components required to safely shutdown the plant and maintain core and spent fuel pool cooling and containment integrity following extreme external events. The AP1000 nuclear power plant has been extensively analyzed and reviewed to demonstrate that it's nuclear island design and plant layout provide protection against both design basis and extreme beyond design basis external hazards such as extreme seismic events, external flooding that exceeds the maximum probable flood limit, and malicious aircraft impact. The AP1000 nuclear power plant uses fail safe passive features to mitigate design basis accidents. The passive safety systems are designed to function without safety-grade support systems (such as AC power, component cooling water, service water, compressed air or HVAC). The plant has been designed to protect systems, structures, and components critical to placing the reactor in a safe shutdown condition within the steel containment vessel which is

Widespread Lake Highstands in the Southernmost Andean Altiplano during Heinrich Event 1: Implications for the South American Summer Monsoon

Science.gov (United States)

Chen, C. Y.; McGee, D.; Quade, J.

2014-12-01

Speleothem-based oxygen isotope records provide strong evidence of anti-phased behavior of the northern and southern hemisphere summer monsoons during Heinrich events, but we lack rigorous constraints on the amount of wetting or drying occurring in monsoon regions. Studies centered on shoreline deposits of closed-basin lakes are well suited for establishing such quantitative controls on water balance changes by providing unequivocal evidence of lake volume variations. Here we present new dating constraints on the highstands of several high-altitude (3800-4350 m) paleolakes in the southern Andean Altiplano, an outlying arid region of the Atacama Desert stretching across the Chilean-Bolivian-Argentinian border east of the Andes (20-25°S). These lakes once occupied the closed basins where only phreatic playas, dry salars, and shallow ponds exist today. Initial U-Th dating of massive shoreline tufas reveals that these deposits are dateable to within ±150 to 300 yrs due to high U concentrations and low initial Th content (as indicated by high 230Th/232Th). Our U-Th and 14C dates show that lake highstands predominantly occur between 18.5 and 14.5 kyrs BP, coinciding with Heinrich Event 1 (HE1) and the expansion of other nearby lakes, such as Lake Titicaca. Because of their (1) location at the modern-day southwestern edge of the summer monsoon, (2) intact shoreline preservation, and (3) precise age control, these lakes may uniquely enable us to reconstruct the evolution of water balance (P-E) changes associated with HE1. Hydrologic modeling constrained by temperature estimates provided by local glacial records is used to provide bounds for past precipitation changes. We also examine North Atlantic cooling as the mechanism for these changes by comparing a compilation of S. American lake level records with various hosing experiments and transient climate simulations at HE1. Our results lend us confidence in expanding our U-Th work to other shoreline tufas in the

Towards a Flood Severity Index

Science.gov (United States)

Kettner, A.; Chong, A.; Prades, L.; Brakenridge, G. R.; Muir, S.; Amparore, A.; Slayback, D. A.; Poungprom, R.

2017-12-01

Flooding is the most common natural hazard worldwide, affecting 21 million people every year. In the immediate moments following a flood event, humanitarian actors like the World Food Program need to make rapid decisions ( 72 hrs) on how to prioritize affected areas impacted by such an event. For other natural disasters like hurricanes/cyclones and earthquakes, there are industry-recognized standards on how the impacted areas are to be classified. Shake maps, quantifying peak ground motion, from for example the US Geological Survey are widely used for assessing earthquakes. Similarly, cyclones are tracked by Joint Typhoon Warning Center (JTWC) and Global Disaster Alert and Coordination System (GDACS) who release storm nodes and tracks (forecasted and actual), with wind buffers and classify the event according to the Saffir-Simpson Hurricane Wind Scale. For floods, the community is usually able to acquire unclassified data of the flood extent as identified from satellite imagery. Most often no water discharge hydrograph is available to classify the event into recurrence intervals simply because there is no gauging station, or the gauging station was unable to record the maximum discharge due to overtopping or flood damage. So, the question remains: How do we methodically turn a flooded area into classified areas of different gradations of impact? Here, we present a first approach towards developing a global applicable flood severity index. The flood severity index is set up such that it considers relatively easily obtainable physical parameters in a short period of time like: flood frequency (relating the current flood to historical events) and magnitude, as well as land cover, slope, and where available pre-event simulated flood depth. The scale includes categories ranging from very minor flooding to catastrophic flooding. We test and evaluate the postulated classification scheme against a set of past flood events. Once a severity category is determined, socio

Development of flood index by characterisation of flood hydrographs

Science.gov (United States)

Bhattacharya, Biswa; Suman, Asadusjjaman

2015-04-01

In recent years the world has experienced deaths, large-scale displacement of people, billions of Euros of economic damage, mental stress and ecosystem impacts due to flooding. Global changes (climate change, population and economic growth, and urbanisation) are exacerbating the severity of flooding. The 2010 floods in Pakistan and the 2011 floods in Australia and Thailand demonstrate the need for concerted action in the face of global societal and environmental changes to strengthen resilience against flooding. Due to climatological characteristics there are catchments where flood forecasting may have a relatively limited role and flood event management may have to be trusted upon. For example, in flash flood catchments, which often may be tiny and un-gauged, flood event management often depends on approximate prediction tools such as flash flood guidance (FFG). There are catchments fed largely by flood waters coming from upstream catchments, which are un-gauged or due to data sharing issues in transboundary catchments the flow of information from upstream catchment is limited. Hydrological and hydraulic modelling of these downstream catchments will never be sufficient to provide any required forecasting lead time and alternative tools to support flood event management will be required. In FFG, or similar approaches, the primary motif is to provide guidance by synthesising the historical data. We follow a similar approach to characterise past flood hydrographs to determine a flood index (FI), which varies in space and time with flood magnitude and its propagation. By studying the variation of the index the pockets of high flood risk, requiring attention, can be earmarked beforehand. This approach can be very useful in flood risk management of catchments where information about hydro-meteorological variables is inadequate for any forecasting system. This paper presents the development of FI and its application to several catchments including in Kentucky in the USA

The Chennai extreme rainfall event in 2015: The Bay of Bengal connection

Science.gov (United States)

Boyaj, Alugula; Ashok, Karumuri; Ghosh, Subimal; Devanand, Anjana; Dandu, Govardhan

2018-04-01

Southeast India experienced a heavy rainfall during 30 Nov-2 Dec 2015. Particularly, the Chennai city, the fourth major metropolitan city in India with a population of 5 million, experienced extreme flooding and causalities. Using various observed/reanalysed datasets, we find that the concurrent southern Bay of Bengal (BoB) sea surface temperatures (SST) were anomalously warm. Our analysis shows that BoB sea surface temperature anomalies (SSTA) are indeed positively, and significantly, correlated with the northeastern Indian monsoonal rainfall during this season. Our sensitivity experiments carried out with the Weather Research and Forecasting (WRF) model at 25 km resolution suggest that, while the strong concurrent El Niño conditions contributed to about 21.5% of the intensity of the extreme Chennai rainfall through its signals in the local SST mentioned above, the warming trend in BoB SST also contributed equally to the extremity of the event. Further, the El Niño southern oscillation (ENSO) impacts on the intensity of the synoptic events in the BoB during the northeast monsoon are manifested largely through the local SST in the BoB as compared through its signature in the atmospheric circulations over the BoB.

Simulation of rainfall-runoff for major flash flood events in Karachi

Science.gov (United States)

Zafar, Sumaira

2016-07-01

Metropolitan city Karachi has strategic importance for Pakistan. With the each passing decade the city is facing urban sprawl and rapid population growth. These rapid changes directly affecting the natural resources of city including its drainage pattern. Karachi has three major cities Malir River with the catchment area of 2252 sqkm and Lyari River has catchment area about 470.4 sqkm. These are non-perennial rivers and active only during storms. Change of natural surfaces into hard pavement causing an increase in rainfall-runoff response. Curve Number is increased which is now causing flash floods in the urban locality of Karachi. There is only one gauge installed on the upstream of the river but there no record for the discharge. Only one gauge located at the upstream is not sufficient for discharge measurements. To simulate the maximum discharge of Malir River rainfall (1985 to 2014) data were collected from Pakistan meteorological department. Major rainfall events use to simulate the rainfall runoff. Maximum rainfall-runoff response was recorded in during 1994, 2007 and 2013. This runoff causes damages and inundation in floodplain areas of Karachi. These flash flooding events not only damage the property but also cause losses of lives

Effect of Monsoon on spatio-temporal variation of groundwater chemistry and stable isotopic signatures: insights for concomitant arsenic mobilization in West Bengal, India

Science.gov (United States)

Majumder, S.; Datta, S.; Nath, B.; Neidhardt, H.; Roman-Ross, G.; Berner, Z.; Hidalgo, M.; Chatterjee, D.; Sarkar, S.

2017-12-01

Large-scale groundwater abstraction was hypothesized to be one of the important factors controlling release and distribution of arsenic (As) in aquifers of Bengal Basin. In this study, we studied the groundwater/surface water geochemistry of two different geomorphic domains within the Chakdaha Block, West Bengal, to identify potential influences of groundwater withdrawal on the hydrochemical evolution of the aquifer. This has been done as a function of different water inputs (monsoon rain, irrigation and downward percolation from surface water impoundments) to the groundwater system and associated As mobilization. A low-land flood plain (with relatively more reducing aquifer) and a natural levee (less reducing aquifer) have been chosen for this purpose. The stable isotopic signatures of oxygen (δ18O) and hydrogen (δ2H) falls sub-parallel to the Global Meteoric Water Line (GMWL), with precipitation and subsequent evaporation seems to be the major controlling factor on the water isotopic composition. This shows a contribution of evaporation influenced water, derived from various surface water bodies, pointing at large-scale groundwater withdrawal helping drawdown of the evaporated surface water. In case of flood plain wells, the stable isotope composition and the Cl/Br molar ratio in local groundwater have revealed vertical recharge within the flood plain area to be the major recharge process, especially during the post-monsoon season. However, both evaporation and vertical mixing are visibly controlling the groundwater recharge in the natural levee area. A possible inflow of organic carbon to the aquifer during the monsoonal recharge process is noticeable, with an increase in dissolved organic carbon (DOC) concentration from 1.33 to 6.29 mg/L on passing from pre- to post-monsoon season. Concomitant increase in AsT, Fe(II) and HCO3- during the post monsoon season, being more pronounced in the flood plain samples, indicates a possible initial episode of reductive

Impacts of Aerosol-Monsoon Interaction on Rainfall and Circulation over Northern India and the Himalaya Foothills

Science.gov (United States)

Lau, William K. M.; Kim, Kyu-Myong; Shi, Jainn-Jong; Matsui, T.; Chin, M.; Tan, Qian; Peters-Lidard, C.; Tao, W. K.

2016-01-01

The boreal summer of 2008 was unusual for the Indian monsoon, featuring exceptional heavy loading of dust aerosols over the Arabian Sea and northern-central India, near normal all- India rainfall, but excessive heavy rain, causing disastrous flooding in the Northern Indian Himalaya Foothills (NIHF) regions, accompanied by persistent drought conditions in central and southern India. Using NASA Unified-physics Weather Research Forecast (NUWRF) model with fully interactive aerosol physics and dynamics, we carried out three sets of 7-day ensemble model forecast experiments: 1) control with no aerosol, 2) aerosol radiative effect only and 3) aerosol radiative and aerosol-cloud-microphysics effects, to study the impacts of aerosol monsoon interactions on monsoon variability over the NIHF during the summer of 2008. Results show that aerosol-radiation interaction (ARI), i.e., dust aerosol transport, and dynamical feedback processes induced by aerosol-radiative heating, plays a key role in altering the large scale monsoon circulation system, reflected by an increased north-south tropospheric temperature gradient, a northward shift of heavy monsoon rainfall, advancing the monsoon onset by 1-5 days over the HF, consistent with the EHP hypothesis (Lau et al. 2006). Additionally, we found that dust aerosols, via the semi-direct effect, increase atmospheric stability, and cause the dissipation of a developing monsoon onset cyclone over northeastern India northern Bay of Bengal. Eventually, in a matter of several days, ARI transforms the developing monsoon cyclone into mesoscale convective cells along the HF slopes. Aerosol-Cloud-microphysics Interaction (ACI) further enhances the ARI effect in invigorating the deep convection cells and speeding up the transformation processes. Results indicate that even in short-term (up to weekly) numerical forecasting of monsoon circulation and rainfall, effects of aerosol-monsoon interaction can be substantial and cannot be ignored.

Field note from Pakistan floods: Preventing future flood disasters

Directory of Open Access Journals (Sweden)

Marcus Oxley

2011-04-01

Full Text Available Unusually heavy monsoon rains in Northern Pakistan have caused disproportionate levels of extreme flooding and unprecedented flood losses across the entire Indus River basin. Extensive land use changes and environmental degradation in the uplands and lowlands of the river basin together with the construction of a “built environment” out of balance with the functioning, capacities, scale and limits of the local ecosystems have exposed millions of people to an increased risk of extreme #ooding. The catastrophic nature of the August #ooding provides a unique opportunity to fundamentally change Pakistan’s current socio-economic development path by incorporating disaster risk reduction and climate change measures into the post-disaster recovery process to rebuild a safer, more resilient nation. In January 2005 one hundred and sixty-eight nations adopted the Hyogo Framework for Action (HFA2005-2015 to bring about a “substantial reduction in disaster losses” by 2015. Despite this global initiative a series of major disasters, including the recent flooding in Pakistan, all indicate that we are not on track to achieve the substantial reduction of disaster losses. The following fieldnote considers what can be done to accelerate progress towards implementation of the Hyogo Framework, drawing on insights and lessons learnt from the August flooding to understand how Pakistan and neighbouring countries can prevent a repeat of such catastrophic disasters in future years.

Mapping the Recent US Hurricanes Triggered Flood Events in Near Real Time

Science.gov (United States)

Shen, X.; Lazin, R.; Anagnostou, E. N.; Wanik, D. W.; Brakenridge, G. R.

2017-12-01

Synthetic Aperture Radar (SAR) observations is the only reliable remote sensing data source to map flood inundation during severe weather events. Unfortunately, since state-of-art data processing algorithms cannot meet the automation and quality standard of a near-real-time (NRT) system, quality controlled inundation mapping by SAR currently depends heavily on manual processing, which limits our capability to quickly issue flood inundation maps at global scale. Specifically, most SAR-based inundation mapping algorithms are not fully automated, while those that are automated exhibit severe over- and/or under-detection errors that limit their potential. These detection errors are primarily caused by the strong overlap among the SAR backscattering probability density functions (PDF) of different land cover types. In this study, we tested a newly developed NRT SAR-based inundation mapping system, named Radar Produced Inundation Diary (RAPID), using Sentinel-1 dual polarized SAR data over recent flood events caused by Hurricanes Harvey, Irma, and Maria (2017). The system consists of 1) self-optimized multi-threshold classification, 2) over-detection removal using land-cover information and change detection, 3) under-detection compensation, and 4) machine-learning based correction. Algorithm details are introduced in another poster, H53J-1603. Good agreements were obtained by comparing the result from RAPID with visual interpretation of SAR images and manual processing from Dartmouth Flood Observatory (DFO) (See Figure 1). Specifically, the over- and under-detections that is typically noted in automated methods is significantly reduced to negligible levels. This performance indicates that RAPID can address the automation and accuracy issues of current state-of-art algorithms and has the potential to apply operationally on a number of satellite SAR missions, such as SWOT, ALOS, Sentinel etc. RAPID data can support many applications such as rapid assessment of damage

Evaluating the use of different precipitation datasets in simulating a flood event

Science.gov (United States)

Akyurek, Z.; Ozkaya, A.

2016-12-01

Floods caused by convective storms in mountainous regions are sensitive to the temporal and spatial variability of rainfall. Space-time estimates of rainfall from weather radar, satellites and numerical weather prediction models can be a remedy to represent pattern of the rainfall with some inaccuracy. However, there is a strong need for evaluation of the performance and limitations of these estimates in hydrology. This study aims to provide a comparison of gauge, radar, satellite (Hydro-Estimator (HE)) and numerical weather prediciton model (Weather Research and Forecasting (WRF)) precipitation datasets during an extreme flood event (22.11.2014) lasting 40 hours in Samsun-Turkey. For this study, hourly rainfall data from 13 ground observation stations were used in the analyses. This event having a peak discharge of 541 m3/sec created flooding at the downstream of Terme Basin. Comparisons were performed in two parts. First the analysis were performed in areal and point based manner. Secondly, a semi-distributed hydrological model was used to assess the accuracy of the rainfall datasets to simulate river flows for the flood event. Kalman Filtering was used in the bias correction of radar rainfall data compared to gauge measurements. Radar, gauge, corrected radar, HE and WRF rainfall data were used as model inputs. Generally, the HE product underestimates the cumulative rainfall amounts in all stations, radar data underestimates the results in cumulative sense but keeps the consistency in the results. On the other hand, almost all stations in WRF mean statistics computations have better results compared to the HE product but worse than the radar dataset. Results in point comparisons indicated that, trend of the rainfall is captured by the radar rainfall estimation well but radar underestimates the maximum values. According to cumulative gauge value, radar underestimated the cumulative rainfall amount by % 32. Contrary to other datasets, the bias of WRF is positive

Combined fluvial and pluvial urban flood hazard analysis: method development and application to Can Tho City, Mekong Delta, Vietnam

Science.gov (United States)

Apel, H.; Trepat, O. M.; Hung, N. N.; Chinh, D. T.; Merz, B.; Dung, N. V.

2015-08-01

Many urban areas experience both fluvial and pluvial floods, because locations next to rivers are preferred settlement areas, and the predominantly sealed urban surface prevents infiltration and facilitates surface inundation. The latter problem is enhanced in cities with insufficient or non-existent sewer systems. While there are a number of approaches to analyse either fluvial or pluvial flood hazard, studies of combined fluvial and pluvial flood hazard are hardly available. Thus this study aims at the analysis of fluvial and pluvial flood hazard individually, but also at developing a method for the analysis of combined pluvial and fluvial flood hazard. This combined fluvial-pluvial flood hazard analysis is performed taking Can Tho city, the largest city in the Vietnamese part of the Mekong Delta, as example. In this tropical environment the annual monsoon triggered floods of the Mekong River can coincide with heavy local convective precipitation events causing both fluvial and pluvial flooding at the same time. Fluvial flood hazard was estimated with a copula based bivariate extreme value statistic for the gauge Kratie at the upper boundary of the Mekong Delta and a large-scale hydrodynamic model of the Mekong Delta. This provided the boundaries for 2-dimensional hydrodynamic inundation simulation for Can Tho city. Pluvial hazard was estimated by a peak-over-threshold frequency estimation based on local rain gauge data, and a stochastic rain storm generator. Inundation was simulated by a 2-dimensional hydrodynamic model implemented on a Graphical Processor Unit (GPU) for time-efficient flood propagation modelling. All hazards - fluvial, pluvial and combined - were accompanied by an uncertainty estimation considering the natural variability of the flood events. This resulted in probabilistic flood hazard maps showing the maximum inundation depths for a selected set of probabilities of occurrence, with maps showing the expectation (median) and the uncertainty by

A Participatory Modeling Application of a Distributed Hydrologic Model in Nuevo Leon, Mexico for the 2010 Hurricane Alex Flood Event

Science.gov (United States)

Baish, A. S.; Vivoni, E. R.; Payan, J. G.; Robles-Morua, A.; Basile, G. M.

2011-12-01

A distributed hydrologic model can help bring consensus among diverse stakeholders in regional flood planning by producing quantifiable sets of alternative futures. This value is acute in areas with high uncertainties in hydrologic conditions and sparse observations. In this study, we conduct an application of the Triangulated Irregular Network (TIN)-based Real-time Integrated Basin Simulator (tRIBS) in the Santa Catarina basin of Nuevo Leon, Mexico, where Hurricane Alex in July 2010 led to catastrophic flooding of the capital city of Monterrey. Distributed model simulations utilize best-available information on the regional topography, land cover, and soils obtained from Mexican government agencies or analysis of remotely-sensed imagery from MODIS and ASTER. Furthermore, we developed meteorological forcing for the flood event based on multiple data sources, including three local gauge networks, satellite-based estimates from TRMM and PERSIANN, and the North American Land Data Assimilation System (NLDAS). Remotely-sensed data allowed us to quantify rainfall distributions in the upland, rural portions of the Santa Catarina that are sparsely populated and ungauged. Rural areas had significant contributions to the flood event and as a result were considered by stakeholders for flood control measures, including new reservoirs and upland vegetation management. Participatory modeling workshops with the stakeholders revealed a disconnect between urban and rural populations in regard to understanding the hydrologic conditions of the flood event and the effectiveness of existing and potential flood control measures. Despite these challenges, the use of the distributed flood forecasts developed within this participatory framework facilitated building consensus among diverse stakeholders and exploring alternative futures in the basin.

Historical flood data series of Eastern Spanish Coast (14th-20th centuries). Improving identification of climatic patterns and human factors of flood events from primary documentary sources

Science.gov (United States)

Alberola, Armando; Barriendos, Mariano; Gil-Guirado, Salvador; Pérez-Morales, Alfredo; Balasch, Carles; Castelltort, Xavier; Mazón, Jordi; Pino, David; Lluís Ruiz-Bellet, Josep; Tuset, Jordi

2016-04-01

Historical flood data series of Eastern Spanish Coast (14th-20th centuries). Improving identification of climatic patterns and human factors of flood events from primary documentary sources Armando Alberola, Barriendos, M., Gil-Guirado, S., Pérez Morales, A., Balasch, C., Castelltort, X., Mazón, J., Pino, D., Ruiz-Bellet, J.L., Tuset, J. Historical flood events in eastern spanish coast have been studied by different research groups and projects. Complexity of flood processes, involving atmospheric, surface and human factors, is not easily understandable when long time series are required. Present analysis from PREDIFLOOD Project Consortium defines a new step of flood event databases: Improved access to primary (documentary) and secondary (bibliographical) sources, data collection for all possible locations where floods are detected, and improved system of classification (Barriendos et al., 2014). A first analysis is applied to 8 selected flood series. Long chronologies from PREDIFLOOD Project for Catalonia region (Girona, Barcelona, Tarragona, Lleida, Tortosa). In addition, to cover all sector of spanish mediterranean coast, we introduce Valencia city in Turia River basin. South Eastern sector is cover with Murcia and Caravaca cities, Segura River basin. Extension of area under study required contributions of research teams experienced in work of documentary primary sources (Alberola, 2006; Gil-Guirado, 2013). Flood frequency analysis for long scale periods show natural climatic oscillations into so-called Little Ice Age. There are general patterns, affecting most of basins, but also some local anomalies or singularities. To explain these differences and analogies it is not enough to use purely climatic factors. In this way, we analyze human factors that have been able to influence the variability of floods along last 6 centuries (demography, hydraulic infrastructures, urban development...). This approach improves strongly understanding of mechanisms producing

Glacial lake outburst floods and fluvial erosion in the Himalaya - insights from the 2016 Bhote Koshi GLOF

Science.gov (United States)

Cook, K. L.; Gimbert, F.; Andermann, C.; Hovius, N.; Adhikari, B. R.

2017-12-01

The Himalaya is a region of rapid erosion where fluvial processes are assumed to be driven by precipitation delivered during the annual Indian Summer Monsoon. However, the rivers in this region are also subject to catastrophic floods caused by the failure of glacial lake and landslide dams. Because these floods are rarely observed, it has been difficult to isolate their impact on the rivers and adjacent hillslopes, and their importance for the long-term evolution of Himalayan valleys is largely unknown. In July 2016, the Bhotekoshi/Sunkoshi River in central Nepal was hit by a glacial lake outburst flood (GLOF) that caused substantial changes to the channel bed, banks, and adjacent hillslopes, causing at least 26 landslides and an average of 11 m of channel widening. The flood passed through a seismic and hydrological observatory installed along the river in June 2015, and we have used the resulting data to constrain the timing, duration, and bedload transport properties of the outburst flood. The impact of the flood on the river can be further observed with hourly time-lapse photographs, daily measurements of suspended sediment load, repeat lidar surveys, and satellite imagery. The outburst flood affected the river on several timescales. In the short term, it transported large amounts of coarse sediment and restructured the river bed during the hours of the flood pulse itself. Over intermediate timescales it resulted in elevated bedload and suspended load transport for several weeks following the flood. Over longer timescales the flood undercut and destabilized the river banks and hillslopes in a number of locations, leading to bank collapses, slumps, and landslides. Our data indicate that impacts of the GLOF far exceed those driven by the annual summer monsoon, likely due to extremely coarse sediment that armors much of the channel. The relatively frequent occurrence of GLOFs and the extremely high discharges relative to monsoon floods suggest that GLOFs may

The Indian Monsoon

Indian Academy of Sciences (India)

The word 'monsoon' is derived from the Arabic word 'mausam' for season and the distinguishing attribute of ... lance, the word monsoon is used for the rainfall in the rainy season. In this article, I discuss the ..... [1] C S Ramage, Monsoon meteorology, International Geophysics Series,. Academic Press, San Diego, California ...

Late Holocene environmental reconstructions and the implications on flood events, typhoon patterns, and agriculture activities in NE Taiwan

Science.gov (United States)

Wang, L.-C.; Behling, H.; Lee, T.-Q.; Li, H.-C.; Huh, C.-A.; Shiau, L.-J.; Chang, Y.-P.

2014-05-01

In this study, we reconstructed the paleoenvironmental changes from a sediment archive of the floodplain lake in Ilan Plain of NE Taiwan on multi-decadal resolution for the last ca. 1900 years. On the basis of pollen and diatom records, we evaluated the record of past vegetation, floods, typhoons and agriculture activities of this area, which is sensitive to the hydrological conditions of the West Pacific. High sedimentation rates with low microfossil preservations reflected multiple flood events and humid climatic conditions during 100-1400 AD. A shortly interrupted dry phase can be found during 940-1010 AD. The driest phase corresponds to the Little Ice Age phase 1 (LIA1, 1400-1620 AD) with less disturbance by flood events, which enhanced the occurrence of wetlands (Cyperaceae) and diatom depositions. Humid phases with frequent typhoons are inferred by high percentages of Lagerstroemia and high ratios of planktonic/benthic diatoms, respectively, during 500-700 AD and Little Ice Age phase 2 (LIA2, 1630-1850 AD). The occurrences of cultivated Poaceae (Oryza) during 1250-1300 AD and the last ~400 years, reflect agriculture activities, which seems to implicate strongly with the environmental stability. Finally, we found flood events which dominated during the El Niño-like stage, but dry events as well as frequent typhoon events happened during the La Niña-like stage. After comparing our results with the reconstructed proxy for tropical hydrological conditions, we suggested that the local hydrology in coastal East Asia were strongly affected by the typhoon-triggered heavy rainfalls which were influenced by the variation of global temperature, expansion of the Pacific warm pool and intensification of ENSO events.

Combining empirical approaches and error modelling to enhance predictive uncertainty estimation in extrapolation for operational flood forecasting. Tests on flood events on the Loire basin, France.

Science.gov (United States)

Berthet, Lionel; Marty, Renaud; Bourgin, François; Viatgé, Julie; Piotte, Olivier; Perrin, Charles

2017-04-01

An increasing number of operational flood forecasting centres assess the predictive uncertainty associated with their forecasts and communicate it to the end users. This information can match the end-users needs (i.e. prove to be useful for an efficient crisis management) only if it is reliable: reliability is therefore a key quality for operational flood forecasts. In 2015, the French flood forecasting national and regional services (Vigicrues network; www.vigicrues.gouv.fr) implemented a framework to compute quantitative discharge and water level forecasts and to assess the predictive uncertainty. Among the possible technical options to achieve this goal, a statistical analysis of past forecasting errors of deterministic models has been selected (QUOIQUE method, Bourgin, 2014). It is a data-based and non-parametric approach based on as few assumptions as possible about the forecasting error mathematical structure. In particular, a very simple assumption is made regarding the predictive uncertainty distributions for large events outside the range of the calibration data: the multiplicative error distribution is assumed to be constant, whatever the magnitude of the flood. Indeed, the predictive distributions may not be reliable in extrapolation. However, estimating the predictive uncertainty for these rare events is crucial when major floods are of concern. In order to improve the forecasts reliability for major floods, an attempt at combining the operational strength of the empirical statistical analysis and a simple error modelling is done. Since the heteroscedasticity of forecast errors can considerably weaken the predictive reliability for large floods, this error modelling is based on the log-sinh transformation which proved to reduce significantly the heteroscedasticity of the transformed error in a simulation context, even for flood peaks (Wang et al., 2012). Exploratory tests on some operational forecasts issued during the recent floods experienced in

Assimilation of flood extent data with 2D flood inundation models for localised intense rainfall events

Science.gov (United States)

Neal, J. C.; Wood, M.; Bermúdez, M.; Hostache, R.; Freer, J. E.; Bates, P. D.; Coxon, G.

2017-12-01

Remote sensing of flood inundation extent has long been a potential source of data for constraining and correcting simulations of floodplain inundation. Hydrodynamic models and the computing resources to run them have developed to the extent that simulation of flood inundation in two-dimensional space is now feasible over large river basins in near real-time. However, despite substantial evidence that there is useful information content within inundation extent data, even from low resolution SAR such as that gathered by Envisat ASAR in wide swath mode, making use of the information in a data assimilation system has proved difficult. He we review recent applications of the Ensemble Kalman Filter (EnKF) and Particle Filter for assimilating SAR data, with a focus on the River Severn UK and compare these with complementary research that has looked at the internal error sources and boundary condition errors using detailed terrestrial data that is not available in most locations. Previous applications of the EnKF to this reach have focused on upstream boundary conditions as the source of flow error, however this description of errors was too simplistic for the simulation of summer flood events where localised intense rainfall can be substantial. Therefore, we evaluate the introduction of uncertain lateral inflows to the ensemble. A further limitation of the existing EnKF based methods is the need to convert flood extent to water surface elevations by intersecting the shoreline location with a high quality digital elevation model (e.g. LiDAR). To simplify this data processing step, we evaluate a method to directly assimilate inundation extent as a EnKF model state rather than assimilating water heights, potentially allowing the scheme to be used where high-quality terrain data are sparse.

Impacts of extreme events of drought and flood on local communities of Amazon basin

Science.gov (United States)

Borma, L. D.; Roballo, S.; Zauner, M.; Nascimento, V. F.

2013-05-01

The analysis of drought events of 1997/98, 2005 and 2010 in terms of discharge anomalies in the Amazon region confirmed previous findings, such as: a) the influence of the El Niño in more than one hydrological year; b) the increase of the influence of the Atlantic Multidecadal Oscillation of 1998, 2005 and 2010 drought events; c) the low levels of discharge observed in the 2010 drought are attributed to the association of discharge anomalies of the northern and southern tributaries of the Amazon river, and d) the 2010 drought lasted around 1 month (August to November) more than the other drought events analized here. The riverine communities located along the river banks of Solimões/Amazonas suit their economic activities to the oscillation of the water level. In general, low water periods favor the access to important sources of food such as fish and livestock, still allowing crop cultivation on fertile agricultural areas of the floodplain. Conversely, periods of drought increases the difficulties of transport and drinking water supply. During the high water, access to the main food supply (described above) are greatly hampered. However, the floods are recognized as an importance process of natural fertilization. Thus, despite the political, social and economic shortcomings, the local community has, since the pre-colonial period, learned to get the best of each season, providing local, regional and national markets with varzea products. During periods of extreme weather, however, the advantages of each season appear to be reduced, and the drawbacks increased. In fact, during flooding extremes, the access to primary sources of food is hampered by a long period of time and families find themselves forced to leave their homes, eventually losing them. Analysis of flow data to the extreme flooding of 2009, indicate a period of about 6 months of positive anomalies discharge (occurring mainly during high water). At the same time, Civil Defense data points to a

Decision support system emergency planning, creating evacuation strategies in the event of flooding

NARCIS (Netherlands)

Windhouwer, C.J.; Klunder, G.A.; Sanders, F.M.

2005-01-01

The Decision Support System (DSS) Emergency Planning is designed for use in the event of sea or river flooding. It makes accessible all the information related to the decision whether to evacuate an area. An important factor in this decision is the time required for the evacuation. The model used by

Probabilistic flood forecasting tool for Andalusia (Spain). Application to September 2012 disaster event in Vera Playa.

Science.gov (United States)

García, Darío; Baquerizo, Asunción; Ortega, Miguel; Herrero, Javier; Ángel Losada, Miguel

2013-04-01

Torrential and heavy rains are frequent in Andalusia (Southern Spain) due to the characteristic Mediterranean climate (semi-arid areas). This, in combination with a massive occupation of floodable (river sides) and coastal areas, produces severe problems of management and damage to the population and social and economical activities when extreme events occur. Some of the most important problems are being produced during last years in Almería (Southeastern Andalusia). Between 27 and 28 September 2012 rainstorms characterized by 240mm in 24h (exceeding precipitation for a return period of 500 years) occurred. Antas River and Jático creek, that are normally dry, became raging torrents. The massive flooding of occupied areas resulted in eleven deaths and two missing in Andalucía, with a total estimated cost of all claims for compensation on the order of 197 million euros. This study presents a probabilistic flood forecasting tool including the effect of river and marine forcings. It is based on a distributed, physically-based hydrological model (WiMMed). For Almería the model has been calibrated with the largest event recorded in Cantoria gauging station (data since 1965) on 19 October 1973. It was then validated with the second strongest event (26 October 1977). Among the different results of the model, it can provide probability floods scenarios in Andalusia with up 10 days weather forecasts. The tool has been applied to Vera, a 15.000 inhabitants town located in the east of Almería along the Antas River at an altitude of 95 meters. Its main economic resource is the "beach and sun" based-tourism, which has experienced an enormous growth during last decades. Its coastal stretch has been completely built in these years, occupying floodable areas and constricting the channel and rivers mouths. Simulations of the model in this area for the 1973 event and published in March 2011 on the internet event already announced that the floods of September 2012 may occur.

