Extraordinary Floods Research Articles

Calculation of nonstationary flood return period considering historical extraordinary flood events

With climate change and intensification of human activities, the flood generation mechanism has been influenced which results in the nonstationarity of flood time series. In this study, in order to use historical flood data for flood frequency analysis, a nonlinear AutoRegressive exogenous (ARX) model was employed to complement missing flood data between the historical and recorded data. The key statistics of the complemented time series agreed well with those of the documented record. Using EWT (the expected waiting time until an exceedance) and ENE (the expected number of events in m year is one), nonstationary flood return periods were estimated by the complemented and recorded annual maximum flood peak series, respectively. The results showed that the return levels under nonstationarity are smaller than those under stationarity due to the construction of small hydraulic structures and many check dams after 1980s. This study implies that it is necessary to refine the flood return levels and the corresponding flood control measures for nonstationary flood series due to environmental change.

Cuatro grandes inundaciones históricas del Ebro en la ciudad de Zaragoza: 1643, 1775, 1871 y 1961

A partir principalmente de documentación de archivo, se describen y analizan cuatro inundaciones extraordinarias registradas del río Ebro en Zaragoza: 1643, 1775, 1871 y 1961. Estas avenidas pueden ser consideradas las más importantes acontecidas en estos últimos siglos. De las dos primeras se aporta información hasta ahora desconocida. El contraste entre todas ellas, con la ayuda de la cartografía histórica y con la reciente cartografía de zonas inundables, constata un patrón secular: el río busca su margen izquierda, hoy profusamente urbanizada, como zona inundable natural; solo la obra humana lo impide. Using mainly historical sources, four extraordinary floods of the Ebro River in Zaragoza are described and analyzed: 1643, 1775, 1871 and 1961. These floods can be considered largest that have taken place along last centuries. New information hitherto unknown of the first two of them is provided. The contrast between all of them, with the aid of historical cartography and recent flood mapping, proves a secular pattern: the river tries to move towards its left bank, nowadays heavily urbanized, as its natural flood zone; only the human work prevents it.

Circulation weather types associated with extreme flood events in Northwestern Mediterranean

ABSTRACTThe aim of this work was to identify the circulation weather types associated with flood events that occurred in Catalonia (Northeastern Spain) during the period 1900–2010. To achieve this objective, 261 extraordinary and catastrophic flood and flash flood events that were recorded during this period were characterized and classified based on impact data. A preliminary analysis of maximum precipitation and discharge was conducted in order to have some quantitative hydrometeorological indicators associated with these kinds of events. The objective classification developed by Jenkinson and Collison, which is based on differences in synoptic patterns according to surface pressure, was implemented. Once the weather regimes for each flood event had been established, a statistical and comparative analysis was performed that allowed us to determine which synoptic patterns were more frequently associated with the different flood types, their differences and their similarities. The results show that most synoptic situations were pure cyclonic structures, in both extraordinary and catastrophic events, although they were more frequent in the latter. Catastrophic floods generally had a synoptic origin enhanced by certain mesoscale factors, while extraordinary floods were usually associated with local flash floods that occurred primarily in summer and early autumn, highlighting the undetermined types that were not reflected at a synoptic scale. As the Mediterranean basin is a region where floods cause serious socio‐economic impacts, this work will help improve prevention measures and provide information for policymakers, mainly for land‐use planning and early warning systems.

Bedload transport and flow resistance in steep channels – introduction to the issues in the context of mountain basins of the Central European region

Although sediment transport in the uppermost parts of mountain basins may be supply- limited, bedload transport in small torrents represents a potential hazard during extraordinary floods. The authors attempt to review recent worldwide research of bedload and hydraulics the results of which could potentially be applied in local steep channels. Approaches to the calculation of flow resistance (Manning relationship, logarithmic and power-law relationships) and critical conditions of the incipient motion of a bed particle (critical shear stress, stream power, flow velocity and discharge) are closely discussed in order to describe hydraulic and bedload transport conditions in steep headwater streams. Difficulties are pointed out in connection with the estimation of critical conditions of bedload transport in headwater streams with poorly sorted bed material and more or less developed bedforms. In the second part of the paper the authors present two pilot studies from the Western Carpathians and test potential applicability of specific formulas in this region. Results of the formulas point to relatively nonselective character of bedload transport during high magnitude floods in Beskydian headwater streams. An important role is played by the intensity of sediment delivery to active channels in limited sediment-supply conditions. The authors also point out that a majority of bedload transport and flow resistance equations were originally created on the basis of flume experiments or they were tested in Alpine torrents and therefore it is supposed that they might work well in local torrents after being calibrated to local conditions.

