scholarly journals Analysis of floods in the upper course of the Hron River in 1930–2010

Geografie ◽  
2012 ◽  
Vol 117 (4) ◽  
pp. 415-433
Author(s):  
Andrea Blahušiaková ◽  
Milada Matoušková
Keyword(s):  
20Th Century ◽  
Frequency Analysis ◽  
Water Levels ◽  
Intense Rainfall ◽  
Extreme Floods ◽  
Extreme Flood ◽  
Extreme Flooding ◽  
Very High ◽  
Gauging Station

The main focus of this research is concentrated on the flood analyses in the upper course of the Hron River in the period 1930–2010. The study includes an evaluation of the flood seasonality, frequency and extremity in two periods 1930–1991 and 1992–2009. The year 2010 has been added because of a very high amount of precipitation between May–September 2010 which caused extreme flooding. The most extreme flood in the 20th century occurred in October 1974. At the gauging station Banská Bystrica, discharge values reached 560 m3.s−1 which corresponds to the 100-year flood. In the last decade, extreme floods occurred in years 2002 and 2010. The main reason for the flooding was an intense rainfall and local storms with high amount of precipitation. The frequency analysis (in equally long periods 1950–1979 and 1980–2009) proved that there is a higher frequency of floods since 1980 (17 in the period 1950–1979 and 27 between 1980–2009). Higher water levels during floods were reached in the period 1950–1979. The summer floods dominate in both observed periods, but winter floods also occurred very often (7 floods in the period 1950–1979 and 12 in 1980–2009). This is due to the hollow relief of the upper course of the Hron River.

scholarly journals Frequency analysis of extreme floods in a highly developed river basin

2016 ◽  
Author(s):  
Tomohiro Tanaka ◽  
Yasuto Tachikawa ◽  
Yutaka Ichikawa ◽  
Kazuaki Yorozu
Keyword(s):  
River Basin ◽  
Frequency Analysis ◽  
River Discharge ◽  
Flood Frequency ◽  
Flood Frequency Analysis ◽  
Discharge Data ◽  
Extreme Floods ◽  
Extreme Flood ◽  
Flood Peaks ◽  
Gauging Station

Abstract. Design flood, river discharge with a particular return period, is fundamental to determine the scale of flood control facilities. In addition, considering a changing climate, not only frequencies of river discharge at design level but those of devastating flooding are also crucial. Characteristics of river discharge during extreme floods largely differ from those during others because of upstream dam operation and/or river overflow; however, flood frequency analysis (FFA) from past discharge data is difficult to represent such impact because river basins rarely experience floods over the design level after river improvement and dam construction. To account for the above impact on extreme flood frequencies, this study presented a rainfall-based flood frequency model (RFFM) that derives flood frequencies from probabilistic rainfall modelling that empirically represents probabilistic structure of rainfall intensity over a catchment by directly using observed spatial-temporal rainfall profiles. The RFFM was applied to the Yodo River basin, Japan and demonstrated that flood frequency estimations by the RFFM well represent past flood frequencies at the Hirakata gauging station. Furthermore, the RFFM showed that return periods of large flood peaks are estimated at extremely large values, reflecting decrease of discharge by the inundation in an upstream area of the gauging station. On the other hand, FFA from past discharge data did not represent this impact because it has not experienced such huge flood peaks in an observation period. This study demonstrated the importance of the RFFM for flood frequency estimations, including those exceeding the design level.

Holocene extreme paleofloods and their climatological context, Upper Colorado River Basin, USA

2020 ◽  
Vol 44 (5) ◽  
pp. 727-745
Author(s):  
Tao Liu ◽  
Lin Ji ◽  
Victor R Baker ◽  
Tessa M Harden ◽  
Michael L Cline
Keyword(s):  
River Basin ◽  
Colorado River ◽  
Meta Analysis ◽  
Flood Frequency ◽  
Colorado River Basin ◽  
Extreme Floods ◽  
Upper Colorado River Basin ◽  
Extreme Flood ◽  
Southwestern Usa ◽  
Extreme Flooding

Given its singular importance for water resources in the southwestern USA, the Upper Colorado River Basin (UCRB) is remarkable for the paucity of its conventional hydrological record of extreme flooding. Short-term record-based flood frequency analyses lead to very great aleatory uncertainties about infrequent extreme flood events and their climate-driven causal associations. This study uses paleoflood hydrology to examine a small portion of the underutilized, but very extensive natural record of Holocene extreme floods in the UCRB. We perform a meta-analysis of 82 extreme paleofloods from 18 slack water deposit sites in the UCRB to show linkages between Holocene climate patterns and extreme floods. The analysis demonstrates several clusters of extreme flood activity: 8040–7960, 4400–4300, 3600–3460, 2900–2740, 2390–1980, 1810–720, and 600–0 years BP. The extreme paleofloods were found to occur during both dry and wet periods in the paleoclimate record. When compared with independent paleoclimatic records across the Rocky Mountains and the southwestern USA, the observed temporal clustering pattern of UCRB extreme paleofloods shows associations with periods of abruptly intensified North Pacific-derived storms connected with enhanced variability of El Niño. This approach demonstrates the value of creating paleohydrological databases and comparing them with hydro-climatic proxies in order to identify natural patterns and to discover possible linkages to fundamental processes such as changes in climate.