FloodProBE: technologies for improved safety of the built environment in relation to flood events

International Nuclear Information System (INIS)

Ree, C.C.D.F. van; Van, M.A.; Heilemann, K.; Morris, M.W.; Royet, P.; Zevenbergen, C.

2011-01-01

The FloodProBE project started as a FP7 research project in November 2009. Floods, together with wind related storms, are considered the major natural hazard in the EU in terms of risk to people and assets. In order to adapt urban areas (in river and coastal zones) to prevent flooding or to be better prepared for floods, decision makers need to determine how to upgrade flood defences and increasing flood resilience of protected buildings and critical infrastructure (power supplies, communications, water, transport, etc.) and assess the expected risk reduction from these measures. The aim of the FloodProBE-project is to improve knowledge on flood resilience and flood protection performance for balancing investments in flood risk management in urban areas. To this end, technologies, methods and tools for assessment purposes and for the adaptation of new and existing buildings and critical infrastructure are developed, tested and disseminated. Three priority areas are addressed by FloodProBE. These are: (i) vulnerability of critical infrastructure and high-density value assets including direct and indirect damage, (ii) the assessment and reliability of urban flood defences including the use of geophysical methods and remote sensing techniques and (iii) concepts and technologies for upgrading weak links in flood defences as well as construction technologies for flood proofing buildings and infrastructure networks to increase the flood resilience of the urban system. The primary impact of FloodProBE in advancing knowledge in these areas is an increase in the cost-effectiveness (i.e. performance) of new and existing flood protection structures and flood resilience measures.

Predicted high-water elevations for selected flood events at the Albert Pike Recreation Area, Ouachita National Forest

Science.gov (United States)

D.A. Marion

2012-01-01

The hydraulic characteristics are determined for the June 11, 2010, flood on the Little Missouri River at the Albert Pike Recreation Area in Arkansas. These characteristics are then used to predict the high-water elevations for the 10-, 25-, 50-, and 100-year flood events in the Loop B, C, and D Campgrounds of the recreation area. The peak discharge and related...

Multi-dimensional flood vulnerability assessment using data envelopment analysis

Science.gov (United States)

Zahid, Zalina; Saharizan, Nurul Syuhada; Hamzah, Paezah; Hussin, Siti Aida Sheikh; Khairi, Siti Shaliza Mohd

2017-11-01

Malaysia has been greatly impacted by flood during monsoon seasons. Even though flood prone areas are well identified, assessment on the vulnerability of the disaster is lacking. Assessment of flood vulnerability, defined as the potential for loss when a disaster occurs, is addressed in this paper. The focus is on the development of flood vulnerability measurement in 11 states in Peninsular Malaysia using a non-parametric approach of Data Envelopment Analysis. Scores for three dimensions of flood vulnerability (Population Vulnerability, Social Vulnerability and Biophysical) were calculated using secondary data of selected input and output variables across an 11-year period from 2004 to 2014. The results showed that Johor and Pahang were the most vulnerable to flood in terms of Population Vulnerability, followed by Kelantan, the most vulnerable to flood in terms of Social Vulnerability and Kedah, Pahang and Terengganu were the most vulnerable to flood in terms of Biophysical Vulnerability among the eleven states. The results also showed that the state of Johor, Pahang and Kelantan to be most vulnerable across the three dimensions. Flood vulnerability assessment is important as it provides invaluable information that will allow the authority to identify and develop plans for flood mitigation and to reduce the vulnerability of flood at the affected regions.

Uni- and multi-variable modelling of flood losses: experiences gained from the Secchia river inundation event.

Science.gov (United States)

Carisi, Francesca; Domeneghetti, Alessio; Kreibich, Heidi; Schröter, Kai; Castellarin, Attilio

2017-04-01

Flood risk is function of flood hazard and vulnerability, therefore its accurate assessment depends on a reliable quantification of both factors. The scientific literature proposes a number of objective and reliable methods for assessing flood hazard, yet it highlights a limited understanding of the fundamental damage processes. Loss modelling is associated with large uncertainty which is, among other factors, due to a lack of standard procedures; for instance, flood losses are often estimated based on damage models derived in completely different contexts (i.e. different countries or geographical regions) without checking its applicability, or by considering only one explanatory variable (i.e. typically water depth). We consider the Secchia river flood event of January 2014, when a sudden levee-breach caused the inundation of nearly 200 km2 in Northern Italy. In the aftermath of this event, local authorities collected flood loss data, together with additional information on affected private households and industrial activities (e.g. buildings surface and economic value, number of company's employees and others). Based on these data we implemented and compared a quadratic-regression damage function, with water depth as the only explanatory variable, and a multi-variable model that combines multiple regression trees and considers several explanatory variables (i.e. bagging decision trees). Our results show the importance of data collection revealing that (1) a simple quadratic regression damage function based on empirical data from the study area can be significantly more accurate than literature damage-models derived for a different context and (2) multi-variable modelling may outperform the uni-variable approach, yet it is more difficult to develop and apply due to a much higher demand of detailed data.

Sub-seasonal Predictability of Heavy Precipitation Events: Implication for Real-time Flood Management in Iran

Science.gov (United States)

Najafi, H.; Shahbazi, A.; Zohrabi, N.; Robertson, A. W.; Mofidi, A.; Massah Bavani, A. R.

2016-12-01

Each year, a number of high impact weather events occur worldwide. Since any level of predictability at sub-seasonal to seasonal timescale is highly beneficial to society, international efforts is now on progress to promote reliable Ensemble Prediction Systems for monthly forecasts within the WWRP/WCRP initiative (S2S) project and North American Multi Model Ensemble (NMME). For water resources managers in the face of extreme events, not only can reliable forecasts of high impact weather events prevent catastrophic losses caused by floods but also contribute to benefits gained from hydropower generation and water markets. The aim of this paper is to analyze the predictability of recent severe weather events over Iran. Two recent heavy precipitations are considered as an illustration to examine whether S2S forecasts can be used for developing flood alert systems especially where large cascade of dams are in operation. Both events have caused major damages to cities and infrastructures. The first severe precipitation was is in the early November 2015 when heavy precipitation (more than 50 mm) occurred in 2 days. More recently, up to 300 mm of precipitation is observed within less than a week in April 2016 causing a consequent flash flood. Over some stations, the observed precipitation was even more than the total annual mean precipitation. To analyze the predictive capability, ensemble forecasts from several operational centers including (European Centre for Medium-Range Weather Forecasts (ECMWF) system, Climate Forecast System Version 2 (CFSv2) and Chinese Meteorological Center (CMA) are evaluated. It has been observed that significant changes in precipitation anomalies were likely to be predicted days in advance. The next step will be to conduct thorough analysis based on comparing multi-model outputs over the full hindcast dataset developing real-time high impact weather prediction systems.

AP1000{sup R} design robustness against extreme external events - Seismic, flooding, and aircraft crash

Energy Technology Data Exchange (ETDEWEB)

Pfister, A.; Goossen, C.; Coogler, K.; Gorgemans, J. [Westinghouse Electric Company LLC, 1000 Westinghouse Drive, Cranberry Township, PA 16066 (United States)

2012-07-01

Both the International Atomic Energy Agency (IAEA) and the U.S. Nuclear Regulatory Commission (NRC) require existing and new nuclear power plants to conduct plant assessments to demonstrate the unit's ability to withstand external hazards. The events that occurred at the Fukushima-Dai-ichi nuclear power station demonstrated the importance of designing a nuclear power plant with the ability to protect the plant against extreme external hazards. The innovative design of the AP1000{sup R} nuclear power plant provides unparalleled protection against catastrophic external events which can lead to extensive infrastructure damage and place the plant in an extended abnormal situation. The AP1000 plant is an 1100-MWe pressurized water reactor with passive safety features and extensive plant simplifications that enhance construction, operation, maintenance and safety. The plant's compact safety related footprint and protection provided by its robust nuclear island structures prevent significant damage to systems, structures, and components required to safely shutdown the plant and maintain core and spent fuel pool cooling and containment integrity following extreme external events. The AP1000 nuclear power plant has been extensively analyzed and reviewed to demonstrate that it's nuclear island design and plant layout provide protection against both design basis and extreme beyond design basis external hazards such as extreme seismic events, external flooding that exceeds the maximum probable flood limit, and malicious aircraft impact. The AP1000 nuclear power plant uses fail safe passive features to mitigate design basis accidents. The passive safety systems are designed to function without safety-grade support systems (such as AC power, component cooling water, service water, compressed air or HVAC). The plant has been designed to protect systems, structures, and components critical to placing the reactor in a safe shutdown condition within the steel

Impact of the Three-Gorges Dam and water transfer project on Changjiang floods

Science.gov (United States)

Nakayama, Tadanobu; Shankman, David

2013-01-01

Increasing frequency of severe floods on the middle and lower Changjiang (Yangtze) River during the past few decades can be attributed to both abnormal monsoon rainfall and landscape changes that include extensive deforestation affecting river sedimentation, and shrinking lakes and levee construction that reduced the areas available for floodwater storage. The Three-Gorges Dam (TGD) and the South-to-North Water Transfer Project (SNWTP) will also affect frequency and intensity of severe floods in the Poyang Lake region of the middle Changjiang. Process-based National Integrated Catchment-based Eco-hydrology (NICE) model predicts that the TGD will increase flood risk during the early summer monsoon against the original justifications for building the dam, relating to complex river-lake-groundwater interactions. Several scenarios predict that morphological change will increase flood risk around the lake. This indicates the importance of managing both flood discharge and sediment deposition for the entire basin. Further, the authors assessed the impact of sand mining in the lake after its prohibition on the Changjiang, and clarified that alternative scenario of sand mining in lakes currently disconnected from the mainstream would reduce the flood risk to a greater extent than intensive dredging along junction channel. Because dry biomasses simulated by the model were linearly related to the Time-Integrated Normalized Difference Vegetation Index (TINDVI) estimated from satellite images, its decadal gradient during 1982-1999 showed a spatially heterogeneous distribution and generally decreasing trends beside the lakes, indicating that the increases in lake reclamation and the resultant decrease in rice productivity are closely related to the hydrologic changes. This integrated approach could help to minimize flood damage and promote better decisions addressing sustainable development.

The 2010 Pakistan Flood and Russian Heat Wave: Teleconnection of Hydrometeorological Extremes

Science.gov (United States)

Lau, William K. M.; Kim, Kyu-Myong

2012-01-01

In this paper, preliminary results are presented showing that the two record-setting extreme events during 2010 summer (i.e., the Russian heat wave-wildfires and Pakistan flood) were physically connected. It is found that the Russian heat wave was associated with the development of an extraordinarily strong and prolonged extratropical atmospheric blocking event in association with the excitation of a large-scale atmospheric Rossby wave train spanning western Russia, Kazakhstan, and the northwestern China-Tibetan Plateau region. The southward penetration of upper-level vorticity perturbations in the leading trough of the Rossby wave was instrumental in triggering anomalously heavy rain events over northern Pakistan and vicinity in mid- to late July. Also shown are evidences that the Russian heat wave was amplified by a positive feedback through changes in surface energy fluxes between the atmospheric blocking pattern and an underlying extensive land region with below-normal soil moisture. The Pakistan heavy rain events were amplified and sustained by strong anomalous southeasterly flow along the Himalayan foothills and abundant moisture transport from the Bay of Bengal in connection with the northward propagation of the monsoonal intraseasonal oscillation.

South America Monsoon variability on millennial to multi-centennial time scale during the Holocene in central eastern Brazil

Science.gov (United States)

Strikis, N. M.; Cruz, F. W.; Cheng, H.; Karmann, I.; Vuille, M.; Edwards, R.; Wang, X.; Paula, M. S.; Novello, V. F.; Auler, A.

2011-12-01

A paleoprecipitation reconstruction based on high resolution and well-dated speleothem oxygen isotope records shows that the monsoon precipitation over central eastern Brazil underwent to strong variations on millennial to multi-centennial time-scales during the Holocene. This new record indicates that abrupt events of increase in monsoon precipitation are correlated to Bond events 6, 5 and 4 and also with 8.2 ky event during the early and mid-Holocene, with a mean amplitude of 1.5 % (PDB). The pacing and structure of such events are general consistent with variations in solar activity suggested by atmospheric Δ14 C records. In the late-Holocene, abrupt events of increase in monsoon precipitation peaking at 3.2, 2.7 and 2.3 ky B.P. are approximately synchronous with periods of low solar minima. In this regard, the most prominent event occurred during the late Holocene occurred at ~2.7 ky B.P. In addition, these positive anomalies of the precipitation recorded in central eastern Brazil are also in good agreement with variations in Titicaca lake level. The good correspondence between the speleothem and marine records imply that the variations in the north Atlantic sea surface temperature is the main forcing for abrupt millennial to multi-centennial precipitations variation within the region under influence of South American Monsoon.

Concentration-discharge relationships during an extreme event: Contrasting behavior of solutes and changes to chemical quality of dissolved organic material in the Boulder Creek Watershed during the September 2013 flood: SOLUTE FLUX IN A FLOOD EVENT

Energy Technology Data Exchange (ETDEWEB)

Rue, Garrett P. [Institute of Arctic and Alpine Research, University of Colorado, Boulder Colorado USA; Rock, Nathan D. [Institute of Arctic and Alpine Research, University of Colorado, Boulder Colorado USA; Gabor, Rachel S. [Institute of Arctic and Alpine Research, University of Colorado, Boulder Colorado USA; Pitlick, John [Department of Geography, University of Colorado, Boulder Colorado USA; Tfaily, Malak [Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, Richland Washington USA; McKnight, Diane M. [Institute of Arctic and Alpine Research, University of Colorado, Boulder Colorado USA

2017-07-01

During the week of September 10-17, 2013, close to 20 inches of rain fell across Boulder County, Colorado, USA. This rainfall represented a 1000-year event that caused massive hillslope erosion, landslides, and mobilization of sediments. The resultant stream flows corresponded to a 100-year flood. For the Boulder Creek Critical Zone Observatory (BC-CZO), this event provided an opportunity to study the effect of extreme rainfall on solute concentration-discharge relationships and biogeochemical catchment processes. We observed base cation and dissolved organic carbon (DOC) concentrations at two sites on Boulder Creek following the recession of peak flow. We also isolated three distinct fractions of dissolved organic matter (DOM) for chemical characterization. At the upper site, which represented the forested mountain catchment, the concentrations of the base cations Ca, Mg and Na were greatest at the peak flood and decreased only slightly, in contrast with DOC and K concentrations, which decreased substantially. At the lower site within urban corridor, all solutes decreased abruptly after the first week of flow recession, with base cation concentrations stabilizing while DOC and K continued to decrease. Additionally, we found significant spatiotemporal trends in the chemical quality of organic matter exported during the flood recession, as measured by fluorescence, 13C-NMR spectroscopy, and FTICR-MS. Similar to the effect of extreme rainfall events in driving landslides and mobilizing sediments, our findings suggest that such events mobilize solutes by the flushing of the deeper layers of the critical zone, and that this flushing regulates terrestrial-aquatic biogeochemical linkages during the flow recession.

The Effects of Rainfall Pulses on Soil Nitrogen Availability in a Chihuahuan Desert Grassland During the Summer Monsoon

Science.gov (United States)

Brown, R. F.; Collins, S. L.; White, C. S.; Sinsabaugh, R. L.

2015-12-01

Nitrogen (N) is an essential but limiting nutrient in most terrestrial environments. While numerous studies have demonstrated a tight coupling between soil N availability and soil volumetric water content, this relationship is not well understood in desert ecosystems where rain events create pulses of biological activity, such as microbial secretion of extracellular enzymes that enable nutrient acquisition. Moreover, climate models are projecting shifts in the size and frequency of rain events across semi-arid ecosystems as a result of anthropogenic activities; therefore these changes are expected to have consequences for soil N availability in these regions. The goals of this study were to determine (1) if soil N availability pulses in response to monsoon rain events of differing size and frequency, and (2) how soil N availability varies over the course of a monsoon season in a semi-arid grassland. To answer these questions, we analyzed soils collected from a northern Chihuahuan Desert grassland during the 2014 summer monsoon. Soils were collected monthly over a period of eight days in conjunction with experimentally manipulated irrigation treatments that varied in both size (small=5mm and large=20mm) and frequency (small=weekly (n=12) and large=monthly (n=3)). Using KCl extraction, soils were processed for their inorganic plant-available nitrogen content (NH4+-N and NO3--N). We found that while soil N availability increased over the monsoon season across all treatment types, large events appeared to saturate soils, creating anaerobic conditions that stimulated nitrogen loss most likely through the denitrification pathway. Soils were also assayed for nitrogen specific extracellular enzyme activities, specifically leucine aminopeptidase (LAP), which breaks down the bond in leucine amino acids to mobilize nitrogen, and N-acetylglucosaminidase (NAG), which breaks down amino sugars in microbial cell walls. Preliminary results suggest that by mid-monsoon, LAP activity

Aerosol and monsoon climate interactions over Asia: AEROSOL AND MONSOON CLIMATE INTERACTIONS

Energy Technology Data Exchange (ETDEWEB)

Li, Zhanqing [State Key Laboratory of Earth Surface Processes and Resource Ecology and College of Global Change and Earth System Science, Beijing Normal University, Beijing China; Department of Atmospheric and Oceanic Science and ESSIC, University of Maryland, College Park Maryland USA; Lau, W. K. -M. [Department of Atmospheric and Oceanic Science and ESSIC, University of Maryland, College Park Maryland USA; Ramanathan, V. [Department of Atmospheric and Climate Sciences, University of California, San Diego California USA; Wu, G. [Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing China; Ding, Y. [National Climate Center, China Meteorological Administration, Beijing China; Manoj, M. G. [Department of Atmospheric and Oceanic Science and ESSIC, University of Maryland, College Park Maryland USA; Liu, J. [Department of Atmospheric and Oceanic Science and ESSIC, University of Maryland, College Park Maryland USA; Qian, Y. [Pacific Northwest National Laboratory, Richland Washington USA; Li, J. [State Key Laboratory of Earth Surface Processes and Resource Ecology and College of Global Change and Earth System Science, Beijing Normal University, Beijing China; Zhou, T. [Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing China; Fan, J. [Pacific Northwest National Laboratory, Richland Washington USA; Rosenfeld, D. [Institute of Earth Sciences, Hebrew University, Jerusalem Israel; Ming, Y. [Geophysical Fluid Dynamic Laboratory, NOAA, Princeton New Jersey USA; Wang, Y. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena California USA; Huang, J. [College of Atmospheric Sciences, Lanzhou University, Lanzhou China; Wang, B. [Department of Atmospheric Sciences, University of Hawaii, Honolulu Hawaii USA; School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing China; Xu, X. [Chinese Academy of Meteorological Sciences, Beijing China; Lee, S. -S. [Department of Atmospheric and Oceanic Science and ESSIC, University of Maryland, College Park Maryland USA; Cribb, M. [Department of Atmospheric and Oceanic Science and ESSIC, University of Maryland, College Park Maryland USA; Zhang, F. [State Key Laboratory of Earth Surface Processes and Resource Ecology and College of Global Change and Earth System Science, Beijing Normal University, Beijing China; Yang, X. [State Key Laboratory of Earth Surface Processes and Resource Ecology and College of Global Change and Earth System Science, Beijing Normal University, Beijing China; Zhao, C. [State Key Laboratory of Earth Surface Processes and Resource Ecology and College of Global Change and Earth System Science, Beijing Normal University, Beijing China; Takemura, T. [Research Institute for Applied Mechanics, Kyushu University, Fukuoka Japan; Wang, K. [State Key Laboratory of Earth Surface Processes and Resource Ecology and College of Global Change and Earth System Science, Beijing Normal University, Beijing China; Xia, X. [Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing China; Yin, Y. [School of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing China; Zhang, H. [National Climate Center, China Meteorological Administration, Beijing China; Guo, J. [Chinese Academy of Meteorological Sciences, Beijing China; Zhai, P. M. [Chinese Academy of Meteorological Sciences, Beijing China; Sugimoto, N. [National Institute for Environmental Studies, Tsukuba Japan; Babu, S. S. [Space Physics Laboratory, Vikram Sarabhai Space Centre, Thiruvananthapuram India; Brasseur, G. P. [Max Planck Institute for Meteorology, Hamburg Germany

2016-11-15

Asian monsoons and aerosols have been studied extensively which are intertwined in influencing the climate of Asia. This paper provides a comprehensive review of ample studies on Asian aerosol, monsoon and their interactions. The region is the primary source of aerosol emissions of varies species, influenced by distinct weather and climatic regimes. On continental scale, aerosols reduce surface insolation and weaken the land-ocean thermal contrast, thus inhibiting the development of monsoons. Locally, aerosol radiative effects alter the thermodynamic stability and convective potential of the lower atmosphere leading to reduced temperatures, increased atmospheric stability, and weakened wind and atmospheric circulation. The atmospheric thermodynamic state may also be altered by the aerosol serving as cloud condensation nuclei or ice nuclei. Many mechanisms have been put forth regarding how aerosols modulate the amplitude, frequency, intensity, and phase of numerous monsoon climate variables. A wide range of theoretical, observational, and modeling findings on the Asian monsoon, aerosols, and their interactions are synthesized. A new paradigm is proposed on investigating aerosol-monsoon interactions, in which natural aerosols such as desert dust, black carbon from biomass burning, and biogenic aerosols from vegetation are considered integral components of an intrinsic aerosol-monsoon climate system, subject to external forcings of global warming, anthropogenic aerosols, and land use and change. Future research on aerosol-monsoon interactions calls for an integrated approach and international collaborations based on long-term sustained observations, process measurements, and improved models, as well as using observations to constrain model simulations and projections.

Impact of agricultural management on pluvial flash floods - Case study of an extreme event observed in Austria in 2016

Science.gov (United States)

Lumassegger, Simon; Achleitner, Stefan; Kohl, Bernhard

2017-04-01

Central Europe was affected by extreme flash floods in summer 2016 triggered by short, high-intensity storm cells. Besides fluvial runoff, local pluvial floods appear to increase recently. In frame of the research project SAFFER-CC (sensitivity assessment of critical condition for local flash floods - evaluating the recurrence under climate change) surface runoff and pluvial flooding is assessed using a coupled hydrological/2D hydrodynamic model for the severely affected municipality of Schwertberg, Upper Austria. In this small catchment several flooding events occurred in the last years, where the most severe event occurred during summer 2016. Several areas could only be reached after the flood wave subsided with observed flood marks up to one meter. The modeled catchment is intensively cultivated with maize, sugar beets, winter wheat and soy on the hillside and hence highly vulnerable to water erosion. The average inclination is relatively steep with 15 % leading to high flow velocities of surface runoff associated with large amounts of transported sediments. To assess the influence of land use and soil conservation on flash floods, field experiments with a portable irrigation spray installation were carried out at different locations. The test plots were subjected to rainfall with constant intensity of 100 mm/h for one hour. Consecutively a super intense, one hour lasting, rainfall hydrograph was applied after 30 minutes at the same plots, ranging from 50 mm/h to 200 mm/h. Surface runoff was collected and measured in a tank and water samples were taken to determine the suspended material load. Large differences of runoff coefficients were determined depending on the agricultural management. The largest discharge was measured in a maize field, where surface runoff occurred immediately after start of irrigation. The determined runoff coefficients ranged from 0.22 for soy up to 0.65 for maize for the same soil type and inclination. The conclusion that runoff is

Changes of extreme precipitation and nonlinear influence of climate variables over monsoon region in China

KAUST Repository

Gao, Tao

2017-07-19

The El Niño-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD), North Atlantic Oscillation (NAO), Atlantic Multidecadal Oscillation (AMO) and Pacific decadal oscillation (PDO) are well understood to be major drivers for the variability of precipitation extremes over monsoon regions in China (MRC). However, research on monsoon extremes in China and their associations with climate variables is limited. In this study, we examine the space-time variations of extreme precipitation across the MRC, and assess the time-varying influences of the climate drivers using Bayesian dynamic linear regression and their combined nonlinear effects through fitting generalized additive models. Results suggest that the central-east and south China is dominated by less frequent but more intense precipitation. Extreme rainfalls show significant positive trends, coupled with a significant decline of dry spells, indicating an increasing chance of occurrence of flood-induced disasters in the MRC during 1960–2014. Majority of the regional indices display some abrupt shifts during the 1990s. The influences of climate variables on monsoon extremes exhibit distinct interannual or interdecadal variations. IOD, ENSO and AMO have strong impacts on monsoon and extreme precipitation, especially during the 1990s, which is generally consistent with the abrupt shifts in precipitation regimes around this period. Moreover, ENSO mainly affects moderate rainfalls and dry spells, while IOD has a more significant impact on precipitation extremes. These findings could be helpful for improving the forecasting of monsoon extremes in China and the evaluations of climate models.

Effectiveness of flood damage mitigation measures: Empirical evidence from French flood disasters

NARCIS (Netherlands)

Poussin, J.K.; Botzen, W.J.W.; Aerts, J.C.J.H.

2015-01-01

Recent destructive flood events and projected increases in flood risks as a result of climate change in many regions around the world demonstrate the importance of improving flood risk management. Flood-proofing of buildings is often advocated as an effective strategy for limiting damage caused by

Estimation of the impact of climate change-induced extreme precipitation events on floods

Science.gov (United States)

Hlavčová, Kamila; Lapin, Milan; Valent, Peter; Szolgay, Ján; Kohnová, Silvia; Rončák, Peter

2015-09-01

In order to estimate possible changes in the flood regime in the mountainous regions of Slovakia, a simple physically-based concept for climate change-induced changes in extreme 5-day precipitation totals is proposed in the paper. It utilizes regionally downscaled scenarios of the long-term monthly means of the air temperature, specific air humidity and precipitation projected for Central Slovakia by two regional (RCM) and two global circulation models (GCM). A simplified physically-based model for the calculation of short-term precipitation totals over the course of changing air temperatures, which is used to drive a conceptual rainfall-runoff model, was proposed. In the paper a case study of this approach in the upper Hron river basin in Central Slovakia is presented. From the 1981-2010 period, 20 events of the basin's most extreme average of 5-day precipitation totals were selected. Only events with continual precipitation during 5 days were considered. These 5-day precipitation totals were modified according to the RCM and GCM-based scenarios for the future time horizons of 2025, 2050 and 2075. For modelling runoff under changed 5-day precipitation totals, a conceptual rainfall-runoff model developed at the Slovak University of Technology was used. Changes in extreme mean daily discharges due to climate change were compared with the original flood events and discussed.

Late Holocene environmental reconstructions and their implications on flood events, typhoon, and agricultural activities in NE Taiwan

Science.gov (United States)

Wang, L.-C.; Behling, H.; Lee, T.-Q.; Li, H.-C.; Huh, C.-A.; Shiau, L.-J.; Chang, Y.-P.

2014-10-01

We reconstructed paleoenvironmental changes from a sediment archive of a lake in the floodplain of the Ilan Plain of NE Taiwan on multi-decadal resolution for the last ca. 1900 years. On the basis of pollen and diatom records, we evaluated past floods, typhoons, and agricultural activities in this area which are sensitive to the hydrological conditions in the western Pacific. Considering the high sedimentation rates with low microfossil preservations in our sedimentary record, multiple flood events were. identified during the period AD 100-1400. During the Little Ice Age phase 1 (LIA 1 - AD 1400-1620), the abundant occurrences of wetland plant (Cyperaceae) and diatom frustules imply less flood events under stable climate conditions in this period. Between AD 500 and 700 and the Little Ice Age phase 2 (LIA 2 - AD 1630-1850), the frequent typhoons were inferred by coarse sediments and planktonic diatoms, which represented more dynamical climate conditions than in the LIA 1. By comparing our results with the reconstructed changes in tropical hydrological conditions, we suggested that the local hydrology in NE Taiwan is strongly influenced by typhoon-triggered heavy rainfalls, which could be influenced by the variation of global temperature, the expansion of the Pacific warm pool, and the intensification of El Niño-Southern Oscillation (ENSO) events.

Flood-Ring Formation and Root Development in Response to Experimental Flooding of Young Quercus robur Trees

Science.gov (United States)

Copini, Paul; den Ouden, Jan; Robert, Elisabeth M. R.; Tardif, Jacques C.; Loesberg, Walter A.; Goudzwaard, Leo; Sass-Klaassen, Ute

2016-01-01

Spring flooding in riparian forests can cause significant reductions in earlywood-vessel size in submerged stem parts of ring-porous tree species, leading to the presence of ‘flood rings’ that can be used as a proxy to reconstruct past flooding events, potentially over millennia. The mechanism of flood-ring formation and the relation with timing and duration of flooding are still to be elucidated. In this study, we experimentally flooded 4-year-old Quercus robur trees at three spring phenophases (late bud dormancy, budswell, and internode expansion) and over different flooding durations (2, 4, and 6 weeks) to a stem height of 50 cm. The effect of flooding on root and vessel development was assessed immediately after the flooding treatment and at the end of the growing season. Ring width and earlywood-vessel size and density were measured at 25- and 75-cm stem height and collapsed vessels were recorded. Stem flooding inhibited earlywood-vessel development in flooded stem parts. In addition, flooding upon budswell and internode expansion led to collapsed earlywood vessels below the water level. At the end of the growing season, mean earlywood-vessel size in the flooded stem parts (upon budswell and internode expansion) was always reduced by approximately 50% compared to non-flooded stem parts and 55% compared to control trees. This reduction was already present 2 weeks after flooding and occurred independent of flooding duration. Stem and root flooding were associated with significant root dieback after 4 and 6 weeks and mean radial growth was always reduced with increasing flooding duration. By comparing stem and root flooding, we conclude that flood rings only occur after stem flooding. As earlywood-vessel development was hampered during flooding, a considerable number of narrow earlywood vessels present later in the season, must have been formed after the actual flooding events. Our study indicates that root dieback, together with strongly reduced hydraulic

Thirty Years Later: Reflections of the Big Thompson Flood, Colorado, 1976 to 2006

Science.gov (United States)

Jarrett, R. D.; Costa, J. E.; Brunstein, F. C.; Quesenberry, C. A.; Vandas, S. J.; Capesius, J. P.; O'Neill, G. B.

2006-12-01

Thirty years ago, over 300 mm of rain fell in about 4 to 6 hours in the middle reaches of the Big Thompson River Basin during the devastating flash flood on July 31, 1976. The rainstorm produced flood discharges that exceeded 40 m3/s/km2. A peak discharge of 883 m3/s was estimated at the Big Thompson River near Drake streamflow-gaging station. The raging waters left 144 people dead, 250 injured, and over 800 people were evacuated by helicopter. Four-hundred eighteen homes and businesses were destroyed, as well as 438 automobiles, and damage to infrastructure left the canyon reachable only via helicopter. Total damage was estimated in excess of $116 million (2006 dollars). Natural hazards similar to the Big Thompson flood are rare, but the probability of a similar event hitting the Front Range, other parts of Colorado, or other parts of the Nation is real. Although much smaller in scale than the Big Thompson flood, several flash floods have happened during the monsoon in early July 2006 in the Colorado foothills that reemphasized the hazards associated with flash flooding. The U.S. Geological Survey (USGS) conducts flood research to help understand and predict the magnitude and likelihood of large streamflow events such as the Big Thompson flood. A summary of hydrologic conditions of the 1976 flood, what the 1976 flood can teach us about flash floods, a description of some of the advances in USGS flood science as a consequence of this disaster, and lessons that we learned to help reduce loss of life from this extraordinary flash flood are discussed. In the 30 years since the Big Thompson flood, there have been important advances in streamflow monitoring and flood warning. The National Weather Service (NWS) NEXRAD radar allows real-time monitoring of precipitation in most places in the United States. The USGS currently (2006) operates about 7,250 real-time streamflow-gaging stations in the United States that are monitored by the USGS, the NWS, and emergency managers

Climatological aspects of cyclonic tracks associated with flood events in Crete, Greece

Science.gov (United States)

Flocas, H. A.; Tsanis, I. K.; Katavoutas, G.; Kouroutzoglou, J.; Iordanidou, V.; Alexakis, D. D.

2017-11-01

In this study, an attempt was made to identify the tracks of the synoptic-scale cyclones associated with flood events in Crete, a Greek island in the southern Aegean Sea and to investigate their kinematic and dynamic characteristics and vertical structure for a period of 25 years. Furthermore, a comparison is made with the corresponding characteristics of the population of surface cyclones passing over Crete during the same period. The Melbourne University Cyclone Tracking Algorithm was employed to examine the genesis and movement of these cyclones while their vertical profile was examined with the aid of the vertical tracing software, Vertical Tracking Scheme (VTS). The input data are based on ERA INTERIM reanalysis datasets with resolution 0.5° × 0.5° during the period 1990 to 2014. It was found that the vast majority originate mainly over the north African coasts, contrasting the preference of all cyclones passing over Crete to develop within the Southeast Mediterranean. Cyclones associated with the flood events are more intense than the cyclonic population, being mainly characterized by long duration and track length. Furthermore, they reveal characteristics of vertically organized baroclinic systems, suggesting that they are mainly driven by baroclinic processes at upper and lower levels.

