scholarly journals Cahokia’s emergence and decline coincided with shifts of flood frequency on the Mississippi River

2015 ◽  
Vol 112 (20) ◽  
pp. 6319-6324 ◽  
Author(s):  
Samuel E. Munoz ◽  
Kristine E. Gruley ◽  
Ashtin Massie ◽  
David A. Fike ◽  
Sissel Schroeder ◽  
...  
Keyword(s):  
Mississippi River ◽  
Agricultural Intensification ◽  
Critical Factor ◽  
Flood Frequency ◽  
Late Prehistoric ◽  
Flood Events ◽  
Regional Center ◽  
High Magnitude ◽  
Agricultural Societies ◽  
Large Floods

Here we establish the timing of major flood events of the central Mississippi River over the last 1,800 y, using floodwater sediments deposited in two floodplain lakes. Shifts in the frequency of high-magnitude floods are mediated by moisture availability over midcontinental North America and correspond to the emergence and decline of Cahokia—a major late prehistoric settlement in the Mississippi River floodplain. The absence of large floods from A.D. 600 to A.D. 1200 facilitated agricultural intensification, population growth, and settlement expansion across the floodplain that are associated with the emergence of Cahokia as a regional center around A.D. 1050. The return of large floods after A.D. 1200, driven by waning midcontinental aridity, marks the onset of sociopolitical reorganization and depopulation that culminate in the abandonment of Cahokia and the surrounding region by A.D. 1350. Shifts in the frequency and magnitude of flooding may be an underappreciated but critical factor in the formation and dissolution of social complexity in early agricultural societies.

Does development reduce fatalities from natural disasters? New evidence for floods

2013 ◽  
Vol 18 (6) ◽  
pp. 649-679 ◽  
Author(s):  
Susana Ferreira ◽  
Kirk Hamilton ◽  
Jeffrey R. Vincent
Keyword(s):  
Natural Disasters ◽  
Flood Frequency ◽  
Lower Income ◽  
Flood Events ◽  
Data Set ◽  
Flood Magnitude ◽  
Lower Income Countries ◽  
The Impact ◽  
New Evidence ◽  
Large Floods

AbstractWe analyze the impact of development on flood fatalities using a new data set of 2,171 large floods in 92 countries between 1985 and 2008. Our results challenge the conventional wisdom that development results in fewer fatalities during natural disasters. Results indicating that higher income and better governance reduce fatalities during flood events do not hold up when unobserved country heterogeneity and within-country correlation of standard errors are taken into account. We find that income does have a significant, indirect effect on flood fatalities by affecting flood frequency and flood magnitude, but this effect is nonmonotonic, with net reductions in fatalities occurring only in lower income countries. We find little evidence that improved governance affects flood fatalities either directly or indirectly.

scholarly journals Aspects of seasonality and flood generating circulation patterns in a mountainous catchment in south-eastern Germany

2007 ◽  
Vol 4 (2) ◽  
pp. 589-625 ◽  
Author(s):  
T. Petrow ◽  
B. Merz ◽  
K.-E. Lindenschmidt ◽  
A. H. Thieken
Keyword(s):  
Flood Frequency ◽  
Flood Frequency Analysis ◽  
Flood Events ◽  
Statistical Parameters ◽  
Discharge Data ◽  
Eastern Germany ◽  
South Eastern ◽  
Circulation Patterns ◽  
Extreme Flood ◽  
Large Floods

Abstract. Analyses of discharge series, precipitation fields and flood producing atmospheric circulation patterns reveal that two governing flood regimes exist in the Mulde catchment in south-eastern Germany: frequent floods during the winter and less frequent but sometimes extreme floods during the summer. Differences in the statistical parameters skewness and coefficient of variation of the discharge data can be found from west to east and are discussed in the context of landscape parameters that influence the discharge. Annual maximum discharge series were assigned to the triggering Großwetterlage in order to evaluate which circulation patterns are likely to produce large floods. It can be shown that the cyclone Vb-weather regime generates the most extreme flood events in the Mulde catchment, whereas westerly winds produce frequently small floods. Vb-weather regimes do not always trigger large flood events in the study area, but large floods are mostly generated by these weather patterns. Based on these findings, it is necessary to revise the traditional flood frequency analysis approach and develop new approaches which can handle different flood triggering processes within the dataset.