Luminescence chronology of late-Holocene palaeofloods in the upper Kaveri basin, India: An insight into the climate–flood relationship

The Holocene ◽  
2019 ◽  
Vol 29 (6) ◽  
pp. 1094-1104 ◽  
Author(s):  
Kartika Goswami ◽  
Mahadev Rawat ◽  
Manoj K Jaiswal ◽  
Vishwas S Kale
Keyword(s):  
20Th Century ◽  
Ice Age ◽  
Flood Events ◽  
Term Relation ◽  
Extreme Flood ◽  
Extreme Flooding ◽  
Major Floods ◽  
The Times ◽  
Floodplain Sediments

Instrumental/historic records have helped to understand the extreme flood–climate relationship in the modern environment; however, few studies are available to understand their long-term relation (102–103 years) due to the poor preservation and lack of dating techniques. It remains uncertain whether extreme flooding is linked with long-term wet phases of climate or a random event caused by an unusual downpour irrespective of climate. Luminescence analysis of quartz grains from river/floodplain sediments in the Kaveri basin, southern India, showed heterogeneous bleaching. We demonstrated the successful application of various statistical age models in estimating ages of heterogeneously bleached young sediments. This study shows distinct flood clusters occurred during the times of major shifts in the monsoon climate, from fluvial dormancy to sudden outburst of monsoons (~2 ka), from warmer to colder (onset of ‘Little Ice Age’ (LIA) ~ 14th century), from colder to warmer (end of LIA ~ 19th century) and ~20th century, indicating that climatic pattern can be associated with more frequent occurrences of extreme flood events. The study also shows that the two major flood events of the 20th century reported from the upper Kaveri were produced by high intensity short duration storms, suggesting that not all wet phases are associated with major floods and all dry phases with low floods/droughts. The excellent match of the chronology with the historical data, instrumental data and published literature based on proxy data on the Indian summer monsoon validates the chronology and the potential of sedimentary archives for future palaeoenvironmental reconstruction of the study area.

scholarly journals Modelling the impact of anthropogenic modifications to river channels on the course of extreme floods. Case study: August 2002 flood, Blanice River basin, Czechia

Geografie ◽  
2008 ◽  
Vol 113 (3) ◽  
pp. 237-252
Author(s):  
Jakub Langhammer ◽  
Jan Sitař
Keyword(s):  
Negative Impact ◽  
Local Level ◽  
River Channel ◽  
Water Levels ◽  
River Channels ◽  
Extreme Floods ◽  
River Bed ◽  
Extreme Flood ◽  
Anthropogenic Modifications ◽  
The Impact

This paper presents the results of analysis of the impact of anthropogenic modifications to river channels on the course of floods by means of hydraulic modelling. The study is focused on the quantitative analysis of changes of the flow dynamics in the river bed and in the inundation zone due to river network modifications. The one-dimensional hydraulic model HEC-RAS coupled with GIS is used to simulate the effect of the river channel changes on the course of extreme flood. The analysis is made on the example of the extreme flood in August 2002 on the down course of Blanice River in Czechia. The results of the simulations proved that the common anthropogenic modifications of river channel have only a minimum impact on the overall course of extreme floods. At the local level, weirs and unsuitably dimensioned bridges have a negative impact on the course of floods. The simulations also showed a negative impact of extensive complex modifications of the river bed, performed in the lower course of Blanice River in the first half of the 20th century. However, the overall impact of common types of river channel modifications on peak flows and water levels in the culmination is negligible.

scholarly journals Projection of Hydro-Climatic Extreme Events under Climate Change in Yom and Nan River Basins, Thailand

Water ◽  
2021 ◽  
Vol 13 (5) ◽  
pp. 665
Author(s):  
Chanchai Petpongpan ◽  
Chaiwat Ekkawatpanit ◽  
Supattra Visessri ◽  
Duangrudee Kositgittiwong
Keyword(s):  
Climate Change ◽  
Air Temperature ◽  
Extreme Events ◽  
River Basins ◽  
Annual Rainfall ◽  
Extreme Floods ◽  
Extreme Flood ◽  
Rcp 8.5 ◽  
Near Future ◽  
Far Future