Flash floods and debris flow: how the risk could can be better managed? The case of the events in Sicily on October 2009

Science.gov (United States)

Aronica, Giuseppe T.; Brigandi', Giuseppina

2010-05-01

Flash floods are phenomena in which the important hydrologic processes are occurring on the same spatial and temporal scales as the intense precipitation. Most of the catchments of the Messina area in the North-East part of Sicily (Italy), are prone to flash flood formation. They are, in fact, small, with a steep slope, and characterised by short concentration times. Moreover, those catchments are predominantly rural in the upper mountainous part, while the areas next to the outlet are highly urbanized with areas that cover not only the floodplain but also the river bed itself as the main roads were previously part of the torrent. This situation involve an high risk of economic losses and human life in case of flash flood in these areas. In the last years the area around Messina has been interested by severe flash floods and debris flow. The events occurred on 25th October 2007 in the Mastroguglielmo torrent and 1st October 2009 on Racinazzi and Gianpilieri torrents are an example of flash floods and debris flow events that caused not only significant economic damages to property, buildings, roads and bridges but also, for this that concern the 1st October 2009 flash flood, loss of human life. The main focus of this work is, basing on the post event analysis of the 2009 flash flood event, to try to understand which could be the better preventive measures and mitigation strategies that can be provided for a better risk management in these areas too many times affected by devastating events. Flood management can be controlled by either structural or non-structural measures. Adoption of a certain measure depends critically on the hydrological and hydraulic characteristics of the river system and the region. Flash flood management includes a number of phases that should be included in any management strategy like prevention, mitigation, preparedness, response and recovery. Forecasting based on hydrological precursors based on the soil moisture condition at the

ENSO, IOD and Indian Summer Monsoon in NCEP climate forecast system

Energy Technology Data Exchange (ETDEWEB)

Pokhrel, Samir; Chaudhari, H.S.; Saha, Subodh K.; Dhakate, Ashish; Yadav, R.K.; Salunke, Kiran; Mahapatra, S.; Rao, Suryachandra A. [Indian Institute of Tropical Meteorology, Pashan, Pune (India)

2012-11-15

El Nino-Southern Oscillation (ENSO), Indian Ocean Dipole (IOD) and Indian Summer Monsoon rainfall features are explored statistically and dynamically using National Centers for Environment Prediction (NCEP) Climate Forecast System (CFSv1) freerun in relation to observations. The 100 years of freerun provides a sufficiently long homogeneous data set to find out the mean state, periodicity, coherence among these climatic events and also the influence of ENSO and IOD on the Indian monsoon. Differences in the occurrence of seasonal precipitation between the observations and CFS freerun are examined as a coupled ocean-atmosphere system. CFS simulated ENSO and IOD patterns and their associated tropical Walker and regional Hadley circulation in pure ENSO (PEN), pure IOD (PIO) and coexisting ENSO-IOD (PEI) events have some similarity to the observations. PEN composites are much closer to the observation as compared to PIO and PEI composites, which suggest a better ENSO prediction and its associated teleconnections as compared to IOD and combined phenomenon. Similar to the observation, the model simulation also show that the decrease in the Indian summer monsoon rainfall during ENSO phases is associated with a descending motion of anomalous Walker circulation and the increase in the Indian summer monsoon rainfall during IOD phase is associated with the ascending branch of anomalous regional Hadley circulation. During co-existing ENSO and IOD years, however, the fate of Indian summer monsoon is dictated by the combined influence of both of them. The shift in the anomalous descending and ascending branches of the Walker and Hadley circulation may be somewhat attributed to the cold (warm) bias over eastern (western) equatorial Indian Ocean basin, respectively in the model. This study will be useful for identifying some of the limitations of the CFS model and consequently it will be helpful in improving the model to unravel the realistic coupled ocean-atmosphere interactions

Flood analyses for Department of Energy Y-12, ORNL and K-25 Plants. Flood analyses in support of flood emergency planning

International Nuclear Information System (INIS)

1995-05-01

The study involved defining the flood potential and local rainfall depth and duration data for the Department of Energy's (DOE) Y-12, Oak Ridge National Laboratory (ORNL), and K-25 plants. All three plants are subject to flooding from the Clinch River. In addition, the Y-12 plant is subject to flooding from East Fork Poplar and Bear Creeks, the ORNL plant from Whiteoak Creek and Melton Branch, and the K-25 plant from Poplar Creek. Determination of flood levels included consideration of both rainfall events and postulated failures of Norris and Melton Hill Dams in seismic events

Seawater-flooding events and impact on freshwater lenses of low-lying islands: Controlling factors, basic management and mitigation

Science.gov (United States)

Gingerich, Stephen B.; Voss, Clifford I.; Johnson, Adam G.

2017-01-01

An unprecedented set of hydrologic observations was collected after the Dec 2008 seawater-flooding event on Roi-Namur, Kwajalein Atoll, Republic of the Marshall Islands. By two days after the seawater flooding that occurred at the beginning of dry season, the observed salinity of water withdrawn by the island’s main skimming well increased to 100% seawater concentration, but by ten days later already decreased to only 10–20% of seawater fraction. However, the damaging impact on the potability of the groundwater supply (when pumped water had concentrations above 1% seawater fraction) lasted 22 months longer. The data collected make possible analyses of the hydrologic factors that control recovery and management of the groundwater-supply quality on Roi-Namur and on similar low-lying islands.With the observed data as a guide, three-dimensional numerical-model simulation analyses reveal how recovery is controlled by the island’s hydrology. These also allow evaluation of the efficacy of basic water-quality management/mitigation alternatives and elucidate how groundwater withdrawal and timing of the seawater-flooding event affect the length of recovery. Simulations show that, as might be expected, by adding surplus captured rainwater as artificial recharge, the freshwater-lens recovery period (after which potable groundwater may again be produced) can be shortened, with groundwater salinity remaining lower even during the dry season, a period during which no artificial recharge is applied. Simulations also show that the recovery period is not lengthened appreciably by groundwater withdrawals during recovery. Simulations further show that had the flooding event occurred at the start of the wet season, the recovery period would have been about 25% (5.5 months) shorter than actually occurred during the monitored flood that occurred at the dry-season start. Finally, analyses show that artificial recharge improves freshwater-lens water quality, making possible longer

Seawater-flooding events and impact on freshwater lenses of low-lying islands: Controlling factors, basic management and mitigation

Science.gov (United States)

Gingerich, Stephen B.; Voss, Clifford I.; Johnson, Adam G.

2017-08-01

An unprecedented set of hydrologic observations was collected after the Dec 2008 seawater-flooding event on Roi-Namur, Kwajalein Atoll, Republic of the Marshall Islands. By two days after the seawater flooding that occurred at the beginning of dry season, the observed salinity of water withdrawn by the island's main skimming well increased to 100% seawater concentration, but by ten days later already decreased to only 10-20% of seawater fraction. However, the damaging impact on the potability of the groundwater supply (when pumped water had concentrations above 1% seawater fraction) lasted 22 months longer. The data collected make possible analyses of the hydrologic factors that control recovery and management of the groundwater-supply quality on Roi-Namur and on similar low-lying islands. With the observed data as a guide, three-dimensional numerical-model simulation analyses reveal how recovery is controlled by the island's hydrology. These also allow evaluation of the efficacy of basic water-quality management/mitigation alternatives and elucidate how groundwater withdrawal and timing of the seawater-flooding event affect the length of recovery. Simulations show that, as might be expected, by adding surplus captured rainwater as artificial recharge, the freshwater-lens recovery period (after which potable groundwater may again be produced) can be shortened, with groundwater salinity remaining lower even during the dry season, a period during which no artificial recharge is applied. Simulations also show that the recovery period is not lengthened appreciably by groundwater withdrawals during recovery. Simulations further show that had the flooding event occurred at the start of the wet season, the recovery period would have been about 25% (5.5 months) shorter than actually occurred during the monitored flood that occurred at the dry-season start. Finally, analyses show that artificial recharge improves freshwater-lens water quality, making possible longer use of

Non-linear regime shifts in Holocene Asian monsoon variability: potential impacts on cultural change and migratory patterns

Science.gov (United States)

Donges, J. F.; Donner, R. V.; Marwan, N.; Breitenbach, S. F. M.; Rehfeld, K.; Kurths, J.

2015-05-01

The Asian monsoon system is an important tipping element in Earth's climate with a large impact on human societies in the past and present. In light of the potentially severe impacts of present and future anthropogenic climate change on Asian hydrology, it is vital to understand the forcing mechanisms of past climatic regime shifts in the Asian monsoon domain. Here we use novel recurrence network analysis techniques for detecting episodes with pronounced non-linear changes in Holocene Asian monsoon dynamics recorded in speleothems from caves distributed throughout the major branches of the Asian monsoon system. A newly developed multi-proxy methodology explicitly considers dating uncertainties with the COPRA (COnstructing Proxy Records from Age models) approach and allows for detection of continental-scale regime shifts in the complexity of monsoon dynamics. Several epochs are characterised by non-linear regime shifts in Asian monsoon variability, including the periods around 8.5-7.9, 5.7-5.0, 4.1-3.7, and 3.0-2.4 ka BP. The timing of these regime shifts is consistent with known episodes of Holocene rapid climate change (RCC) and high-latitude Bond events. Additionally, we observe a previously rarely reported non-linear regime shift around 7.3 ka BP, a timing that matches the typical 1.0-1.5 ky return intervals of Bond events. A detailed review of previously suggested links between Holocene climatic changes in the Asian monsoon domain and the archaeological record indicates that, in addition to previously considered longer-term changes in mean monsoon intensity and other climatic parameters, regime shifts in monsoon complexity might have played an important role as drivers of migration, pronounced cultural changes, and the collapse of ancient human societies.

Dynamics of pollutant indicators during flood events in a small river under strong anthropogenic pressures

Science.gov (United States)

Brion, Natacha; Carbonnel, Vincent; Elskens, Marc; Claeys, Philippe; Verbanck, Michel A.

2017-04-01

In densely populated regions, human activities profoundly modify natural water circulation as well as water quality, with increased hydrological risks (floods, droughts,…) and chemical hazards (untreated sewage releases, industrial pollution,…) as consequence. In order to assess water and pollutants dynamics and their mass-balance in strongly modified river system, it is important to take into account high flow events as a significant fraction of water and pollutants loads may occur during these short events which are generally underrepresented in classical mass balance studies. A good example of strongly modified river systems is the Zenne river in and around the city of Brussels (Belgium).The Zenne River (Belgium) is a rather small but dynamic rain fed river (about 10 m3/s in average) that is under the influence of strong contrasting anthropogenic pressures along its stretch. While the upstream part of its basin is rather characterized by agricultural land-use, urban and industrial areas dominate the downstream part. In particular, the city of Brussels (1.1M inhabitants) discharges in the Zenne River amounts of wastewater that are large compared to the natural riverine flow. In order to assess water and pollutants dynamics and their mass-balance in the Zenne hydrographic network, we followed water flows and concentrations of several water quality tracers during several flood episodes with an hourly frequency and at different locations along the stretch of the River. These parameters were chosen as indicators of a whole range of pollutions and anthropogenic activities. Knowledge of the high-frequency pollutants dynamics during floods is required for establishing accurate mass-balances of these elements. We thus report here the dynamics of selected parameters during entire flood events, from the baseline to the decreasing phase and at hourly frequency. Dynamics at contrasting locations, in agricultural or urban environments are compared. In particular, the

Recent advances in flood forecasting and flood risk assessment

Directory of Open Access Journals (Sweden)

G. Arduino

2005-01-01

Full Text Available Recent large floods in Europe have led to increased interest in research and development of flood forecasting systems. Some of these events have been provoked by some of the wettest rainfall periods on record which has led to speculation that such extremes are attributable in some measure to anthropogenic global warming and represent the beginning of a period of higher flood frequency. Whilst current trends in extreme event statistics will be difficult to discern, conclusively, there has been a substantial increase in the frequency of high floods in the 20th century for basins greater than 2x105 km2. There is also increasing that anthropogenic forcing of climate change may lead to an increased probability of extreme precipitation and, hence, of flooding. There is, therefore, major emphasis on the improvement of operational flood forecasting systems in Europe, with significant European Community spending on research and development on prototype forecasting systems and flood risk management projects. This Special Issue synthesises the most relevant scientific and technological results presented at the International Conference on Flood Forecasting in Europe held in Rotterdam from 3-5 March 2003. During that meeting 150 scientists, forecasters and stakeholders from four continents assembled to present their work and current operational best practice and to discuss future directions of scientific and technological efforts in flood prediction and prevention. The papers presented at the conference fall into seven themes, as follows.

Characterization of a Flood Event through a Sediment Analysis: The Tescio River Case Study

Directory of Open Access Journals (Sweden)

Silvia Di Francesco

2016-07-01

Full Text Available This paper presents the hydrological analysis and grain size characteristics of fluvial sediments in a river basin and their combination to characterize a flood event. The overall objective of the research is the development of a practical methodology based on experimental surveys to reconstruct the hydraulic history of ungauged river reaches on the basis of the modifications detected on the riverbed during the dry season. The grain size analysis of fluvial deposits usually requires great technical and economical efforts and traditional sieving based on physical sampling is not appropriate to adequately represent the spatial distribution of sediments in a wide area of a riverbed with a reasonable number of samples. The use of photographic sampling techniques, on the other hand, allows for the quick and effective determination of the grain size distribution, through the use of a digital camera and specific graphical algorithms in large river stretches. A photographic sampling is employed to characterize the riverbed in a 3 km ungauged reach of the Tescio River, a tributary of the Chiascio River, located in central Italy, representative of many rivers in the same geographical area. To this end, the particle size distribution is reconstructed through the analysis of digital pictures of the sediments taken on the riverbed in dry conditions. The sampling has been performed after a flood event of known duration, which allows for the identification of the removal of the armor in one section along the river reach under investigation. The volume and composition of the eroded sediments made it possible to calculate the average flow rate associated with the flood event which caused the erosion, by means of the sediment transport laws and the hydrological analysis of the river basin. A hydraulic analysis of the river stretch under investigation was employed to verify the validity of the proposed procedure.

The role of potential vorticity anomalies in the Somali Jet on Indian Summer Monsoon Intraseasonal Variability

Science.gov (United States)

Rai, P.; Joshi, M.; Dimri, A. P.; Turner, A. G.

2018-06-01

The climate of the Indian subcontinent is dominated by rainfall arising from the Indian summer monsoon (ISM) during June to September. Intraseasonal variability during the monsoon is characterized by periods of heavy rainfall interspersed by drier periods, known as active and break events respectively. Understanding and predicting such events is of vital importance for forecasting human impacts such as water resources. The Somali Jet is a key regional feature of the monsoon circulation. In the present study, we find that the spatial structure of Somali Jet potential vorticity (PV) anomalies varies considerably during active and break periods. Analysis of these anomalies shows a mechanism whereby sea surface temperature (SST) anomalies propagate north/northwestwards through the Arabian Sea, caused by a positive feedback loop joining anomalies in SST, convection, modification of PV by diabatic heating and mixing in the atmospheric boundary layer, wind-stress curl, and ocean upwelling processes. The feedback mechanism is consistent with observed variability in the coupled ocean-atmosphere system on timescales of approximately 20 days. This research suggests that better understanding and prediction of monsoon intraseasonal variability in the South Asian monsoon may be gained by analysis of the day-to-day dynamical evolution of PV in the Somali Jet.

The role of potential vorticity anomalies in the Somali Jet on Indian Summer Monsoon Intraseasonal Variability

Science.gov (United States)

Rai, P.; Joshi, M.; Dimri, A. P.; Turner, A. G.

2017-08-01

The climate of the Indian subcontinent is dominated by rainfall arising from the Indian summer monsoon (ISM) during June to September. Intraseasonal variability during the monsoon is characterized by periods of heavy rainfall interspersed by drier periods, known as active and break events respectively. Understanding and predicting such events is of vital importance for forecasting human impacts such as water resources. The Somali Jet is a key regional feature of the monsoon circulation. In the present study, we find that the spatial structure of Somali Jet potential vorticity (PV) anomalies varies considerably during active and break periods. Analysis of these anomalies shows a mechanism whereby sea surface temperature (SST) anomalies propagate north/northwestwards through the Arabian Sea, caused by a positive feedback loop joining anomalies in SST, convection, modification of PV by diabatic heating and mixing in the atmospheric boundary layer, wind-stress curl, and ocean upwelling processes. The feedback mechanism is consistent with observed variability in the coupled ocean-atmosphere system on timescales of approximately 20 days. This research suggests that better understanding and prediction of monsoon intraseasonal variability in the South Asian monsoon may be gained by analysis of the day-to-day dynamical evolution of PV in the Somali Jet.

The Indian Monsoon

Indian Academy of Sciences (India)

Pacific Oceans, on subseasonal scales of a few days and on an interannual scale. ... over the Indian monsoon zone2 (Figure 3) during the summer monsoon .... each 500 km ×500 km grid over the equatorial Indian Ocean, Bay of Bengal and ...

Flood-proof motors

Energy Technology Data Exchange (ETDEWEB)

Schmitt, Marcus [AREVA NP GmbH, Erlangen (Germany)

2013-07-01

Even before the Fukushima event occurred some German nuclear power plants (NPP) have considered flooding scenarios. As a result of one of these studies, AREVA performed an upgrade project in NPP Isar 1 with flood-proof motors as a replacement of existing air-cooled low-voltage and high-voltage motors of the emergency cooling chain. After the Fukushima event, in which the cooling chains failed, the topic flood-proof equipment gets more and more into focus. This compact will introduce different kinds of flood-proof electrical motors which are currently installed or planned for installation into NPPs over the world. Moreover the process of qualification, as it was performed during the project in NPP Isar 1, will be shown. (orig.)

Flood-proof motors

International Nuclear Information System (INIS)

Schmitt, Marcus

2013-01-01

Even before the Fukushima event occurred some German nuclear power plants (NPP) have considered flooding scenarios. As a result of one of these studies, AREVA performed an upgrade project in NPP Isar 1 with flood-proof motors as a replacement of existing air-cooled low-voltage and high-voltage motors of the emergency cooling chain. After the Fukushima event, in which the cooling chains failed, the topic flood-proof equipment gets more and more into focus. This compact will introduce different kinds of flood-proof electrical motors which are currently installed or planned for installation into NPPs over the world. Moreover the process of qualification, as it was performed during the project in NPP Isar 1, will be shown. (orig.)

Estimating the proportion of groundwater recharge from flood events in relation to total annual recharge in a karst aquifer

Science.gov (United States)

Dvory, N. Z.; Ronen, A.; Livshitz, Y.; Adar, E.; Kuznetsov, M.; Yakirevich, A.

2017-12-01

Sustainable groundwater production from karstic aquifers is primarily dictated by its recharge rate. Therefore, in order to limit over-exploitation, it is essential to accurately quantify groundwater recharge. Infiltration during erratic floods in karstic basins may contribute substantial amount to aquifer recharge. However, the complicated nature of karst systems, which are characterized in part by multiple springs, sinkholes, and losing/gaining streams, present a large obstacle to accurately assess the actual contribution of flood water to groundwater recharge. In this study, we aim to quantify the proportion of groundwater recharge during flood events in relation to the annual recharge for karst aquifers. The role of karst conduits on flash flood infiltration was examined during four flood and artificial runoff events in the Sorek creek near Jerusalem, Israel. The events were monitored in short time steps (four minutes). This high resolution analysis is essential to accurately estimating surface flow volumes, which are of particular importance in arid and semi-arid climate where ephemeral flows may provide a substantial contribution to the groundwater reservoirs. For the present investigation, we distinguished between direct infiltration, percolation through karst conduits and diffused infiltration, which is most affected by evapotranspiration. A water balance was then calculated for the 2014/15 hydrologic year using the Hydrologic Engineering Center - Hydrologic Modelling System (HEC-HMS). Simulations show that an additional 8% to 24% of the annual recharge volume is added from runoff losses along the creek that infiltrate through the karst system into the aquifer. The results improve the understanding of recharge processes and support the use of the proposed methodology for quantifying groundwater recharge.

Unexpected flood loss correlations across Europe

Science.gov (United States)

Booth, Naomi; Boyd, Jessica

2017-04-01

Floods don't observe country borders, as highlighted by major events across Europe that resulted in heavy economic and insured losses in 1999, 2002, 2009 and 2013. Flood loss correlations between some countries occur along multi-country river systems or between neighbouring nations affected by the same weather systems. However, correlations are not so obvious and whilst flooding in multiple locations across Europe may appear independent, for a re/insurer providing cover across the continent, these unexpected correlations can lead to high loss accumulations. A consistent, continental-scale method that allows quantification and comparison of losses, and identifies correlations in loss between European countries is therefore essential. A probabilistic model for European river flooding was developed that allows estimation of potential losses to pan-European property portfolios. By combining flood hazard and exposure information in a catastrophe modelling platform, we can consider correlations between river basins across Europe rather than being restricted to country boundaries. A key feature of the model is its statistical event set based on extreme value theory. Using historical river flow data, the event set captures spatial and temporal patterns of flooding across Europe and simulates thousands of events representing a full range of possible scenarios. Some known correlations were identified, such as between neighbouring Belgium and Luxembourg where 28% of events that affect either country produce a loss in both. However, our model identified some unexpected correlations including between Austria and Poland, and Poland and France, which are geographically distant. These correlations in flood loss may be missed by traditional methods and are key for re/insurers with risks in multiple countries. The model also identified that 46% of European river flood events affect more than one country. For more extreme events with a return period higher than 200 years, all events

The use of a flood index to characterise flooding in the north-eastern region of Bangladesh

Directory of Open Access Journals (Sweden)

Bhattacharya B.

2016-01-01

Full Text Available Flooding in the Haor region in the north-east of Bangladesh is presented in this paper. A haor is a saucershaped depression, which is used during the dry period (Dec to mid-May for agriculture and as a fishery during the wet period (Jun-Nov. Pre-monsoon flooding till mid-May causes agricultural loss. The area is bordering India, and is fed by some flashy Indian catchments. The area is drained mainly by the Surma-Kushiyara river system. The terrain generally is flat and the flashy characteristics die out within a short distance from the border. Limited studies on the region, particularly with the help of numerical models, have been carried out in the past. Therefore, an objective of the current research was to set up numerical models capable of reasonably emulating the physical system. Such models could, for example, associate different gauges to the spatio-temporal variation of hydrodynamic variables and help in carrying out a systemic study on the flood propagation. A 1D2D model, with one-dimensional model for the rivers (based on MIKE 11 from DHI and a two-dimensional model for the haors (based on MIKE 21 from DHI were developed. In order to characterize flooding in the large area a flood index is proposed, which is computed based on the hydrograph characteristics such as the rising curve gradient, flood magnitude ratio and time to peak. The index was used in characterising flooding in the Haor region. In general, two groups of rivers were identified. The study enabled identifying the hot-spots in the study area with risks from flooding.

Urban pluvial flood prediction

DEFF Research Database (Denmark)

Thorndahl, Søren Liedtke; Nielsen, Jesper Ellerbæk; Jensen, David Getreuer

2016-01-01

Flooding produced by high-intensive local rainfall and drainage system capacity exceedance can have severe impacts in cities. In order to prepare cities for these types of flood events – especially in the future climate – it is valuable to be able to simulate these events numerically both...... historically and in real-time. There is a rather untested potential in real-time prediction of urban floods. In this paper radar data observations with different spatial and temporal resolution, radar nowcasts of 0–2 h lead time, and numerical weather models with lead times up to 24 h are used as inputs...... to an integrated flood and drainage systems model in order to investigate the relative difference between different inputs in predicting future floods. The system is tested on a small town Lystrup in Denmark, which has been flooded in 2012 and 2014. Results show it is possible to generate detailed flood maps...

Diagnosis of the Asian summer monsoon variability and the climate prediction of monsoon precipitation via physical decomposition

Science.gov (United States)

Lim, Young-Kwon

This study investigates the space-time evolution of the dominant modes that constitute the Asian summer monsoon (ASM), and, as an ultimate goal, the climate prediction of the ASM rainfall. Precipitation and other synoptic variables during the prominent life cycle of the ASM (May 21 to September 17) are used to show the detailed features of dominant modes, which are identified as the seasonal cycle, the ISO defined by the 40--50 day intraseasonal oscillation including the Madden-Julian oscillation, and the El Nino mode. The present study reveals that the ISO is the second largest component of the ASM rainfall variation. Correlation analysis indicates that ISO explains a larger fraction of the variance of the observed precipitation (without climatology) than the ENSO mode. The dominant ISO signal faithfully explains the northward propagation of the ISO toward the Asian continent causing intraseasonal active/break periods. The interannual variation of the ISO strength suggests that the ENSO exerts some influence on the ISO. The composite convective ISO anomaly and Kelvin-Rossby wave response over the Indian Ocean shows that the ISO tends to be stronger during the early stage of the ASM than normal in El Nino (La Nina) years, indicating greater (smaller) possibility of ISO-related extreme rainfall over India, Bangladesh, and the Bay of Bengal. The ENSO mode reveals that the following factors affect the evolution of the ASM system in El Nino (La Nina) years. (1) The anomalous sea surface temperature and sea level pressure over the Indian Ocean during the early stage of the ASM weaken (enhance) the meridional pressure gradient. (2) As a result, the westerly jet and the ensuing moisture transport toward India and the Bay of Bengal become weak (strong) and delayed (expedited), providing a less (more) favorable condition for regional monsoon onsets. (3) The Walker circulation anomaly results in an enhanced subsidence (ascent) and drought (flood) over the Maritime continent

Protection from annual flooding is correlated with increased cholera prevalence in Bangladesh: a zero-inflated regression analysis

Directory of Open Access Journals (Sweden)

Yunus Mohammad

2010-03-01

Full Text Available Abstract Background Alteration of natural or historical aquatic flows can have unintended consequences for regions where waterborne diseases are endemic and where the epidemiologic implications of such change are poorly understood. The implementation of flood protection measures for a portion of an intensely monitored population in Matlab, Bangladesh, allows us to examine whether cholera outcomes respond positively or negatively to measures designed to control river flooding. Methods Using a zero inflated negative binomial model, we examine how selected covariates can simultaneously account for household clusters reporting no cholera from those with positive counts as well as distinguishing residential areas with low counts from areas with high cholera counts. Our goal is to examine how residence within or outside a flood protected area interacts with the probability of cholera presence and the effect of flood protection on the magnitude of cholera prevalence. Results In Matlab, living in a household that is protected from annual monsoon flooding appears to have no significant effect on whether the household experiences cholera, net of other covariates. However, counter-intuitively, among households where cholera is reported, living within the flood protected region significantly increases the number of cholera cases. Conclusions The construction of dams or other water impoundment strategies for economic or social motives can have profound and unanticipated consequences for waterborne disease. Our results indicate that the construction of a flood control structure in rural Bangladesh is correlated with an increase in cholera cases for residents protected from annual monsoon flooding. Such a finding requires attention from both the health community and from governments and non-governmental organizations involved in ongoing water management schemes.

Developing a Malaysia flood model

Science.gov (United States)

Haseldine, Lucy; Baxter, Stephen; Wheeler, Phil; Thomson, Tina

2014-05-01

Faced with growing exposures in Malaysia, insurers have a need for models to help them assess their exposure to flood losses. The need for an improved management of flood risks has been further highlighted by the 2011 floods in Thailand and recent events in Malaysia. The increasing demand for loss accumulation tools in Malaysia has lead to the development of the first nationwide probabilistic Malaysia flood model, which we present here. The model is multi-peril, including river flooding for thousands of kilometres of river and rainfall-driven surface water flooding in major cities, which may cause losses equivalent to river flood in some high-density urban areas. The underlying hazard maps are based on a 30m digital surface model (DSM) and 1D/2D hydraulic modelling in JFlow and RFlow. Key mitigation schemes such as the SMART tunnel and drainage capacities are also considered in the model. The probabilistic element of the model is driven by a stochastic event set based on rainfall data, hence enabling per-event and annual figures to be calculated for a specific insurance portfolio and a range of return periods. Losses are estimated via depth-damage vulnerability functions which link the insured damage to water depths for different property types in Malaysia. The model provides a unique insight into Malaysian flood risk profiles and provides insurers with return period estimates of flood damage and loss to property portfolios through loss exceedance curve outputs. It has been successfully validated against historic flood events in Malaysia and is now being successfully used by insurance companies in the Malaysian market to obtain reinsurance cover.

The impact of extreme flooding events and anthropogenic stressors on the macrobenthic communities’ dynamics

Science.gov (United States)

Cardoso, P. G.; Raffaelli, D.; Lillebø, A. I.; Verdelhos, T.; Pardal, M. A.

2008-02-01

Marine and coastal environments are among the most ecologically and socio-economically important habitats on Earth. However, climate change associated with a variety of anthropogenic stressors (e.g. eutrophication) may interact to produce combined impacts on biodiversity and ecosystem functioning, which in turn will have profound implications for marine ecosystems and the economic and social systems that depend upon them. Over period 1980-2000, the environment of the Mondego estuary, Portugal, has deteriorated through eutrophication, manifested in the replacement of seagrasses by opportunistic macroalgae, degradation of water quality and increased turbidity, and the system has also experienced extreme flood events. A restoration plan was implemented in 1998 which aimed to reverse the eutrophication effects, especially to restore the original natural seagrass ( Zostera noltii) community. This paper explores the interactions between extreme weather events (e.g. intense floods) and anthropogenic stressors (e.g. eutrophication) on the dynamics of the macrobenthic assemblages and the socio-economic implications that follow. We found that during the previous decade, the intensification of extreme flooding events had significant effects on the structure and functioning of macrobenthic communities, specifically a decline in total biomass, a decline in species richness and a decline in suspension feeders. However, the earlier eutrophication process also strongly modified the macrobenthic community, seen as a decline in species richness, increase in detritivores and a decline in herbivores together with a significant increase in small deposit-feeding polychaetes. After the implementation of the management plan, macrobenthic assemblages seemed to be recovering from eutrophication, but it is argued here that those earlier impacts reduced system stability and the resilience of the macrobenthic assemblages, so that its ability to cope with other stressors was compromised. Thus

Spring Soil Temperature Anomalies over Tibetan Plateau and Summer Droughts/Floods in East Asia

Science.gov (United States)

Xue, Y.; Li, W.; LI, Q.; Diallo, I.; Chu, P. C.; Guo, W.; Fu, C.

2017-12-01

Recurrent extreme climate events, such as droughts and floods, are important features of the climate of East Asia, especially over the Yangtze River basin. Many studies have attributed these episodes to variability and anomaly of global sea surface temperatures (SST) anomaly. In addition, snow in the Tibetan Plateau has also been considered as one of the factors affecting the Asian monsoon variability. However, studies have consistently shown that SST along is unable to explain the extreme climate events fully and snow has difficulty to use as a predictor. Remote effects of observed large-scale land surface temperature (LST) and subsurface temperature variability in Tibetan Plateau (TP) on East Asian regional droughts/floods, however, have been largely ignored. We conjecture that a temporally filtered response to snow anomalies may be preserved in the LST anomaly. In this study, evidence from climate observations and model simulations addresses the LST/SUBT effects. The Maximum Covariance Analysis (MCA) of observational data identifies that a pronounce spring LST anomaly pattern over TP is closely associated with precipitation anomalies in East Asia with a dipole pattern, i.e., negative/positive TP spring LST anomaly is associated with the summer drought/flood over the region south of the Yangtze River and wet/dry conditions to the north of the Yangtze River. Climate models were used to demonstrate a causal relationship between spring cold LST anomaly in the TP and the severe 2003 drought over the southern part of the Yangtze River in eastern Asia. This severe drought resulted in 100 x 106 kg crop yield losses and an economic loss of 5.8 billion Chinese Yuan. The modeling study suggests that the LST effect produced about 58% of observed precipitation deficit; while the SST effect produced about 32% of the drought conditions. Meanwhile, the LST and SST effects also simulated the observed flood over to the north of the Yangtze River. This suggests that inclusion of

Decrease in hydroclimatic conditions generating floods in the southeast of Belgium over the last 50 years resulting from changes in seasonal snow cover and extreme precipitation events

Science.gov (United States)

Wyard, Coraline; Fettweis, Xavier

2016-04-01

As a consequence of climate change, several studies concluded that winter flood occurrence could increase in the future in many rivers of northern and western Europe in response to an increase in extreme precipitation events. This study aims to determine if trends in extreme hydroclimatic events generating floods can already be detected over the last century. In particular, we focus on the Ourthe River (southeast of Belgium) which is one of the main tributaries of the Meuse River with a catchment area of 3500 km². In this river, most of the floods occur during winter and about 50% of them are due to rainfall events associated with the melting of the snow which covers the Ardennes during winter. In this study, hydroclimatic conditions favorable to flooding were reconstructed over the 20th century using the regional climate model MAR ("Modèle Atmosphérique Régional") forced by the following reanalyses: the ERA-20C, the ERA-Interim and the NCEP/NCAR-v1. The use of the MAR model allows to compute precipitation, snow depth and run-off resulting from precipitation events and snow melting in any part of the Ourthe river catchment area. Therefore, extreme hydroclimatic events, namely extreme run-off events, which could potentially generate floods, can be reconstructed using the MAR model. As validation, the MAR results were compared to weather station-based data. A trend analysis was then performed in order to study the evolution of conditions favorable to flooding in the Ourthe River catchment. The results show that the MAR model allows the detection of more than 95% of the hydroclimatic conditions which effectively generated observed floods in the Ourthe River over the 1974-2014 period. Conditions favorable to flooding present a negative trend over the last 50 years as a result of a decrease in snow accumulation and in extreme precipitation events. However, significance of these trends depends on the reanalysis used to force the regional climate model as well as the

Characterization of remarkable floods in France, a transdisciplinary approach applied on generalized floods of January 1910

Science.gov (United States)

Boudou, Martin; Lang, Michel; Vinet, Freddy; Coeur, Denis

2014-05-01

The 2007 Flood Directive promotes the integration and valorization of historical and significant floods in flood risk management (Flood Directive Text, chapter II, and article 4). Taking into account extreme past floods analysis seems necessary in the mitigation process of vulnerability face to flooding risk. In France, this aspect of the Directive was carried out through the elaboration of Preliminary Flood Risk Assessment (PFRA) and the establishment of a 2000 floods list. From this first list, a sample of 176 floods, considered as remarkable has been selected. These floods were compiled in discussion with local authorities in charge of flood management (Lang et al., 2012) and have to be integrated in priority in local risk management policies. However, a consideration emerges about this classification: how a remarkable flood can be defined? According which criteria can it be considered as remarkable? To answer these questions, a methodology has been established by building an evaluation grid of remarkable floods in France. The primary objective of this grid is to analyze the remarkable flood's characteristics (hydrological and meteorological characteristics, sociological- political and economic impacts), and secondly to propose a classification of significant floods selected in the 2011 PFRA. To elaborate this evaluation grid, several issues had to be taken into account. First, the objective is to allow the comparison of events from various periods. These temporal disparities include the integration of various kinds of data and point out the importance of historical hydrology. It is possible to evaluate accurately the characteristics of recent floods by interpreting quantitative data (for example hydrological records. However, for floods that occurred before the 1960's it is necessary resorting to qualitative information such as written sources is necessary (Coeur, Lang, 2008). In a second part the evaluation grid requires equitable criteria in order not to

Flood simulation and verification with IoT sensors

Science.gov (United States)

Chang, Che-Hao; Hsu, Chih-Tsung; Wu, Shiang-Jen; Huang, Sue-Wei

2017-04-01

2D flood dynamic simulation is a vivid tool to demonstrate the possible expose area that sustain impact of high rise of water level. Along with progress in high resolution digital terrain model, the simulation results are quite convinced yet not proved to be close to what is really happened. Due to the dynamic and uncertain essence, the expose area usually could not be well defined during a flood event. Recent development in IoT sensors bring a low power and long distance communication which help us to collect real time flood depths. With these time series of flood depths at different locations, we are capable of verifying the simulation results corresponding to the flood event. 16 flood gauges with IoT specification as well as two flood events in Annan district, Tainan city, Taiwan are examined in this study. During the event in 11, June, 2016, 12 flood gauges works well and 8 of them provide observation match to simulation.