Climatic seasonality, hydrological variability, and geomorphology shape fish assemblage structure in a subtropical floodplain

AbstractWe applied a multiscale approach to understand the patterns of longitudinal, lateral, and temporal variability in fish assemblage structure of a large floodplain river and explored their relationships with climatic seasonality, hydrological variability, and floodplain geomorphology. We studied the fish assemblage structure of 35 connected lakes along a 600-km section of the Parana River over 5 y. Longitudinal changes in fish assemblage structure were associated with a latitudinal climatic gradient, whereas temporal changes were associated with climatic seasonality and hydrological variability. Longitudinal and seasonal changes in assemblage structure were probably based on different thermal preferences of species that migrate seasonally along the main river axis. Extraordinary floods in summer promoted downstream dispersal of several species, which increased similarity between downstream and upstream regions. Thermal seasonality of this subtropical system was a strong factor driving temporal chang...

Mid-Holocene palaeoflood events recorded at the Zhongqiao Neolithic cultural site in the Jianghan Plain, middle Yangtze River Valley, China

Palaeo-hydrological and archaeological investigations were carried out in the Jianghan Plain in the middle reaches of the Yangtze River. Based on a comparative analysis of modern flood sediments and multidisciplinary approaches such as AMS14C and archaeological dating, zircon micromorphology, grain size, magnetic susceptibility, and geochemistry, we identified palaeoflood sediments preserved at the Zhongqiao archaeological site. The results indicate that three palaeoflood events (i.e. 4800–4597, 4479–4367, and 4168-3850 cal. yr BP) occurred at the Zhongqiao Site. Comparisons of palaeoflood deposit layers at a number of Neolithic cultural sites show that two extraordinary palaeoflood events occurred in the Jianghan Plain during approximately 4900–4600 cal. yr BP (i.e.mid-late Qujialing cultural period) and 4100-3800 cal. yr BP (i.e. from late Shijiahe cultural period to the Xia Dynasty). Further analysis of the environmental context suggests that these flooding events might have been connected with great climate variability during approximately 5000–4500 cal. yr BP and at ca. 4000 cal. yr BP. These two palaeoflood events were closely related to the expansion of the Jianghan lakes driven by the climatic change, which in turn influenced the rise and fall of the Neolithic cultures in the middle reaches of the Yangtze River. Other evidence also suggests that the intensified discrepancy between social development and environmental change processes (especially the hydrological process) during the late Shijiahe cultural period might be the key factor causing the collapse of the Shijiahe Culture. The extraordinary floods related to the climatic anomaly at ca. 4000 cal. yr BP and political conflicts from internal or other cultural areas all accelerated the collapse of the Shijiahe Culture.

Holocene palaeoflood events recorded by slackwater deposits along the Jin-shan Gorges of the middle Yellow River, China

