The Historic Flood Map is a GIS layer showing the maximum extent of individual Recorded Flood Outlines from river, the sea and groundwater springs that meet a set criteria. It shows areas of land that have previously been subject to flooding in England. This excludes flooding from surface water, except in areas where it is impossible to determine whether the source is fluvial or surface water but the dominant source is fluvial.

The majority of records began in 1946 when predecessor bodies to the Environment Agency started collecting detailed information about flooding incidents, although we hold limited details about flooding incidents prior to this date.

If an area is not covered by the Historic Flood Map it does not mean that the area has never flooded, only that we do not currently have records of flooding in this area that meet the criteria for inclusion. It is also possible that the pattern of flooding in this area has changed and that this area would now flood or not flood under different circumstances. Outlines that don’t meet this criteria are stored in the Recorded Flood Outlines dataset.

The Historic Flood Map takes into account the presence of defences, structures, and other infrastructure where they existed at the time of flooding. It will include flood extents that may have been affected by overtopping, breaches or blockages.

Flooding is shown to the land and does not necessarily indicate that properties were flooded internally.

This record is for Approval for Access product AfA435. Listing of Severe Flood Warnings, Flood Warnings and Flood Alerts issued since the flood warning system went live on January 26th 2006 to the present. This dataset includes flood warnings issued by the Environment Agency. Flood warnings are issued for flooding from rivers and the sea and, for a limited number of locations, for groundwater flooding. There are three flood warning codes and a notification when warnings are removed. These are: - Severe Flood Warning: Severe flooding. Danger to life. - Flood Warning: Flooding is expected. Immediate action required. - Flood Alert: Flooding is possible. Be prepared. - Warning no longer in force: Flood warnings and flood alerts that have been removed in the last 24 hours. Live flood warnings in force are shown on GOV.UK and are available as a separate live feed on GOV.UK.

Flood risk areas display the extent of known historical flood events as well as areas that have a probability of flooding as determined from historical records. The polygon data includes the description of the flood event, the typical causes of the flood and any associated place name keys. The line data indicates the limits of the flood risk mapping information and the 2008 and 2018 flood data. Flood extents for the 2008 and 2018 Lower Saint John River floods are included.

Collection of flood and inundation maps over Queensland at various scales 1893-1974, these show flood levels and probable inundation areas at various flood heights. A number of the map series include key maps.

Note: Each CSV in this series includes basic metadata about each map in the series and a URL to access a high resolution scan of each map.

Recorded Flood Outlines is a GIS layer which shows all our records of historic flooding from rivers, the sea, groundwater and surface water. Each individual Recorded Flood Outline contains a consistent list of information about the recorded flood.

Records began in 1946 when predecessor bodies to the Environment Agency started collecting detailed information about flooding incidents, although we may hold limited details about flooding incidents prior to this date.

The absence of coverage by Recorded Flood Outlines for an area does not mean that the area has never flooded, only that we do not currently have records of flooding in this area.

It is also possible that the pattern of flooding in this area has changed and that this area would now flood or not flood under different circumstances.

The Recorded Flood Outlines take into account the presence of defences, structures, and other infrastructure where they existed at the time of flooding. It includes flood extents that may have been affected by overtopping, breaches or blockages.

Any flood extents shown do not necessarily indicate that properties were flooded internally.

A companion dataset Historic Flood Map contains a subset of these Recorded Flood Outlines which satisfy a certain criteria. Attribution statement: © Environment Agency copyright and/or database right 2018. All rights reserved.

Historically, low-lying land adjacent to rivers and coastlines has been favoured for settlement as they provided sources of fresh water, food, transportation and waste disposal. These areas become affected by flooding during sufficiently heavy or prolonged rainfall, high tides or storm surges and cyclones. In the north-west of the State flooding is most likely to be caused by the summer monsoon or tropical cyclones while floods in the south-west are more likely to occur in response to heavy winter rainfalls. While historical flood records and information extend as far back as 1830, detailed information on peak flood levels is typically limited to the last few decades. This dataset contains the available surveyed peak flood level information for major flood events that have occurred in Western Australia. The flood levels are referenced to the Australian Height Datum (AHD). Note: To see the full scope of the historical flood mapping, 3 dataset layers are required to be loaded in the following order:

Montana DNRC’s Floodplain Mapping Program strives to assist local communities with floodplain mapping needs, identifying and mapping current flood risks, and providing tools to help communities reduce their flood risks and build community resiliency. This is achieved through comprehensive planning, effective outreach, and communication from DNRC mapping and community assistance staff. DNRC works hard to build trust and foster relationships with elected officials, floodplain administrators, and stakeholders.Local communities across Montana work with the Federal Emergency Management Agency (FEMA) and Montana Department of Natural Resources and Conservation (DNRC) to update and produce new floodplain maps. Many of the existing floodplain maps are based on data from the late 1970s. Updated Flood Insurance Rate Maps will provide more accurate, current, and detailed data and mapping of flood risk areas.