Evaluation of NCMRWF unified model vertical cloud structure with CloudSat over the Indian summer monsoon region

Science.gov (United States)

Jayakumar, A.; Mamgain, Ashu; Jisesh, A. S.; Mohandas, Saji; Rakhi, R.; Rajagopal, E. N.

2016-05-01

Representation of rainfall distribution and monsoon circulation in the high resolution versions of NCMRWF Unified model (NCUM-REG) for the short-range forecasting of extreme rainfall event is vastly dependent on the key factors such as vertical cloud distribution, convection and convection/cloud relationship in the model. Hence it is highly relevant to evaluate the vertical structure of cloud and precipitation of the model over the monsoon environment. In this regard, we utilized the synergy of the capabilities of CloudSat data for long observational period, by conditioning it for the synoptic situation of the model simulation period. Simulations were run at 4-km grid length with the convective parameterization effectively switched off and on. Since the sample of CloudSat overpasses through the monsoon domain is small, the aforementioned methodology may qualitatively evaluate the vertical cloud structure for the model simulation period. It is envisaged that the present study will open up the possibility of further improvement in the high resolution version of NCUM in the tropics for the Indian summer monsoon associated rainfall events.

Flood/Typhoon vulnerability indicators of nuclear power plant in South Korea considering climate change impacts

Energy Technology Data Exchange (ETDEWEB)

Lee, Gyu Min; Jun, Kyung Soo [Sungkyunkwan Univ., Suwon (Korea, Republic of); Chung, Eun Sung [Seoul National Univ of Science and technology, Seoul (Korea, Republic of); Min, Byung Il; Suh, Kyung Suk [KAERI, Daejeon (Korea, Republic of)

2012-10-15

The Republic of Korea lies in the principal course of the typhoon that is occurred to the Pacific Northwest. It has distinct monsoon wind, a rainy period from the East Asian Monsoon locally called 'Changma', typhoon, and while often heavy snowfalls in winter. It belongs to a relatively wet region due to much more precipitation than that of the world average. In the last 10 years, there frequently was a lot of damage due to flooding with typhoon. In particular, the damage was estimated at up to 5,000 billion KRW by the USA in 2002. Lately, after the 9.0 magnitude earthquake and resultant tsunami hit Japan on March 11, 2011, consecutively approached Typhoon Ro ke made a larger threat. Although it fortunately passed without significant impact. That is, not only typhoon and flood are one of a threat to nuclear power plant but also it could lead to overwhelming damage when it overlapped the other accident. Therefore, flood/typhoon vulnerability assessment could provide important information for the safety management of nuclear power plants. This study derived all the feasible indicators and their corresponding weights for a Flood/Typhoon Vulnerability Index (FTVI) to nuclear power plant considering climate change. In addition selection of the candidates and determination of their weights were estimated using a Delphi process, which is an advanced method for opinion measurement.

GIS Support for Flood Rescue

DEFF Research Database (Denmark)

Liang, Gengsheng; Mioc, Darka; Anton, François

2007-01-01

Under flood events, the ground traffic is blocked in and around the flooded area due to damages to roads and bridges. The traditional transportation network may not always help people to make a right decision for evacuation. In order to provide dynamic road information needed for flood rescue, we...... to retrieve the shortest and safest route in Fredericton road network during flood event. It enables users to make a timely decision for flood rescue. We are using Oracle Spatial to deal with emergency situations that can be applied to other constrained network applications as well....... developed an adaptive web-based transportation network application using Oracle technology. Moreover, the geographic relationships between the road network and flood areas are taken into account. The overlay between the road network and flood polygons is computed on the fly. This application allows users...

Evaluation of internal flooding in a BWR

International Nuclear Information System (INIS)

Shiu, K.; Papazoglou, I.A.; Sun, Y.H.; Anavim, E.; Ilberg, D.

1985-01-01

Flooding inside a nuclear power station is capable of concurrently disabling redundant safety systems. This paper presents the results of a recent review study performed on internally-generated floods inside a boiling water reactor (BWR) reactor building. The study evaluated the flood initiator frequency due to either maintenance or ruptures using Markovian models. A time phased event tree approach was adopted to quantify the core damage frequency based on the flood initiator frequency. It is found in the study that the contribution to the total core damage due to internal flooding events is not insignificant and is comparable to other transient contributors. The findings also indicate that the operator plays an important role in the prevention as well as the mitigation of a flooding event

Source and composition of surface water dissolved organic matter (DOM) and the effect of flood events on the organic matter cycling

Science.gov (United States)

Bondar-Kunze, Elisabeth; Welti, Nina; Tritthart, Michael; Baker, Andrew; Pinay, Gilles; Hein, Thomas

2014-05-01

Floodplains are often simultaneously affected by land use change, river regulation and loss of hydrological dynamics which alter the surface water connectivity between floodplain and river main channel. These alterations can have significant impacts on the sources of organic matter and their degradation and thus, the carbon cycling of riverine landscapes. Although floodplains are known to be important sources of dissolved organic matter (DOM) within watersheds, reduced hydrological connectivity impair their role. The key questions of our research were to determine i) to what extent the degree of connection between the Danube River and its floodplain controlled the DOM composition with its backwater systems, and ii) what were the effects of the DOM changes on carbon cycling in floodplains during two flood events with different magnitude? In this study we report on the variations in DOM spectrophotometric properties of surface waters in different connected floodplain areas and during two flood events of different magnitude in a section of the Alluvial Zone National Park of the Danube River downstream Vienna, Austria. Two backwater floodplain systems were studied, one backwater system mostly disconnected from the fluvial dynamics except during high flood events (Lower Lobau) and the second one, recently restored and connected even during mean flow conditions (Orth). Fluorescence excitation-emission matrix (EEM) spectrophotometry and water chemical analyses were applied to investigate the DOM dynamics. In both backwater systems 15 sites were sampled monthly for two years and every second day during a flood event.

Treatment of external events in the linked event tree methodology NPP Goesgen - Daeniken example

International Nuclear Information System (INIS)

Kozlik, Thomas

2014-01-01

The NPP Goesgen-Daeniken uses a combined level 1 / level 2 PSA model for its event analyses. The model uses a linked event tree approach, using the software RISKMAN R . Each initiating event passes through a modularized event tree structure, consisting of external events pre-trees, alignment and support systems trees and front-line and containment response trees. This paper explains the structure of the linked event trees. Switches are used to bypass certain trees for specific initiating events. The screening process applied to possible external events is explained. The final scope of considered natural external events in the Goesgen PSA consists of earthquakes, seasonal events causing cooling water intake plugging or external floods. The structure of the natural external events pre-trees is explained. The treatment of external floods is explained in more detail. Floods at the Goesgen site are caused by extreme river flows into the old branch of the Aare river. A new model has been developed to analyse the probabilistic flood hazard using a bivariate distribution (water level and flood duration). Analysing the statistical data, the time trend had to be considered. The Goesgen PSA models 7 external flood initiating events, considering different water levels and durations at the flooded plant site. The building fragilities were developed in terms of resistance times. The RISKMAN R external flood pre-tree consists of top events for operator actions and failure of the building functions, which leads to the functional failure of equipment located at the lower elevation of the building. (author)

Ecological Aspect of Dam Design for Flood Regulation and Sustainable Urban Development

Directory of Open Access Journals (Sweden)

Badenko Vladimir

2016-01-01

Full Text Available Many floodplains are excluded from urban development because the floods cause considerable damage to people’s lives and properties. This requires the development of new approaches to flood management and mitigation for support sustainable urban development. In present study as the measures for mitigation of flash floods, the regulation of river flow by the system of detention reservoirs for flood diversion with dams, which do not need any operation management, are analyzed concerning of Far East region of Russia. The main objective of this paper is to develop a method for analysis how the dam site selection meets the environmental criterion. The method to justify a selection of self-regulated flood dam parameters, primarily a height of a dam and its location on a water stream, providing minimization of impact on the environment have been developed. The result for Selemdzha river basin in Far East monsoon region of Russian Federation is analyzed. The result shows the robustness of the method.

The use of water marks mapping to understand flood overflow events inside karstic cavities: Cueva Fría and Cueva Rosa (Asturias, NW Spain)

Science.gov (United States)

González Lemos, Saúl; Stoll, Heather M.

2014-05-01

Several karst systems in Asturias (NW Spain) present evidence of fluvial deposits cemented in speleothems that may provide good chronology of past flood events inside the caves. This flood record is under research in two karstic caves of this region, Cueva Fría and Cueva Rosa, which have in common the presence of a perennial stream inside the cave and a low gradient of the cave passage. Immediately after a flood overflow event, water marks, foam and detritus are visible at different heights on the cave walls and correspond to heights of bottlenecks in overflow drainage through the cave passage. Flood events also deposit sand and gravel on terraces on the cave wall and move large volumes of sand in the cave bed. We have noted that detrital particles (like sand or silt particles) are preserved as inclusions inside the stalagmites and that their abundance inside coeval stalagmites decreases as altitude and distance from the perennial stream increase, supporting its fluvial affinity. However, not all the stalagmites that contain detrital particles are located close to the perennial streams. In this work, we have mapped the water marks preserved in the cave walls to reconstruct water levels associated to flood overflow events of different magnitude. We have found that water mark correlation along the cave passage is very useful to define the hydrological behaviour and flood model of the cave during these extreme events. The water mark mapping and correlation have been also useful to prove that during periods of high rainfall, the movement of the sand-bars inside the cave can cover partially or completely active stalagmites, facilitating the cementation process and trapping abundant detrital material inside the stalagmite carbonate. 14C and U/Th dating of the stalagmites can provide a chronology for the detrital rich layers, so that the abundance of fluvial material in the stalagmites can reveal periods of enhanced vs. reduced flooding in the cave over the past several

Evaluating resilience of DNP3-controlled SCADA systems against event buffer flooding

Energy Technology Data Exchange (ETDEWEB)

Yan, Guanhua [Los Alamos National Laboratory; Nicol, David M [UNIV OF IL; Jin, Dong [UNIV OF IL

2010-12-16

The DNP3 protocol is widely used in SCADA systems (particularly electrical power) as a means of communicating observed sensor state information back to a control center. Typical architectures using DNP3 have a two level hierarchy, where a specialized data aggregator device receives observed state from devices within a local region, and the control center collects the aggregated state from the data aggregator. The DNP3 communication between control center and data aggregator is asynchronous with the DNP3 communication between data aggregator and relays; this leads to the possibility of completely filling a data aggregator's buffer of pending events, when a relay is compromised or spoofed and sends overly many (false) events to the data aggregator. This paper investigates how a real-world SCADA device responds to event buffer flooding. A Discrete-Time Markov Chain (DTMC) model is developed for understanding this. The DTMC model is validated by a Moebius simulation model and data collected on real SCADA testbed.

Framework for probabilistic flood risk assessment in an Alpine region

Science.gov (United States)

Schneeberger, Klaus; Huttenlau, Matthias; Steinberger, Thomas; Achleitner, Stefan; Stötter, Johann

2014-05-01

Flooding is among the natural hazards that regularly cause significant losses to property and human lives. The assessment of flood risk delivers crucial information for all participants involved in flood risk management and especially for local authorities and insurance companies in order to estimate the possible flood losses. Therefore a framework for assessing flood risk has been developed and is introduced with the presented contribution. Flood risk is thereby defined as combination of the probability of flood events and of potential flood damages. The probability of occurrence is described through the spatial and temporal characterisation of flood. The potential flood damages are determined in the course of vulnerability assessment, whereas, the exposure and the vulnerability of the elements at risks are considered. Direct costs caused by flooding with the focus on residential building are analysed. The innovative part of this contribution lies on the development of a framework which takes the probability of flood events and their spatio-temporal characteristic into account. Usually the probability of flooding will be determined by means of recurrence intervals for an entire catchment without any spatial variation. This may lead to a misinterpretation of the flood risk. Within the presented framework the probabilistic flood risk assessment is based on analysis of a large number of spatial correlated flood events. Since the number of historic flood events is relatively small additional events have to be generated synthetically. This temporal extrapolation is realised by means of the method proposed by Heffernan and Tawn (2004). It is used to generate a large number of possible spatial correlated flood events within a larger catchment. The approach is based on the modelling of multivariate extremes considering the spatial dependence structure of flood events. The input for this approach are time series derived from river gauging stations. In a next step the

Millennial-Scale Asian Monsoon Influenced Longjie Lake Evolution during Marine Isotope Stage 3, Upper Stream of Changjiang (Yangtze River, China

Directory of Open Access Journals (Sweden)

Chaozhu Li

2015-01-01

Full Text Available Millennial-scale climate change in Asian monsoon region during MIS 3 has been studied using stalagmite, loess, and peat sediments. However, records from more materials are essential to further illustrate dynamics of these events. In the present study, a time-series of grain size covering 60–30 ka was reconstructed from lake sediments in the Yunnan Province, southwestern China. The time-series contains 14 obvious millennial-scale events during the period. On millennial-scale, the grain size record is generally consistent with mean stalagmite δ18O from Hulu Cave, grain size of Gulang loess sequence, Chinese Loess Plateau, and Greenland ice core δ18O. The results show that the millennial-scale variation was well compared with the Dansgaard-Oeschger (DO events, indicating that those global events were well documented in lake sediments in the Asian monsoon region. Because the grain size can be used as a proxy for water discharge, we suggest that signal of the DO events might be transmitted to lake evolution by Asian monsoon.

Energetics and monsoon bifurcations

Science.gov (United States)

Seshadri, Ashwin K.

2017-01-01

Monsoons involve increases in dry static energy (DSE), with primary contributions from increased shortwave radiation and condensation of water vapor, compensated by DSE export via horizontal fluxes in monsoonal circulations. We introduce a simple box-model characterizing evolution of the DSE budget to study nonlinear dynamics of steady-state monsoons. Horizontal fluxes of DSE are stabilizing during monsoons, exporting DSE and hence weakening the monsoonal circulation. By contrast latent heat addition (LHA) due to condensation of water vapor destabilizes, by increasing the DSE budget. These two factors, horizontal DSE fluxes and LHA, are most strongly dependent on the contrast in tropospheric mean temperature between land and ocean. For the steady-state DSE in the box-model to be stable, the DSE flux should depend more strongly on the temperature contrast than LHA; stronger circulation then reduces DSE and thereby restores equilibrium. We present conditions for this to occur. The main focus of the paper is describing conditions for bifurcation behavior of simple models. Previous authors presented a minimal model of abrupt monsoon transitions and argued that such behavior can be related to a positive feedback called the `moisture advection feedback'. However, by accounting for the effect of vertical lapse rate of temperature on the DSE flux, we show that bifurcations are not a generic property of such models despite these fluxes being nonlinear in the temperature contrast. We explain the origin of this behavior and describe conditions for a bifurcation to occur. This is illustrated for the case of the July-mean monsoon over India. The default model with mean parameter estimates does not contain a bifurcation, but the model admits bifurcation as parameters are varied.

Coping with Pluvial Floods by Private Households

Directory of Open Access Journals (Sweden)

Viktor Rözer

2016-07-01

Full Text Available Pluvial floods have caused severe damage to urban areas in recent years. With a projected increase in extreme precipitation as well as an ongoing urbanization, pluvial flood damage is expected to increase in the future. Therefore, further insights, especially on the adverse consequences of pluvial floods and their mitigation, are needed. To gain more knowledge, empirical damage data from three different pluvial flood events in Germany were collected through computer-aided telephone interviews. Pluvial flood awareness as well as flood experience were found to be low before the respective flood events. The level of private precaution increased considerably after all events, but is mainly focused on measures that are easy to implement. Lower inundation depths, smaller potential losses as compared with fluvial floods, as well as the fact that pluvial flooding may occur everywhere, are expected to cause a shift in damage mitigation from precaution to emergency response. However, an effective implementation of emergency measures was constrained by a low dissemination of early warnings in the study areas. Further improvements of early warning systems including dissemination as well as a rise in pluvial flood preparedness are important to reduce future pluvial flood damage.

Simulation of Flash-Flood-Producing Storm Events in Saudi Arabia Using the Weather Research and Forecasting Model

KAUST Repository

Deng, Liping; McCabe, Matthew; Stenchikov, Georgiy L.; Evans, Jason P.; Kucera, Paul A.

2015-01-01

The challenges of monitoring and forecasting flash-flood-producing storm events in data-sparse and arid regions are explored using the Weather Research and Forecasting (WRF) Model (version 3.5) in conjunction with a range of available satellite

Flood model for Brazil

Science.gov (United States)

Palán, Ladislav; Punčochář, Petr

2017-04-01

Looking on the impact of flooding from the World-wide perspective, in last 50 years flooding has caused over 460,000 fatalities and caused serious material damage. Combining economic loss from ten costliest flood events (from the same period) returns a loss (in the present value) exceeding 300bn USD. Locally, in Brazil, flood is the most damaging natural peril with alarming increase of events frequencies as 5 out of the 10 biggest flood losses ever recorded have occurred after 2009. The amount of economic and insured losses particularly caused by various flood types was the key driver of the local probabilistic flood model development. Considering the area of Brazil (being 5th biggest country in the World) and the scattered distribution of insured exposure, a domain covered by the model was limited to the entire state of Sao Paolo and 53 additional regions. The model quantifies losses on approx. 90 % of exposure (for regular property lines) of key insurers. Based on detailed exposure analysis, Impact Forecasting has developed this tool using long term local hydrological data series (Agencia Nacional de Aguas) from riverine gauge stations and digital elevation model (Instituto Brasileiro de Geografia e Estatística). To provide most accurate representation of local hydrological behaviour needed for the nature of probabilistic simulation, a hydrological data processing focused on frequency analyses of seasonal peak flows - done by fitting appropriate extreme value statistical distribution and stochastic event set generation consisting of synthetically derived flood events respecting realistic spatial and frequency patterns visible in entire period of hydrological observation. Data were tested for homogeneity, consistency and for any significant breakpoint occurrence in time series so the entire observation or only its subparts were used for further analysis. The realistic spatial patterns of stochastic events are reproduced through the innovative use of d-vine copula

Forest operations, extreme flooding events, and considerations for hydrologic modeling in the Appalachians--A review

Science.gov (United States)

M.A. Eisenbies; W.M. Aust; J.A. Burger; M.B. Adams

2007-01-01

The connection between forests and water resources is well established, but the relationships among controlling factors are only partly understood. Concern over the effects of forestry operations, particularly harvesting, on extreme flooding events is a recurrent issue in forest and watershed management. Due to the complexity of the system, and the cost of installing...

Case studies of extended model-based flood forecasting: prediction of dike strength and flood impacts

Science.gov (United States)

Stuparu, Dana; Bachmann, Daniel; Bogaard, Tom; Twigt, Daniel; Verkade, Jan; de Bruijn, Karin; de Leeuw, Annemargreet

2017-04-01

Flood forecasts, warning and emergency response are important components in flood risk management. Most flood forecasting systems use models to translate weather predictions to forecasted discharges or water levels. However, this information is often not sufficient for real time decisions. A sound understanding of the reliability of embankments and flood dynamics is needed to react timely and reduce the negative effects of the flood. Where are the weak points in the dike system? When, how much and where the water will flow? When and where is the greatest impact expected? Model-based flood impact forecasting tries to answer these questions by adding new dimensions to the existing forecasting systems by providing forecasted information about: (a) the dike strength during the event (reliability), (b) the flood extent in case of an overflow or a dike failure (flood spread) and (c) the assets at risk (impacts). This work presents three study-cases in which such a set-up is applied. Special features are highlighted. Forecasting of dike strength. The first study-case focusses on the forecast of dike strength in the Netherlands for the river Rhine branches Waal, Nederrijn and IJssel. A so-called reliability transformation is used to translate the predicted water levels at selected dike sections into failure probabilities during a flood event. The reliability of a dike section is defined by fragility curves - a summary of the dike strength conditional to the water level. The reliability information enhances the emergency management and inspections of embankments. Ensemble forecasting. The second study-case shows the setup of a flood impact forecasting system in Dumfries, Scotland. The existing forecasting system is extended with a 2D flood spreading model in combination with the Delft-FIAT impact model. Ensemble forecasts are used to make use of the uncertainty in the precipitation forecasts, which is useful to quantify the certainty of a forecasted flood event. From global

Review of the flood risk management system in Germany after the major flood in 2013

Directory of Open Access Journals (Sweden)

Annegret H. Thieken

2016-06-01

Full Text Available Widespread flooding in June 2013 caused damage costs of €6 to 8 billion in Germany, and awoke many memories of the floods in August 2002, which resulted in total damage of €11.6 billion and hence was the most expensive natural hazard event in Germany up to now. The event of 2002 does, however, also mark a reorientation toward an integrated flood risk management system in Germany. Therefore, the flood of 2013 offered the opportunity to review how the measures that politics, administration, and civil society have implemented since 2002 helped to cope with the flood and what still needs to be done to achieve effective and more integrated flood risk management. The review highlights considerable improvements on many levels, in particular (1 an increased consideration of flood hazards in spatial planning and urban development, (2 comprehensive property-level mitigation and preparedness measures, (3 more effective flood warnings and improved coordination of disaster response, and (4 a more targeted maintenance of flood defense systems. In 2013, this led to more effective flood management and to a reduction of damage. Nevertheless, important aspects remain unclear and need to be clarified. This particularly holds for balanced and coordinated strategies for reducing and overcoming the impacts of flooding in large catchments, cross-border and interdisciplinary cooperation, the role of the general public in the different phases of flood risk management, as well as a transparent risk transfer system. Recurring flood events reveal that flood risk management is a continuous task. Hence, risk drivers, such as climate change, land-use changes, economic developments, or demographic change and the resultant risks must be investigated at regular intervals, and risk reduction strategies and processes must be reassessed as well as adapted and implemented in a dialogue with all stakeholders.

A vigorous Mesoamerican monsoon during the Last Glacial Maximum driven by orbital and oceanic forcing

Science.gov (United States)

Lachniet, M. S.; Asmerom, Y.; Bernal, J. P.; Polyak, V.; Vazquez-Selem, L. V.

2012-12-01

The external forcings on global monsoon strength include summer orbital insolation and ocean circulation changes, both of which are key control knobs on Earth's climate. However, few records of the North American Monsoon (NAM) are available to test its sensitivity to variations in the precession-dominated insolation signal and Atlantic Meridional Overturning Circulation (AMOC) for the Last Glacial Maximum (LGM; 21 ± 3 cal ka BP) and deglacial periods. In particular, well-dated and high-resolution records from the southern sector of the NAM, referred to informally as the Mesoamerican monsoon to distinguish it from the more northerly 'core' NAM, are needed to better elucidate paleoclimate change in North America. Here, we present a 22 ka (ka = kilo years) rainfall history from absolutely-dated speleothems from tropical southwestern Mexico that documents a vigorous LGM summer monsoon, in contradiction to previous interpretations, and that the monsoon collapsed during the Heinrich stadial 1 and Younger Dryas cold events. We conclude that a strong Mesoamerican monsoon requires both a large ocean-to-land temperature contrast, driven as today by summer insolation, and a proximal latitudinal position of the Intertropical Convergence Zone, forced by active AMOC.

Characterising Record Flooding in the United Kingdom

Science.gov (United States)

Cox, A.; Bates, P. D.; Smith, J. A.

2017-12-01

Though the most notable floods in history have been carefully explained, there remains a lack of literature that explores the nature of record floods as a whole in the United Kingdom. We characterise the seasonality, statistical and spatial distribution, and meteorological causes of peak river flows for 521 gauging stations spread across the British Isles. We use annual maximum data from the National River Flow Archive, catchment descriptors from the Flood Estimation Handbook, and historical records of large floods. What we aim to find is in what ways, if any, the record flood for a station is different from more 'typical' floods. For each station, we calculate two indices: the seasonal anomaly and the flood index. Broadly, the seasonal anomaly is the degree to which a station's record flood happens at a different time of year compared to typical floods at that site, whilst the flood index is a station's record flood discharge divided by the discharge of the 1-in-10-year return period event. We find that while annual maximum peaks are dominated by winter frontal rainfall, record floods are disproportionately caused by summer convective rainfall. This analysis also shows that the larger the seasonal anomaly, the higher the flood index. Additionally, stations across the country have record floods that occur in the summer with no notable spatial pattern, yet the most seasonally anomalous record events are concentrated around the south and west of the British Isles. Catchment descriptors tell us little about the flood index at a particular station, but generally areas with lower mean annual precipitation have a higher flood index. The inclusion of case studies from recent and historical examples of notable floods across the UK supplements our analysis and gives insight into how typical these events are, both statistically and meteorologically. Ultimately, record floods in general happen at relatively unexpected times and with unpredictable magnitudes, which is a

Improving Flash Flood Prediction in Multiple Environments

Science.gov (United States)

Broxton, P. D.; Troch, P. A.; Schaffner, M.; Unkrich, C.; Goodrich, D.; Wagener, T.; Yatheendradas, S.

2009-12-01

Flash flooding is a major concern in many fast responding headwater catchments . There are many efforts to model and to predict these flood events, though it is not currently possible to adequately predict the nature of flash flood events with a single model, and furthermore, many of these efforts do not even consider snow, which can, by itself, or in combination with rainfall events, cause destructive floods. The current research is aimed at broadening the applicability of flash flood modeling. Specifically, we will take a state of the art flash flood model that is designed to work with warm season precipitation in arid environments, the KINematic runoff and EROSion model (KINEROS2), and combine it with a continuous subsurface flow model and an energy balance snow model. This should improve its predictive capacity in humid environments where lateral subsurface flow significantly contributes to streamflow, and it will make possible the prediction of flooding events that involve rain-on-snow or rapid snowmelt. By modeling changes in the hydrologic state of a catchment before a flood begins, we can also better understand the factors or combination of factors that are necessary to produce large floods. Broadening the applicability of an already state of the art flash flood model, such as KINEROS2, is logical because flash floods can occur in all types of environments, and it may lead to better predictions, which are necessary to preserve life and property.

The Indian Monsoon

Indian Academy of Sciences (India)

user

and led to the expectation that the impact of the monsoon on the ... a lead time of 10 days to a month for rainfall, temperature, etc., ... trying to predict, such as clouds or a monsoon depression (in ... occur because (i) the models are not perfect (involving many ... ally at many centres in the world, long-range predictions are.

Flood hazards for nuclear power plants

International Nuclear Information System (INIS)

Yen, B.C.

1988-01-01

Flooding hazards for nuclear power plants may be caused by various external geophysical events. In this paper the hydrologic hazards from flash floods, river floods and heavy rain at the plant site are considered. Depending on the mode of analysis, two types of hazard evaluation are identified: 1) design hazard which is the probability of flooding over an expected service period, and 2) operational hazard which deals with real-time forecasting of the probability of flooding of an incoming event. Hazard evaluation techniques using flood frequency analysis can only be used for type 1) design hazard. Evaluation techniques using rainfall-runoff simulation or multi-station correlation can be used for both types of hazard prediction. (orig.)

Flood modelling with a distributed event-based parsimonious rainfall-runoff model: case of the karstic Lez river catchment

Directory of Open Access Journals (Sweden)

M. Coustau

2012-04-01

Full Text Available Rainfall-runoff models are crucial tools for the statistical prediction of flash floods and real-time forecasting. This paper focuses on a karstic basin in the South of France and proposes a distributed parsimonious event-based rainfall-runoff model, coherent with the poor knowledge of both evaporative and underground fluxes. The model combines a SCS runoff model and a Lag and Route routing model for each cell of a regular grid mesh. The efficiency of the model is discussed not only to satisfactorily simulate floods but also to get powerful relationships between the initial condition of the model and various predictors of the initial wetness state of the basin, such as the base flow, the Hu2 index from the Meteo-France SIM model and the piezometric levels of the aquifer. The advantage of using meteorological radar rainfall in flood modelling is also assessed. Model calibration proved to be satisfactory by using an hourly time step with Nash criterion values, ranging between 0.66 and 0.94 for eighteen of the twenty-one selected events. The radar rainfall inputs significantly improved the simulations or the assessment of the initial condition of the model for 5 events at the beginning of autumn, mostly in September–October (mean improvement of Nash is 0.09; correction in the initial condition ranges from −205 to 124 mm, but were less efficient for the events at the end of autumn. In this period, the weak vertical extension of the precipitation system and the low altitude of the 0 °C isotherm could affect the efficiency of radar measurements due to the distance between the basin and the radar (~60 km. The model initial condition S is correlated with the three tested predictors (R² > 0.6. The interpretation of the model suggests that groundwater does not affect the first peaks of the flood, but can strongly impact subsequent peaks in the case of a multi-storm event. Because this kind of model is based on a limited

Simulating a 40-year flood event climatology of Australia with a view to ocean-land teleconnections

Science.gov (United States)

Schumann, Guy J.-P.; Andreadis, Konstantinos; Stampoulis, Dimitrios; Bates, Paul

2015-04-01

We develop, for the first time, a proof-of-concept version for a high-resolution global flood inundation model to generate a flood inundation climatology of the past 40 years (1973-2012) for the entire Australian continent at a native 1 km resolution. The objectives of our study includes (1) deriving an inundation climatology for a continent (Australia) as a demonstrator case to understand the requirements for expanding globally; (2) developing a test bed to assess the potential and value of current and future satellite missions (GRACE, SMAP, ICESat-2, AMSR-2, Sentinels and SWOT) in flood monitoring; and (3) answering science questions such as the linking of inundation to ocean circulation teleconnections. We employ the LISFLOOD-FP hydrodynamic model to generate a flood inundation climatology. The model will be built from freely available SRTM-derived data (channel widths, bank heights and floodplain topography corrected for vegetation canopy using ICESat canopy heights). Lakes and reservoirs are represented and channel hydraulics are resolved using actual channel data with bathymetry inferred from hydraulic geometry. Simulations are run with gauged flows and floodplain inundation climatology are compared to observations from GRACE, flood maps from Landsat, SAR, and MODIS. Simulations have been completed for the entire Australian continent. Additionally, changes in flood inundation have been correlated with indices related to global ocean circulation, such as the El Niño Southern Oscillation index. We will produce data layers on flood event climatology and other derived (default) products from the proposed model including channel and floodplain depths, flow direction, velocity vectors, floodplain water volume, shoreline extent and flooded area. These data layers will be in the form of simple vector and raster formats. Since outputs will be large in size we propose to upload them onto Google Earth under the GEE API license.

Variation in the Asian monsoon intensity and dry-wet condition since the Little Ice Age in central China revealed by an aragonite stalagmite

Science.gov (United States)

Yin, J.-J.; Yuan, D.-X.; Li, H.-C.; Cheng, H.; Li, T.-Y.; Edwards, R. L.; Lin, Y.-S.; Qin, J.-M.; Tang, W.; Zhao, Z.-Y.; Mii, H.-S.

