Looking Forward from the Past: Assessing the Potential Flood Hazard and Damage in Polesine Region by Revisiting the 1950 Flood Event

Timely mapping, measuring and impact assessment of flood events are crucial for the coordination of flood relief efforts and the elaboration of flood management and risk mitigation plans. However, this task is often challenging and time consuming with traditional land-based techniques. In this study, Sentinel-1 radar and Landsat images were utilized in collaboration with hydraulic modelling to obtain flood characteristics and land use/cover (LULC), and to assess flood impact in agricultural areas. Furthermore, indirect estimation of the recurrence interval of a flood event in a poorly gauged catchment was attempted by combining remote sensing (RS) and hydraulic modelling. To this end, a major flood event that occurred in Sperchios river catchment, in Central Greece, which is characterized by extensive farming activity was used as a case study. The synergistic usage of multitemporal RS products and hydraulic modelling has allowed the estimation of flood characteristics, such as extent, inundation depth, peak discharge, recurrence interval and inundation duration, providing valuable information for flood impact estimation and the future examination of flood hazard in poorly gauged basins. The capabilities of the ESA Sentinel-1 mission, which provides improved spatial and temporal analysis, allowing thus the mapping of the extent and temporal dynamics of flood events more accurately and independently from the weather conditions, were also highlighted. Both radar and optical data processing methods, i.e., thresholding, image differencing and water index calculation, provided similar and satisfactory results. Conclusively, multitemporal RS data and hydraulic modelling, with the selected techniques, can provide timely and useful flood observations during and right after flood disasters, applicable in a large part of the world where instrumental hydrological data are scarce and when an apace survey of the condition and information about temporal dynamics in the influenced region is crucial. However, future missions that will reduce further revisiting times will be valuable in this endeavor.

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Possible impacts of a hydropower reservoir on the flood hazard of an Alpine valley

10.5194/egusphere-egu2020-10355 ◽

2020 ◽

Author(s):

Katharina Lebiedzinski ◽

Josef Fürst ◽

Karsten Schulz ◽

Mathew Herrnegger

Keyword(s):

Power Plant ◽

Power Plants ◽

Flood Hazard ◽

Policy Coordination ◽

Flood Event ◽

High Mountain ◽

Residential Areas ◽

Alpine Catchments ◽

Flood Dynamics ◽

Flood Retention

High mountain ranges are characterised by steep slopes and high precipitation rates, making Alpine catchments prone to frequent flood events. Fast runoff during heavy rainfall events, sometimes in combination with snow melt events, can cause severe damages in residential areas. Flood retention mainly depends on retention properties of the headwater catchment area and its interaction with the occurring flood regime. However, due to their special characteristics, Alpine catchments are ideal candidates for storage power plants as well. Currently, around 70 storage power plants are operating in Austria. Their large artificial reservoirs alter the flood retention properties in the upper catchment by potentially providing a higher flood peak attenuation, which of course depends on the available storage volume at the time of flooding. Since it already has been reported that climate change driven processes will increase flood intensity and frequency in Austria, it is of particular interest to understand how hydropower reservoirs alter flood dynamics and if they systematically could be used for flood retention in the future.In this study the influence of a storage power plant on flood dynamics is shown for an example in the central Austrian Alps. The chain of analysed reservoirs is situated in the headwaters of the river Salzach, a Danube tributary. Based on observed runoff, the retention potential is analysed by comparing the possible natural flood event and the retained flood event in the catchment influenced by the storage power plant. Then its possible impact on the flood hazard downstream is investigated until the tributary drains into the Danube.&#160;This contribution is part of the interdisciplinary research project &#8220;Policy Coordination in Flood Risk Management&#8221; (PoCo-FLOOD), which is funded by the Earth System Sciences program of the Austrian Academy of Sciences.

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Brief communication: Comparing hydrological and hydrogeomorphic paradigms for global flood hazard mapping

Natural Hazards and Earth System Science ◽

10.5194/nhess-20-1415-2020 ◽

2020 ◽

Vol 20 (5) ◽

pp. 1415-1419 ◽

Cited By ~ 1

Author(s):

Giuliano Di Baldassarre ◽

Fernando Nardi ◽

Antonio Annis ◽

Vincent Odongo ◽

Maria Rusca ◽

...