Groundwater is the water that soaks into the ground from rain and can be stored beneath the ground. Groundwater floods occur when the water stored beneath the ground rises above the land surface. The Historic Groundwater Flood Map shows the observed peak flood extents caused by groundwater in Ireland. This map was made using satellite images (Copernicus Programme Sentinel-1), field data, aerial photos, as well as flood records from the past. Most of the data was collected during the flood events of winter 2015 / 2016, as in most areas this data showed the largest floods on record.This map is to the scale 1:20,000. This means it should be viewed at that scale. When printed at that scale 1cm on the map relates to a distance of 200m.The map is a vector dataset. Vector data portray the world using points, lines, and polygons (area). The floods are shown as polygons. Each polygon has info about the type of flood, the data source, and the area of the flood.The flood extents were calculated using data and techniques with various precision levels, and as such, it may not show the true historic peak flood extents.The Winter 2015/2016 Surface Water Flooding map shows fluvial (rivers) and pluvial (rain) floods, excluding urban areas, during the winter 2015/2016 flood event, and was developed as a by-product of the historic groundwater flood map.This map is to the scale 1:20,000. This means it should be viewed at that scale. When printed at that scale 1cm on the map relates to a distance of 200m.The map is a vector dataset. The floods are shown as polygons. Each polygon has info about the type of flood, the data source, and the area of the flood.The flood extents were made using remote sensing images (Copernicus Programme Sentinel-1), which covered any site in Ireland every 4-6 days. As such, it may not show the true peak flood extents.The Synthetic Aperture Radar (SAR) Seasonal Flood Maps shows observed peak flood extents which took place between Autumn 2015 and Summer 2021. The maps were made using Synthetic Aperture Radar (SAR) images from the Copernicus Programme Sentinel-1 satellites. SAR systems emit radar pulses and record the return signal at the satellite. Flat surfaces such as water return a low signal. Based on this low signal, SAR imagery can be classified into non-flooded and flooded (i.e. flat) pixels.Flood extents were created using Python 2.7 algorithms developed by Geological Survey Ireland. They were refined using a series of post processing filters. Please read the lineage for more information.The flood maps shows flood extents which have been observed to occur. A lack of flooding in any part of the map only implies that a flood was not observed. It does not imply that a flood cannot occur in that location at present or in the future.This flood extent are to the scale 1:20,000. This means they should be viewed at that scale. When printed at that scale 1cm on the maps relates to a distance of 200m.They are vector datasets. Vector data portray the world using points, lines, and polygons (areas). The flood extents are shown as polygons. Each polygon has information on the confidence of the flood extent (high, medium or low), a flood id and a unique id.The Groundwater Flooding High Probability map shows the expected flood extent of groundwater flooding in limestone regions for annual exceedance probabilities (AEP’s) of 10%, which correspond with a return period of every 10 years. The map was created using groundwater levels measured in the field, satellite images and hydrological models.This map is to the scale 1:20,000. This means it should be viewed at that scale. When printed at that scale 1cm on the map relates to a distance of 200m.The map is a vector dataset. The floods are shown as polygons. Each polygon has info on the data source, and the area of the flood.The flood extents were calculated using remote sensing data and hydrological modelling techniques with various precision levels. As such, it should be used with caution.The Groundwater Flooding Medium Probability map shows the expected flood extent of groundwater flooding in limestone regions for annual exceedance probabilities (AEP’s) of 1%, which correspond with a return period of every 100 years. The map was created using groundwater levels measured in the field, satellite images and hydrological models.This map is to the scale 1:20,000. This means it should be viewed at that scale. When printed at that scale 1cm on the map relates to a distance of 200m.The map is a vector dataset. The floods are shown as polygons. Each polygon has info on the data source, and the area of the flood.The flood extents were calculated using remote sensing data and hydrological modelling techniques with various precision levels. As such, it should be used with caution.The Groundwater Flooding Low Probability map shows the expected flood extent of groundwater flooding in limestone regions for annual exceedance probabilities (AEP’s) of 0.1%, which correspond with a return period of every 1000 years.The map was created using groundwater levels measured in the field, satellite images and hydrological models.This map is to the scale 1:20,000. This means it should be viewed at that scale. When printed at that scale 1cm on the map relates to a distance of 200m.The map is a vector dataset. Vector data portray the world using points, lines, and polygons (area). The floods are shown as polygons. Each polygon has info on the data source, and the area of the flood.The flood extents were calculated using remote sensing data and hydrological modelling techniques with various precision levels. As such, it should be used with caution.