Changes in mechanisms and intensity of Western U.S. floods, 1960-2013

2021 ◽  
Author(s):  
Jessica Fayne ◽  
Huilin Huang ◽  
Mike Fischella ◽  
Yufei Liu ◽  
Zhaoxin Ban ◽  
...  
Keyword(s):  
Extreme Precipitation ◽  
Large Scale ◽  
Critical Factor ◽  
Flood Frequency ◽  
Atmospheric Rivers ◽  
Convective Storms ◽  
Noticeable Increase ◽  
Complex Interactions ◽  
Different Types ◽  
The Impact

<p>Extreme precipitation, a critical factor in flooding, has selectively increased with warmer temperatures in the Western U.S. Despite this, the streamflow measurements have captured no noticeable increase in large-scale flood frequency or intensity. As flood studies have mostly focused on specific flood events in particular areas, analyses of large-scale floods and their changes have been scarce. For floods during 1960-2013, we identify six flood generating mechanisms (FGMs) that are prominent across the Western U.S., including atmospheric rivers and non-atmospheric rivers, monsoons, convective storms, radiation-driven snowmelt, and rain-on-snow, in order to identify to what extent different types of floods are changing based on the dominant FGM. The inconsistency between extreme precipitation and lack of flood increase suggests that the impact of climate change on flood risk has been modulated by hydro-meteorological and physiographic processes such as sharp increases in temperature that drive increased evapotranspiration and decreased soil moisture. Our results emphasize the importance of FGMs in understanding the complex interactions of flooding and climatic changes and explain the broad spatiotemporal changes that have occurred across the vast Western U.S. for the past 50 years.</p>

scholarly journals Analysing flood history and simulating the nature of future floods using Gumbel method and Log-Pearson Type III: the case of the Mayurakshi River Basin, India

2021 ◽  
Vol 19 (1) ◽  
pp. 43-69
Author(s):  
Aznarul Islam ◽  
Biplab Sarkar
Keyword(s):  
River Basin ◽  
Low Frequency ◽  
Flood Frequency ◽  
Flood Events ◽  
Significance Level ◽  
Type Iii ◽  
Return Probability ◽  
Pearson Type ◽  
Anderson Darling ◽  
Normally Distributed

AbstractFloods of the Mayurakshi River Basin (MRB) have been historically documented since 1860. The high magnitude, low-frequency flood events have drastically changed to low magnitude, high-frequency flood events in the post-dam period, especially after the 1950s, when the major civil structures (Massanjore dam, Tilpara barrage, Brahmani barrage, Deucha barrage, and Bakreshwar weir) were constructed in the MRB. The present study intends to find out the nature of flood frequency using the extreme value method of Gumbel and Log-Pearson type III (LP-III). The results show that the highest flood magnitude (11,327 m3 s−1) was observed during 1957–2009 for the Tilpara barrage with a return probability of 1.85% and the lowest (708 m3 s−1) recorded by the Bakreshwar weir during 1956–77 with a return probability of 4.55%. In the present endeavour, we have computed the predicted discharge for the different return periods, like 2, 5, 10, 25, 50,100, and 200 years. The quantile-quantile plot shows that the expected discharge calculated using LP-III is more normally distributed than that of Gumbel. Moreover, Kolmogorov–Smirnov (KS) test, Anderson–Darling (AD), and x2 distribution show that LP-III distribution is more normally distributed than the Gumbel at 0.01 significance level, implying its greater reliability and acceptance in the flood simulation of the MRB.

scholarly journals Spatiotemporal variation in global floods with different affected areas and the contribution of influencing factors to flood-induced mortality (1985–2019)

2022 ◽  
Author(s):  
Tian Liu ◽  
Peijun Shi ◽  
Jian Fang
Keyword(s):  
Influencing Factors ◽  
Large Scale ◽  
Human Life ◽  
Flood Frequency ◽  
Spatiotemporal Variation ◽  
Mountainous Area ◽  
Flood Events ◽  
Protection Measures ◽  
Flood Duration ◽  
Level Ii