2014-04-01

Highlight: this paper focuses on the climate variability in central China since 1300 AD, involving: 1. A well-dated, 1.5 year resolution stalagmite δ18O record from Lianhua Cave, central China; 2. Links of the δ18O record with regional dry-wet condition, monsoon intensity, and temperature over eastern China; 3. Correlations among drought events in the Lianhua record, solar irradiation, and ENSO index. We present a highly precisely 230Th/U dated, 1.5 year resolution δ18O record of an aragonite stalagmite (LHD1) collected from Lianhua Cave in Wuling mountain area of central China. The comparison of the δ18O record with the local instrumental record and historical documents exhibits at least 15 drought events in the Wuling mountain and adjacent areas during the Little Ice Age, in which some of them were corresponding to megadrought events in the broad Asian monsoonal region of China. Thus, the stalagmite δ18O record reveals variations in the summer monsoon precipitation and dry-wet condition in Wuling mountain area. The eastern China temperature varied with the solar activity, showing higher temperature under stronger solar irradiation which produces stronger summer monsoon. During Maunder, Dalton and 1900 sunspot minima, more severe drought events occurred, indicating weakening of the summer monsoon when solar activity decreased on decadal time scales. On interannual time scale, dry conditions in the studying area were prevailing under El Niño condition, which is also supported by the spectrum analysis. Hence, our record illustrates the linkage of Asian summer monsoon precipitation to solar irradiation and ENSO: wetter condition under stronger summer monsoon during warm periods and vice versa; During cold periods, the Walker circulation will shift toward central Pacific under El Niño condition, resulting further weakening of Asian summer monsoon. However, the δ18O of LHD1 record is positively correlated with temperature after ~1940 AD which is opposite to the

Quantification of uncertainty in flood risk assessment for flood protection planning: a Bayesian approach

Science.gov (United States)

Dittes, Beatrice; Špačková, Olga; Ebrahimian, Negin; Kaiser, Maria; Rieger, Wolfgang; Disse, Markus; Straub, Daniel

2017-04-01

Flood risk estimates are subject to significant uncertainties, e.g. due to limited records of historic flood events, uncertainty in flood modeling, uncertain impact of climate change or uncertainty in the exposure and loss estimates. In traditional design of flood protection systems, these uncertainties are typically just accounted for implicitly, based on engineering judgment. In the AdaptRisk project, we develop a fully quantitative framework for planning of flood protection systems under current and future uncertainties using quantitative pre-posterior Bayesian decision analysis. In this contribution, we focus on the quantification of the uncertainties and study their relative influence on the flood risk estimate and on the planning of flood protection systems. The following uncertainty components are included using a Bayesian approach: 1) inherent and statistical (i.e. limited record length) uncertainty; 2) climate uncertainty that can be learned from an ensemble of GCM-RCM models; 3) estimates of climate uncertainty components not covered in 2), such as bias correction, incomplete ensemble, local specifics not captured by the GCM-RCM models; 4) uncertainty in the inundation modelling; 5) uncertainty in damage estimation. We also investigate how these uncertainties are possibly reduced in the future when new evidence - such as new climate models, observed extreme events, and socio-economic data - becomes available. Finally, we look into how this new evidence influences the risk assessment and effectivity of flood protection systems. We demonstrate our methodology for a pre-alpine catchment in southern Germany: the Mangfall catchment in Bavaria that includes the city of Rosenheim, which suffered significant losses during the 2013 flood event.

Fault tree analysis for urban flooding

NARCIS (Netherlands)

Ten Veldhuis, J.A.E.; Clemens, F.H.L.R.; Van Gelder, P.H.A.J.M.

2008-01-01

Traditional methods to evaluate flood risk mostly focus on storm events as the main cause of flooding. Fault tree analysis is a technique that is able to model all potential causes of flooding and to quantify both the overall probability of flooding and the contributions of all causes of flooding to

LiDAR and IFSAR-Based Flood Inundation Model Estimates for Flood-Prone Areas of Afghanistan

Science.gov (United States)

Johnson, W. C.; Goldade, M. M.; Kastens, J.; Dobbs, K. E.; Macpherson, G. L.

2014-12-01

Extreme flood events are not unusual in semi-arid to hyper-arid regions of the world, and Afghanistan is no exception. Recent flashfloods and flashflood-induced landslides took nearly 100 lives and destroyed or damaged nearly 2000 homes in 12 villages within Guzargah-e-Nur district of Baghlan province in northeastern Afghanistan. With available satellite imagery, flood-water inundation estimation can be accomplished remotely, thereby providing a means to reduce the impact of such flood events by improving shared situational awareness during major flood events. Satellite orbital considerations, weather, cost, data licensing restrictions, and other issues can often complicate the acquisition of appropriately timed imagery. Given the need for tools to supplement imagery where not available, complement imagery when it is available, and bridge the gap between imagery based flood mapping and traditional hydrodynamic modeling approaches, we have developed a topographic floodplain model (FLDPLN), which has been used to identify and map river valley floodplains with elevation data ranging from 90-m SRTM to 1-m LiDAR. Floodplain "depth to flood" (DTF) databases generated by FLDPLN are completely seamless and modular. FLDPLN has been applied in Afghanistan to flood-prone areas along the northern and southern flanks of the Hindu Kush mountain range to generate a continuum of 1-m increment flood-event models up to 10 m in depth. Elevation data used in this application of FLDPLN included high-resolution, drone-acquired LiDAR (~1 m) and IFSAR (5 m; INTERMAP). Validation of the model has been accomplished using the best available satellite-derived flood inundation maps, such as those issued by Unitar's Operational Satellite Applications Programme (UNOSAT). Results provide a quantitative approach to evaluating the potential risk to urban/village infrastructure as well as to irrigation systems, agricultural fields and archaeological sites.

Decoupling of monsoon activity across the northern and southern Indo-Pacific during the Late Glacial

Science.gov (United States)

Denniston, R. F.; Asmerom, Y.; Polyak, V. J.; Wanamaker, A. D.; Ummenhofer, C. C.; Humphreys, W. F.; Cugley, J.; Woods, D.; Lucker, S.

2017-11-01

Recent studies of stalagmites from the Southern Hemisphere tropics of Indonesia reveal two shifts in monsoon activity not apparent in records from the Northern Hemisphere sectors of the Austral-Asian monsoon system: an interval of enhanced rainfall at ∼19 ka, immediately prior to Heinrich Stadial 1, and a sharp increase in precipitation at ∼9 ka. Determining whether these events are site-specific or regional is important for understanding the full range of sensitivities of the Austral-Asian monsoon. We present a discontinuous 40 kyr carbon isotope record of stalagmites from two caves in the Kimberley region of the north-central Australian tropics. Heinrich stadials are represented by pronounced negative carbon isotopic anomalies, indicative of enhanced rainfall associated with a southward shift of the intertropical convergence zone and consistent with hydroclimatic changes observed across Asia and the Indo-Pacific. Between 20 and 8 ka, however, the Kimberley stalagmites, like the Indonesian record, reveal decoupling of monsoon behavior from Southeast Asia, including the early deglacial wet period (which we term the Late Glacial Pluvial) and the abrupt strengthening of early Holocene monsoon rainfall.

Application of Flood Nomograph for Flood Forecasting in Urban Areas

Directory of Open Access Journals (Sweden)

Eui Hoon Lee

2018-01-01

Full Text Available Imperviousness has increased due to urbanization, as has the frequency of extreme rainfall events by climate change. Various countermeasures, such as structural and nonstructural measures, are required to prepare for these effects. Flood forecasting is a representative nonstructural measure. Flood forecasting techniques have been developed for the prevention of repetitive flood damage in urban areas. It is difficult to apply some flood forecasting techniques using training processes because training needs to be applied at every usage. The other flood forecasting techniques that use rainfall data predicted by radar are not appropriate for small areas, such as single drainage basins. In this study, a new flood forecasting technique is suggested to reduce flood damage in urban areas. The flood nomograph consists of the first flooding nodes in rainfall runoff simulations with synthetic rainfall data at each duration. When selecting the first flooding node, the initial amount of synthetic rainfall is 1 mm, which increases in 1 mm increments until flooding occurs. The advantage of this flood forecasting technique is its simple application using real-time rainfall data. This technique can be used to prepare a preemptive response in the process of urban flood management.

Relationship between summer monsoon rainfall and cyclogenesis over Bay of Bengal during post-monsoon (October-December) season

Digital Repository Service at National Institute of Oceanography (India)

Sadhuram, Y; Maneesha, K.

peak monsoon (October–November) season and concluded that the frequency of cyclones is modulated by negative and positive IOD rather than El-Nino and La-Nina. In this study, the relationship between southwest monsoon rainfall (June–September) and TNDC... Relationship between summer monsoon rainfall and cyclogenesis over Bay of Bengal during post-monsoon (October–December) season Y Sadhuram∗ and K Maneesha CSIR–National Institute of Oceanography, 176, Lawsons Bay Colony, Visakhapatnam 530 017, India...

Determinants of property damage recovery time amongst households affected by an extreme flood event in Metro Manila, Philippines

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Jamil Paolo Francisco

2014-08-01

Full Text Available This study identified the factors that influence household recovery following an extreme flood event, measured in terms of the length of time to repair, rebuild or replace damaged private property. Data was obtained through a survey of 400 households in Marikina City in Metro Manila, Philippines. Results from the empirical analysis indicated that household income, access to credit (borrowing, the use of a flood alarm system, access to safe shelter, membership in a community organisation, adoption of disaster-specific anticipatory measures and adoption of general preventive measures significantly reduced the time it took for affected households to recover from property damage. Evacuation, relief aid, type of housing, education, household size and frequency of flooding in the area did not have significant effects.

Flood risk analysis for flood control and sediment transportation in sandy regions: A case study in the Loess Plateau, China

Science.gov (United States)

Guo, Aijun; Chang, Jianxia; Wang, Yimin; Huang, Qiang; Zhou, Shuai

2018-05-01

Traditional flood risk analysis focuses on the probability of flood events exceeding the design flood of downstream hydraulic structures while neglecting the influence of sedimentation in river channels on regional flood control systems. This work advances traditional flood risk analysis by proposing a univariate and copula-based bivariate hydrological risk framework which incorporates both flood control and sediment transport. In developing the framework, the conditional probabilities of different flood events under various extreme precipitation scenarios are estimated by exploiting the copula-based model. Moreover, a Monte Carlo-based algorithm is designed to quantify the sampling uncertainty associated with univariate and bivariate hydrological risk analyses. Two catchments located on the Loess plateau are selected as study regions: the upper catchments of the Xianyang and Huaxian stations (denoted as UCX and UCH, respectively). The univariate and bivariate return periods, risk and reliability in the context of uncertainty for the purposes of flood control and sediment transport are assessed for the study regions. The results indicate that sedimentation triggers higher risks of damaging the safety of local flood control systems compared with the event that AMF exceeds the design flood of downstream hydraulic structures in the UCX and UCH. Moreover, there is considerable sampling uncertainty affecting the univariate and bivariate hydrologic risk evaluation, which greatly challenges measures of future flood mitigation. In addition, results also confirm that the developed framework can estimate conditional probabilities associated with different flood events under various extreme precipitation scenarios aiming for flood control and sediment transport. The proposed hydrological risk framework offers a promising technical reference for flood risk analysis in sandy regions worldwide.

Meteorological analysis of flash floods in Artvin (NE Turkey on 24 August 2015

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H. Baltaci

2017-07-01

Full Text Available On 24 August 2015 intense rainfall episodes generated flash floods and landslides on the eastern Black Sea coast of Turkey. As a consequence of the heavy rainstorm activity over Artvin and its surroundings (NE Turkey, 11 people died and economic losses totaled a million dollars. Over the 6 h of the event (from 05:00 to 11:00 UTC, total accumulated rainfall amounts of 136, 64, and 109 mm were measured in the Hopa, Arhavi, and Borçka settlements of Artvin city, respectively. This study comprehensively investigates the meteorological characteristics of those flash floods. In terms of synoptic mechanisms, the cutoff surface low from the summer Asian monsoon settled over the eastern Black Sea. After two days of quasistationary conditions of this cyclone, sea surface temperatures (SSTs reached 27.5 °C (1.5 °C higher than normal and low-level moisture convergence developed. In addition, transfer of moisture by warm northerly flows from the Black Sea and relatively cool southerly flows from the land coasts of the Artvin district exacerbated the unstable conditions and thus played a significant role in the development of deep convective cells. Severe rainstorms as well as the slope instability of the region triggered landslides and worsened flood damages in the Artvin area. This study supports conventional weather analysis, satellite images, and forecast model output to alert forecasters to the potential for heavy rainfall.

Monsoon Rainfall and Landslides in Nepal

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Dahal, R. K.; Hasegawa, S.; Bhandary, N. P.; Yatabe, R.

2009-12-01

A large number of human settlements on the Nepal Himalayas are situated either on old landslide mass or on landslide-prone areas. As a result, a great number of people are affected by large- and small-scale landslides all over the Himalayas especially during monsoon periods. In Nepal, only in the half monsoon period (June 10 to August 15), 70, 50 and 68 people were killed from landslides in 2007, 2008 and 2009, respectively. In this context, this paper highlights monsoon rainfall and their implications in the Nepal Himalaya. In Nepal, monsoon is major source of rainfall in summer and approximately 80% of the annual total rainfall occurs from June to September. The measured values of mean annual precipitation in Nepal range from a low of approximately 250 mm at area north of the Himalaya to many areas exceeding 6,000 mm. The mean annual rainfall varying between 1500 mm and 2500 mm predominate over most of the country. In Nepal, the daily distribution of precipitation during rainy season is also uneven. Sometime 10% of the total annual precipitation can occur in a single day. Similarly, 50% total annual rainfall also can occur within 10 days of monsoon. This type of uneven distribution plays an important role in triggering many landslides in Nepal. When spatial distribution of landslides was evaluated from record of more than 650 landslides, it is found that more landslides events were concentrated at central Nepal in the area of high mean annual rainfall. When monsoon rainfall and landslide relationship was taken into consideration, it was noticed that a considerable number of landslides were triggered in the Himalaya by continuous rainfall of 3 to 90 days. It has been noticed that continuous rainfall of few days (5 days or 7 days or 10 days) are usually responsible for landsliding in the Nepal Himalaya. Monsoon rains usually fall with interruptions of 2-3 days and are generally characterized by low intensity and long duration. Thus, there is a strong role of

Precipitation Thresholds for Triggering Floods in the Corgo Basin, Portugal

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Mónica Santos

2016-08-01

Full Text Available Thresholds based on critical combinations of amount/duration of precipitation and flood events were estimated for the Corgo hydrographic basin, in northern Portugal. Thirty-one flood events in the Corgo basin were identified between 1865 and 2011 from a database of hydrometeorological disasters in Portugal. The minimum, maximum, and pre-warning thresholds that define the boundaries for flood occurrence were determined. The results show that the ratio between the total number of floods and precipitation events exceeding the minimum threshold denotes a relatively low probability of successful forecasting. This result may be due to the reduced number of flooding events in the floods database, which only include floods that caused damage as reported by the media. The estimated maximum threshold is not adequate for use in floods, since the majority of true positives are below this limit. However, and more interestingly, the retrospective verification of the estimated thresholds suggests that the minimum and pre-warning thresholds are well adjusted. Therefore, the application of these precipitation thresholds may contribute to minimize possible situations of pre-crisis or immediate crisis by reducing the flood consequences and the resources involved in emergency response to flood events.

A GIS-Based Model for the analysis of an urban flash flood and its hydro-geomorphic response. The Valencia event of 1957

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Portugués-Mollá, I.; Bonache-Felici, X.; Mateu-Bellés, J. F.; Marco-Segura, J. B.

2016-10-01

Flash floods are recurrent events around the Mediterranean region. Extreme episodes activate hydro-geomorphic high-intensity processes with low frequency. In urban environments, the complexity becomes higher due to the existence of very quick-response runoff. However, immediate recovery works remove the urban marks. After a short time both the significance and magnitude of the hydro-geomorphic event become completely unrecognizable. Nevertheless, these episodes generate extensive documentation which is testimony of the processes in almost real time. It is necessary to exploit this source typology in order to draw flood sketches when events far in time may lack a sufficiently rich database. This is particularly the case for the Valencia flash flood (October 1957), located in the lower Turia River basin (Eastern Spain). It left numerous pieces of hydro-geomorphic evidence, but its tracks were covered a short while after the flood. In any case, it remains part of a non-systematic legacy that has not yet been exploited, consisting of immediate aerial and oblique high resolution photography, pictures at street level, water marks and administrative records. Paradoxically, despite being considered a milestone in metropolitan territorial planning (the river was definitely diverted), an accurate reconstruction of the hydraulic behaviour was required from an integrated point of view. To this aim, the development of a GIS-Based Model enabled the utilisation of the above-mentioned materials. This non-conventional information was treated jointly from a new perspective. It provided database support through a vast amount of organised, structured and georeferenced information about the 1957 event. In a second stage, the GBM made it possible to characterise the Turia urban reach and interpret both the hydro-geomorphic (trenches along barrier beaches, erosion, deposition, etc.) and hydraulic (urban streams along the streets, flow directions, flood extent, levees breaks, overflows

Effect of catchment properties and flood generation regime on copula selection for bivariate flood frequency analysis

Science.gov (United States)

Filipova, Valeriya; Lawrence, Deborah; Klempe, Harald

2018-02-01

Applying copula-based bivariate flood frequency analysis is advantageous because the results provide information on both the flood peak and volume. More data are, however, required for such an analysis, and it is often the case that only data series with a limited record length are available. To overcome this issue of limited record length, data regarding climatic and geomorphological properties can be used to complement statistical methods. In this paper, we present a study of 27 catchments located throughout Norway, in which we assess whether catchment properties, flood generation processes and flood regime have an effect on the correlation between flood peak and volume and, in turn, on the selection of copulas. To achieve this, the annual maximum flood events were first classified into events generated primarily by rainfall, snowmelt or a combination of these. The catchments were then classified into flood regime, depending on the predominant flood generation process producing the annual maximum flood events. A contingency table and Fisher's exact test were used to determine the factors that affect the selection of copulas in the study area. The results show that the two-parameter copulas BB1 and BB7 are more commonly selected in catchments with high steepness, high mean annual runoff and rainfall flood regime. These findings suggest that in these types of catchments, the dependence structure between flood peak and volume is more complex and cannot be modeled effectively using a one-parameter copula. The results illustrate that by relating copula types to flood regime and catchment properties, additional information can be supplied for selecting copulas in catchments with limited data.

Tidal Influence on the Diel Vertical Migration Pattern of Zooplankton in a Tropical Monsoonal Estuary

KAUST Repository

Vineetha, G.

2015-04-03

Monsoonal estuaries, located along the coastline of the Indian subcontinent, differ from other estuaries by their time dependence on the salinity characteristics. Effective sustenance and retention of the mesozooplankton community in the estuarine habitats is often determined by their dominant behavioral patterns: diel vertical migration (DVM) and tidal vertical migration (TVM). The modes of these endogenous rhythms often vary among estuaries based on the river runoff and tidal characteristics. The present study is a pioneering attempt to depict the vertical migration pattern of zooplankton along a diel and tidal scale in a tropical, microtidal, monsoonal estuary. We observed that in spite of the prominent asymmetry in the magnitude of the river runoff between the seasons, most of the zooplankton groups exhibited strong DVM, with a clear increase in biomass and abundance in surface waters during night. The peak increase in biomass and abundance at night always synchronized with the slack periods in the tidal cycles, which differed from the general concepts of downward migration during ebb tide and upward migration during flood tide in estuarine systems. The weak currents during the slack period might have favored the effective vertical migration of the mesozooplankton community in this monsoonal estuarine system. © 2015 Society of Wetland Scientists

Global monsoons in the mid-Holocene and oceanic feedback

Energy Technology Data Exchange (ETDEWEB)

Liu, Z.; Kutzbach, J. [Center for Climatic Research, University of Wisconsin-Madison, 1225 W. Dayton Street, Madison, WI 53706 (United States); Harrison, S.P. [Max Planck Institute for Biogeochemistry, P.O. Box 100164, 07701 Jena (Germany); Otto-Bliesner, B. [National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307 (United States)

2004-03-01

The response of the six major summer monsoon systems (the North American monsoon, the northern Africa monsoon, the Asia monsoon, the northern Australasian monsoon, the South America monsoon and the southern Africa monsoon) to mid-Holocene orbital forcing has been investigated using a coupled ocean-atmosphere general circulation model (FOAM), with the focus on the distinct roles of the direct insolation forcing and oceanic feedback. The simulation result is also found to compare well with the NCAR CSM. The direct effects of the change in insolation produce an enhancement of the Northern Hemisphere monsoons and a reduction of the Southern Hemisphere monsoons. Ocean feedbacks produce a further enhancement of the northern Africa monsoon and the North American monsoon. However, ocean feedbacks appear to weaken the Asia monsoon, although the overall effect (direct insolation forcing plus ocean feedback) remains a strengthened monsoon. The impact of ocean feedbacks on the South American and southern African monsoons is relatively small, and therefore these regions, especially the South America, experienced a reduced monsoon regime compared to present. However, there is a strong ocean feedback on the northern Australian monsoon that negates the direct effects of orbital changes and results in a strengthening of austral summer monsoon precipitation in this region. A new synthesis is made for mid-Holocene paleoenvironmental records and is compared with the model simulations. Overall, model simulations produce changes in regional climates that are generally consistent with paleoenvironmental observations. (orig.)

Effects of the November 2012 Flood Event on the Mobilization of Hg from the Mount Amiata Mining District to the Sediments of the Paglia River Basin

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Giulia Pattelli

2014-04-01

Full Text Available The Mount Amiata mining district (southern Tuscany, Italy was, for decades, one of the world’s largest mercury (Hg producing regions, where mining activity lasted until the 1980s. The Paglia River drains the eastern part of the district and is also the main western tributary of the Tiber River. Recent studies show that, still today, high total Hg contents severely affect the downstream ecosystems of these rivers. In November 2012, a major flood event occurred in the Paglia River basin, which drastically changed the river morphology and, possibly, the Hg concentrations. In the present work, stream sediment was sampled before and after the flood to evaluate possible changes in sediment total Hg concentrations as a consequence of this event. The comparison between pre- and post-flood Hg concentrations shows that Hg content increased up to an order of magnitude after the flood, suggesting that this event triggered Hg mobilization in the basin rather than its dilution.

A mechanism for land-ocean contrasts in global monsoon trends in a warming climate

Energy Technology Data Exchange (ETDEWEB)

Fasullo, J. [National Center for Atmospheric Research, CAS/NCAR, Boulder, CO (United States)

2012-09-15

A central paradox of the global monsoon record involves reported decreases in rainfall over land during an era in which the global hydrologic cycle is both expected and observed to intensify. It is within this context that this work develops a physical basis for both interpreting the observed record and anticipating changes in the monsoons in a warming climate while bolstering the concept of the global monsoon in the context of shared feedbacks. The global-land monsoon record across multiple reanalyses is first assessed. Trends that in other studies have been taken as real are shown to likely be spurious as a result of changes in the assimilated data streams both prior to and during the satellite era. Nonetheless, based on satellite estimates, robust increases in monsoon rainfall over ocean do exist and a physical basis for this land-ocean contrast remains lacking. To address the contrast's causes, simulated trends are therefore assessed. While projections of total rainfall are inconsistent across models, the robust land-ocean contrast identified in observations is confirmed. A feedback mechanism is proposed rooted in the facts that land areas warm disproportionately relative to ocean, and onshore flow is the chief source of monsoonal moisture. Reductions in lower tropospheric relative humidity over land domains are therefore inevitable and these have direct consequences for the monsoonal convective environment including an increase in the lifting condensation level and a shift in the distribution of convection generally towards less frequent and potentially more intense events. The mechanism is interpreted as an important modulating influence on the ''rich-get-richer'' mechanism. Caveats for regional monsoons exist and are discussed. (orig.)

Budgeting suspended sediment fluxes in tropical monsoonal watersheds with limited data: the Lake Tana basin

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Zimale Fasikaw A.

2018-03-01

Full Text Available Soil erosion decreases soil fertility of the uplands and causes siltation of lakes and reservoirs; the lakes and reservoirs in tropical monsoonal African highlands are especially affected by sedimentation. Efforts in reducing loads by designing management practices are hampered by lack of quantitative data on the relationship of erosion in the watersheds and sediment accumulation on flood plains, lakes and reservoirs. The objective of this study is to develop a prototype quantitative method for estimating sediment budget for tropical monsoon lakes with limited observational data. Four watersheds in the Lake Tana basin were selected for this study. The Parameter Efficient Distributed (PED model that has shown to perform well in the Ethiopian highlands is used to overcome the data limitations and recreate the missing sediment fluxes. PED model parameters are calibrated using daily discharge data and the occasionally collected sediment concentration when establishing the sediment rating curves for the major rivers. The calibrated model parameters are then used to predict the sediment budget for the 1994-2009 period. Sediment retained in the lake is determined from two bathymetric surveys taken 20 years apart whereas the sediment leaving the lake is calculated based on measured discharge and observed sediment concentrations. Results show that annually on average 34 t/ha/year of sediment is removed from the gauged part of the Lake Tana watersheds. Depending on the up-scaling method from the gauged to the ungauged part, 21 to 32 t/ha/year (equivalent to 24-38 Mt/year is transported from the upland watersheds of which 46% to 65% is retained in the flood plains and 93% to 96% is trapped on the flood plains and in the lake. Thus, only 4-7% of all sediment produced in the watersheds leaves the Lake Tana Basin.

Damaging Rainfall and Flooding. The Other Sahel Hazards

Energy Technology Data Exchange (ETDEWEB)

Tarhule, A. [Department of Geography, University of Oklahoma, 100 East Boyd Street, Norman, OK, 73079 (United States)

2005-10-01

Damaging rainfall and rain-induced flooding occur from time to time in the drought-prone Sahel savannah zone of Niger in West Africa but official records of these events and their socioeconomic impacts do not exist. This paper utilized newspaper accounts between 1970 and 2000 to survey and illustrate the range of these flood hazards in the Sahel. During the study interval, 53 newspaper articles reported 79 damaging rainfall and flood events in 47 different communities in the Sahel of Niger. Collectively, these events destroyed 5,580 houses and rendered 27,289 people homeless. Cash losses and damage to infrastructure in only three events exceeded $4 million. Sahel residents attribute these floods to five major causes including both natural and anthropogenic, but they view the flood problem as driven primarily by land use patterns. Despite such awareness, traditional coping strategies appear inadequate for dealing with the problems in part because of significant climatic variability. Analysis of several rainfall measures indicates that the cumulative rainfall in the days prior to a heavy rain event is an important factor influencing whether or not heavy rainfall results in flooding. Thus, despite some limitations, newspaper accounts of historical flooding are largely consistent with measured climatic variables. The study demonstrates that concerted effort is needed to improve the status of knowledge concerning flood impacts and indeed other natural and human hazards in the Sahel.

Modeling urban coastal flood severity from crowd-sourced flood reports using Poisson regression and Random Forest

Science.gov (United States)

Sadler, J. M.; Goodall, J. L.; Morsy, M. M.; Spencer, K.

2018-04-01

Sea level rise has already caused more frequent and severe coastal flooding and this trend will likely continue. Flood prediction is an essential part of a coastal city's capacity to adapt to and mitigate this growing problem. Complex coastal urban hydrological systems however, do not always lend themselves easily to physically-based flood prediction approaches. This paper presents a method for using a data-driven approach to estimate flood severity in an urban coastal setting using crowd-sourced data, a non-traditional but growing data source, along with environmental observation data. Two data-driven models, Poisson regression and Random Forest regression, are trained to predict the number of flood reports per storm event as a proxy for flood severity, given extensive environmental data (i.e., rainfall, tide, groundwater table level, and wind conditions) as input. The method is demonstrated using data from Norfolk, Virginia USA from September 2010 to October 2016. Quality-controlled, crowd-sourced street flooding reports ranging from 1 to 159 per storm event for 45 storm events are used to train and evaluate the models. Random Forest performed better than Poisson regression at predicting the number of flood reports and had a lower false negative rate. From the Random Forest model, total cumulative rainfall was by far the most dominant input variable in predicting flood severity, followed by low tide and lower low tide. These methods serve as a first step toward using data-driven methods for spatially and temporally detailed coastal urban flood prediction.

Asian monsoon variability, cyclicities, and forcing mechanisms

Digital Repository Service at National Institute of Oceanography (India)

Naidu, P.D.

in monsoonal intensity from 5 to 2Ma. Uplift of the Himalayas and the Tibetan Plateau occurred coeval with the increase in strength of the Asian Monsoon between 9.5 and 5Ma. Variability of monsoon on glacial and interglacial time scale Multi proxy based... in the Western Ghats of India 131 Fig. 3. Multi proxy monsoon reconstructions show that summer monsoon strength was stronger during interglacials (shaded intervals) as compared to glacials 0 2 4 6 8 10 12 14 16 18 20 0 100 200 300 400 0 50...

On the relationship between the Indian summer monsoon rainfall and the EQUINOO in the CFSv2

Science.gov (United States)

Vishnu, S.; Francis, P. A.; Ramakrishna, S. S. V. S.; Shenoi, S. S. C.

2018-03-01

Several recent studies have shown that positive (negative) phase of Equatorial Indian Ocean Oscillation (EQUINOO) is favourable (unfavourable) to the Indian summer monsoon. However, many ocean-atmosphere global coupled models, including the state-of-the-art Climate Forecast System (CFS) version 2 have difficulty in reproducing this link realistically. In this study, we analyze the retrospective forecasts by the CFS model for the period 1982-2010 with an objective to identify the reasons behind the failure of the model to simulate the observed links between Indian summer monsoon and EQUINOO. It is found that, in the model hindcasts, the rainfall in the core monsoon region was mainly due to westward propagating synoptic scale systems, that originated from the vicinity of the tropical convergence zone (TCZ). Our analysis shows that unlike in observations, in the CFS, majority of positive (negative) EQUINOO events are associated with El Niño (La Niña) events in the Pacific. In addition to this, there is a strong link between EQUINOO and Indian Ocean Dipole (IOD) in the model. We show that, during the negative phase of EQUINOO/IOD, northward propagating TCZs remained stationary over the Bay of Bengal for longer period compared to the positive phase of EQUINOO/IOD. As a result, compared to the positive phase of EQUINOO/IOD, during a negative phase of EQUINOO/IOD, more westward propagating synoptic scale systems originated from the vicinity of TCZ and moved on to the core monsoon region, which resulted in higher rainfall over this region in the CFS. We further show that frequent, though short-lived, westward propagating systems, generated near the vicinity of TCZ over the Bay moved onto the mainland were responsible for less number of break monsoon spells during the negative phase of EQUINOO/IOD in the model hindcasts. This study underlines the necessity for improving the skill of the coupled models, particularly CFS model, to simulate the links between EQUINOO/IOD and

Near Real Time Flood Warning System for National Capital Territory of Delhi

Science.gov (United States)

Goyal, A.; Yadav, H.; Tyagi, H.; Gosain, A. K.

2017-12-01

Extreme floods are common phenomena during Indian Monsoons. The National Capital Territory area of India, Delhi, frequently experiences fluvial as well as pluvial inundation due to its proximity to river Yamuna and poor functioning of its stormwater drainage system. The urban floods result in severe waterlogging and heavy traffic snarls, bringing life in this megapolis to a halt. The city has witnessed six major floods since 1900 and thus its residents are well conscious of potential flood risks but the city still lacks a flood warning system. The flood related risks can be considerably reduced, if not eliminated, by issuing timely warnings and implementing adaptive measures. Therefore, the present study attempts to develop a web based platform that integrates Web-GIS technology and mathematical simulation modelling to provide an effective and reliable early flood warning service for Delhi. The study makes use of India Metorological Department's Doppler radar-derived near real time rainfall estimates of 15 minutes time step. The developed SWMM model has been validated using information from gauges, monitoring sensors and crowd sourcing techniques and utilises capabilities of cloud computing on server side for fast processing. This study also recommends safe evacuation policy and remedial measures for flooding hotspots as part of flood risk management plan. With heightened risk of floods in fast urbanizing areas, this work becomes highly pertinent as flood warning system with adequate lead time can not only save precious lives but can also substantially reduce flood damages.

Flash floods in Catalonia: a recurrent situation

Science.gov (United States)

Llasat, M. C.; Lindbergh, S.; Llasat-Botija, M.; Rodríguez, A.; Zaragoza, A.

2009-09-01

A database with information about the social impact produced by all the flood events recorded in Catalonia between 1982 and 2007 has been built. Original information comes from the INUNGAMA database (1900-2000) presented by Barnolas and Llasat (2007), the PRESSGAMA database (1982-2007) (Llasat et al., in rev.) and information from different published works (Barriendos et al, 2003; Barriendos and Pomés, 1993). Social impact has been obtained systematically in basis to news press data and, occasionally, in basis to insurance data. Flood events have been classified in ordinary floods, extraordinary floods and catastrophic ones, following the proposal of Llasat et al (2005). However, having in mind the flash floods effects, some new categories concerning casualties and car damages have also been introduced. The spatial and temporal distribution of these flood events has been analysed. Results have been compared with those obtained for the period 1900-2000 (Barnolas and Llasat, 2007) and 1350-2000 (Barrera et al, 2006). In order to better estimate the social impact and vulnerability some indicators have been defined and analyzed for some specific cases and a specific region. Besides the indicators applied in the INUNCAT Plan to obtain a cartography of flood risk in Catalonia, other ones like the number of cars affected or the number of request received by the meteorological service, has been also taken into account. These indicators allow analyzing global and temporal trends as well as characterizing the events. The selected region has been the Maresme, which is a flood prone region with a great density of population and that experiences every year one or more flash floods. The annual number of floods shows a positive trend that cannot be justified by the rainfall trend. Both vulnerability and hazard components have been considered and a discussion about the flood prevention measures is presented. The third part of this work has been centred in the analysis and

Investigating the temporal dynamics of suspended sediment during flood events with 7Be and 210Pbxs measurements in a drained lowland catchment

Science.gov (United States)

Le Gall, Marion; Evrard, Olivier; Foucher, Anthony; Laceby, J. Patrick; Salvador-Blanes, Sébastien; Manière, Louis; Lefèvre, Irène; Cerdan, Olivier; Ayrault, Sophie

2017-02-01

Soil erosion is recognized as one of the main processes of land degradation in agricultural areas. High suspended sediment loads, often generated from eroding agricultural landscapes, are known to degrade downstream environments. Accordingly, there is a need to understand soil erosion dynamics during flood events. Suspended sediment was therefore sampled in the river network and at tile drain outlets during five flood events in a lowland drained catchment in France. Source and sediment fallout radionuclide concentrations (7Be, 210Pbxs) were measured to quantify both the fraction of recently eroded particles transported during flood events and their residence time. Results indicate that the mean fraction of recently eroded sediment, estimated for the entire Louroux catchment, increased from 45 ± 20% to 80 ± 20% between December 2013 and February 2014, and from 65 ± 20% to 80 ± 20% in January 2016. These results demonstrate an initial flush of sediment previously accumulated in the river channel before the increasing supply of sediment recently eroded from the hillslopes during subsequent events. This research highlights the utility of coupling continuous river monitoring and fallout radionuclide measurements to increase our understanding of sediment dynamics and improve the management of soil and water resources in agricultural catchments.