The Global Flood Database contains maps of the extent and temporal distribution of 913 flood events occurring between 2000-2018. For more information, see the associated journal article. Flood events were collected from the Dartmouth Flood Observatory and used to collect MODIS imagery. The selected 913 events are those that were successfully mapped (passed quality control as having significant inundation beyond permanent water) using 12,719 scenes from Terra and Aqua MODIS sensors. Each pixel was classified as water or non-water at 250-meter resolution during the full date range of each flood event and subsequent data products were generated including maximum flood extent ("flooded" band) and the duration of inundation in days ("duration" band). Water and non-water classifications during a flood event include permanent water (here resampling the 30-meter JRC Global Surface Water dataset representing permanent water to 250-meter resolution), which can be masked out to isolate flood water using the "jrc_perm_water" band. Extra data quality bands were added representing cloud conditions during the flood event (e.g., "clear_views" representing the number of clear days the flood was observed between its start and end dates and "clear_perc" representing the percentage of clear day observation of the total event duration in days). Each image in the ImageCollection represents the map of an individual flood. The collection can be filtered by date, country, or Dartmouth Flood Observatory original ID.

Listing of Severe Flood Warnings, Flood Warnings, Update Flood Warnings and Flood Alerts issued since the Floodline Warnings Direct service went live on January 26th 2006 to the present. This dataset includes flood warnings issued by Natural Resources Wales (NRW) from 1 April 2013. Flood Alerts and Warnings are issued for flooding from rivers and the sea . For Flood Alerts this is generally river catchments or stretches of coastline. For Flood Warnings and Severe Flood Warnings this is specific communities or parts of communities. Live flood warnings and alerts can be viewed here. .

The dataset contains the modelled historical flood envelope of the main rivers of the Rhine-Meuse Basin

In the Rhine-Meuse Basin when they were produced: Historical flood: Areas exposed to historical flooding observed in the past

VERBATIM: The flood zone atlas consists of three types of zoning: (the modelled centennial flood,the surface obtained by the hydrogeomorphological method, historical floods. The latter result from different methods and therefore have a different meaning. Any exploitation or representation of these data must be made knowingly with a distinction between the different zonings.

Data produced on the Large Flood Risk Territories (HRT) under the Flood Directive have not been added to previously produced Flood Hazardous Area Atlas (AZI) data. They should be added to supplement the AZI.

This project would compare the 100-year and 500-year floodplains in the area before and after the development of the Timarron Lakes neighborhood. Additionally, this analysis would map and compare the most severe flooding events in the past few decades.

The PHE benchmarks are an important element in the flood risk prevention and information system, as they make it possible to provide a concrete visual and precise element of the threat of major flooding that weighs on a large number of rivers in France. Watch out! The reported historical flood levels are by no means a guarantee that the water level will not rise above. It only testifies to the reality of a prevailing and cyclical risk in the area. To learn more about high water markers and high flood markers, you can visit the major hazards site: Prim.net: link in “Internet Address (URL)”.

Early event detection and response can significantly reduce the societal impact of floods. Currently, early warning systems rely on gauges, radar data, models and informal local sources. However, the scope and reliability of these systems are limited. Recently, the use of social media for detecting disasters has shown promising results, especially for earthquakes. Here, we present a new database for detecting floods in real-time on a global scale using Twitter. The method was developed using 88 million tweets, from which we derived over 10.000 flood events (i.e., flooding occurring in a country or first order administrative subdivision) across 176 countries in 11 languages in just over four years. Using strict parameters, validation shows that approximately 90% of the events were correctly detected. In countries where the first official language is included, our algorithm detected 63% of events in NatCatSERVICE disaster database at admin 1 level. Moreover, a large number of flood events not included in NatCatSERVICE are detected. All results are publicly available on www.globalfloodmonitor.org.

Flood extents and maximum flood maps for flood events of May 2003, Dec 2007, Nov-Dec 2008, May 2010, and Dec 2014, based on a time series of EO SAR data and optical data. The satellite imagery used, and validation and accuracy measures vary by flood event. Please consult the resources for details from respective flood events. This dataset is one of the products produced under the 2014-2016 World Bank (WBG) European Space Agency (ESA) partnership, and is published in the partnership report: Earth Observation for Sustainable Development, June 2016.

Historic Flood Outlines is a spatial dataset which outlines the maximum extent of all recorded individual Historic Flood Events Outlines from river, the sea and groundwater springs and shows areas of land that have previously been subject to flooding in Wales. It is also possible that the pattern of flooding in this area has changed and that this area would now flood under different circumstances. In addition, absence of coverage by the Historic Flood Map for an area does not mean that the area has never flooded, only that we do not currently have records of flooding in this area.

This dataset, created in September 2022, represents the 2022 flood extent inside the Brisbane City Council local government area.This layer contributes to the historic Flood Awareness Map.The Feb 2022 Creek and River flood extent has been generated by Brisbane City Council and does not include the potential overland flow flooding.