Keyword(s):

Flood Risk ◽

Flood Hazard ◽

Hazard Mapping ◽

River Flooding ◽

The Past ◽

Floodplain Mapping

Abstract. Global floodplain mapping has rapidly progressed over the past few years. Different methods have been proposed to identify areas prone to river flooding, resulting in a plethora of available products. Here we assess the potential and limitations of two main paradigms and provide guidance on the use of these global products in assessing flood risk in data-poor regions.

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Flash-flood hazard hydro-geomorphic characterization and mapping: analysis of the 2019 and 1994 Francolí river flood effects.

10.5194/egusphere-egu2020-10393 ◽

2020 ◽

Author(s):

Llanos Valera-Prieto ◽

Sergi Cortés ◽

Glòria Furdada ◽

Marta González ◽

Jordi Pinyol ◽

...

Keyword(s):

Preferential Flow ◽

Flash Flood ◽

Flood Hazard ◽

Field Work ◽

Water Levels ◽

Low Flow ◽

Flood Event ◽

Economic Damage ◽

Active Band ◽

Flooded Areas

On October 22, 2019, intense rains took place in Catalonia (292,6 mm in 24 hours at Prades), associated with a meteorological isolated depression at high atmospheric level (DANA in Spanish language). These rains caused a sudden discharge increase and a major flash-flood in the Francol&#237; river (Tarragona, Catalonia, Spain). As a result, the river swept along a large quantity of vegetation, crops and infrastructures, such as bridges, roads, and houses. Unfortunately, the flood caused a considerable economic damage (exceeding 100 million euros), and a loss of six human lives. This area was also affected by the 1994 flood, which produced 10 fatalities and losses worth 17,000 million euros.The Francol&#237; river watershed has an area of 853 km2 and a length of 59 km. The study area stretches for ~20 km along the upper basin, without regulatory infrastructures. It covers the localities of Vimbod&#237;, L&#180;Espluga de Francol&#237;, Montblanc and Vilaverd, with a population of 12,463 people. Downstream Vilaverd, the river crosses the strait of La Riba at the west of the Prades mountains. The Francol&#237; River has low water levels much of the year and a strong seasonal regime. It presents high sediment mobility and large transportation capacity.Orthophotographs, LiDAR and field work data, including GNSS-RTK data of river sections, are fundamental for this hydro-geomorphic analysis. It is performed mostly through classical and stereo-anaglyph photo-interpretation and comparison of the 2019 (post-flood event), 2016 (pre-flood event), 1995 (after the 1994 flood) and 1945-56 orthophotographs (provided by the Geological and Cartographic Institute of Catalonia). The main effects considered are: a) channel migration, cuts or changes in the sinuosity of meanders; b) significant bank erosion; c) pull up and dragging of vegetation; d) channel widening and braiding; e) development of secondary active channels during the flood; f) significant erosive and sedimentary morphologies; g) extension of the flooded areas through ephemeral evidence. From the geomorphological effects of the 2019 and 1994 floods, the Active Band is determined and mapped. This characterization highlights that the Francol&#237; river is, geomorphologically, very active. In consequence, when defining flood hazard zones, hydraulic modelling would not be able to capture the complexity of this system and would produce biased results.Once the Active Band is determined and with the estimation of peak flows in crucial localities, the Preferential Flow Zone (PFZ) can be defined. PFZ is the envelope of the areas where the flow concentrates during major floods or, also, the most frequently flooded areas in minor floods. This zoning allows us to discriminate areas with high and low flow energies, and to identify the margins most prone to erosion. Accordingly, varying levels of flood hazard can be mapped, and flood areas classified.This combined analysis of indicators allows us to characterize the flood hazard more precisely in the studied stretch. The method can serve to better understand and predict the flash-floods associated hydro-geomorphic hazards in these kind of geomorphologically active rivers.The authors thank the financial support from PROMONTEC project (CGL2017-84720-R AEI/FEDER, UE), Spanish MINEICO.