Exploitation of Documented Historical Floods for Achieving Better Flood Defense

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Slobodan Kolaković

2016-01-01

Full Text Available Establishing Base Flood Elevation for a stream network corresponding to a big catchment is feasible by interdisciplinary approach, involving stochastic hydrology, river hydraulics, and computer aided simulations. A numerical model calibrated by historical floods has been exploited in this study. The short presentation of the catchment of the Tisza River in this paper is followed by the overview of historical floods which hit the region in the documented period of 130 years. Several well documented historical floods provided opportunity for the calibration of the chosen numerical model. Once established, the model could be used for investigation of different extreme flood scenarios and to establish the Base Flood Elevation. The calibration has shown that the coefficient of friction in case of the Tisza River is dependent both on the actual water level and on the preceding flood events. The effect of flood plain maintenance as well as the activation of six potential detention ponds on flood mitigation has been examined. Furthermore, the expected maximum water levels have also been determined for the case if the ever observed biggest 1888 flood hit the region again. The investigated cases of flood superposition highlighted the impact of tributary Maros on flood mitigation along the Tisza River.

Analysis of core-concrete interaction event with flooding for the Advanced Neutron Source reactor

International Nuclear Information System (INIS)

Kim, S.H.; Taleyarkhan, R.P.; Georgevich, V.; Navarro-Valenti, S.

1993-01-01

This paper discusses salient aspects of the methodology, assumptions, and modeling of various features related to estimation of source terms from an accident involving a molten core-concrete interaction event (with and without flooding) in the Advanced Neutron Source (ANS) reactor at the Oak Ridge National Laboratory. Various containment configurations are considered for this postulated severe accident. Several design features (such as rupture disks) are examined to study containment response during this severe accident. Also, thermal-hydraulic response of the containment and radionuclide transport and retention in the containment are studied. The results are described as transient variations of source terms, which are then used for studying off-site radiological consequences and health effects for the support of the Conceptual Safety Analysis Report for ANS. The results are also to be used to examine the effectiveness of subpile room flooding during this type of severe accident

Identification of homogeneous regions for rainfall regional frequency analysis considering typhoon event in South Korea

Science.gov (United States)

Heo, J. H.; Ahn, H.; Kjeldsen, T. R.

2017-12-01

South Korea is prone to large, and often disastrous, rainfall events caused by a mixture of monsoon and typhoon rainfall phenomena. However, traditionally, regional frequency analysis models did not consider this mixture of phenomena when fitting probability distributions, potentially underestimating the risk posed by the more extreme typhoon events. Using long-term observed records of extreme rainfall from 56 sites combined with detailed information on the timing and spatial impact of past typhoons from the Korea Meteorological Administration (KMA), this study developed and tested a new mixture model for frequency analysis of two different phenomena; events occurring regularly every year (monsoon) and events only occurring in some years (typhoon). The available annual maximum 24 hour rainfall data were divided into two sub-samples corresponding to years where the annual maximum is from either (1) a typhoon event, or (2) a non-typhoon event. Then, three-parameter GEV distribution was fitted to each sub-sample along with a weighting parameter characterizing the proportion of historical events associated with typhoon events. Spatial patterns of model parameters were analyzed and showed that typhoon events are less commonly associated with annual maximum rainfall in the North-West part of the country (Seoul area), and more prevalent in the southern and eastern parts of the country, leading to the formation of two distinct typhoon regions: (1) North-West; and (2) Southern and Eastern. Using a leave-one-out procedure, a new regional frequency model was tested and compared to a more traditional index flood method. The results showed that the impact of typhoon on design events might previously have been underestimated in the Seoul area. This suggests that the use of the mixture model should be preferred where the typhoon phenomena is less frequent, and thus can have a significant effect on the rainfall-frequency curve. This research was supported by a grant(2017-MPSS31

Rainfall estimation in the context of post-event flash flood analysis

Science.gov (United States)

Delrieu, Guy; Boudevillain, Brice; Bouilloud, Ludovic

2010-05-01

Due to their spatial coverage and space-time resolution, operational weather radar networks offer unprecedented opportunities for the observation of flash flood generating storms. However, the radar rainfall estimation quality highly depends on the relative locations of the event and the radar(s). A mountainous environment obviously adds to the complexity of the radar quantitative precipitation estimation (QPE). A pragmatic methodology was developed within the EC-funded HYDRATE project to take the best benefit of the existing rainfall observations (radar and raingauge data) for given flash-flood cases: 1) A precise documentation of the radar characteristics (location, parameters, operating protocol, data archives and processing) needs first to be established. The radar(s) detection domain(s) can then be characterized using the "hydrologic visibility" concepts (Pellarin et al. J Hydrometeor 3(5) 539-555 2002). 2) Rather dense raingauge observations (operational, amateur) are usually available at the event time scale while few raingauge time series exist at the hydrologic time steps. Such raingauge datasets need to be critically analysed; a geostatistical approach is proposed for this task. 3) A number of identifications can be implemented prior to the radar data re-processing: a) Special care needs to be paid to (residual) ground clutter which has a dramatic impact of radar QPE. Dry-weather maps and rainfall accumulation maps may help in this task. b) Various sources of power losses such as screening, wet radome, attenuation in rain need to be identified and quantified. It will be shown that mountain returns can be used to quantify attenuation effects at C-band. c) Radar volume data is required to characterize the vertical profile of reflectivity (VPR), eventually conditioned on rain type (convective, widespread). When such data is not available, knowledge of the 0°C isotherm and the scanning protocol may help detecting bright-band contaminations that critically

Assessing the continuity of the upland sediment cascade, fluvial geomorphic response of an upland river to an extreme flood event: Storm Desmond, Cumbria, UK.

Science.gov (United States)

Joyce, Hannah; Hardy, Richard; Warburton, Jeff

2017-04-01

Hillslope erosion and accelerated lake sedimentation are often viewed as the source and main storage elements in the upland sediment cascade. However, the continuity of sediment transfer through intervening valley systems has rarely been evaluated during extreme events. Storm Desmond (4th - 6th December, 2015) produced record-breaking rainfall maximums in the UK: 341.4 mm rainfall was recorded in a 24 hour period at Honister Pass, Western Lake District, and 405 mm of rainfall was recorded in a 38 hour period at Thirlmere, central Lake District. The storm was the largest in a 150 year local rainfall series, and exceeded previous new records set in the 2005 and 2009 floods. During this exceptional event, rivers over topped flood defences, and caused damage to over 257 bridges, flooded over 5000 homes and businesses, and caused substantial geomorphic change along upland rivers. This research quantifies the geomorphic and sedimentary response to Storm Desmond along a regulated gravel-bed river: St John's Beck. St John's Beck (length 7.8 km) is a channelised low gradient river (0.005) downstream of Thirlmere Reservoir, which joins the River Greta, and flows through Keswick, where major flooding has occurred, before discharging into Bassenthwaite Lake. St John's Beck has a history of chronic sediment aggradation, erosion and reports of historic flooding date back to 1750. During Storm Desmond, riverbanks were eroded, coarse sediment was deposited across valuable farmland and access routes were destroyed, including a bridge and footpaths, disrupting local business. A sediment budget framework has been used to quantify geomorphic change and sedimentary characteristics of the event along St John's Beck. The volume and sediment size distribution of flood deposits, channel bars, tributary deposits, floodplain scour, riverbank erosion and in-channel bars were measured directly in the field and converted to mass using local estimates of coarse and fine sediment bulk densities

Thunderstorms and flooding of August 17, 2007, with a context provided by a history of other large storm and flood events in the Black Hills area of South Dakota

Science.gov (United States)

Driscoll, Daniel G.; Bunkers, Matthew J.; Carter, Janet M.; Stamm, John F.; Williamson, Joyce E.

2010-01-01

The Black Hills area of western South Dakota has a history of damaging flash floods that have resulted primarily from exceptionally strong rain-producing thunderstorms. The best known example is the catastrophic storm system of June 9-10, 1972, which caused severe flooding in several major drainages near Rapid City and resulted in 238 deaths. More recently, severe thunderstorms caused flash flooding near Piedmont and Hermosa on August 17, 2007. Obtaining a thorough understanding of peak-flow characteristics for low-probability floods will require a comprehensive long-term approach involving (1) documentation of scientific information for extreme events such as these; (2) long-term collection of systematic peak-flow records; and (3) regional assessments of a wide variety of peak-flow information. To that end, the U.S. Geological Survey cooperated with the South Dakota Department of Transportation and National Weather Service to produce this report, which provides documentation regarding the August 17, 2007, storm and associated flooding and provides a context through examination of other large storm and flood events in the Black Hills area. The area affected by the August 17, 2007, storms and associated flooding generally was within the area affected by the larger storm of June 9-10, 1972. The maximum observed 2007 precipitation totals of between 10.00 and 10.50 inches occurred within about 2-3 hours in a small area about 5 miles west of Hermosa. The maximum documented precipitation amount in 1972 was 15.0 inches, and precipitation totals of 10.0 inches or more were documented for 34 locations within an area of about 76 square miles. A peak flow of less than 1 cubic foot per second occurred upstream from the 2007 storm extent for streamflow-gaging station 06404000 (Battle Creek near Keystone); whereas, the 1972 peak flow of 26,200 cubic feet per second was large, relative to the drainage area of only 58.6 square miles. Farther downstream along Battle Creek, a 2007

Prompt Proxy Mapping of Flood Damaged Rice Fields Using MODIS-Derived Indices

Directory of Open Access Journals (Sweden)

Youngjoo Kwak

2015-11-01

Full Text Available Flood mapping, particularly hazard and risk mapping, is an imperative process and a fundamental part of emergency response and risk management. This paper aims to produce a flood risk proxy map of damaged rice fields over the whole of Bangladesh, where monsoon river floods are dominant and frequent, affecting over 80% of the total population. This proxy risk map was developed to meet the request of the government on a national level. This study represents a rapid, straightforward methodology for estimating rice-crop damage in flood areas of Bangladesh during the large flood from July to September 2007, despite the lack of primary data. We improved a water detection algorithm to achieve a better discrimination capacity to discern flood areas by using a modified land surface water index (MLSWI. Then, rice fields were estimated utilizing a hybrid rice field map from land-cover classification and MODIS-derived indices, such as the normalized difference vegetation index (NDVI and enhanced vegetation index (EVI. The results showed that the developed method is capable of providing instant, comprehensive, nationwide mapping of flood risks, such as rice field damage. The detected flood areas and damaged rice fields during the 2007 flood were verified by comparing them with the Advanced Land Observing Satellite (ALOS AVNIR-2 images (a 10 m spatial resolution and in situ field survey data with moderate agreement (K = 0.57.

Nogales flood detention study

Science.gov (United States)

Norman, Laura M.; Levick, Lainie; Guertin, D. Phillip; Callegary, James; Guadarrama, Jesus Quintanar; Anaya, Claudia Zulema Gil; Prichard, Andrea; Gray, Floyd; Castellanos, Edgar; Tepezano, Edgar; Huth, Hans; Vandervoet, Prescott; Rodriguez, Saul; Nunez, Jose; Atwood, Donald; Granillo, Gilberto Patricio Olivero; Ceballos, Francisco Octavio Gastellum

2010-01-01

Flooding in Ambos Nogales often exceeds the capacity of the channel and adjacent land areas, endangering many people. The Nogales Wash is being studied to prevent future flood disasters and detention features are being installed in tributaries of the wash. This paper describes the application of the KINEROS2 model and efforts to understand the capacity of these detention features under various flood and urbanization scenarios. Results depict a reduction in peak flow for the 10-year, 1-hour event based on current land use in tributaries with detention features. However, model results also demonstrate that larger storm events and increasing urbanization will put a strain on the features and limit their effectiveness.

Flood-inundation and flood-mitigation modeling of the West Branch Wapsinonoc Creek Watershed in West Branch, Iowa

Science.gov (United States)

Cigrand, Charles V.

2018-03-26

The U.S. Geological Survey (USGS) in cooperation with the city of West Branch and the Herbert Hoover National Historic Site of the National Park Service assessed flood-mitigation scenarios within the West Branch Wapsinonoc Creek watershed. The scenarios are intended to demonstrate several means of decreasing peak streamflows and improving the conveyance of overbank flows from the West Branch Wapsinonoc Creek and its tributary Hoover Creek where they flow through the city and the Herbert Hoover National Historic Site located within the city.Hydrologic and hydraulic models of the watershed were constructed to assess the flood-mitigation scenarios. To accomplish this, the models used the U.S. Army Corps of Engineers Hydrologic Engineering Center-Hydrologic Modeling System (HEC–HMS) version 4.2 to simulate the amount of runoff and streamflow produced from single rain events. The Hydrologic Engineering Center-River Analysis System (HEC–RAS) version 5.0 was then used to construct an unsteady-state model that may be used for routing streamflows, mapping areas that may be inundated during floods, and simulating the effects of different measures taken to decrease the effects of floods on people and infrastructure.Both models were calibrated to three historic rainfall events that produced peak streamflows ranging between the 2-year and 10-year flood-frequency recurrence intervals at the USGS streamgage (05464942) on Hoover Creek. The historic rainfall events were calibrated by using data from two USGS streamgages along with surveyed high-water marks from one of the events. The calibrated HEC–HMS model was then used to simulate streamflows from design rainfall events of 24-hour duration ranging from a 20-percent to a 1-percent annual exceedance probability. These simulated streamflows were incorporated into the HEC–RAS model.The unsteady-state HEC–RAS model was calibrated to represent existing conditions within the watershed. HEC–RAS model simulations with the

Annual monsoon rains recorded by Jurassic dunes.

Science.gov (United States)

Loope, D B; Rowe, C M; Joeckel, R M

2001-07-05

Pangaea, the largest landmass in the Earth's history, was nearly bisected by the Equator during the late Palaeozoic and early Mesozoic eras. Modelling experiments and stratigraphic studies have suggested that the supercontinent generated a monsoonal atmospheric circulation that led to extreme seasonality, but direct evidence for annual rainfall periodicity has been lacking. In the Mesozoic era, about 190 million years ago, thick deposits of wind-blown sand accumulated in dunes of a vast, low-latitude desert at Pangaea's western margin. These deposits are now situated in the southwestern USA. Here we analyse slump masses in the annual depositional cycles within these deposits, which have been described for some outcrops of the Navajo Sandstone. Twenty-four slumps, which were generated by heavy rainfall, appear within one interval representing 36 years of dune migration. We interpret the positions of 20 of these masses to indicate slumping during summer monsoon rains, with the other four having been the result of winter storms. The slumped lee faces of these Jurassic dunes therefore represent a prehistoric record of yearly rain events.

Pleistocene Indian Monsoon Rainfall Variability

Science.gov (United States)

Yirgaw, D. G.; Hathorne, E. C.; Giosan, L.; Collett, T. S.; Sijingeo, A. V.; Nath, B. N.; Frank, M.

2014-12-01

The past variability of the Indian Monsoon is mostly known from records of wind strength over the Arabian Sea. Here we investigate proxies for fresh water input and runoff in a region of strong monsoon precipitation that is a major moisture source for the east Asian Monsoon. A sediment core obtained by the IODP vessel JOIDES Resolution and a gravity core from the Alcock Seamount complex in the Andaman Sea are used to examine the past monsoon variability on the Indian sub-continent and directly over the ocean. The current dataset covers the last glacial and deglacial but will eventually provide a Pleistocene record. We utilise the ecological habitats of G. sacculifer and N. dutertrei to investigate the freshwater-induced stratification with paired Mg/Ca and δ18O analyses to estimate seawater δ18O (δ18Osw). During the last 60 kyrs, Ba/Ca ratios and δ18Osw values generally agree well between the two cores and suggest the weakest surface runoff and monsoon during the LGM and strongest monsoon during the Holocene. The difference in δ18O between the species, interpreted as a proxy for upper ocean stratification, implies stratification developed around 37 ka and remained relatively constant during the LGM, deglacial and Holocene. To investigate monsoon variability for intervals in the past, single shell Mg/Ca and δ18O analyses have been conducted. Mg/Ca ratios from individual shells of N. dutertrei suggest relatively small changes in temperature. However, individual N. dutertrei δ18O differ greatly between the mid-Holocene and samples from the LGM and a nearby core top. The mid-Holocene individuals have a greater range and large skew towards negative values indicating greater fresh water influence.

Amplification of flood frequencies with local sea level rise and emerging flood regimes

Science.gov (United States)

Buchanan, Maya K.; Oppenheimer, Michael; Kopp, Robert E.

2017-06-01

The amplification of flood frequencies by sea level rise (SLR) is expected to become one of the most economically damaging impacts of climate change for many coastal locations. Understanding the magnitude and pattern by which the frequency of current flood levels increase is important for developing more resilient coastal settlements, particularly since flood risk management (e.g. infrastructure, insurance, communications) is often tied to estimates of flood return periods. The Intergovernmental Panel on Climate Change’s Fifth Assessment Report characterized the multiplication factor by which the frequency of flooding of a given height increases (referred to here as an amplification factor; AF). However, this characterization neither rigorously considered uncertainty in SLR nor distinguished between the amplification of different flooding levels (such as the 10% versus 0.2% annual chance floods); therefore, it may be seriously misleading. Because both historical flood frequency and projected SLR are uncertain, we combine joint probability distributions of the two to calculate AFs and their uncertainties over time. Under probabilistic relative sea level projections, while maintaining storm frequency fixed, we estimate a median 40-fold increase (ranging from 1- to 1314-fold) in the expected annual number of local 100-year floods for tide-gauge locations along the contiguous US coastline by 2050. While some places can expect disproportionate amplification of higher frequency events and thus primarily a greater number of historically precedented floods, others face amplification of lower frequency events and thus a particularly fast growing risk of historically unprecedented flooding. For example, with 50 cm of SLR, the 10%, 1%, and 0.2% annual chance floods are expected respectively to recur 108, 335, and 814 times as often in Seattle, but 148, 16, and 4 times as often in Charleston, SC.

Sex-specific responses to winter flooding, spring waterlogging and post-flooding recovery in Populus deltoides

OpenAIRE

Ling-Feng Miao; Fan Yang; Chun-Yu Han; Yu-Jin Pu; Yang Ding; Li-Jia Zhang

2017-01-01

Winter flooding events are common in some rivers and streams due to dam constructions, and flooding and waterlogging inhibit the growth of trees in riparian zones. This study investigated sex-specific morphological, physiological and ultrastructural responses to various durations of winter flooding and spring waterlogging stresses, and post-flooding recovery characteristics in Populus deltoides. There were no significant differences in the morphological, ultrastructural and the majority of ph...

Visualization of the Impact of the Catastrophic Flooding Events

DEFF Research Database (Denmark)

Mioc, Darka; Anton, François; Moreri, K. K.

maps. This can greatly help decision makers with the emergency measures and mitigation in most of the cases. In this article, we present a case study about mapping of flood risks due to a dam burst showing risk maps of flood hazards and available emergency facilities and their significance for risk...... prevention and mitigation....

Modeling Compound Flood Hazards in Coastal Embayments

Science.gov (United States)

Moftakhari, H.; Schubert, J. E.; AghaKouchak, A.; Luke, A.; Matthew, R.; Sanders, B. F.

2017-12-01

Coastal cities around the world are built on lowland topography adjacent to coastal embayments and river estuaries, where multiple factors threaten increasing flood hazards (e.g. sea level rise and river flooding). Quantitative risk assessment is required for administration of flood insurance programs and the design of cost-effective flood risk reduction measures. This demands a characterization of extreme water levels such as 100 and 500 year return period events. Furthermore, hydrodynamic flood models are routinely used to characterize localized flood level intensities (i.e., local depth and velocity) based on boundary forcing sampled from extreme value distributions. For example, extreme flood discharges in the U.S. are estimated from measured flood peaks using the Log-Pearson Type III distribution. However, configuring hydrodynamic models for coastal embayments is challenging because of compound extreme flood events: events caused by a combination of extreme sea levels, extreme river discharges, and possibly other factors such as extreme waves and precipitation causing pluvial flooding in urban developments. Here, we present an approach for flood risk assessment that coordinates multivariate extreme analysis with hydrodynamic modeling of coastal embayments. First, we evaluate the significance of correlation structure between terrestrial freshwater inflow and oceanic variables; second, this correlation structure is described using copula functions in unit joint probability domain; and third, we choose a series of compound design scenarios for hydrodynamic modeling based on their occurrence likelihood. The design scenarios include the most likely compound event (with the highest joint probability density), preferred marginal scenario and reproduced time series of ensembles based on Monte Carlo sampling of bivariate hazard domain. The comparison between resulting extreme water dynamics under the compound hazard scenarios explained above provides an insight to the

Flood-ring formation and root development in response to experimental flooding of young Quercus robur trees

NARCIS (Netherlands)

Copini, Paul; Ouden, den Jan; Robert, Elisabeth M.R.; Tardif, Jacques C.; Loesberg, Walter A.; Goudzwaard, Leo; Sass-Klaassen, Ute

2016-01-01

Spring flooding in riparian forests can cause significant reductions in earlywood-vessel size in submerged stem parts of ring-porous tree species, leading to the presence of ‘flood rings’ that can be used as a proxy to reconstruct past flooding events, potentially over millennia. The mechanism of

Convective environment in pre-monsoon and monsoon conditions over the Indian subcontinent: the impact of surface forcing

Directory of Open Access Journals (Sweden)

L. Thomas

2018-05-01

Full Text Available Thermodynamic soundings for pre-monsoon and monsoon seasons from the Indian subcontinent are analysed to document differences between convective environments. The pre-monsoon environment features more variability for both near-surface moisture and free-tropospheric temperature and moisture profiles. As a result, the level of neutral buoyancy (LNB and pseudo-adiabatic convective available potential energy (CAPE vary more for the pre-monsoon environment. Pre-monsoon soundings also feature higher lifting condensation levels (LCLs. LCL heights are shown to depend on the availability of surface moisture, with low LCLs corresponding to high surface humidity, arguably because of the availability of soil moisture. A simple theoretical argument is developed and showed to mimic the observed relationship between LCLs and surface moisture. We argue that the key element is the partitioning of surface energy flux into its sensible and latent components, that is, the surface Bowen ratio, and the way the Bowen ratio affects surface buoyancy flux. We support our argument with observations of changes in the Bowen ratio and LCL height around the monsoon onset, and with idealized simulations of cloud fields driven by surface heat fluxes with different Bowen ratios.

Validation of individual and aggregate global flood hazard models for two major floods in Africa.

Science.gov (United States)

Trigg, M.; Bernhofen, M.; Whyman, C.

2017-12-01

A recent intercomparison of global flood hazard models undertaken by the Global Flood Partnership shows that there is an urgent requirement to undertake more validation of the models against flood observations. As part of the intercomparison, the aggregated model dataset resulting from the project was provided as open access data. We compare the individual and aggregated flood extent output from the six global models and test these against two major floods in the African Continent within the last decade, namely severe flooding on the Niger River in Nigeria in 2012, and on the Zambezi River in Mozambique in 2007. We test if aggregating different number and combination of models increases model fit to the observations compared with the individual model outputs. We present results that illustrate some of the challenges of comparing imperfect models with imperfect observations and also that of defining the probability of a real event in order to test standard model output probabilities. Finally, we propose a collective set of open access validation flood events, with associated observational data and descriptions that provide a standard set of tests across different climates and hydraulic conditions.

Citizen involvement in flood risk governance: flood groups and networks

Directory of Open Access Journals (Sweden)

Twigger-Ross Clare

2016-01-01

Full Text Available Over the past decade has been a policy shift withinUK flood risk management towards localism with an emphasis on communities taking ownership of flood risk. There is also an increased focus on resilience and, more specifically, on community resilience to flooding. This paper draws on research carried out for UK Department for Environment Food and Rural Affairs to evaluate the Flood Resilience Community Pathfinder (FRCP scheme in England. Resilience is conceptualised as multidimensional and linked to exisiting capacities within a community. Creating resilience to flooding is an ongoing process of adaptation, learning from past events and preparing for future risks. This paper focusses on the development of formal and informal institutions to support improved flood risk management: institutional resilience capacity. It includes new institutions: e.g. flood groups, as well as activities that help to build inter- and intra- institutional resilience capacity e.g. community flood planning. The pathfinder scheme consisted of 13 projects across England led by local authorities aimed at developing community resilience to flood risk between 2013 – 2015. This paper discusses the nature and structure of flood groups, the process of their development, and the extent of their linkages with formal institutions, drawing out the barriers and facilitators to developing institutional resilience at the local level.

Development of a customised design flood estimation tool to ...

African Journals Online (AJOL)

The estimation of design flood events, i.e., floods characterised by a specific magnitude-frequency relationship, at a particular site in a specific region is necessary for the planning, design and operation of hydraulic structures. Both the occurrence and frequency of flood events, along with the uncertainty involved in the ...

May flood-poor periods be more dangerous than flood-rich periods?

Science.gov (United States)

Salinas, Jose Luis; Di Baldassarre, Giuliano; Viglione, Alberto; Kuil, Linda; Bloeschl, Guenter

2014-05-01

River floods are among the most devastating natural hazards experienced by populations that, since the earliest recorded civilisations, have settled in floodplains because they offer favourable conditions for trade, agriculture, and economic development. The occurrence of a flood may cause loss of lives and tremendous economic damages and, therefore, is rightly seen as a very negative event by the communities involved. Occurrence of many floods in a row is, of course, even more frustrating and is rightly considered a unbearable calamity. Unfortunately, the occurrence of many floods in a limited number of consecutive years is not unusual. In many places in the world, it has been observed that extreme floods do not arrive randomly but cluster in time into flood-poor and flood-rich periods consistent with the Hurst effect. If this is the case, when are the people more in danger? When should people be more scared? In flood-poor or flood-rich periods? In this work, a Socio-Hydrology model (Di Baldassarre et al., 2013; Viglione et al., 2014) is used to show that, maybe counter-intuitively, flood-poor periods may be more dangerous than flood-rich periods. The model is a conceptualisation of a hypothetical setting of a city at a river where a community evolves, making choices between flood management options on the floodplain. The most important feedbacks between the economic, political, technological and hydrological processes of the evolution of that community are represented in the model. In particular, the model also accounts in a dynamic way for the evolution of the the community awareness to flood risk. Occurrence of floods tends to increase peoples' recognition that their property is in an area that is potentially at risk of flooding, both at the scales of individuals and communities, which is one of the main reasons why flood coping actions are taken. It is shown through examples that frequent flood events may result in moderate damages because they ensure that the

Can we predict the next urban flood?

DEFF Research Database (Denmark)

Thorndahl, Søren; Nielsen, Jesper Ellerbæk; Jensen, David Getreuer

2015-01-01

Flooding produced by high-intensive local rainfall and drainage system capacity exceedance can have severe impacts in cities. In order to prepare cities for these types of flood events – especially in the future climate – it is valuable to be able to simulate these events numericallyboth...... historically and in real-time. There is a rather untested potential in real-time prediction of urban floods. In this paper radar data observations with different spatial and temporal resolution, radar nowcasts of 0-2 hours leadtime, and numerical weather models with leadtimes up to 24 h are used as inputs...... to an integrated flood and drainage systems model with the purpose to investigate the potential for predicting future floods. The system is tested on a small town Lystrup in Denmark, which has been recently flooded. Results show that it is possible to generate detailed flood maps in real-time with high resolution...

Explanatory analysis of the relationship between atmospheric circulation and occurrence of flood generating events in a coastal city

DEFF Research Database (Denmark)

Åström, Helena Lisa Alexandra; Sunyer Pinya, Maria Antonia; Madsen, H.

2016-01-01

The aim of this study is to enhance the understanding of the occurrence of flood generating events in urban areas by analyzing the relationship between large-scale atmospheric circulation and extreme precipitation events, extreme sea water level events and their simultaneous occurrence......, respectively. To describe the atmospheric circulation we used the Lamb circulation type (LCT) classification and re-grouped it into Lamb circulation classes (LCC). The daily LCCs/LCTs were connected with rare precipitation and water level events in Aarhus, a Danish coastal city. Westerly and cyclonic LCCs (W......, C, SW, and NW) showed a significantly high occurrence of extreme precipitation. Similarly, for extreme water level events westerly LCCs (W and SW) showed a significantly high occurrence. Significantly low occurrence of extreme precipitation and water level events was obtained in easterly LCCs (NE, E...

The record precipitation and flood event in Iberia in December 1876: description and synoptic analysis

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Ricardo Machado Trigo

2014-04-01

Full Text Available The first week of December 1876 was marked by extreme weather conditions that affected the south-western sector of the Iberian Peninsula, leading to an all-time record flow in two large international rivers. As a direct consequence, several Portuguese and Spanish towns and villages located in the banks of both rivers suffered serious flood damage on 7 December 1876. These unusual floods were amplified by the preceding particularly autumn wet months, with October 1876 presenting extremely high precipitation anomalies for all western Iberia stations. Two recently digitised stations in Portugal (Lisbon and Evora, present a peak value on 5 December 1876. Furthermore, the values of precipitation registered between 28 November and 7 December were so remarkable that, the episode of 1876 still corresponds to the maximum average daily precipitation values for temporal scales between 2 and 10 days. Using several different data sources, such as historical newspapers of that time, meteorological data recently digitised from several stations in Portugal and Spain and the recently available 20th Century Reanalysis, we provide a detailed analysis on the socio-economic impacts, precipitation values and the atmospheric circulation conditions associated with this event. The atmospheric circulation during these months was assessed at the monthly, daily and sub-daily scales. All months considered present an intense negative NAO index value, with November 1876 corresponding to the lowest NAO value on record since 1865. We have also computed a multivariable analysis of surface and upper air fields in order to provide some enlightening into the evolution of the synoptic conditions in the week prior to the floods. These events resulted from the continuous pouring of precipitation registered between 28 November and 7 December, due to the consecutive passage of Atlantic low-pressure systems fuelled by the presence of an atmospheric-river tropical moisture flow over

Mechanism of ENSO influence on the South Asian monsoon rainfall in global model simulations

Science.gov (United States)

Joshi, Sneh; Kar, Sarat C.

2018-02-01

Coupled ocean atmosphere global climate models are increasingly being used for seasonal scale simulation of the South Asian monsoon. In these models, sea surface temperatures (SSTs) evolve as coupled air-sea interaction process. However, sensitivity experiments with various SST forcing can only be done in an atmosphere-only model. In this study, the Global Forecast System (GFS) model at T126 horizontal resolution has been used to examine the mechanism of El Niño-Southern Oscillation (ENSO) forcing on the monsoon circulation and rainfall. The model has been integrated (ensemble) with observed, climatological and ENSO SST forcing to document the mechanism on how the South Asian monsoon responds to basin-wide SST variations in the Indian and Pacific Oceans. The model simulations indicate that the internal variability gets modulated by the SSTs with warming in the Pacific enhancing the ensemble spread over the monsoon region as compared to cooling conditions. Anomalous easterly wind anomalies cover the Indian region both at 850 and 200 hPa levels during El Niño years. The locations and intensity of Walker and Hadley circulations are altered due to ENSO SST forcing. These lead to reduction of monsoon rainfall over most parts of India during El Niño events compared to La Niña conditions. However, internally generated variability is a major source of uncertainty in the model-simulated climate.

Flood damage: a model for consistent, complete and multipurpose scenarios

Science.gov (United States)

Menoni, Scira; Molinari, Daniela; Ballio, Francesco; Minucci, Guido; Mejri, Ouejdane; Atun, Funda; Berni, Nicola; Pandolfo, Claudia

2016-12-01

Effective flood risk mitigation requires the impacts of flood events to be much better and more reliably known than is currently the case. Available post-flood damage assessments usually supply only a partial vision of the consequences of the floods as they typically respond to the specific needs of a particular stakeholder. Consequently, they generally focus (i) on particular items at risk, (ii) on a certain time window after the occurrence of the flood, (iii) on a specific scale of analysis or (iv) on the analysis of damage only, without an investigation of damage mechanisms and root causes. This paper responds to the necessity of a more integrated interpretation of flood events as the base to address the variety of needs arising after a disaster. In particular, a model is supplied to develop multipurpose complete event scenarios. The model organizes available information after the event according to five logical axes. This way post-flood damage assessments can be developed that (i) are multisectoral, (ii) consider physical as well as functional and systemic damage, (iii) address the spatial scales that are relevant for the event at stake depending on the type of damage that has to be analyzed, i.e., direct, functional and systemic, (iv) consider the temporal evolution of damage and finally (v) allow damage mechanisms and root causes to be understood. All the above features are key for the multi-usability of resulting flood scenarios. The model allows, on the one hand, the rationalization of efforts currently implemented in ex post damage assessments, also with the objective of better programming financial resources that will be needed for these types of events in the future. On the other hand, integrated interpretations of flood events are fundamental to adapting and optimizing flood mitigation strategies on the basis of thorough forensic investigation of each event, as corroborated by the implementation of the model in a case study.

Combined Effect of an Atmospheric River and a Cut-off Low in Hiroshima Flooding Event on August 19, 2014

Science.gov (United States)

Takayabu, Y. N.; Hirota, N.; Kato, M.; Arakane, S.

