Extreme flood events and their frequency variations during the middle to late-Holocene recorded in the sediment of Lake Suigetsu, central Japan

The Holocene ◽  
2020 ◽  
Vol 31 (1) ◽  
pp. 121-133
Author(s):  
Yoshiaki Suzuki ◽  
Ryuji Tada ◽  
Kana Nagashima ◽  
Takeshi Nakagawa ◽  
Katsuya Gotanda ◽  
...  
Keyword(s):  
Late Holocene ◽  
Temporal Variations ◽  
Continental Margins ◽  
Flood Events ◽  
Central Japan ◽  
Westerly Jet ◽  
Extreme Flood ◽  
Western Japan ◽  
High Flood ◽  
Event Layers

Many studies are reconstructing flood records in the continental margins during the middle to late-Holocene. However, distinguishing the frequency and magnitude of flood events was difficult. Light gray event layers (GELs) in the sediment of Lake Suigetsu in Central Japan can solve this problem because they are recording the occurrence and magnitude of flood events during the last 80 years. Using these GELs, we aimed to reconstruct the frequency and magnitude of flood events during the last 8000 years. First, we verified whether GELs maintained the recording of flood events. We found that thin GELs (less than 40 mg/cm2 in mass) were rare, probably because of bioturbation, whereas thick GELs (larger than 40 mg/cm2 in mass) were rarely erased. We also found that GELs formed by the same amount of rainfall could have been thinner before 100 years ago. We revealed that the occurrence of extreme flood-origin event layers (EFELs: GELs thicker than 40 mg/cm2) during the last 8000 years may indicate the occurrence of extreme flood events (EFEs). Mass accumulation of EFELs may indicate the minimum estimation of rainfall on EFEs. There are several periods with higher frequency and magnitude of EFEs than those of the present level, agreeing with the periods of high flood activity in western Japan and East China. The frequency and magnitude of EFEs show different temporal variations. Northward and southward shifts in the westerly jet and monsoon fronts can partially explain such patterns.

scholarly journals Repeated flood disturbance enhances rotifer dominance and diversity in a zooplankton community of a small dammed mountain pond

2016 ◽  
Author(s):  
Carmen Gabaldón ◽  
Miloslav Devetter ◽  
Josef Hejzlar ◽  
Karel Šimek ◽  
Petr Znachor ◽  
...  
Keyword(s):  
Biotic Interactions ◽  
Zooplankton Community ◽  
High Ratio ◽  
Flood Events ◽  
Physical Conditions ◽  
Short Period ◽  
Extreme Flood ◽  
Zero Values ◽  
Colonization Ability ◽  
High Flood

<p>The zooplankton community in a relatively small and mountain pond was studied during the spring growing season. To investigate which factors operate in the community structure, we explored several physical conditions, such as high inflows, and the biotic dynamics of the main zooplankton groups (i.e., rotifers, cladocerans and copepods).  Two extreme flood events occurred during the investigated period and caused dramatic changes in physical conditions and reduction of the planktonic community abundances. The short period between both high-flow events was enough for the recovery of microplankton, but not for the metazoan zooplankton. Our results are in agreement with the common situation in which high flood events commonly favour rotifers over crustaceans, likely due to rotifer species have great colonization ability and grow faster. However, we found that the dominance of rotifers over crustaceans in our system is evidenced by an extremely, unusual high ratio between their abundances.  We observed that, at the time of the great floods, crustacean abundances as well as rotifer populations notably decreased until near zero values. Although rotifer abundance began declining before high floods, the decrease was particularly notable when the great flood happened.  Our results evidenced that i) dilution rate and temperature were the main drivers which are operating in the structure of the zooplankton community; and ii) no negative biotic interactions were detected between large and small cladocerans and rotifers. Additionally, we found surprisingly that a repeated disturbance caused by high flood events does increase the species diversity of rotifers. Finally, our study also detected some cues which may indicate that diapausing egg bank is also playing an important role in the zooplankton community, favouring the dominance of rotifers; however, this phenomenon deserves further studies. </p>

A global analysis of the interplay between flood severity ad human dynamics in floodplains

2021 ◽  
Author(s):  
Maurizio Mazzoleni ◽  
Johanna Mård ◽  
Maria Rusca ◽  
Vincent Odongo ◽  
Sara Lindersson ◽  
...  
Keyword(s):  
Human Population ◽  
Global Analysis ◽  
Economic Losses ◽  
Flood Events ◽  
Human Dynamics ◽  
Policies And Measures ◽  
Extreme Flood ◽  
Severe Flood ◽  
Flood Losses ◽  
High Flood