Palaeoflood slackwater deposits (SWDs) are the natural record of overbank flooding and are often found within aeolian loess-soil profiles along the river valleys of the middle Yellow River basin. Palaeo-hydrological field investigation was carried out along the Jin-shan Gorges of the middle Yellow River after the great flood in 2012. We founded the new palaeoflood SWDs profile (YHG-B) on the basis of previous results in the YHG site, and collected the 2012 flood slackwater deposits. Analytical results, including magnetic susceptibility and particle size distribution, which is similar to the flood SWDs in 2012, indicate that these well-sorted palaeoflood SWD beds were deposited from the suspended sediment load in floodwaters. They have recorded the extraordinary palaeoflood events which occurred between 3200 and 3000 a BP as dated by the optically stimulated luminescence method in combination with pedo-stratigraphic correlations with the previously studied Holocene pedo-stratigraphy in the Yellow River drainage basin. According to the palaeoflood peak stages indicated by YHG-A and YHG-B, the peak discharges of these palaeoflood events vary in a range from 28 340 to 48 410 m3/s by using HEC-RAS one dimensional model. This discharges result error is less than 5% with previous published discharges by using Slop-Area method in 2012. The extraordinary flood events were documented not only on the Yellow River, but also on its tributaries such as the Weihe River, the Jinghe River, and the Qishuihe River. The flooding events are therefore considered to be a regional expression of known climatic events in the northern hemisphere and demonstrate Holocene climate was far from stable. This work will increase our understanding of the interactions between fluvial environment and climatic change in the semi-arid and sub-humid regions, and provide information that is useful for interpretation and calibration of the modern short-term gauged records.

Extreme hydrological events and the influence of reservoirs in a highly regulated river basin of northeastern Spain

Study regionThe Segre basin (northeastern Spain). Study focusThe Segre basin is extensively regulated, through a dense network of dams, during the second half of the 20th century. This study assessed the impact of river regulation on the evolution of hydroclimatological extreme events across the basin during the past six decades (1950–2013). We assessed whether the occurrence of floods and hydrological droughts has changed, and whether these changes have differed spatially between the headwaters and lower areas of the basin. For this purpose, we employed a set of hydroclimatological indices in order to quantify the evolution of the amount as well as the frequency of quantiles of high precipitation and flood events. Changes in these variables were assessed by means of the nonparametric Mann–Kendall Tau coefficient. New hydrological insightsResults reveal a general reduction in the occurrence of extreme precipitation events in the Segre basin from 1950 to 2013, which corresponded to a general reduction in high flows measured at various gauged stations across the basin. While this study demonstrates spatial differences in the decrease of streamflow between the headwaters and the lower parts of the basin, mainly associated with changes in river regulation, there was no reduction in the frequency of the extraordinary floods. Changes in water management practices in the basin have significantly impacted the frequency, duration, and severity of hydrological droughts downstream of the main dams, as a consequence of the intense water regulation to meet water demands for irrigation and livestock farms. Nonetheless, the hydrological response of the headwaters to these droughts differed markedly from that of the lower areas of the basin.

Research of Extraordinary Floods Disaster Scenario Construction and Simulation— Taking Yongding River as an Example

The Yongding River flood disasters frequently occur, which has great harm to the safe operation of Beijing city. Through the study of the catastrophic floods of Yongding river scenario construction, it demonstrates in the development of Yongding river catastrophic floods. Disaster simulation was carried out by MIKE RR model，the emergency response capacity gap was analyzed according to the simulation results, and the countermeasures and working mechanism of the flood disaster in Yongding River Basin were improved. Disaster simulation of MIKE RR model provides data basis for disaster prevention and response work, and on the basis of perfecting flood control and emergency response plan, in order to prevent catastrophic floods emergencies to provide strong support and technical support.

Analysis of the Hazard, Vulnerability, and Exposure to the Risk of Flooding (Alba de Yeltes, Salamanca, Spain)

The present work has developed a method using GIS technology to evaluate the danger, vulnerability, and exposure to the risk of flooding in the Alba de Yeltes area (Salamanca, Spain). It is a non-structural measure for the prevention and mitigation of the risk of extraordinary flooding. After completing a full analysis of the physical environment (climate, geology, geomorphology, hydrology, hydrogeology, and land use), hydrological-hydraulic modeling was carried out using the GeoHecRas river analysis software. The results obtained from the analysis and the models have generated a danger map that facilitates the efficient evaluation of the spatial distribution of the different severity parameters (depth of the watersheet, current flow rate, and flood-prone areas). Also, map algebra and the databases associated with GIS tools, together with the vulnerability and exposure cartography, have allowed the risk to be analyzed in an integrate manner and the production of an environmental diagnostic map. The results of this study propose that there are inhabited areas close to the Yeltes-Morasverdes riverbed that have a high risk of flooding, indicating the need for proper land planning and the implementation of a series of measures that will help to reduce the risk of flooding and its impact.