2015-12-01

An extraordinary precipitation over 100 mmhr-1in Hiroshima on August 19, 2014, caused a flash flood which resulted in 74 fatalities and collapse of 330 houses. In order to examine the meteorological background of this flooding event, we carried out a detailed analysis utilizing rain gauge data, satellite precipitation dataset, and a meso scale and a global scale objective analyses provided from the Japan Meteorological Agency. Then, we performed numerical experiments using a nonhydrostatic compressible equation model called the Cloud-Resolving Storm Simulator (CReSS). As a result, a combined effect of an atmospheric river (AR) and a cut-off low (COL) in this flooding event was elucidated. During the event, a filamentary transport of moisture extending from the Indochina Peninsula to the Japanese Islands was observed along the southern side of the subtropical jet, forming an AR. This AR had a deep structure with an amount of free tropospheric moisture comparable to that of the boundary layer. Concurrently, there was a COL, detached from the Mid-Pacific Trough, moving northwestward toward the Japanese Archipelago. With various sensitivity experiments, we concluded that a mid-tropospheric instability associated with the cold core of the COL and a dynamical ascent induced in its foreside, collaboratively worked with the anomalous moisture in the free troposphere associated with the AR, to extraordinarily enhance the precipitation over Hiroshima region. An orographic effect to concentrate the precipitation in this region was also confirmed. An implication on a difference in effects of AR in this event with a climatologically moist boundary layer, from those in the US west coast with a very dry environment, was also obtained. Acknowledgment: This study is supported by the Environment Research and Technology Development Fund (2-1503) of the Ministry of the Environment, Japan, and by the Ministry of Education, Culture, Sports, Science and Technology, Japan.

Modeling Flood & Drought Scenario for Water Management in Porali River Basin, Balochistan

Directory of Open Access Journals (Sweden)

Shoaib Ahmed

2013-12-01

Full Text Available Recent history shows that floods have become a frequently occurring disaster in Balochistan, especially during monsoon season. Two rivers, river Porali and river Kud overflows, inundating its banks and causing destruction to cultivated land and property. This study is an attempt to identify flood prone areas of Porali river basin for future flood scenario and propose possible reservoir locations for excess flood water storage. Computer-based models Hydrological Simulation Program-FORTRAN (HSPF and HEC-river analysis system (HEC-RAS are used as tools to simulate existing and future flood and drought scenarios. Models are calibrated and validated using data from 3 weather stations, namely Wadh, Bela, and Uthal and stream flow data from two gauging stations. The highest and the lowest 10 years of precipitation data are extracted, from historic dataset of all stations, to attain future flooding and drought scenarios, respectively. Flood inundation map is generated highlighting agricultural prone land and settlements of the watershed. Using Digital Elevation Model (DEM and volume of water calculated from the flood scenario, possible locations for reservoirs are marked that can store excess water for the use in drought years. Flow and volume of water has also been simulated for drought scenario. Analyses show that 3 × 109 m3 of water available due to immense flooding that is sufficient for the survival for one drought year, as the volume of water for latter scenario is 2.9 × 108m3.

Lessons learned from international flood PSAS in Korea

International Nuclear Information System (INIS)

Kim, Myungro; Lee, Beomsu; Kang, Sunkoo

1998-01-01

Risk due to internal flooding has been one of the major concerns for the design and operation of nuclear power plants. To reduce the risk from internal flooding, two design approaches for flood protection systems, active and passive, can be considered. The approaches to flood protection design are different for each plant design, and they are highly dependent on the plant type. The flood PSA revealed that the potential plant risk due to a flooding event is highly dependent on the flood design. The major design characteristics are 1) the location of systems that utilize sea water and their impact to other safety related systems, and 2) the existence of emergency overflow paths and an emergency sump which can transfer and accommodate flood water to prevent a significant flooding event. To identify and compare the effectiveness and potential vulnerability of various Korean nuclear power plants' flood designs, the flood PSAs have been performed for three plant designs, such as existing Korean PWR plants, CANDU type PHWR plants, and Korean Standard Nuclear Plants. Based on the evaluation, several design changes were recommended. (author)

Peak flood estimation using gene expression programming

Science.gov (United States)

Zorn, Conrad R.; Shamseldin, Asaad Y.

2015-12-01

As a case study for the Auckland Region of New Zealand, this paper investigates the potential use of gene-expression programming (GEP) in predicting specific return period events in comparison to the established and widely used Regional Flood Estimation (RFE) method. Initially calibrated to 14 gauged sites, the GEP derived model was further validated to 10 and 100 year flood events with a relative errors of 29% and 18%, respectively. This is compared to the RFE method providing 48% and 44% errors for the same flood events. While the effectiveness of GEP in predicting specific return period events is made apparent, it is argued that the derived equations should be used in conjunction with those existing methodologies rather than as a replacement.

Predicting Coastal Flood Severity using Random Forest Algorithm

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Sadler, J. M.; Goodall, J. L.; Morsy, M. M.; Spencer, K.

2017-12-01

Coastal floods have become more common recently and are predicted to further increase in frequency and severity due to sea level rise. Predicting floods in coastal cities can be difficult due to the number of environmental and geographic factors which can influence flooding events. Built stormwater infrastructure and irregular urban landscapes add further complexity. This paper demonstrates the use of machine learning algorithms in predicting street flood occurrence in an urban coastal setting. The model is trained and evaluated using data from Norfolk, Virginia USA from September 2010 - October 2016. Rainfall, tide levels, water table levels, and wind conditions are used as input variables. Street flooding reports made by city workers after named and unnamed storm events, ranging from 1-159 reports per event, are the model output. Results show that Random Forest provides predictive power in estimating the number of flood occurrences given a set of environmental conditions with an out-of-bag root mean squared error of 4.3 flood reports and a mean absolute error of 0.82 flood reports. The Random Forest algorithm performed much better than Poisson regression. From the Random Forest model, total daily rainfall was by far the most important factor in flood occurrence prediction, followed by daily low tide and daily higher high tide. The model demonstrated here could be used to predict flood severity based on forecast rainfall and tide conditions and could be further enhanced using more complete street flooding data for model training.

The impact of bathymetry input on flood simulations

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Khanam, M.; Cohen, S.

2017-12-01

Flood prediction and mitigation systems are inevitable for improving public safety and community resilience all over the worldwide. Hydraulic simulations of flood events are becoming an increasingly efficient tool for studying and predicting flood events and susceptibility. A consistent limitation of hydraulic simulations of riverine dynamics is the lack of information about river bathymetry as most terrain data record water surface elevation. The impact of this limitation on the accuracy on hydraulic simulations of flood has not been well studies over a large range of flood magnitude and modeling frameworks. Advancing our understanding of this topic is timely given emerging national and global efforts for developing automated flood predictions systems (e.g. NOAA National Water Center). Here we study the response of flood simulation to the incorporation of different bathymetry and floodplain surveillance source. Different hydraulic models are compared, Mike-Flood, a 2D hydrodynamic model, and GSSHA, a hydrology/hydraulics model. We test a hypothesis that the impact of inclusion/exclusion of bathymetry data on hydraulic model results will vary in its magnitude as a function of river size. This will allow researcher and stake holders more accurate predictions of flood events providing useful information that will help local communities in a vulnerable flood zone to mitigate flood hazards. Also, it will help to evaluate the accuracy and efficiency of different modeling frameworks and gage their dependency on detailed bathymetry input data.

Synoptic thermodynamic and dynamic patterns associated with Quitandinha River flooding events in Petropolis, Rio de Janeiro (Brazil)

Science.gov (United States)

da Silva, Fabricio Polifke; Justi da Silva, Maria Gertrudes Alvarez; Rotunno Filho, Otto Corrêa; Pires, Gisele Dornelles; Sampaio, Rafael João; de Araújo, Afonso Augusto Magalhães

2018-05-01

Natural disasters are the result of extreme or intense natural phenomena that cause severe impacts on society. These impacts can be mitigated through preventive measures that can be aided by better knowledge of extreme phenomena and monitoring of forecasting and alert systems. The city of Petropolis (in a mountainous region of the state of Rio de Janeiro, Brazil) is prone to heavy rain events, often leading to River overflows, landslides, and loss of life. In that context, this work endeavored to characterize the thermodynamic and dynamic synoptic patterns that trigger heavy rainfall episodes and the corresponding flooding of Quitandinha River. More specifically, we reviewed events from the time period between January 2013 and December 2014 using reanalysis data. We expect that the overall description obtained of synoptic patterns should provide adequate qualitative aid to the decision-making processes involved in operational forecasting procedures. We noticed that flooding events were related to the presence of the South Atlantic Convergence Zone (SACZ), frontal systems (FS), and convective storms (CS). These systems showed a similar behavior on high-frequency wind components, notably with respect to northwest winds before precipitation and to a strong southwest wind component during rainfall events. Clustering analyses indicated that the main component for precipitation formation with regard to CS systems comes from daytime heating, with the dynamic component presenting greater efficiency for the FS configurations. The SACZ events were influenced by moisture availability along the vertical column of the atmosphere and also due to dynamic components of precipitation efficiency and daytime heating, the latter related to the continuous transport of moisture from the Amazon region and South Atlantic Ocean towards Rio de Janeiro state.

A climate-based multivariate extreme emulator of met-ocean-hydrological events for coastal flooding

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Camus, Paula; Rueda, Ana; Mendez, Fernando J.; Tomas, Antonio; Del Jesus, Manuel; Losada, Iñigo J.

2015-04-01

Atmosphere-ocean general circulation models (AOGCMs) are useful to analyze large-scale climate variability (long-term historical periods, future climate projections). However, applications such as coastal flood modeling require climate information at finer scale. Besides, flooding events depend on multiple climate conditions: waves, surge levels from the open-ocean and river discharge caused by precipitation. Therefore, a multivariate statistical downscaling approach is adopted to reproduce relationships between variables and due to its low computational cost. The proposed method can be considered as a hybrid approach which combines a probabilistic weather type downscaling model with a stochastic weather generator component. Predictand distributions are reproduced modeling the relationship with AOGCM predictors based on a physical division in weather types (Camus et al., 2012). The multivariate dependence structure of the predictand (extreme events) is introduced linking the independent marginal distributions of the variables by a probabilistic copula regression (Ben Ayala et al., 2014). This hybrid approach is applied for the downscaling of AOGCM data to daily precipitation and maximum significant wave height and storm-surge in different locations along the Spanish coast. Reanalysis data is used to assess the proposed method. A commonly predictor for the three variables involved is classified using a regression-guided clustering algorithm. The most appropriate statistical model (general extreme value distribution, pareto distribution) for daily conditions is fitted. Stochastic simulation of the present climate is performed obtaining the set of hydraulic boundary conditions needed for high resolution coastal flood modeling. References: Camus, P., Menéndez, M., Méndez, F.J., Izaguirre, C., Espejo, A., Cánovas, V., Pérez, J., Rueda, A., Losada, I.J., Medina, R. (2014b). A weather-type statistical downscaling framework for ocean wave climate. Journal of

Crowdsourcing detailed flood data

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Walliman, Nicholas; Ogden, Ray; Amouzad*, Shahrzhad

2015-04-01

Over the last decade the average annual loss across the European Union due to flooding has been 4.5bn Euros, but increasingly intense rainfall, as well as population growth, urbanisation and the rising costs of asset replacements, may see this rise to 23bn Euros a year by 2050. Equally disturbing are the profound social costs to individuals, families and communities which in addition to loss of lives include: loss of livelihoods, decreased purchasing and production power, relocation and migration, adverse psychosocial effects, and hindrance of economic growth and development. Flood prediction, management and defence strategies rely on the availability of accurate information and flood modelling. Whilst automated data gathering (by measurement and satellite) of the extent of flooding is already advanced it is least reliable in urban and physically complex geographies where often the need for precise estimation is most acute. Crowdsourced data of actual flood events is a potentially critical component of this allowing improved accuracy in situations and identifying the effects of local landscape and topography where the height of a simple kerb, or discontinuity in a boundary wall can have profound importance. Mobile 'App' based data acquisition using crowdsourcing in critical areas can combine camera records with GPS positional data and time, as well as descriptive data relating to the event. This will automatically produce a dataset, managed in ArcView GIS, with the potential for follow up calls to get more information through structured scripts for each strand. Through this local residents can provide highly detailed information that can be reflected in sophisticated flood protection models and be core to framing urban resilience strategies and optimising the effectiveness of investment. This paper will describe this pioneering approach that will develop flood event data in support of systems that will advance existing approaches such as developed in the in the UK

The monsoon system: Land-sea breeze or the ITCZ?

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Gadgil, Sulochana

2018-02-01

For well over 300 years, the monsoon has been considered to be a gigantic land-sea breeze driven by the land-ocean contrast in surface temperature. In this paper, this hypothesis and its implications for the variability of the monsoon are discussed and it is shown that the observations of monsoon variability do not support this popular theory of the monsoon. An alternative hypothesis (whose origins can be traced to Blanford's (1886) remarkably perceptive analysis) in which the basic system responsible for the Indian summer monsoon is considered to be the Intertropical Convergence Zone (ITCZ) or the equatorial trough, is then examined and shown to be consistent with the observations. The implications of considering the monsoon as a manifestation of the seasonal migration of the ITCZ for the variability of the Indian summer monsoon and for identification of the monsoonal regions of the world are briefly discussed.

Observational Analysis of Two Contrasting Monsoon Years

Science.gov (United States)

Karri, S.; Ahmad, R.; Sujata, P.; Jose, S.; Sreenivas, G.; Maurya, D. K.

2014-11-01

The Indian summer monsoon rainfall contributes about 75 % of the total annual rainfall and exhibits considerable interannual variations. The agricultural economy of the country depends mainly on the monsoon rainfall. The long-range forecast of the monsoon rainfall is, therefore of significant importance in agricultural planning and other economic activities of the country. There are various parameters which influence the amount of rainfall received during the monsoon. Some of the important parameters considered by the Indian Meteorological Department (IMD) for the study of monsoon are Outgoing Longwave Radiation (OLR), moisture content of the atmosphere, zonal wind speed, low level vorticity, pressure gradient etc. Compared to the Long Period Average (LPA) value of rain fall, the country as a whole received higher amount of rainfall in June, 2013 (34 % more than LPA). The same month showed considerable decrease next year as the amount of rainfall received was around 43 % less compared to LPA. This drastic difference of monsoon prompted to study the behaviour of some of the monsoon relevant parameters. In this study we have considered five atmospheric parameters as the indicators of monsoon behaviour namely vertical relative humidity, OLR, aerosol optical depth (AOD), wind at 850 hPa and mean sea level pressure (MSLP). In the initial analysis of weekly OLR difference for year 2013 and 2014 shows positive values in the month of May over north-western parts of India (region of heat low). This should result in a weaker monsoon in 2014. This is substantiated by the rainfall data received for various stations over India. Inference made based on the analysis of RH profiles coupled with AOD values is in agreement with the rainfall over the corresponding stations.

Characterisation of seasonal flood types according to timescales in mixed probability distributions

Science.gov (United States)

Fischer, Svenja; Schumann, Andreas; Schulte, Markus

2016-08-01

When flood statistics are based on annual maximum series (AMS), the sample often contains flood peaks, which differ in their genesis. If the ratios among event types change over the range of observations, the extrapolation of a probability distribution function (pdf) can be dominated by a majority of events that belong to a certain flood type. If this type is not typical for extraordinarily large extremes, such an extrapolation of the pdf is misleading. To avoid this breach of the assumption of homogeneity, seasonal models were developed that differ between winter and summer floods. We show that a distinction between summer and winter floods is not always sufficient if seasonal series include events with different geneses. Here, we differentiate floods by their timescales into groups of long and short events. A statistical method for such a distinction of events is presented. To demonstrate their applicability, timescales for winter and summer floods in a German river basin were estimated. It is shown that summer floods can be separated into two main groups, but in our study region, the sample of winter floods consists of at least three different flood types. The pdfs of the two groups of summer floods are combined via a new mixing model. This model considers that information about parallel events that uses their maximum values only is incomplete because some of the realisations are overlaid. A statistical method resulting in an amendment of statistical parameters is proposed. The application in a German case study demonstrates the advantages of the new model, with specific emphasis on flood types.

Possible Influences of Air Pollution, Dust and Sandstorms on the Indian Monsoon

Science.gov (United States)

Lau, William K. M.; Kim, Kyu-Myong; Hsu, Christina N.; Holben, Brent N.

2010-01-01

In Asian monsoon countries, such as China and India, human health and safety problems caused by air pollution are becoming increasingly serious, due to the increased loading of atmospheric pollutants from waste gas emissions and from rising energy demand associated with the rapid pace of industrialization and modernization. Meanwhile, uneven distribution of monsoon rain associated with flash floods or prolonged drought, has caused major loss of human life and damage to crops and.property with devastating societal impacts. Historically, air-pollution and monsoons research are treated as separate problems. However recent studies have suggested that the two problems may be intrinsically linked and need to be studied jointly. Fundamentally, aerosols can affect precipitation through radiative effects cif suspended particles in the atmosphere (direct effect) and/or by interfering and changing: the cloud and precipitation formation processes (indirect effect). Based on their optical properties, aerosols can be classified into two types.: those that absorb solar radiation, and those that do not. Both types of aerosols scatter sunlight and reduce the amount of solar radiation from reaching the Earth's surface, causing it to cool. The surface cooling increases atmospheric stability and reduces convection potential, Absorbing aerosols, however, in addition to cooling the surface, can heat the atmosphere. The heating of the atmosphere may reduce the amount of low clouds by increased evaporation in cloud drops. The heating, however, may induce rising motion, enhance low-level moisture, convergence and, hence, increases rainfall, The latent heating from enhanced rainfall may excite feedback processes in the large-scale circulation, further amplify.the initial response to aerosol heating and producing more rain. Additionally, aerosols can increase the concentration of cloud condensation nuclei (CCN), increase cloud amount and decrease coalescence and collision rates, leading to

More frequent flooding? Changes in flood frequency in the Pearl River basin, China, since 1951 and over the past 1000 years

Science.gov (United States)

Zhang, Qiang; Gu, Xihui; Singh, Vijay P.; Shi, Peijun; Sun, Peng

2018-05-01

Flood risks across the Pearl River basin, China, were evaluated using a peak flood flow dataset covering a period of 1951-2014 from 78 stations and historical flood records of the past 1000 years. The generalized extreme value (GEV) model and the kernel estimation method were used to evaluate frequencies and risks of hazardous flood events. Results indicated that (1) no abrupt changes or significant trends could be detected in peak flood flow series at most of the stations, and only 16 out of 78 stations exhibited significant peak flood flow changes with change points around 1990. Peak flood flow in the West River basin increased and significant increasing trends were identified during 1981-2010; decreasing peak flood flow was found in coastal regions and significant trends were observed during 1951-2014 and 1966-2014. (2) The largest three flood events were found to cluster in both space and time. Generally, basin-scale flood hazards can be expected in the West and North River basins. (3) The occurrence rate of floods increased in the middle Pearl River basin but decreased in the lower Pearl River basin. However, hazardous flood events were observed in the middle and lower Pearl River basin, and this is particularly true for the past 100 years. However, precipitation extremes were subject to moderate variations and human activities, such as building of levees, channelization of river systems, and rapid urbanization; these were the factors behind the amplification of floods in the middle and lower Pearl River basin, posing serious challenges for developing measures of mitigation of flood hazards in the lower Pearl River basin, particularly the Pearl River Delta (PRD) region.

Stochastic Urban Pluvial Flood Hazard Maps Based upon a Spatial-Temporal Rainfall Generator

Directory of Open Access Journals (Sweden)

Nuno Eduardo Simões

2015-06-01

Full Text Available It is a common practice to assign the return period of a given storm event to the urban pluvial flood event that such storm generates. However, this approach may be inappropriate as rainfall events with the same return period can produce different urban pluvial flooding events, i.e., with different associated flood extent, water levels and return periods. This depends on the characteristics of the rainfall events, such as spatial variability, and on other characteristics of the sewer system and the catchment. To address this, the paper presents an innovative contribution to produce stochastic urban pluvial flood hazard maps. A stochastic rainfall generator for urban-scale applications was employed to generate an ensemble of spatially—and temporally—variable design storms with similar return period. These were used as input to the urban drainage model of a pilot urban catchment (~9 km2 located in London, UK. Stochastic flood hazard maps were generated through a frequency analysis of the flooding generated by the various storm events. The stochastic flood hazard maps obtained show that rainfall spatial-temporal variability is an important factor in the estimation of flood likelihood in urban areas. Moreover, as compared to the flood hazard maps obtained by using a single spatially-uniform storm event, the stochastic maps generated in this study provide a more comprehensive assessment of flood hazard which enables better informed flood risk management decisions.

Pluvial, urban flood mechanisms and characteristics - Assessment based on insurance claims

Science.gov (United States)

Sörensen, Johanna; Mobini, Shifteh

2017-12-01

Pluvial flooding is a problem in many cities and for city planning purpose the mechanisms behind pluvial flooding are of interest. Previous studies seldom use insurance claim data to analyse city scale characteristics that lead to flooding. In the present study, two long time series (∼20 years) of flood claims from property owners have been collected and analysed in detail to investigate the mechanisms and characteristics leading to urban flooding. The flood claim data come from the municipal water utility company and property owners with insurance that covers property loss from overland flooding, groundwater intrusion through basement walls and flooding from the drainage system. These data are used as a proxy for flood severity for several events in the Swedish city of Malmö. It is discussed which rainfall characteristics give most flooding and why some rainfall events do not lead to severe flooding, how city scale topography and sewerage system type influence spatial distribution of flood claims, and which impact high sea level has on flooding in Malmö. Three severe flood events are described in detail and compared with a number of smaller flood events. It was found that the main mechanisms and characteristics of flood extent and its spatial distribution in Malmö are intensity and spatial distribution of rainfall, distance to the main sewer system as well as overland flow paths, and type of drainage system, while high sea level has little impact on the flood extent. Finally, measures that could be taken to lower the flood risk in Malmö, and other cities with similar characteristics, are discussed.

An attempt to estimate the economic value of the loss of human life due to landslide and flood events in Italy

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Salvati, Paola; Bianchi, Cinzia; Hussin, Haydar; Guzzetti, Fausto

2013-04-01

Landslide and flood events in Italy cause wide and severe damage to buildings and infrastructure, and are frequently involved in the loss of human life. The cost estimates of past natural disasters generally refer to the amount of public money used for the restoration of the direct damage, and most commonly do not account for all disaster impacts. Other cost components, including indirect losses, are difficult to quantify and, among these, the cost of human lives. The value of specific human life can be identified with the value of a statistical life (VLS), defined as the value that an individual places on a marginal change in their likelihood of death This is different from the value of an actual life. Based on information of fatal car accidents in Italy, we evaluate the cost that society suffers for the loss of life due to landslide and flood events. Using a catalogue of fatal landslide and flood events, for which information about gender and age of the fatalities is known, we determine the cost that society suffers for the loss of their life. For the purpose, we calculate the economic value in terms of the total income that the working-age population involved in the fatal events would have earned over the course of their life. For the computation, we use the pro-capita income calculated as the ratio between the GDP and the population value in Italy for each year, since 1980. Problems occur for children and retired people that we decided not to include in our estimates.

Economic Assessment of Mitigating Damage of Flood Events : Cost–Benefit Analysis of Flood-Proofing Commercial Buildings in Umbria, Italy

NARCIS (Netherlands)

Botzen, W. J.Wouter; Monteiro, Érika; Estrada, Francisco; Pesaro, Giulia; Menoni, Scira

2017-01-01

Floods are among the costliest natural disasters worldwide. Integrated flood risk management approaches involving both public and private measures have been proposed to cope with trends in flood risk. These approaches are hampered by a lack of information about the cost-effectiveness of private

North-East monsoon rainfall extremes over the southern peninsular India and their association with El Niño

Science.gov (United States)

Singh, Prem; Gnanaseelan, C.; Chowdary, J. S.

2017-12-01

The present study investigates the relationship between extreme north-east (NE) monsoon rainfall (NEMR) over the Indian peninsula region and El Niño forcing. This turns out to be a critical science issue especially after the 2015 Chennai flood. The puzzle being while most El Niños favour good NE monsoon, some don't. In fact some El Niño years witnessed deficit NE monsoon. Therefore two different cases (or classes) of El Niños are considered for analysis based on standardized NEMR index and Niño 3.4 index with case-1 being both Niño-3.4 and NEMR indices greater than +1 and case-2 being Niño-3.4 index greater than +1 and NEMR index less than -1. Composite analysis suggests that SST anomalies in the central and eastern Pacific are strong in both cases but large differences are noted in the spatial distribution of SST over the Indo-western Pacific region. This questions our understanding of NEMR as mirror image of El Niño conditions in the Pacific. It is noted that the favourable excess NEMR in case-1 is due to anomalous moisture transport from Bay of Bengal and equatorial Indian Ocean to southern peninsular India. Strong SST gradient between warm western Indian Ocean (and Bay of Bengal) and cool western Pacific induced strong easterly wind anomalies during NE monsoon season favour moisture transport towards the core NE monsoon region. Further anomalous moisture convergence and convection over the core NE monsoon region supported positive rainfall anomalies in case-1. While in case-2, weak SST gradients over the Indo-western Pacific and absence of local low level convergence over NE monsoon region are mainly responsible for deficit rainfall. The ocean dynamics in the Indian Ocean displayed large differences during case-1 and case-2, suggesting the key role of Rossby wave dynamics in the Indian Ocean on NE monsoon extremes. Apart from the large scale circulation differences the number of cyclonic systems land fall for case-1 and case-2 have also contributed for

Volcanic suppression of Nile summer flooding triggers revolt and constrains interstate conflict in ancient Egypt.

Science.gov (United States)

Manning, Joseph G; Ludlow, Francis; Stine, Alexander R; Boos, William R; Sigl, Michael; Marlon, Jennifer R

2017-10-17

Volcanic eruptions provide tests of human and natural system sensitivity to abrupt shocks because their repeated occurrence allows the identification of systematic relationships in the presence of random variability. Here we show a suppression of Nile summer flooding via the radiative and dynamical impacts of explosive volcanism on the African monsoon, using climate model output, ice-core-based volcanic forcing data, Nilometer measurements, and ancient Egyptian writings. We then examine the response of Ptolemaic Egypt (305-30 BCE), one of the best-documented ancient superpowers, to volcanically induced Nile suppression. Eruptions are associated with revolt onset against elite rule, and the cessation of Ptolemaic state warfare with their great rival, the Seleukid Empire. Eruptions are also followed by socioeconomic stress with increased hereditary land sales, and the issuance of priestly decrees to reinforce elite authority. Ptolemaic vulnerability to volcanic eruptions offers a caution for all monsoon-dependent agricultural regions, presently including 70% of world population.The degree to which human societies have responded to past climatic changes remains unclear. Here, using a novel combination of approaches, the authors show how volcanically-induced suppression of Nile summer flooding led to societal unrest in Ptolemaic Egypt (305-30 BCE).

Environmental status of groundwater affected by chromite ore processing residue (COPR) dumpsites during pre-monsoon and monsoon seasons.

Science.gov (United States)

Matern, Katrin; Weigand, Harald; Singh, Abhas; Mansfeldt, Tim

2017-02-01

Chromite ore processing residue (COPR) is generated by the roasting of chromite ores for the extraction of chromium. Leaching of carcinogenic hexavalent chromium (Cr(VI)) from COPR dumpsites and contamination of groundwater is a key environmental risk. The objective of the study was to evaluate Cr(VI) contamination in groundwater in the vicinity of three COPR disposal sites in Uttar Pradesh, India, in the pre-monsoon and monsoon seasons. Groundwater samples (n = 57 pre-monsoon, n = 70 monsoon) were taken in 2014 and analyzed for Cr(VI) and relevant hydrochemical parameters. The site-specific ranges of Cr(VI) concentrations in groundwater were Rania), <0.005 to 115 mg L -1 (Chhiwali), and <0.005 to 2.0 mg L -1 (Godhrauli). Maximum levels of Cr(VI) were found close to the COPR dumpsites and significantly exceeded safe drinking water limits (0.05 mg L -1 ). No significant dependence of Cr(VI) concentration on monsoons was observed.

Identification of tipping elements of the Indian Summer Monsoon using climate network approach

Science.gov (United States)

Stolbova, Veronika; Surovyatkina, Elena; Kurths, Jurgen

2015-04-01

Spatial and temporal variability of the rainfall is a vital question for more than one billion of people inhabiting the Indian subcontinent. Indian Summer Monsoon (ISM) rainfall is crucial for India's economy, social welfare, and environment and large efforts are being put into predicting the Indian Summer Monsoon. For predictability of the ISM, it is crucial to identify tipping elements - regions over the Indian subcontinent which play a key role in the spatial organization of the Indian monsoon system. Here, we use climate network approach for identification of such tipping elements of the ISM. First, we build climate networks of the extreme rainfall, surface air temperature and pressure over the Indian subcontinent for pre-monsoon, monsoon and post-monsoon seasons. We construct network of extreme rainfall event using observational satellite data from 1998 to 2012 from the Tropical Rainfall Measuring Mission (TRMM 3B42V7) and reanalysis gridded daily rainfall data for a time period of 57 years (1951-2007) (Asian Precipitation Highly Resolved Observational Data Integration Towards the Evaluation of Water Resources, APHRODITE). For the network of surface air temperature and pressure fields, we use re-analysis data provided by the National Center for Environmental Prediction and National Center for Atmospheric Research (NCEP/NCAR). Second, we filter out data by coarse-graining the network through network measures, and identify tipping regions of the ISM. Finally, we compare obtained results of the network analysis with surface wind fields and show that occurrence of the tipping elements is mostly caused by monsoonal wind circulation, migration of the Intertropical Convergence Zone (ITCZ) and Westerlies. We conclude that climate network approach enables to select the most informative regions for the ISM, providing realistic description of the ISM dynamics with fewer data, and also help to identify tipping regions of the ISM. Obtained tipping elements deserve a

Using an extended 2D hydrodynamic model for evaluating damage risk caused by extreme rain events: Flash-Flood-Risk-Map (FFRM) Upper Austria

Science.gov (United States)

Humer, Günter; Reithofer, Andreas

2016-04-01

Using an extended 2D hydrodynamic model for evaluating damage risk caused by extreme rain events: Flash-Flood-Risk-Map (FFRM) Upper Austria Considering the increase in flash flood events causing massive damage during the last years in urban but also rural areas [1-4], the requirement for hydrodynamic calculation of flash flood prone areas and possible countermeasures has arisen to many municipalities and local governments. Besides the German based URBAS project [1], also the EU-funded FP7 research project "SWITCH-ON" [5] addresses the damage risk caused by flash floods in the sub-project "FFRM" (Flash Flood Risk Map Upper Austria) by calculating damage risk for buildings and vulnerable infrastructure like schools and hospitals caused by flash-flood driven inundation. While danger zones in riverine flooding are established as an integral part of spatial planning, flash floods caused by overland runoff from extreme rain events have been for long an underrated safety hazard not only for buildings and infrastructure, but man and animals as well. Based on the widespread 2D-model "hydro_as-2D", an extension was developed, which calculates the runoff formation from a spatially and temporally variable precipitation and determines two dimensionally the land surface area runoff and its concentration. The conception of the model is to preprocess the precipitation data and calculate the effective runoff-volume for a short time step of e.g. five minutes. This volume is applied to the nodes of the 2D-model and the calculation of the hydrodynamic model is started. At the end of each time step, the model run is stopped, the preprocessing step is repeated and the hydraulic model calculation is continued. In view of the later use for the whole of Upper Austria (12.000 km²) a model grid of 25x25 m² was established using digital elevation data. Model parameters could be estimated for the small catchment of river Ach, which was hit by an intense rain event with up to 109 mm per hour

BDHI: a French national database on historical floods

Directory of Open Access Journals (Sweden)

Lang Michel

2016-01-01

Full Text Available The paper describes the various features of the BDHI database (objects, functions, content. This document database provides document sheets on historical floods from various sources: technical reports from water authorities, scientific accounts (meteorology, hydrology, hydraulics..., post-disaster reports, newspapers or book extracts... It is complemented by fact sheets on flood events, which provide a summary text on significant past floods: location, date and duration, type of flood, extent, probability, adverse consequences A search engine is provided for information search based on time (specific date or period, on location (district, basin, city or thematic topic (document type, flood type, flood magnitude, flood impact.... We conclude by some future challenges in relation to the next cycle of the Floods Directive (2016-2022, with the inventory of past floods which had significant adverse impacts. What are the flood events that need to be integrated (new ones later than 2011 and/or previous floods that had not yet been selected? How can the process of historical data integration be extended at a local scale, with an adequate process of validation? How to promote the use of BDHI database in relation with the development of the culture of risk?

Validation of the Impact of Event Scale-Revised for adolescents experiencing the floods and mudslides

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Cheng-Sheng Chen

2011-12-01

Full Text Available The purpose of this study was to validate the Impact of Event Scale-Revised (IES-R for adolescents who had experienced the floods and mudslides caused by Typhoon Morakot in Taiwan. The internal consistency, construct validity, and criteria validity of the instrument were examined. Principal component analysis followed by an oblique rotation was used to derive a three-factor solution. These factors were labeled intrusion, hyperarousal, and avoidance; all three factors together accounted for 58.1% of the variance. The total Cronbach’s alpha of 0.94 reflected the good internal consistency of the instrument. With reference to diagnosis of posttraumatic stress disorder, the IES-R cutoff point for posttraumatic stress disorder was 19 of 20 with a sensitivity of 85.7% and specificity of 84.1%. In conclusion, the IES-R can be used as a reliable and valid instrument when evaluating psychological distress among adolescents who have experienced a natural disaster, such as flooding and mudslides.