Abstract

This dataset and its metadata statement were supplied to the Bioregional Assessment Programme by a third party and are presented here as originally supplied.

Polygon data delineating modelled statistical flood extent with an Average Recurrence Interval (ARI) of 100 years. For historical/actual flood extents, refer to 'Historic_extent' layer. Also known as the 1 in 100 year flood layer, it is used, among other things, in the creation of 'Land Subject to Inundation' areas as used in Planning Scheme Zones. The 1 in 100 year data is not restricted. This data is part of a group of layers depicting a range of statistical ARI extents. Current layers include 5, 10, 20, 30, 50, 100, 200, 500, 1000 year intervals, each in a separate dataset. The layer called EXTENT_PMF represents areas of 'probable maximum flood' and is also part of this group. The data is statistically derived using hydrological models, historic flood extents and heights.

Purpose

Mainly used for municipal planning and risk assessment. The EXTENT_100Y_ARI layer is deemed the most appropriate to use for determining areas at risk of flooding. This layer directly inputs into the Land Subject to Inundation overlay. (LSIO)

Dataset History

Lineage: Primary

Positional Accuracy: Precision: 5m to 100m Initial data, flagged as 'modified = 20000101' varies in accuracy, and should be treated with caution, particularly at scales less than 1:25,000. Data with 'modified' values later than 20000101 are quite accurate and mostly sourced from flood studies. This data is suitable to use at township and parcel level. Reliability field provides clues to the accuracy, where a value of 1 is best and 3 is worst.

Attribute Accuracy: Attributes are verified and should be accurate. Overall reliability of the source material is indicated in RELIABILITY field, where 'HIGH' is good and 'LOW' is poor quality source information.

Logical Consistency: Attributes are consistent with other related layers e.g. flood height contours

Data Source: Flood data dates back to mid 1800s and historically has been predominantly located in DNRE Floodplain Management. Some data is located in Water Authorities.

Completeness: Floodplain Management Unit mapping conventions on definitions of flood mapping height data will be followed.

Additional Metadata: Recommend liaison with Floodplain Management Unit to clarify use of this layer

Refer to mapping reports for each major data capture effort to be kept at DNRE Floodplain Management Unit.

Dataset Citation

Victorian Department of Environment and Primary Industries (2014) Victoria - 1 in 100 Year Flood Extent. Bioregional Assessment Source Dataset. Viewed 05 October 2018, http://data.bioregionalassessments.gov.au/dataset/6e59ed35-3fde-48e3-8135-eb05263ce4aa.

Representation of the causes of flooding events in the form of multiple points. The point groupings correspond to the set of locations that were affected by the same event. The inventory of past flooding events was compiled from various public sources and standardized into a common data model. Sources used are included in the data.

Event locations have been extensively revised to have one location per location reported as affected by the flood. Flood events for which no location was included in the sources used are positioned on the place name of the location affected by the flood. The event positions do not indicate where the flooding occurred. Flood events that affected more than one locality are represented by a multipoint.

For each event after January 1, 1980 caused by a heavy rainfall or a coastal storm , a precipitation analysis document, a precipitation animation and the precipitation data are available. These documents are the result of a collaboration with Environment and Climate Change Canada.

Disclaimer:

It should be noted that no consultation was conducted with the various providers and stakeholders of the historic flood data. Disparities in content among the various sources result in an incomlete product. No warranty is given as to the accuracy or completeness of the information provided. The absence of information does not mean that no flooding has occurred.

Flood maps calculated from space-borne remote sensing Synthetic Aperture Radar (SAR) VV backscatter data during the extreme hydro-meteorological events occurred along the Panaro River . Sentinel 1/TerraSarX SAR data has been processed by a method combining thresholding and segmentation (CThS method). The main idea of CThS is to find some samples which are definitely seeds of the flood water areas. In doing so, a statistical measure of randomness, i.e. entropy filtering, is applied to characterize the texture of the input image. It tries to find locally some pixels, which contain the entropy values of the 3-by-3 neighborhood around the corresponding pixel in the input image. What the local filtering identifies is areas with a significant difference with the surrounding areas. These areas could contain different ground targets, which have the same signature as water. Then histogram thresholding is performed. The histogram of all pixels extracted by filtering is reasonably bimodal so that a suitable threshold value can be determined by fitting a curve to the histogram to separate water and non-water pixels. Having separated water seed points, an active contour segmentation method is used to delineate the full flood extent. The dataset contains flood maps for the dates: 12 and 13 December 2017 and water maps on 20 January 2014 and 8 December 2020. You are not authorized to view this dataset. You may email the responsible party OPERANDUM to request access. Flood maps of historical flood events (Panaro)