AbstractFloods are great threats to human life and property. Extensive research has investigated the spatiotemporal variation in flood occurrence, while few have studied the heterogeneity in global flood events of different sizes, which may require different coping strategies and risk reduction policies. In this study, we analysed the spatiotemporal patterns of global flood events with different affected areas (classified in three levels) during 1985–2019 and examined the contribution of different influencing factors to flood-induced mortality using Geodetector. The results show that (1) the increase in global flood frequency was mainly caused by Level II and Level III floods, and the average area affected by flood events has been increasing yearly since 1985. (2) In America and Africa, the frequency of Level III floods has increased monotonically. At the same time, the frequency of Level I floods in Europe and Level II floods in Asia has increased significantly. (3) For Europe and Asia, most of the deaths occurred with Level II floods; while for America and Africa, Level III floods caused the most mortality. (4) The top three factors contributing to the spatial heterogeneity in flood-induced mortality were the affected population, GDP per capita and flood duration. The contribution of each factor varied among the different types of floods. Topographic factors (percentage of mountainous area) magnified flood-induced mortality during extreme events with heavy rainfall, especially for Level III floods. The heterogeneity in flood frequency and flood-induced mortality indicates that flood protection measures should be more targeted. In addition, the increase in large-scale floods (Level III) highlights the need for transregional cooperation in flood risk management.

Data-based attribution of changes in flood quantiles across Europe between 1960 and 2010

2021 ◽  
Author(s):  
Miriam Bertola ◽  
Alberto Viglione ◽  
Sergiy Vorogushyn ◽  
David Lun ◽  
Bruno Merz ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Return Period ◽  
Extreme Precipitation ◽  
Western Europe ◽  
Expert Knowledge ◽  
Flood Frequency ◽  
Antecedent Soil Moisture ◽  
Flood Quantiles ◽  
Comparable Magnitude ◽  
Large Floods

<p>Changes in European floods during past decades have been analysed and detected by several studies. These studies typically focused on the mean flood behaviour, without distinguishing small and large floods. In this work, we investigate the causes of the detected flood trends across Europe over five decades (1960-2010), as a function of the return period. We adopt a regional non-stationary flood frequency approach to attribute observed flood changes to potential drivers, used as covariates of the parameters of the regional probability distribution of floods. The elasticities of floods with respect to the drivers and the regional contributions of the drivers to changes in flood quantiles associated with small and large return periods (i.e. 2-year and 100-year floods, respectively) are estimated by Bayesian inference, with prior information on the elasticity parameters obtained from expert knowledge and the literature. The data-based attribution approach is applied to annual maximum flood discharge seires from 2370 hydrometric stations in Europe. Extreme precipitation, antecedent soil moisture and snowmelt are the potential drivers considered. Results show that extreme precipitation mainly contributes to positive flood changes in North-western Europe. Both antecedent soil moisture and extreme precipitation contribute to negative flood changes in Southern Europe, with relative contributions varying with the return period. Antecedent soil moisture contributes the most to changes in small floods (i.e. T=2-10 years), while the two drivers contribute with comparable magnitude to changes in more extreme events. In eastern Europe, snowmelt clearly drives negative changes in both small and large floods.</p>

scholarly journals Historical changes in frequency of extreme floods in Prague

2015 ◽  
Vol 19 (10) ◽  
pp. 4307-4315 ◽  
Author(s):  
L. Elleder
Keyword(s):  
Flood Frequency ◽  
Flood Frequency Analysis ◽  
Flood Events ◽  
Central European ◽  
Extreme Floods ◽  
Flood Peak ◽  
The Past ◽  
Documentary Sources ◽  
Instrumental Period ◽  
Peak Discharges

Abstract. This study presents a flood frequency analysis for the Vltava River catchment using a major profile in Prague. The estimates of peak discharges for the pre-instrumental period of 1118–1824 based on documentary sources were carried out using different approaches. 187 flood peak discharges derived for the pre-instrumental period augmented 150 records for the instrumental period of 1825–2013. Flood selection was based on Q10 criteria. Six flood-rich periods in total were identified for 1118–2013. Results of this study correspond with similar studies published earlier for some central European catchments, except for the period around 1750. Presented results indicate that the territory of the present Czech Republic might have experienced extreme floods in the past, comparable – with regard to peak discharge (higher than or equal to Q10) and frequency – to the flood events recorded recently.