Due to a continuous increase in global temperature, the climate has been changing without sign of alleviation. An increase in the air temperature has caused changes in the hydrologic cycle, which have been followed by several emergencies of natural extreme events around the world. Thailand is one of the countries that has incurred a huge loss in assets and lives from the extreme flood and drought events, especially in the northern part. Therefore, the purpose of this study was to assess the hydrological regime in the Yom and Nan River basins, affected by climate change as well as the possibility of extreme floods and droughts. The hydrological processes of the study areas were generated via the physically-based hydrological model, namely the Soil and Water Assessment Tool (SWAT) model. The projected climate conditions were dependent on the outputs of the Global Climate Models (GCMs) as the Representative Concentration Pathways (RCPs) 2.6 and 8.5 between 2021 and 2095. Results show that the average air temperature, annual rainfall, and annual runoff will be significantly increased in the intermediate future (2046–2070) onwards, especially under RCP 8.5. According to the Flow Duration Curve and return period of peak discharge, there are fluctuating trends in the occurrence of extreme floods and drought events under RCP 2.6 from the future (2021–2045) to the far future (2071–2095). However, under RCP 8.5, the extreme flood and drought events seem to be more severe. The probability of extreme flood remains constant from the reference period to the near future, then rises dramatically in the intermediate and the far future. The intensity of extreme droughts will be increased in the near future and decreased in the intermediate future due to high annual rainfall, then tending to have an upward trend in the far future.

scholarly journals Reanalysis Product-Based Nonstationary Frequency Analysis for Estimating Extreme Design Rainfall

Atmosphere ◽  
2021 ◽  
Vol 12 (2) ◽  
pp. 191
Author(s):  
Dong-IK Kim ◽  
Dawei Han ◽  
Taesam Lee
Keyword(s):  
South Korea ◽  
20Th Century ◽  
Frequency Analysis ◽  
Systematic Errors ◽  
Quantile Mapping ◽  
Reanalysis Product ◽  
Rainfall Analysis ◽  
Future Evolution ◽  
Design Rainfall ◽  
Nonstationary Frequency

Nonstationarity is one major issue in hydrological models, especially in design rainfall analysis. Design rainfalls are typically estimated by annual maximum rainfalls (AMRs) of observations below 50 years in many parts of the world, including South Korea. However, due to the lack of data, the time-dependent nature may not be sufficiently identified by this classic approach. Here, this study aims to explore design rainfall with nonstationary condition using century-long reanalysis products that help one to go back to the early 20th century. Despite its useful representation of the past climate, the reanalysis products via observational data assimilation schemes and models have never been tested in representing the nonstationary behavior in extreme rainfall events. We used daily precipitations of two century-long reanalysis datasets as the ERA-20c by the European Centre for Medium-Range Weather Forecasts (ECMWF) and the 20th century reanalysis (20CR) by the National Oceanic and Atmospheric Administration (NOAA). The AMRs from 1900 to 2010 were derived from the grids over South Korea. The systematic errors were downgraded through quantile delta mapping (QDM), as well as conventional stationary quantile mapping (SQM). The evaluation result of the bias-corrected AMRs indicated the significant reduction of the errors. Furthermore, the AMRs present obvious increasing trends from 1900 to 2010. With the bias-corrected values, we carried out nonstationary frequency analysis based on the time-varying location parameters of generalized extreme value (GEV) distribution. Design rainfalls with certain return periods were estimated based on the expected number of exceedance (ENE) interpretation. Although there is a significant range of uncertainty, the design quantiles by the median parameters showed the significant relative difference, from −30.8% to 42.8% for QDM, compared with the quantiles by the multi-decadal observations. Even though the AMRs from the reanalysis products are challenged by various errors such as quantile mapping (QM) and systematic errors, the results from the current study imply that the proposed scheme with employing the reanalysis product might be beneficial to predict the future evolution of extreme precipitation and to estimate the design rainfall accordingly.

scholarly journals Stochastic semi-continuous simulation for extreme flood estimation in catchments with combined rainfall–snowmelt flood regimes

2014 ◽  
Vol 14 (5) ◽  
pp. 1283-1298 ◽  
Author(s):  
D. Lawrence ◽  
E. Paquet ◽  
J. Gailhard ◽  
A. K. Fleig
Keyword(s):  
Frequency Analysis ◽  
Probabilistic Model ◽  
Extreme Precipitation ◽  
Flood Frequency ◽  
Flood Frequency Analysis ◽  
Continuous Simulation ◽  
Weather Patterns ◽  
Extreme Flood ◽  
Flood Estimation