Lattice Boltzmann Method of a Flooding Accident at Gopeng, Perak, Malaysia

The extraordinary flood had hit the residential area at Taman Raia Mesra, Gopeng, Perak, Malaysia, in November 2016. The event illustrated how the river basin had been fully inundated due to the heavy rainfall and caused the overflow to this affected area. It was reported that the occurrence became worst as the outlet of retention pond which connects to the river is unsuitable for the water outflow. Henceforth, this paper attempts to evaluate the causal factor of this recent disaster by using a model developed from Lattice Boltzmann Method (LBM). The model also incorporated with the rainfall and stormwater in LABSWE™. The simulation was commenced with the basic tests for model validation comprising turbulent and jet-forced flow in a circular channel, which resulted in a good agreement for both models. The simulation continued by using LABSWE model to reveal the water depth and velocity profile at the study site. These results had proven the incompatibility size of the outlet pond which is too small for the water to flow out to the river. The study is capable of providing the authorities with a sustainable design of proper drainage system, especially in Malaysia which is constantly receiving the outrageous heavy rainfall.

The flood risk data mining based on POT and P-IOSM

为了从有限的实测资料中挖掘更多洪水信息，以武江流域为研究对象，在考证历史洪水进行特大值处理基础上，基于犁市（二）水文站1956-2009年实测日流量数据提取了POT样本，构建基于P-Ⅲ模型确定控制点而改进的非等步长内集-外集模型（P-IOSM）进行洪水风险信息挖掘. 结果表明：结合POT和P-IOSM模型的洪水风险评估能够从有限的实测资料中获取更多的洪水风险信息，得到更贴近事实的风险评估结果，能为决策者提供更多的依据，从而使决策结果更加可靠实用.;In order to get more information about the flood risk, the Peak-over-threshold (POT) flood samples are extracted after extraordinary flood processing with historical information based on daily flow data of Lishi(2) station in the Wujiang River Basin form 1956-2009. Then the improved non-isochronous Interior-Outer-Set Model (IOSM) which uses P-Ⅲ to determine the control point is applied to analyse the flood risk. The results show that: we can get more flood risk information from limited data and flood risk assessment result that is closer to fact by combining POT and P-IOSM models. It will provide more evidence for policy-makers which makes the decision-making more reliable and practical.

Extraordinary flood events and the response to monsoonal climatic change during the last 3000 years along the middle Yangtze River valley, China

Well-dated long-term flood data series is very important in studying of hydrological response to past climatic change along the mainstream of the Yangtze River. Five palaeoflood events recorded by slackwater deposits were identified by the sedimentological criteria and analytical results. A detailed chronological framework of palaeoflood events during the late Holocene was established by optically stimulated luminescence dating in combination with anthropogenic remains, and with pedo-stratigraphic correlations with well dated Holocene loess-soil profiles within the middle Yangtze River basin. The five palaeoflood events were dated to 2.43±0.18ka, 1.82±0.17ka, 0.94±0.07ka, 0.72±0.06ka and 0.59±0.05ka, respectively. These results are consistent with geological records at other palaeoflood sites and historical flood records along the middle Yangtze River valley. A regional synthesis of the palaeoflood chronology over the last 3000years was compiled along the middle Yangtze River. Extraordinary flood events generally seem to be correlated with late Holocene climatic variability (i.e. Neoglacial cooling, Roman Warm Period, Dark Ages Cold Period, Medieval Climate Anomaly, and Little Ice Age). The high-resolution climatic proxies from stalagmites of the Dongge cave and Heshang cave, ice-cores of the GRIP, the total solar irradiance variations and sunspot number, and ENSO activities suggest that these hydroclimatic events are possibly related to the weaker Asia summer monsoon and the cooling climatic events, as well as the stronger ENSO activities during the late Holocene in the Yangtze River valley. These results provide insights into the response of hydroclimatic system to global change in the large rivers of Asia.