44 CFR 61.17 - Group Flood Insurance Policy.

Science.gov (United States)

2010-10-01

... U.S.C. 5174) of an Individuals and Households Program (IHP) award for flood damage as a result of... flood-damage losses sustained by the insured property in the course of any subsequent flooding event..., DEPARTMENT OF HOMELAND SECURITY INSURANCE AND HAZARD MITIGATION National Flood Insurance Program INSURANCE...

Internal flooding analyses results of Slovak NPPs

International Nuclear Information System (INIS)

Sopira, Vladimir

2000-01-01

The assessment of the flood risk was the objective of the internal flooding analysis for NPPs Bohunice V1, V2 and Mochovce. All important flooding sources were identified. The rooms containing safety important components were analyzed from the point of view of: Integrity of flood boundaries; Capability for drainage; Flood signalisation; Flood localization and liquidation; Vulnerability of safety system component. The redundancies of safety systems are located mostly separately and no flood can endanger more than single train. It can be concluded that NPPs with WWER-440 are very safe against the flooding initiating event

An operational procedure for rapid flood risk assessment in Europe

Science.gov (United States)

Dottori, Francesco; Kalas, Milan; Salamon, Peter; Bianchi, Alessandra; Alfieri, Lorenzo; Feyen, Luc

2017-07-01

The development of methods for rapid flood mapping and risk assessment is a key step to increase the usefulness of flood early warning systems and is crucial for effective emergency response and flood impact mitigation. Currently, flood early warning systems rarely include real-time components to assess potential impacts generated by forecasted flood events. To overcome this limitation, this study describes the benchmarking of an operational procedure for rapid flood risk assessment based on predictions issued by the European Flood Awareness System (EFAS). Daily streamflow forecasts produced for major European river networks are translated into event-based flood hazard maps using a large map catalogue derived from high-resolution hydrodynamic simulations. Flood hazard maps are then combined with exposure and vulnerability information, and the impacts of the forecasted flood events are evaluated in terms of flood-prone areas, economic damage and affected population, infrastructures and cities.An extensive testing of the operational procedure has been carried out by analysing the catastrophic floods of May 2014 in Bosnia-Herzegovina, Croatia and Serbia. The reliability of the flood mapping methodology is tested against satellite-based and report-based flood extent data, while modelled estimates of economic damage and affected population are compared against ground-based estimations. Finally, we evaluate the skill of risk estimates derived from EFAS flood forecasts with different lead times and combinations of probabilistic forecasts. Results highlight the potential of the real-time operational procedure in helping emergency response and management.

Aerosol Meteorology of the Maritime Continent for the 2012 7SEAS Southwest Monsoon Intensive Study - Part 1: Regional-scale Phenomena

Science.gov (United States)

Reid, Jeffrey S.; Xian, Peng; Holben, Brent N.; Hyer, Edward J.; Reid, Elizabeth A.; Salinas, Santo V.; Zhang, Jianglong; Campbell, James R.; Chew, Boon Ning; Holz, Robert E.;

Identification and diagnosis of spatiotemporal hydrometeorological structure of heavy precipitation induced floods in Southeast Asia

Science.gov (United States)

Lu, M.; Hao, X.; Devineni, N.

2017-12-01

Extreme floods have a long history of being an important cause of death and destruction worldwide. It is estimated by Munich RE and Swiss RE that floods and severe storms dominate all other natural hazards globally in terms of average annual property loss and human fatalities. The top 5 most disastrous floods in the period from 1900 to 2015, ranked by economic damage, are all in the Asian monsoon region. This study presents an interdisciplinary approach integrating hydrometeorology, atmospheric science and state-of-the-art space-time statistics and modeling to investigate the association between the space-time characteristics of floods, precipitation and atmospheric moisture transport in a statistical and physical framework, using tropical moisture export dataset and curve clustering algorithm to study the source-to-destination features; explore the teleconnected climate regulations on the moisture formation process at different timescales (PDO, ENSO and MJO), and study the role of the synoptic-to-large atmospheric steering on the moisture transport and convergence.

Flooding from Intense Rainfall: an overview of project SINATRA

Science.gov (United States)

Cloke, Hannah

2014-05-01

Project SINATRA (Susceptibility of catchments to INTense RAinfall and flooding) is part of the UK NERC's Flooding From Intense Rainfall (FFIR) research programme which aims to reduce the risks of damage and loss of life caused by surface water and flash floods through improved identification, characterisation and prediction of interacting meteorological, hydrological and hydro-morphological processes that contribute to flooding associated with high-intensity rainfall events. Extreme rainfall events may only last for a few hours at most, but can generate terrifying and destructive floods. Their impact can be affected by a wide range factors (or processes) such as the location and intensity of the rainfall, the shape and steepness of the catchment it falls on, how much sediment is moved by the water and the vulnerability of the communities in the flood's path. Furthermore, FFIR are by their nature rapid, making it very difficult for researchers to 'capture' measurements during events. The complexity, speed and lack of field measurements on FFIR make it difficult to create computer models to predict flooding and often we are uncertain as to their accuracy. In addition there is no consensus on how to identify how particular catchments may be vulnerable to FFIR, due to factors such as catchment area, shape, geology and soil type as well as land-use. Additionally, the catchments most susceptible to FFIR are often small and un-gauged. Project SINATRA will: (1) Increase our understanding of what factors cause FFIR and gathering new, high resolution measurements of FFIR by: assembling an archive of past FFIR events in Britain and their impacts, as a prerequisite for improving our ability to predict future occurrences of FFIR; making real time observations of flooding during flood events as well as post-event surveys and historical event reconstruction, using fieldwork and crowd-sourcing methods; and characterizing the physical drivers for UK summer flooding events by

Comparing flood loss models of different complexity

Science.gov (United States)

Schröter, Kai; Kreibich, Heidi; Vogel, Kristin; Riggelsen, Carsten; Scherbaum, Frank; Merz, Bruno

2013-04-01

Any deliberation on flood risk requires the consideration of potential flood losses. In particular, reliable flood loss models are needed to evaluate cost-effectiveness of mitigation measures, to assess vulnerability, for comparative risk analysis and financial appraisal during and after floods. In recent years, considerable improvements have been made both concerning the data basis and the methodological approaches used for the development of flood loss models. Despite of that, flood loss models remain an important source of uncertainty. Likewise the temporal and spatial transferability of flood loss models is still limited. This contribution investigates the predictive capability of different flood loss models in a split sample cross regional validation approach. For this purpose, flood loss models of different complexity, i.e. based on different numbers of explaining variables, are learned from a set of damage records that was obtained from a survey after the Elbe flood in 2002. The validation of model predictions is carried out for different flood events in the Elbe and Danube river basins in 2002, 2005 and 2006 for which damage records are available from surveys after the flood events. The models investigated are a stage-damage model, the rule based model FLEMOps+r as well as novel model approaches which are derived using data mining techniques of regression trees and Bayesian networks. The Bayesian network approach to flood loss modelling provides attractive additional information concerning the probability distribution of both model predictions and explaining variables.

On breaks of the Indian monsoon

Indian Academy of Sciences (India)

R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

quadrapole is a basic feature of weak spells of the intraseasonal variation over the Asia-west Pacific region. ... (Earth Planet. Sci.), 112 .... be useful to define the break monsoon (and active ... monsoon zone, different scientists have used the.

Reconciling societal and scientific definitions for the monsoon

Science.gov (United States)

Reeve, Mathew; Stephenson, David

2014-05-01

Science defines the monsoon in numerous ways. We can apply these definitions to forecast data, reanalysis data, observations, GCMs and more. In a basic research setting, we hope that this work will advance science and our understanding of the monsoon system. In an applied research setting, we often hope that this work will benefit a specific stakeholder or community. We may want to inform a stakeholder when the monsoon starts, now and in the future. However, what happens if the stakeholders cannot relate to the information because their perceptions do not align with the monsoon definition we use in our analysis? We can resolve this either by teaching the stakeholders or learning from them about how they define the monsoon and when they perceive it to begin. In this work we reconcile different scientific monsoon definitions with the perceptions of agricultural communities in Bangladesh. We have developed a statistical technique that rates different scientific definitions against the people's perceptions of when the monsoon starts and ends. We construct a probability mass function (pmf) around each of the respondent's answers in a questionnaire survey. We can use this pmf to analyze the time series of monsoon onsets and withdrawals from the different scientific definitions. We can thereby quantitatively judge which definition may be most appropriate for a specific applied research setting.

Continental and global scale flood forecasting systems

NARCIS (Netherlands)

Emerton, Rebecca E.; Stephens, Elisabeth M.; Pappenberger, Florian; Pagano, Thomas P.; Weerts, A.H.; Wood, A.; Salamon, Peter; Brown, James D.; Hjerdt, Niclas; Donnelly, Chantal; Baugh, Calum A.; Cloke, Hannah L.

2016-01-01

Floods are the most frequent of natural disasters, affecting millions of people across the globe every year. The anticipation and forecasting of floods at the global scale is crucial to preparing for severe events and providing early awareness where local flood models and warning services may not

Analysis of the flooding event of October 22-23, 2005 in a small basin in the province of Bari (Southern Italy

Directory of Open Access Journals (Sweden)

Tiziana Bisantino

2016-12-01

Full Text Available In the province of Bari the hydrographic network consists of ephemeral streams called lame. In these watercourses the absence of runoff for long periods contributed to unfounded beliefs concerning the hydraulic safety of the landscape and therefore uncontrolled changes in streambeds and floodplains. In these streams high water discharges can occur during heavy rainfalls, as demonstrated by the floods that hit the city of Bari in the late nineteenth and early twentieth century. The flooding event of October 22-23, 2005 can be considered catastrophic as it resulted in six deaths, numerous injuries and substantial damage sustained by road and railway infrastructures at the intersection with the hydrographic network. This study aims to analyse the severity of the event in terms of the response of the landscape with reference to the case of the lama Scappagrano basin, where a Eurostar train derailed due to the collapse of the railway embankment. Coupled hydrological and two-dimensional hydraulic modelling was performed to reconstruct the flood hydrograph and water depths on the upstream side of the embankment. The results were used to set the boundary conditions to analyse the internal stability of the embankment using a finite element method.

On the nature of rainfall in dry climate: Space-time patterns of convective rain cells over the Dead Sea region and their relations with synoptic state and flash flood generation

Science.gov (United States)

Belachsen, Idit; Marra, Francesco; Peleg, Nadav; Morin, Efrat

2017-04-01

Space-time patterns of rainfall are important climatic characteristics that influence runoff generation and flash flood magnitude. Their derivation requires high-resolution measurements to adequately represent the rainfall distribution, and is best provided by remote sensing tools. This need is further emphasized in dry climate regions, where rainfall is scarce and, often, local and highly variable. Our research is focused on understanding the nature of rainfall events in the dry Dead Sea region (Eastern Mediterranean) by identifying and characterizing the spatial structure and the dynamics of convective storm cores (known as rain cells). To do so, we take advantage of 25 years of corrected and gauge-adjusted weather radar data. A statistical analysis of convective rain-cells spatial and temporal characteristics was performed with respect to synoptic pattern, geographical location, and flash flood generation. Rain cells were extracted from radar data using a cell segmentation method and a tracking algorithm and were divided into rain events. A total of 10,500 rain cells, 2650 cell tracks and 424 rain events were elicited. Rain cell properties, such as mean areal and maximal rain intensity, area, life span, direction and speed, were derived. Rain events were clustered, according to several ERA-Interim atmospheric parameters, and associated with three main synoptic patterns: Cyprus Low, Low to the East of the study region and Active Red Sea Trough. The first two originate from the Mediterranean Sea, while the third is an extension of the African monsoon. On average, the convective rain cells in the region are 90 km2 in size, moving from West to East in 13 ms-1 and living 18 minutes. Several significant differences between rain cells of the various synoptic types were observed. In particular, Active Red Sea Trough rain cells are characterized by higher rain intensities and lower speeds, suggesting a higher flooding potential for small catchments. The north

Real Time Estimation of the Calgary Floods Using Limited Remote Sensing Data

Directory of Open Access Journals (Sweden)

Emily Schnebele

2014-02-01

Full Text Available Every year, flood disasters are responsible for widespread destruction and loss of human life. Remote sensing data are capable of providing valuable, synoptic coverage of flood events but are not always available because of satellite revisit limitations, obstructions from cloud cover or vegetation canopy, or expense. In addition, knowledge of road accessibility is imperative during all phases of a flood event. In June 2013, the City of Calgary experienced sudden and extensive flooding but lacked comprehensive remote sensing coverage. Using this event as a case study, this work illustrates how data from non-authoritative sources are used to augment traditional data and methods to estimate flood extent and identify affected roads during a flood disaster. The application of these data, which may have varying resolutions and uncertainities, provide an estimation of flood extent when traditional data and methods are lacking or incomplete. When flooding occurs over multiple days, it is possible to construct an estimate of the advancement and recession of the flood event. Non-authoritative sources also provide flood information at the micro-level, which can be difficult to capture from remote sensing data; however, the distibution and quantity of data collected from these sources will affect the quality of the flood estimations.

Rethinking the relationship between flood risk perception and flood management.

Science.gov (United States)

Birkholz, S; Muro, M; Jeffrey, P; Smith, H M

2014-04-15

Although flood risk perceptions and their concomitant motivations for behaviour have long been recognised as significant features of community resilience in the face of flooding events, there has, for some time now, been a poorly appreciated fissure in the accompanying literature. Specifically, rationalist and constructivist paradigms in the broader domain of risk perception provide different (though not always conflicting) contexts for interpreting evidence and developing theory. This contribution reviews the major constructs that have been applied to understanding flood risk perceptions and contextualises these within broader conceptual developments around risk perception theory and contemporary thinking around flood risk management. We argue that there is a need to re-examine and re-invigorate flood risk perception research, in a manner that is comprehensively underpinned by more constructivist thinking around flood risk management as well as by developments in broader risk perception research. We draw attention to an historical over-emphasis on the cognitive perceptions of those at risk to the detriment of a richer understanding of a wider range of flood risk perceptions such as those of policy-makers or of tax-payers who live outside flood affected areas as well as the linkages between these perspectives and protective measures such as state-supported flood insurance schemes. Conclusions challenge existing understandings of the relationship between risk perception and flood management, particularly where the latter relates to communication strategies and the extent to which those at risk from flooding feel responsible for taking protective actions. Copyright © 2014 Elsevier B.V. All rights reserved.

Flooding Effect on Earth Walls

Directory of Open Access Journals (Sweden)

Meysam Banimahd

2010-12-01

Full Text Available Earth building is a sustainable, environmentally friendly and economical method of construction that has been used worldwide for many centuries. For the past three decades, earth has seen a revival as a building material for a modern construction method due to its benefits in terms of low carbon content, low cost and energy involved during construction, as well as the fact that it is a sustainable technology of building. Climate change is influencing precipitation levels and patterns around the world, and as a consequence, flood risk is increasing rapidly. When flooding occurs, earth buildings are exposed to water by submersion, causing an increase in the degree of saturation of the earth structures and therefore a decrease of the suction between particles. This study investigated the effect of cycles of flooding (consecutive events of flooding followed by dry periods on earth walls. A series of characterization tests were carried out to obtain the physical and mechanical properties of the studied earth material. In a second stage, Flooding Simulation Tests (FST were performed to explore the earth walls’ response to repeated flooding events. The results obtained for the tested earth wall/samples with reinforced material (straw reveal hydraulic hysteresis when wall/samples are subject to cycles of wetting and drying.

Reconstruction of peak water levels, peak discharges and long-term occurrence of extreme- as well as smaller pre-instrumental flood events of river Aare, Limmat, Reuss, Rhine and Saane in Switzerland. Part I

Science.gov (United States)

Wetter, Oliver; Tuttenuj, Daniel

2016-04-01

Part I: Dr. Oliver Wetter. (Oeschger Centre for Climate Change Research, University of Bern, Switzerland) Part II: PhD student Daniel Tuttenuj (Oeschger Centre of Climate Change Research, University of Bern, Switzerland) The methodology developed by Wetter et al. (2011) combines different documentary and instrumental sources, retaining relevant information for the reconstruction of extreme pre-instrumental flood events. These include hydrological measurements (gauges), historic river profiles (cross and longitudinal profiles), flood marks, historic city maps, documentary flood evidence (reports in chronicles and newspapers) as well as paintings and drawings. It has been shown that extreme river Rhine flood events of the pre-instrumental period can be reconstructed in terms of peak discharges for the last 750 years by applying this methodology to the site of Basel. Pfister & Wetter (2011) furthermore demonstrated that this methodology is also principally transferable to other locations and rivers. Institutional documentary evidence has not been systematically analysed in the context of historical hydrology in Switzerland so far. The term institutional documentary evidence generally outlines sources that were produced by governments or other (public) bodies including the church, hospitals, and the office of the bridge master. Institutional bodies were typically not directly interested in describing climate or hydrological events but they were obliged to document their activities, especially if they generated financial costs (bookkeeping), and in doing so they often indirectly recorded climatologic or hydrological events. The books of weekly expenditures of Basel ("Wochenausgabenbücher der Stadt Basel") were first analysed by Fouquet (1999). He found recurring records of wage expenditures for a squad of craftsmen that was called up onto the bridge with the task of preventing the bridge from being damaged by fishing out drifting logs from the flood waters. Fouquet

Reconstruction of peak water levels, peak discharges and long-term occurrence of extreme- as well as smaller pre-instrumental flood events of river Aare, Limmat, Reuss, Rhine and Saane in Switzerland. Part II.

Science.gov (United States)

Tuttenuj, Daniel; Wetter, Oliver

2016-04-01

The methodology developed by Wetter et al. (2011) combines different documentary and instrumental sources, retaining relevant information for the reconstruction of extreme pre-instrumental flood events. These include hydrological measurements (gauges), historic river profiles (cross and longitudinal profiles), flood marks, historic city maps, documentary flood evidence (reports in chronicles and newspapers) as well as paintings and drawings. It has been shown that extreme river Rhine flood events of the pre-instrumental period can be reconstructed in terms of peak discharges for the last 750 years by applying this methodology to the site of Basel. Pfister & Wetter (2011) furthermore demonstrated that this methodology is also principally transferable to other locations and rivers in Switzerland. Institutional documentary evidence has not been systematically analysed in the context of historical hydrology in Switzerland so far. The term institutional documentary evidence generally outlines sources that were produced by governments or other (public) bodies including the church, hospitals, and the office of the bridge master. Institutional bodies were typically not directly interested in describing climate or hydrological events but they were obliged to document their activities, especially if they generated financial costs (bookkeeping), and in doing so they often indirectly recorded climatologic or hydrological events. The books of weekly expenditures of Basel ("Wochenausgabenbücher der Stadt Basel") were first analysed by Fouquet (1999). He found recurring records of wage expenditures for a squad of craftsmen that was called up onto the bridge with the task of preventing the bridge from being damaged by fishing out drifting logs from the flood waters. Fouquet systematically analysed the period from 1446-1542 and could prove a large number of pre-instrumental flood events of river Rhine, Birs, Birsig and Wiese in Basel. All in all the weekly led account books

Increasing Flood Risk due to Run-off Outflow near Estuarine City during Storm Event

Science.gov (United States)

Son, S.; Lee, C.; Do, K.; Jung, T.

2017-12-01

Tropical cyclone easily causes inundation damage to low-lying coastal area and the damage may be amplified due to tide motion, sea-level rise, riverine discharges. Specifically, typhoons are accompanied by intensive rainfall, which will of course raise the river water level and thus enhance the flooding damages. If the tidal cycle coincides the high water, flooding will be even aggravated. In the present study, we simulated storm surge motions at the coastal area considering combined effects of tidal and river discharge with aim to improve the accuracy of flooding prediction. The quasi 3-dimension ocean circulation model, Delf3D was used which solves the unsteady shallow water equation in the 2D and 3D. Since Delft3D is much applicable to accommodate the indirect flooding factors such as riverine discharge and short waves, outer-coupled modeling system was established to account for combined tide-surge-riverine discharge effects. In such integrated system, 11 tidal constituents were input as open boundary condition using TPXO 7.2 model, while the water level per unit time was preliminary calculated by HEC-HMS model and input as the upstream boundary conditions for river inside the domain. Typhoon MAEMI which attacked Masan city located at southern coast of South Korea and caused severe inundation damages in 2003 was selected for the study event. Basic information for typhoon such as path, wind speed, atmospheric pressure every 3 hours was provided by the Korea Meteorological Agency and was adopted. The simulation was implemented with tide and storm surge boundary conditions focusing on the target area, Masan, while the additional consideration on the discharge of the river inside the domain was also made. Simulated water level at the fixed location was compared to the observation for its verification and the extent of inundation areas of Masan were compared between observed and calculated. The marginal contribution of riverine discharge on the flooding area

Volcanically-Induced Nile Flood Failure Promotes Internal Revolt and Suppresses Interstate Conflict in Hellenistic Egypt, 305-30 BCE

Science.gov (United States)

Ludlow, Francis; Manning, Joseph; Stine, Alexander; Boos, William; Storelvmo, Trude; Sigl, Michael; Marlon, Jennifer

2016-04-01

Explosive volcanic eruptions are a primary driver of abrupt short-term climatic changes. State-of-the-art revisions to polar ice-core chronologies now allow us to track the impacts of a sequence of major and closely-recurring volcanic eruptions on the great Ptolemaic kingdom centred in Egypt, between 305-30 BCE. This was a formidable Mediterranean cultural and economic power in the efflorescent Hellenistic era of the first four centuries BCE, a period bracketed by Alexander the Great on one end and Cleopatra on the other, and known for its considerable advancement in science and material culture. In this paper we show a link between major volcanic eruptions that register through elevated sulphate deposition in the polar ice, and a suppression of the agriculturally-critical Nile summer flood, identifiable in annual Nilometer measurements from Rhoda, Cairo, between 641 and 1469 CE. This likely relates to a volcanic perturbation of the East African monsoon, responsible for the rainfall in the Ethiopian highlands that drives the annual summer flood, and the effect can also be identified in ancient papyri that indicate the quality of the Nile flood in the first several centuries BCE. Volcanic eruptions in this period are also shown to correspond in timing with the initiation of a series of hitherto poorly understood internal revolts against Ptolemaic rule in Egypt, while also corresponding in timing to the cessation of major interstate conflicts (the nine "Syrian Wars", running 274-96 BCE) between the Ptolemaic kingdom and their powerful Near Eastern rival, the Seleukid empire. Subsistence crises driven by volcanically-induced suppression of the Nile flood are likely to have played a key causal role in these events, an understanding that helps to advance our knowledge of the major historical events of the formative Hellenistic era, which set the scene for the rise of the Roman Empire. Our findings also suggest the potential of integrating human and natural archives to

Relative role of pre-monsoon conditions and intraseasonal oscillations in determining early-vs-late indian monsoon intensity in a GCM

Science.gov (United States)

Ghosh, Rohit; Chakraborty, Arindam; Nanjundiah, Ravi S.

2018-01-01

The aim of this paper is to identify relative roles of different land-atmospheric conditions, apart from sea surface temperature (SST), in determining early vs. late summer monsoon intensity over India in a high resolution general circulation model (GCM). We find that in its early phase (June-July; JJ), pre-monsoon land-atmospheric processes play major role to modulate the precipitation over Indian region. These effects of pre-monsoon conditions decrease substantially during its later phase (August-September; AS) for which the interannual variation is mainly governed by the low frequency northward propagating intraseasonal oscillations. This intraseasonal variability which is related to mean vertical wind shear has a significant role during the early phase of monsoon as well. Further, using multiple linear regression, we show that interannual variation of early and late monsoon rainfall over India is best explained when all these land-atmospheric parameters are taken together. Our study delineates the relative role of different processes affecting early versus later summer monsoon rainfall over India that can be used for determining its subseasonal predictability.

Indian monsoon variability on millennial-orbital timescales.

Science.gov (United States)

Kathayat, Gayatri; Cheng, Hai; Sinha, Ashish; Spötl, Christoph; Edwards, R Lawrence; Zhang, Haiwei; Li, Xianglei; Yi, Liang; Ning, Youfeng; Cai, Yanjun; Lui, Weiguo Lui; Breitenbach, Sebastian F M

2016-04-13

The Indian summer monsoon (ISM) monsoon is critical to billions of people living in the region. Yet, significant debates remain on primary ISM drivers on millennial-orbital timescales. Here, we use speleothem oxygen isotope (δ(18)O) data from Bittoo cave, Northern India to reconstruct ISM variability over the past 280,000 years. We find strong coherence between North Indian and Chinese speleothem δ(18)O records from the East Asian monsoon domain, suggesting that both Asian monsoon subsystems exhibit a coupled response to changes in Northern Hemisphere summer insolation (NHSI) without significant temporal lags, supporting the view that the tropical-subtropical monsoon variability is driven directly by precession-induced changes in NHSI. Comparisons of the North Indian record with both Antarctic ice core and sea-surface temperature records from the southern Indian Ocean over the last glacial period do not suggest a dominant role of Southern Hemisphere climate processes in regulating the ISM variability on millennial-orbital timescales.

Challenges estimating the return period of extreme floods for reinsurance applications

Science.gov (United States)

Raven, Emma; Busby, Kathryn; Liu, Ye

2013-04-01

Mapping and modelling extreme natural events is fundamental within the insurance and reinsurance industry for assessing risk. For example, insurers might use a 1 in 100-year flood hazard map to set the annual premium of a property, whilst a reinsurer might assess the national scale loss associated with the 1 in 200-year return period for capital and regulatory requirements. Using examples from a range of international flood projects, we focus on exploring how to define what the n-year flood looks like for predictive uses in re/insurance applications, whilst considering challenges posed by short historical flow records and the spatial and temporal complexities of flood. First, we shall explore the use of extreme value theory (EVT) statistics for extrapolating data beyond the range of observations in a marginal analysis. In particular, we discuss how to estimate the return period of historical flood events and explore the impact that a range of statistical decisions have on these estimates. Decisions include: (1) selecting which distribution type to apply (e.g. generalised Pareto distribution (GPD) vs. generalised extreme value distribution (GEV)); (2) if former, the choice of the threshold above which the GPD is fitted to the data; and (3) the necessity to perform a cluster analysis to group flow peaks to temporally represent individual flood events. Second, we summarise a specialised multivariate extreme value model, which combines the marginal analysis above with dependence modelling to generate industry standard event sets containing thousands of simulated, equi-probable floods across a region/country. These events represent the typical range of anticipated flooding across a region and can be used to estimate the largest or most widespread events that are expected to occur. Finally, we summarise how a reinsurance catastrophe model combines the event set with detailed flood hazard maps to estimate the financial cost of floods; both the full event set and also

Transport of short-lived climate forcers/pollutants (SLCF/P) to the Himalayas during the South Asian summer monsoon onset

International Nuclear Information System (INIS)

Cristofanelli, P; Putero, D; Landi, T C; Marinoni, A; Duchi, R; Calzolari, F; Bonasoni, P; Adhikary, B; Stocchi, P; Verza, G; Vuillermoz, E; Laj, P; Kang, S; Ming, J

2014-01-01

Over the course of six years (2006–2011), equivalent black carbon (eqBC), coarse aerosol mass (PM 1–10 ), and surface ozone (O 3 ), observed during the monsoon onset period at the Nepal Climate Observatory–Pyramid WMO/GAW Global Station (NCO-P, 5079 m a.s.l.), were analyzed to investigate events characterized by a significant increase in these short-lived climate forcers/pollutants (SLCF/P). These events occurred during periods characterized by low (or nearly absent) rain precipitation in the central Himalayas, and they appeared to be related to weakening stages (or ‘breaking’) of the South Asian summer monsoon system. As revealed by the combined analysis of atmospheric circulation, air-mass three-dimensional back trajectories, and satellite measurements of atmospheric aerosol loading, surface open fire, and tropospheric NO x , the large amount of SLCF/P reaching the NCO-P appeared to be related to natural (mineral dust) and anthropogenic emissions occurring within the PBL of central Pakistan (i.e., Thar Desert), the Northwestern Indo-Gangetic plain, and the Himalayan foothills. The systematic occurrence of these events appeared to represent the most important source of SLCF/P inputs into the central Himalayas during the summer monsoon onset period, with possible important implications for the regional climate and for hydrological cycles. (letter)

Estimating floodwater depths from flood inundation maps and topography

Science.gov (United States)

Cohen, Sagy; Brakenridge, G. Robert; Kettner, Albert; Bates, Bradford; Nelson, Jonathan M.; McDonald, Richard R.; Huang, Yu-Fen; Munasinghe, Dinuke; Zhang, Jiaqi

2018-01-01

Information on flood inundation extent is important for understanding societal exposure, water storage volumes, flood wave attenuation, future flood hazard, and other variables. A number of organizations now provide flood inundation maps based on satellite remote sensing. These data products can efficiently and accurately provide the areal extent of a flood event, but do not provide floodwater depth, an important attribute for first responders and damage assessment. Here we present a new methodology and a GIS-based tool, the Floodwater Depth Estimation Tool (FwDET), for estimating floodwater depth based solely on an inundation map and a digital elevation model (DEM). We compare the FwDET results against water depth maps derived from hydraulic simulation of two flood events, a large-scale event for which we use medium resolution input layer (10 m) and a small-scale event for which we use a high-resolution (LiDAR; 1 m) input. Further testing is performed for two inundation maps with a number of challenging features that include a narrow valley, a large reservoir, and an urban setting. The results show FwDET can accurately calculate floodwater depth for diverse flooding scenarios but also leads to considerable bias in locations where the inundation extent does not align well with the DEM. In these locations, manual adjustment or higher spatial resolution input is required.

Late Quaternary glaciation history of monsoon-dominated Dingad basin, central Himalaya, India

Science.gov (United States)

Shukla, Tanuj; Mehta, Manish; Jaiswal, Manoj K.; Srivastava, Pradeep; Dobhal, D. P.; Nainwal, H. C.; Singh, Atul K.

2018-02-01

The study presents the Late Quaternary glaciation history of monsoon-dominated Dokriani Glacier valley, Dingad basin, central Himalaya, India. The basin is tested for the mechanism of landforms preservation in high relief and abundant precipitation regimes of the Higher Himalaya. Field geomorphology and remote sensing data, supported by Optical Stimulated Luminescence (OSL) dating enabled identification of five major glacial events of decreasing magnitude. The oldest glacial stage, Dokriani Glacial Stage I (DGS-I), extended down to ∼8 km (2883 m asl) from present-day snout (3965 m asl) followed by other four glaciations events viz. DGS-II, DGS-III, DGS-IV and DGS-V terminating at ∼3211, 3445, 3648 and ∼3733 m asl respectively. The DGS-I glaciation (∼25-∼22 ka BP) occurred during early Marine Isotope Stage (MIS) -2, characterized as Last Glacial Maximum (LGM) extension of the valley. Similarly, DGS-II stage (∼14-∼11 ka BP) represents the global cool and dry Older Dryas and Younger Dryas event glaciation. The DGS-III glaciation (∼8 ka BP) coincides with early Holocene 8.2 ka cooling event, the DGS-IV glaciations (∼4-3.7 ka BP) corresponds to 4.2 ka cool and drier event, DGS-V (∼2.7-∼1 ka BP) represents the cool and moist late Holocene glacial advancement of the valley. This study suggests that the Dokriani Glacier valley responded to the global lowering of temperature and variable precipitation conditions. This study also highlights the close correlation between the monsoon-dominated valley glaciations and Northern Hemisphere cooling events influenced by North Atlantic climate.

Mass accumulation rate and monsoon records from Xifeng, Chinese Loess Plateau, based on a luminescence age model

DEFF Research Database (Denmark)

Stevens, Thomas; Buylaert, Jan-Pieter; Lu, Huayu

2016-01-01

common than previously realized. MARs from undisturbed portions of Xifeng vary dramatically, with peaks potentially matching the timing of Heinrich events. The last glacial maximum peak MAR (22–27 ka) matches the Pacific and Greenland dust flux records, although appears earlier than peak MARs seen...... in many other OSL‐dated Loess Plateau sites. East Asian monsoon grain‐size and magnetic susceptibility records also show several differences between independently dated loess sites. This complicates our understanding of any lag between insolation forcing and monsoon response. Nevertheless, the Xifeng...

Comparison of different multi-objective calibration criteria using a conceptual rainfall-runoff model of flood events

Directory of Open Access Journals (Sweden)

R. Moussa

2009-04-01

Full Text Available A conceptual lumped rainfall-runoff flood event model was developed and applied on the Gardon catchment located in Southern France and various single-objective and multi-objective functions were used for its calibration. The model was calibrated on 15 events and validated on 14 others. The results of both the calibration and validation phases are compared on the basis of their performance with regards to six criteria, three global criteria and three relative criteria representing volume, peakflow, and the root mean square error. The first type of criteria gives more weight to large events whereas the second considers all events to be of equal weight. The results show that the calibrated parameter values are dependent on the type of criteria used. Significant trade-offs are observed between the different objectives: no unique set of parameters is able to satisfy all objectives simultaneously. Instead, the solution to the calibration problem is given by a set of Pareto optimal solutions. From this set of optimal solutions, a balanced aggregated objective function is proposed, as a compromise between up to three objective functions. The single-objective and multi-objective calibration strategies are compared both in terms of parameter variation bounds and simulation quality. The results of this study indicate that two well chosen and non-redundant objective functions are sufficient to calibrate the model and that the use of three objective functions does not necessarily yield different results. The problems of non-uniqueness in model calibration, and the choice of the adequate objective functions for flood event models, emphasise the importance of the modeller's intervention. The recent advances in automatic optimisation techniques do not minimise the user's responsibility, who has to choose multiple criteria based on the aims of the study, his appreciation on the errors induced by data and model structure and his knowledge of the