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How Flood Hazard Maps Improve the Understanding of Ecologically Active Floodplains

Water ◽

10.3390/w13070937 ◽

2021 ◽

Vol 13 (7) ◽

pp. 937

Author(s):

Stephanie Natho

Keyword(s):

Human Impacts ◽

Flood Hazard ◽

Nutrient Retention ◽

Water Volume ◽

The European Union ◽

Hazard Maps ◽

The Past ◽

Regulation Functions ◽

Original Size ◽

Flood Hazard Maps

Floodplains are threatened ecosystems and are not only ecologically meaningful but also important for humans by creating multiple benefits. Many underlying functions, like nutrient retention, carbon sequestration or water regulation, strongly depend on regular inundation. So far, these are approached on the basis of what are called ‘active floodplains’. Active floodplains, defined as statistically inundated once every 100 years, represent less than 10% of a floodplain’s original size. Still, should this remaining area be considered as one homogenous surface in terms of floodplain function, or are there any alternative approaches to quantify ecologically active floodplains? With the European Flood Hazard Maps, the extent of not only medium floods (T-medium) but also frequent floods (T-frequent) needs to be modelled by all member states of the European Union. For large German rivers, both scenarios were compared to quantify the extent, as well as selected indicators for naturalness derived from inundation. It is assumed that the more naturalness there is, the more inundation and the better the functioning. Real inundation was quantified using measured discharges from relevant gauges over the past 20 years. As a result, land uses indicating strong human impacts changed significantly from T-frequent to T-medium floodplains. Furthermore, the extent, water depth and water volume stored in the T-frequent and T-medium floodplains is significantly different. Even T-frequent floodplains experienced inundation for only half of the considered gauges during the past 20 years. This study gives evidence for considering regulation functions on the basis of ecologically active floodplains, meaning in floodplains with more frequent inundation that T-medium floodplains delineate.

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Brief communication: Comparing top-down and bottom-up paradigms for global flood hazard mapping

10.5194/nhess-2019-418 ◽

2020 ◽

Author(s):

Giuliano Di Baldassarre ◽

Fernando Nardi ◽

Antonio Annis ◽

Vincent Odongo ◽

Maria Rusca ◽

...

Keyword(s):

Flood Risk ◽

Flood Hazard ◽

Hazard Mapping ◽

Top Down ◽

Bottom Up ◽

The Past ◽

Floodplain Mapping

Abstract. Global floodplain mapping has rapidly progressed over the past few years. Different methods have been proposed to identify areas prone to flooding, resulting into a plethora of freely available products. Here we assess the potential and limitations of two main paradigms, and provide guidance on the use of these global products in assessing flood risk in data-poor regions.

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Flood hazard zonation of upper kolodyne using GIS and multi criteria decision analysis in Mizoram, India

Disaster Advances ◽

10.25303/1412da001012 ◽

2021 ◽

Vol 14 (12) ◽

pp. 1-12

Author(s):

Ch Vabeihmo ◽

Malsawm Tluanga ◽

John Blick ◽

Sathing Sangchungnunga ◽

Francis Zodinthara

Keyword(s):

Geographic Information Systems ◽

Decision Analysis ◽

Flood Control ◽

Flood Hazard ◽

Control Measures ◽

Hazard Zonation ◽

Multi Criteria Decision Analysis ◽

The Past ◽

International Border ◽

Very High

Kolodyne is the largest river in Mizoram. The river originates in Myanmar where it flows in a southerly direction and enters Mizoram where it is called Chhimtuipui river and it becomes the international border between India and Myanmar. The Kolodyne river meets several rivers in Mizoram before it enters Chin State in Myanmar again. The upper Kolodyne river has caused destructive floods recently, however, attempts to delineate the flood hazard zones have not been carried out. This river is a source of livelihood for many families in the region and it had wrecked havoc in the past monsoon seasons with the loss of lives and property. The potential flood hazard zonation of the upper Kolodyne watershed using geographic information systems and multi-criteria decision analysis has revealed that about 40% of the total watershed fall in the high and very high potential zones and flood control measures are needed to be updated.

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Maximum river runoff regime in The North Caucasus under the influence of recent climate change

10.5194/egusphere-egu2020-18161 ◽

2020 ◽

Author(s):

Ivan Durmanov ◽

Ekaterina Rets ◽

Maria Kireeva

Keyword(s):