Mapping of Inundation Damage Prediction using GIS Technology

For the purposes of this study, to prepare for emergencies on domestic demand inundation and the breaking of an river levee by extraordinary flood and local torrential rainfalls, producing a inundation damage prediction map through the analysis result of external demand inundation in inland and demand inundation data. This is in order to protect their lives and property through a rapid deal with residents of the damaged district. To calculate these aspects of flooding scope efficiently, in case of actual inundation Gangneung City Gangwon Province were studied to reflect the extent of damage by frequency using one-dimensional HEC-RAS model and tow-dimensional XP-SWMM. Based on the CAD and GIS, which is presented through this study or existing similar research, using Arcmap program that can be create frequency map. Further, in order to reflect the target area we are scanning the high-resolution satellite images in the flooded region with more enhanced the accuracy and emphasis on increasing the utilization of a more efficient flood damage prediction map to the downtown area.

PETROGLYPHS OF KHABAROVSK TERRITORY: THE IMPACT OF THE 2013 AMUR AND USSURI FLOODING

The Sikachi-Alyan and Sheremetyevo rock art sites are in the province of Lower Amur and Ussuri rock art. A history of their discovery is sketched, and their state of preservation is described. In 2013, many of them were damaged by extraordinary flooding. The effects of water and temperature fluctuations and of wind erosion are assessed. In Sikachi-Alyan, the main factors of rock art decay were silting of boulders with petroglyphs, and their displacement caused by seasonal rise of water-level and ice-drift. In Sheremetyevo, destruction resulted mainly from bioagents. The removal of lichen revealed new petroglyphs, and known ones were recorded in details. Boulders with rare zoomorphic and anthropomorphic petroglyphs were discovered in the riverside bush and on the floodplain terrace.

Holocene climatic events recorded in palaeoflood slackwater deposits along the middle Yiluohe River valley, middle Yellow River basin, China

Palaeohydrological investigations were carried out in the middle reaches of the Yiluohe River, a major tributary in the lower–middle Yellow River basin. Typical palaeoflood slackwater deposits (SWDs) were identified in the Holocene pedostratigraphy on the cliffy river banks. Analytical results, including magnetic susceptibility and grain-size distribution data, indicated that these SWDs were deposited from the suspended sediment load in flood water. These SWDs are different from eolian loess, soils and aeolian sands in the riverbank profile. They recorded several episodes of extraordinary palaeoflood events. In the Longmenxia reaches of the Yihe River valley, these flood events were dated at 3100–3000a, 1800–1700a, 770–610a, and 420–340a using the optically stimulated luminescence method in combination with the pedostratigraphic correlations. In the Longhutan reaches of the Luohe River valley, the palaeoflood events were dated at 1975–1466a, i.e., from the Han to Wei dynasties (AD 25–534), during which the capital city on the river banks was flooded many times, as recorded in the literature. These extraordinary flood events are well correlated chronologically with the known Holocene climatic events that occurred in the Northern Hemisphere. Thus, the monsoonal climate was highly variable with both floods and droughts occurring frequently during these episodes. These results are important for understanding the response of river systems in eastern Asia to global changes.

Half a century of changes in the riverine landscape of Limay River: the origin of a riparian neoecosystem in Patagonia (Argentina)

Our study aims to determine the dynamic that led to the spread of exotic Salicaceae on the Limay River floodplain and its implications in shaping the current neoecosystem. We used images obtained by the HRG sensor on board the SPOT-5 satellite. We selected two images dates allowed a comparison of the floodplain under different flooding regimes programmed by the Interjuridiccional Basin Authority, at a rate of 1290 m3/s in Spring and a flow rate of less than 400 m3/s in Summer. To characterize the vegetation cover, the Normalized Difference Vegetation Index (NDVI) was used to compare images of September and December, also the Normalized Difference Water Index (NDWI) was applied to delineate the riverbed and floodplain in September. To evaluate the influence of flooding regime on the detected patches a Principal Component Analysis (PCA), was performed; and biotic and abiotic factors on the composition of the dominant tree species in each patch by Multiple Factor Analysis (MFA) were analized. A 58.4 % coverage of forest patches had developed on the Limay River floodplain. Patches of older trees grew on surfaces at 1.5 m above the water level. However, the surfaces not reached by floods >1.5 m have a very low rocky coverage (1 %). The analysis of the age of the trees downstream of the dam system showed that the vegetation, often exposed to high floods before the dams were built (1971), was composed of the native willow (Salix humboldtiana) and the exotic Salix alba. As the river regime was attenuated and extraordinary floods disappeared with the operation of the dam Arroyito in 1980, the first patches of Populus nigra spread.