The unusual floods and flood frequency in 1858–1878 dry period in Central and Western Europe

2020 ◽  
Author(s):  
Libor Elleder ◽  
Ladislav Kašpárek ◽  
Jakub Krejčí ◽  
Jolana Šírová ◽  
Stanislav Racko
Keyword(s):  
Western Europe ◽  
Flash Flood ◽  
Flood Frequency ◽  
Point Of View ◽  
Ice Age ◽  
Flood Events ◽  
Dry Period ◽  
Drought Period ◽  
Extreme Flood ◽  
Strong Winds

<p>According to the present knowledge, the second half of the 19<sup>th</sup> century meant the end of the Little Ice Age and gradual warming.  This is, however, undoubtedly a fairly simplified statement.  Our contribution presents the period of 1858–1878: (1) from the point of view of drought but also (2) regarding frequency of floods. The aggregation for this period of weather-driven risks such as droughts, floods, strong winds and high tides, is worth attention.  The length of the drought period of 1858–1878, the absolute value of rainfall deficits and the length of seasonal droughts, as well as their impacts, are a certain warning in terms of our present.</p><p>Surprisingly, in such a dry period we witness an accumulation of important and extreme flood episodes as well. The regional catastrophic floods of 1858, and winter extensive floods of 1862 and 1876, may serve as excellent examples.  Furthermore, the Elbe catchment recorded floods with return periods of 10–20 years in 1860, 1865 and 1872. For this period, an occurrence of intensive mesoscale flash flood events with extreme hydrological parameters, high number of fatalities and large damages are of the utmost importance (e.g. 1868-Switzerland, 1872-Czechlands, 1874- Catalonia, 1875-South France). Our contribution builds on earlier analysed flood events of 1872, 1875 and drought period presented at EGU earlier. The contribution stresses the analogies and differences with present situation in 2014–2019.  We mainly address the situation in Czech lands, Central Europe interpreted in wider European context.</p>

Flood hazard in mountain streams: the key role of geomorphic processes during high magnitude events

2020 ◽  
Author(s):  
Nicola Surian ◽  
Andrea Brenna ◽  
Marco Borga ◽  
Marco Cavalli ◽  
Francesco Comiti ◽  
...  
Keyword(s):  
Hazard Assessment ◽  
Flood Hazard ◽  
Channel Width ◽  
Mountain Streams ◽  
Channel Network ◽  
Channel Dynamics ◽  
High Magnitude ◽  
Channel Widening ◽  
Large Floods ◽  
Geomorphic Processes

<p>Although channel dynamics (i.e. channel lateral mobility, intense sediment and wood transport) are commonly dominant processes in mountain streams during high-magnitude floods, hazard assessment still mostly focuses on water flooding only. Therefore, there is a need to include river geomorphological hazard to produce reliable flood hazard mapping and define effective mitigation measures. This work deals with the “Vaia” storm that occurred in the Eastern Alps (Italy) on 27-30 October 2018. Our aims are (i) to improve the understanding of geomorphic processes in response to large floods and (ii) to improve the prediction capability of the reaches more prone to undergo intense channel dynamics (e.g. channel widening, in-channel sedimentation) during such events.</p><p>An integrated approach was deployed to study the flood event in the Cordevole river catchment (876 km<sup>2</sup>). The approach includes (i) analysis of geomorphological processes, by comparing remote sensing data acquired before and after floods and field survey (e.g. recognition of different flow types); (ii) hydrological and hydraulic analysis (collection of rainfall and streamflow data, estimation of peak discharges at multiple sites in ungauged streams, and model-based consistency check of rainfall and discharge data); (iii) landslide mapping and analysis of sediment delivery to the channel network.</p><p>Intense sediment and wood transport took place. A wide range of transport processes (i.e. debris, hyperconcentrated and water flows) was recognized in the channel network and notable channel aggradation occurred at specific location (e.g. in channelized reaches). Channel widening was the most relevant geomorphic response along the fluvial network. Width ratio (i.e. channel width after / channel width before the flood) reached up to 2.1 and 4.4, respectively in the Cordevole and in its tributaries. Locally, the valley slopes were eroded (e.g. slope retreat up to 14 m). This means that the lateral channel dynamics affected not only large portions of the valley floor (e.g. forested floodplain) but also the valley slopes, especially if made of Quaternary deposits or soft bedrock.</p><p>These results have several implications in terms of flood hazard assessment in mountain streams. Since channel widening is a major process (streams may take up the whole floodplain and, locally, erode the valley slopes), so-called “river morphodynamic corridors” need to be defined and integrated into flood hazard maps. During high-magnitude floods the sediment mobilization may take place through mechanisms (e.g. hyperconcentrated flows) that can be different from those expected for ordinary water floods. Since major channel changes commonly occur during large floods, their prediction is needed and should accompany flood hydraulic modelling to obtain reliable flood event scenarios.</p>

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