Extreme Values ◽

Flood Hazard ◽

Water Discharge ◽

Maximum Flow ◽

Positive Trend ◽

North Caucasus ◽

The Past ◽

The North ◽

Recent Climate ◽

Maximum Runoff

Difficult climatic conditions characterized The North Caucasus and high flood hazard in this region. Over the past decades, significant climate changes have occurred, which has influenced the flow of mountain rivers, including the maximum flow. Since the end of the last century, there has been an increase in the number of dangerous floods in the basins of North Caucasus rivers, which led to significant material damage and deaths. In the flood zone were several tens of thousands of houses. In addition, infrastructure facilities were destroyed and hydraulic structures damaged. In this regard, there is an urgent task of analyzing the spatio-temporal changes in the characteristics of the maximum runoff and the factors that determine them.In the course of the study, methods of statistical analysis, geoinformation methods, graphoanalytic, and the method of geographical generalization were used. Calculation of statistical parameters and visualization were carried out using the programming languages R and FORTRAN.The spatial variability of the maximum runoff of the rivers of the North Caucasus over the past 70-80 years was analyzed. The results indicate a predominantly negative trend of maximum water discharge in the highlands of the North Caucasus and a positive in the middle reaches of the Kuban. This is consistent with data on the absence of a positive trend in average annual temperatures in the highlands due to lower temperatures in the winter, as well as with an increase in the number of days with heavy rainfall. The latter factor determined the almost universal increase in interannual variability of maximum expenditures, which indicates an increase in flood hazard throughout the region.An analysis of the characteristics of the flood flow showed that the dependence of floods on precipitation in the mountains manifests itself at extreme values, while for all the main factor is air temperature. The maximum discharge of rain floods tends to increase in foothill areas, while no changes have been detected in the mountains.The results can give a clearer view of the processes of changing the maximum flow, and become the basis for the development of measures to minimize the damage from such natural disasters.This work was financial supported by RFBR (Project 20-35-70024)

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Flood fatality hazard and flood damage hazard: combining multiple hazard characteristics into meaningful maps for spatial planning

Natural Hazards and Earth System Science ◽

10.5194/nhess-15-1297-2015 ◽

2015 ◽

Vol 15 (6) ◽

pp. 1297-1309 ◽

Cited By ~ 12

Author(s):

K. M. de Bruijn ◽

F. Klijn ◽

B. van de Pas ◽

C. T. J. Slager

Keyword(s):

Risk Management ◽

Flood Risk ◽

Spatial Planning ◽

Flood Hazard ◽

Flood Damage ◽

Flood Risk Management ◽

Mitigation Measures ◽

Accurate Information ◽

Hazard Maps ◽

The Past

Abstract. For comprehensive flood risk management, accurate information on flood hazards is crucial. While in the past an estimate of potential flood consequences in large areas was often sufficient to make decisions on flood protection, there is currently an increasing demand to have detailed hazard maps available to be able to consider other risk-reducing measures as well. Hazard maps are a prerequisite for spatial planning, but can also support emergency management, the design of flood mitigation measures, and the setting of insurance policies. The increase in flood risks due to population growth and economic development in hazardous areas in the past shows that sensible spatial planning is crucial to prevent risks increasing further. Assigning the least hazardous locations for development or adapting developments to the actual hazard requires comprehensive flood hazard maps. Since flood hazard is a multi-dimensional phenomenon, many different maps could be relevant. Having large numbers of maps to take into account does not, however, make planning easier. To support flood risk management planning we therefore introduce a new approach in which all relevant flood hazard parameters can be combined into two comprehensive maps of flood damage hazard and flood fatality hazard.

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Hurricane Sandy’s flood frequency increasing from year 1800 to 2100

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1604386113 ◽

2016 ◽

Vol 113 (43) ◽

pp. 12071-12075 ◽

Cited By ~ 64

Author(s):

Ning Lin ◽

Robert E. Kopp ◽

Benjamin P. Horton ◽

Jeffrey P. Donnelly

Keyword(s):

New York ◽

Sea Level ◽

Storm Surge ◽

21St Century ◽

Return Period ◽

Temporal Evolution ◽

Flood Hazard ◽

Flood Frequency ◽

The Past ◽

Probabilistic Projections

Coastal flood hazard varies in response to changes in storm surge climatology and the sea level. Here we combine probabilistic projections of the sea level and storm surge climatology to estimate the temporal evolution of flood hazard. We find that New York City’s flood hazard has increased significantly over the past two centuries and is very likely to increase more sharply over the 21st century. Due to the effect of sea level rise, the return period of Hurricane Sandy’s flood height decreased by a factor of ∼3× from year 1800 to 2000 and is estimated to decrease by a further ∼4.4× from 2000 to 2100 under a moderate-emissions pathway. When potential storm climatology change over the 21st century is also accounted for, Sandy’s return period is estimated to decrease by ∼3× to 17× from 2000 to 2100.

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