Abstract. Simulation methods for extreme flood estimation represent an important complement to statistical flood frequency analysis because a spectrum of catchment conditions potentially leading to extreme flows can be assessed. In this paper, stochastic, semi-continuous simulation is used to estimate extreme floods in three catchments located in Norway, all of which are characterised by flood regimes in which snowmelt often has a significant role. The simulations are based on SCHADEX, which couples a precipitation probabilistic model with a hydrological simulation such that an exhaustive set of catchment conditions and responses is simulated. The precipitation probabilistic model is conditioned by regional weather patterns, and a bottom–up classification procedure was used to define a set of weather patterns producing extreme precipitation in Norway. SCHADEX estimates for the 1000-year (Q1000) discharge are compared with those of several standard methods, including event-based and long-term simulations which use a single extreme precipitation sequence as input to a hydrological model, statistical flood frequency analysis based on the annual maximum series, and the GRADEX method. The comparison suggests that the combination of a precipitation probabilistic model with a long-term simulation of catchment conditions, including snowmelt, produces estimates for given return periods which are more in line with those based on statistical flood frequency analysis, as compared with the standard simulation methods, in two of the catchments. In the third case, the SCHADEX method gives higher estimates than statistical flood frequency analysis and further suggests that the seasonality of the most likely Q1000 events differs from that of the annual maximum flows. The semi-continuous stochastic simulation method highlights the importance of considering the joint probability of extreme precipitation, snowmelt rates and catchment saturation states when assigning return periods to floods estimated by precipitation-runoff methods. The SCHADEX methodology, as applied here, is dependent on observed discharge data for calibration of a hydrological model, and further study to extend its application to ungauged catchments would significantly enhance its versatility.

scholarly journals Quick estimate of extreme floods water levels

2016 ◽  
Vol 7 ◽  
pp. 10007
Author(s):  
André Paquie ◽  
Christine Poulard ◽  
Jean-Baptiste Faure
Keyword(s):  
Water Levels ◽  
Extreme Floods ◽  
Quick Estimate

scholarly journals Modelling Spatiotemporal Dynamics of Large Wood Recruitment, Transport, and Deposition at the River Reach Scale during Extreme Floods

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1134 ◽  
Author(s):  
Andreas Zischg ◽  
Niccolo Galatioto ◽  
Silvana Deplazes ◽  
Rolf Weingartner ◽  
Bruno Mazzorana
Keyword(s):  
Simulation Model ◽  
Transport Model ◽  
Large Wood ◽  
Flow Paths ◽  
Extreme Floods ◽  
Reliable Assessment ◽  
Extreme Flood ◽  
Floodplain Inundation ◽  
Irregular Meshes ◽  
River Reach

Large wood (LW) can lead to clogging at bridges and thus cause obstruction, followed by floodplain inundation. Moreover, colliding logs can cause severe damage to bridges, defense structures, and other infrastructure elements. The factors influencing spatiotemporal LW dynamics (LWD) during extreme floods vary remarkably across river basins and flood scenarios. However, there is a lack of methods to estimate the amount of LW in rivers during extreme floods. Modelling approaches allow for a reliable assessment of LW dynamics during extreme flood events by determining LW recruitment, transport, and deposition patterns. Here, we present a method for simulating LWD on a river reach scale implemented in R (LWDsimR). We extended a previously developed LW transport model with a tree recognition model on the basis of Light Detection and Ranging (LiDAR) data for LW recruitment simulation. In addition, we coupled the LWD simulation model with the hydrodynamic simulation model Basic Simulation Environment for Computation of Environmental Flow and Natural Hazard Simulation (BASEMENT-ETH) by adapting the existing LW transport model to be used on irregular meshes. The model has been applied in the Aare River basin (Switzerland) to quantify mobilized LW volumes and the associated flow paths in a probable maximum flood scenario.

Modal verbs in English essays written by Czech secondary-school students

2020 ◽  
Author(s):  
Věra Sládková
Keyword(s):  
Secondary School ◽  
Frequency Analysis ◽  
Secondary School Students ◽  
Past Tense ◽  
English School ◽  
School Students ◽  
High Stakes ◽  
Modal Verbs ◽  
Learner Corpus ◽  
Very High

This paper presents the findings of a frequency analysis of modal verbs and their complementation in 390 English school-leaving essays written by Czech secondary-school students in a high-stakes B1 level exam. These constitute a learner corpus, CZEMATELC 2017. The study reveals a very high proportion of correct complementation patterns, but predominantly with lexical verbs at A1 and A2 CEFR levels. The most frequent errors are the complementation of modal verbs by past-tense forms of lexical verbs and the absence of complementation.

Sign in / Sign up

Export Citation Format

Share Document