Dynamics of an upland stream fish community over 40 years: trajectories and support for the loose equilibrium concept

Previous theoretical models and empirical studies suggested that communities can exist in a "stochastic" or "loose" equilibrium, diverging transiently but eventually returning toward earlier or average structure, in what we call here the "loose equilibrium concept" (LEC). We sampled the fish communities at 12 local stream reaches spaced broadly throughout a relatively undisturbed watershed in the Ozark Mountains of northern Arkansas, USA, in 11 surveys from 1972 to 2012 at a scale of decades, and at a subset of five of these local sites in a total of 16 surveys, allowing tests of the LEC at different spatial and temporal scales. Multivariate analyses of the dynamics of communities over the 40-year period provided support for the LEC at both "global" and "local" scales within the watershed. At the broadest spatial scale, core species numerically dominated the community, and most common species remained so across all decades. In spite of two extraordinary floods, and interannual variation in abundance of some species, the 12-site and five-site global communities and eight of 12 local communities repeatedly returned toward average positions in multivariate space. Trajectories of the global and local fish communities varied relative to model hypothetical trajectories that were based on gradual vs. saltatory changes, and prevalence of returns toward average community structure. Beta diversity among sites was variable across time, but beta partitioning consistently showed that pure spatial turnover dominated over nestedness, because many common species were consistently distributed either upstream or downstream. This study suggests that vertebrate communities in relatively undisturbed environments may display dynamics consistent with the LEC. The LEC, combined with quantification of community trajectory patterns, can help to clarify whether systems are moving about within ranges of conditions that reflect expected noise, or, conversely, have moved so far out of previous bounds, as a result of climate change or human intervention, that they are permanently changed or "novel."

La riada del Turia de 1731. Una aproximación a la literatura de la catástrofe

Los sucesos naturales de carácter extraordinario que se han sucedido a lo largo de la historia han dejado tras de sí un gran legado documental. Fenómenos como los terremotos, las erupciones volcánicas, las sequías, las plagas, etc. han constituido desde siempre un motivo de preocupación para las poblaciones expuestas y una ocasión para desatar la imaginación de los cronistas. En el caso de la ciudad de Valencia, ningún fenómeno natural ha influido tanto en su historia como las avenidas recurrentes del río Turia. Una de ellas, la riada extraordinaria de septiembre de 1731, quedó registrada en documentos de todo tipo que pueden englobarse bajo la denominación común de literatura de la catástrofe. En este artículo se analizan cuatro relaciones impresas del suceso y dos dietarios personales manuscritos, en un intento de ampliar los datos conocidos del desastre y, sobre todo, de enmarcarlo en el contexto social y político en el que tuvo lugar.

Historical floods in Tabasco and Chiapas during sixteenth–twentieth centuries

It is presented a chronology of historical floods during sixteenth–twentieth centuries in the Mexican states of Tabasco and Chiapas. There were 41 historical flooding events during 1528–1948, 16 of them were catastrophic flooding and 25 were extraordinary ones. There were periods of historical floods between 1651–1652, 1676–1677, 1679–1680, 1888–1889, 1927–1929, 1931–1933 and 1940–1944. During the instrumental period (1949–1999) there were only four extraordinary flood events in the Usumacinta River. Most of flood periods coincided with the warm phase of the Atlantic Multidecadal Oscillation (AMO). The flood period of 1940–1944 was as long as the most recent one (2007–2011). Wavelet analysis found flood periodicities of 2.5, 52 and 83 years, but only the last one was statistical significant and their occurrence was in phase with the AMO. Logistic regression showed that AMO index was the most correlated index with flood events. In fact, the odds ratio showed that floods were 1.90 times more likely to occur when AMO index was positive. This regression model predicted correctly 64.70 % of flood occurrences during twentieth century using its flood information only as validation data.