&lt;p&gt;This study aims at exploring whether changes in the spatial distribution of the human population and the built-up areas within floodplains can be associated with extreme flood events generating severe economic losses and fatalities. We relate economic losses and fatalities caused by floods during 1990&amp;#8208;2000, with changes in human population and built&amp;#8208;up areas in floodplains during 2000&amp;#8208;2015 by exploiting global archives as the Global Human Settlement, GFPLAIN250m, and the EM-DAT datasets. Despite the frequent flood losses in the previous period 1990&amp;#8208;2000, we found that population and built&amp;#8208;up areas in floodplains increased in the period 2000&amp;#8208;2015 for the majority of the analyzed countries. On the other hand, we observed a reduction in floodplains population after more severe flood losses that occurred in the period 1975&amp;#8208;2000. Finally, floodplains population increased after a period of high flood fatalities in low&amp;#8208;income countries, while built&amp;#8208;up areas increased after a period of frequent economic losses in upper&amp;#8208;middle and high&amp;#8208;income countries. This study can be used as a general framework for advancing knowledge of human&amp;#8208;flood interactions and support the development of sustainable policies and measures for flood risk management and disaster risk reduction.&lt;/p&gt;

scholarly journals Ectomycorrhiza resilience and recovery to extreme flood events in Tuber aestivum and Quercus robur

Mycorrhiza ◽  
2021 ◽  
Author(s):  
P. W. Thomas
Keyword(s):  
Climate Change ◽  
Seedling Growth ◽  
Quercus Robur ◽  
Root Systems ◽  
Fruiting Bodies ◽  
Flood Events ◽  
Tuber Aestivum ◽  
Soil Zone ◽  
Extreme Flood ◽  
The Impact

AbstractVery little is known about the impact of flooding and ground saturation on ectomycorrhizal fungi (EcM) and increasing flood events are expected with predicted climate change. To explore this, seedlings inoculated with the EcM species Tuber aestivum were exposed to a range of flood durations. Oak seedlings inoculated with T. aestivum were submerged for between 7 and 65 days. After a minimum of 114-day recovery, seedling growth measurements were recorded, and root systems were destructively sampled to measure the number of existing mycorrhizae in different zones. Number of mycorrhizae did not display correlation with seedling growth measurements. Seven days of submersion resulted in a significant reduction in mycorrhizae numbers and numbers reduced most drastically in the upper zones. Increases in duration of submersion further impacted mycorrhizae numbers in the lowest soil zone only. T. aestivum mycorrhizae can survive flood durations of at least 65 days. After flooding, mycorrhizae occur in higher numbers in the lowest soil zone, suggesting a mix of resilience and recovery. The results will aid in furthering our understanding of EcM but also may aid in conservation initiatives as well as providing insight for those whose livelihoods revolve around the collection of EcM fruiting bodies or cropping of the plant partners.

Envelope Curves for Extreme Flood Events

1982 ◽  
Vol 108 (10) ◽  
pp. 1208-1212
Author(s):  
John R. Crippen
Keyword(s):  
Flood Events ◽  
Extreme Flood

scholarly journals Contributions of historical hydrogeomorphology to determine floodable areas from extreme flood events

Huellas ◽  
2019 ◽  
Vol 23 (1) ◽  
pp. 11-26
Author(s):  
Volonte Antonela ◽  
◽  
Veronica Gil ◽  
◽  
◽  
...  
Keyword(s):  
Flood Events ◽  
Extreme Flood

Extreme flood events favour floodplain mollusc diversity

Hydrobiologia ◽  
2008 ◽  
Vol 621 (1) ◽  
pp. 63-73 ◽  
Author(s):  
Christiane Ilg ◽  
Francis Foeckler ◽  
Oskar Deichner ◽  
Klaus Henle
Keyword(s):  
Flood Events ◽  
Extreme Flood

Hydraulic modelling of extreme flood event of semi-arid river basin

2021 ◽  
Author(s):  
Mohamedmaroof Shaikh ◽  
Sanjaykumar Yadav ◽  
Vivek Manekar
Keyword(s):  
Cross Sections ◽  
Management Strategy ◽  
Retaining Wall ◽  
Hydraulic Model ◽  
Flood Event ◽  
Railway Bridge ◽  
Hydraulic Modelling ◽  
One Dimensional ◽  
Extreme Flood ◽  
High Flood

&lt;p&gt;Floods are among the severe weather disasters that cause catastrophic damage to surroundings and adversely impact populations. This study aims to create a one-dimensional (1D) hydraulic model using HEC-RAS for the Rel River in Banaskantha, Gujarat, India. The model has been developed for the extreme flood event of July 2017. A total of hundred cross-sections have been used as geometric data. The peak discharge of 3355 m&lt;sup&gt;3&lt;/sup&gt;/s and the river slope has been applied as upstream and downstream boundary conditions. The model has been calibrated and validated using observed water depth at Railway bridge and Highway bridge. Critical cross-sections have been identified using the 1D hydraulic model. Eight out of the hundred cross-sections were safe for a flood discharge of 3355 m&lt;sup&gt;3&lt;/sup&gt;/s. The villages at high flood risk are identified for this discharge. To mitigating floods, the construction of a retaining wall or levees is recommended to protect these villages. This study can help a disaster management strategy for the cities and town in the River&amp;#8217;s vicinity.&lt;/p&gt;

Regional Determination of Historical Heavy Rain for Reconstruction of Extreme Flood Events

In Extremis ◽  
2010 ◽  
pp. 90-102
Author(s):  
Paul Dostal ◽  
Florian Imbery ◽  
Katrin Bürger ◽  
Jochen Seidel
Keyword(s):  
Heavy Rain ◽  
Flood Events ◽  
Extreme Flood ◽  
Regional Determination
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