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.

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.

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.

The Flood Mapping Team within NRCan’s Canada Centre for Mapping and Earth Observation (CCMEO) has completed the digitization of these approximately 1400 historical flood events. By scraping publication records for flood event details, they created a publicly available data layer consisting of point data with attributes for flood location, years/seasons, and details. Sources are available for every point. The maps can be a starting point for understanding regional flood trends or for training machine learning models for predicting nation-wide flood risk.CCMEO’s Flood Mapping Team is advancing flood mapping practices in Canada by leading the Flood Hazard Identification and Mapping Program, compiling existing flood hazard data through the National Flood Hazard Data Layer, digitizing historical flood maps, publishing flood mapping guidelines, and researching innovative ways to advance flood mapping practices relating to geomatics. Overall, the modernization of flood mapping practices will help communities understand and manage their flood risk.The point groupings correspond to the locations that were affected by the same event. The inventory of past flooding has been compiled from various public sources and standardized into a common data model. Flooding events for which no location was included in the sources are positioned on the place name of the location affected by the flooding. The event positions do not indicate where the flooding occurred. It should be noted that no consultation was conducted with the various providers and stakeholders of historical flood data. Disparities in content between the various sources result in an inconsistent 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.Additional Resources:Historical flood events (HFE) data page on open.canada.caArticle on the historical flood events layerFlood Hazard Identification and Mapping ProgramUpdate Frequency: Ongoing

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.

The Flood Map for Planning (Rivers and Sea) includes several layers of information. This dataset covers Flood Zone 3. It is our best estimate of the areas of land at risk of flooding, when the presence of flood defences are ignored and covers land with a 1 in 100 (1%) or greater chance of flooding each year from Rivers; or with a 1 in 200 (0.5%) or greater chance of flooding each year from the Sea.This dataset is designed to support flood risk assessments in line with Planning Practice Guidance; and raise awareness of the likelihood of flooding to encourage people living and working in areas prone to flooding to find out more and take appropriate action.The information provided is largely based on modelled data and is therefore indicative rather than specific.Locations may also be at risk from other sources of flooding, such as high groundwater levels, overland run off from heavy rain, or failure of infrastructure such as sewers and storm drains.The information indicates the flood risk to areas of land and is not sufficiently detailed to show whether an individual property is at risk of flooding, therefore properties may not always face the same chance of flooding as the areas that surround them. This is because we do not hold details about properties and their floor levels.Information on flood depth, speed or volume of flow is not included.NOTE: We have paused quarterly updates of this dataset. Please visit the “Pause to Updates of Flood Risk Maps” announcement on our support pages for further information. We will provide notifications on the Flood Map for Planning website to indicate where we have new flood risk information. Other data related to the Flood Map for Planning will continue to be updated, including data relating to flood history, flood defences, and water storage areas.

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:

PLEASE NOTE: This dataset has been retired. It has been superseded by https://environment.data.gov.uk/dataset/04532375-a198-476e-985e-0579a0a11b47.The Flood Map for Planning (Rivers and Sea) includes several layers of information. This dataset covers Flood Zone 2 and should not be used without Flood Zone 3. It is our best estimate of the areas of land at risk of flooding, when the presence of flood defences are ignored and covers land between Zone 3 and the extent of the flooding from rivers or the sea with a 1 in 1000 (0.1%) chance of flooding each year. This dataset also includes those areas defined in Flood Zone 3.This dataset is designed to support flood risk assessments in line with Planning Practice Guidance ; and raise awareness of the likelihood of flooding to encourage people living and working in areas prone to flooding to find out more and take appropriate action.The information provided is largely based on modelled data and is therefore indicative rather than specific. Locations may also be at risk from other sources of flooding, such as high groundwater levels, overland run off from heavy rain, or failure of infrastructure such as sewers and storm drains.The information indicates the flood risk to areas of land and is not sufficiently detailed to show whether an individual property is at risk of flooding, therefore properties may not always face the same chance of flooding as the areas that surround them. This is because we do not hold details about properties and their floor levels. Information on flood depth, speed or volume of flow is not included.NOTE: We have paused quarterly updates of this dataset. Please visit the “Pause to Updates of Flood Risk Maps” announcement on our support pages for further information. We will provide notifications on the Flood Map for Planning website to indicate where we have new flood risk information. Other data related to the Flood Map for Planning will continue to be updated, including data relating to flood history, flood defences, and water storage 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.

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.

Heavy rainfall occurred across Louisiana during March 8-19, 2016, as a result of a massive, slow-moving southward dip in the jet stream, which moved eastward across Mexico, then neared the Gulf Coast, funneling deep tropical moisture into parts of the Gulf States and the Mississippi River Valley. The storm caused major flooding in north-central and southeastern Louisiana. Digital flood-inundation maps for a 4.3-mile reach within the community of Monroe near Black Bayou in Ouachita Parish, LA was created by the U.S. Geological Survey (USGS) in cooperation with Federal Emergency Management Agency (FEMA) to support response and recovery operations following a March 8-19, 2016 flood event. The inundation maps depict estimates of the areal extent and depth of flooding corresponding to 4 high-water marks (HWM) identified and surveyed by the USGS following the flood event.

With a risk index score of 9.9, Bangladesh, Egypt, and Vietnam are the top countries worldwide regarding river flood risk, based on their physical exposure to this type of event. Thailand followed a close second, with a risk index score of 9.8. Where are flooding events most common? In 2024, nine out of the top 10 countries in terms of exposure to river flood risk were located in Asia, in particular in the south and eastern regions of the continent. Southeast Asia is prone to frequent and intense flooding events due to several factors, which include low average elevations, high incidence of tropical storms and heavy rains, prolonged monsoons, and underdeveloped flood protection infrastructure. In addition, climate change is also contributing to the increase in frequency and severity of these events. It is estimated that the global population exposed to flooding incidents will increase by 30 percent in a two-degrees-Celsius warming scenario. Record-breaking floods in Pakistan and Bangladesh Amongst the countries most exposed to floods in Southeast Asia, Bangladesh and Pakistan were particularly affected by floods in 2022. Torrential rain and unceasing downpours struck the countries from early June that year, leading to one of the worst flooding events in their history. In Pakistan, the floods have caused more than 1,700 deaths. In Bangladesh, an estimated 7.2 million people were affected by widespread damage to homes, infrastructure, croplands, and sanitation facilities. Overall, Pakistan and Bangladesh had some of the largest populations exposed to flood risk worldwide.

Polygon features representing the observed, derived or estimated inundation extent for floods that have occurred in Victoria. These are not linked to modelled flood data. Confirmed flood observations are derived from the automated and manual processing of data from the sources listed below. Note that while flood observations have manual oversight and corrections during the event, they are based on a point in time and may not necessarily represent the maximum flood extent. -\tAerial photography -\tAIG observation -\tAir observation -\tLinescans -\tGPS -\tGround Observer -\tSatellite imagery interpretations

The derived flood extent is from automated and manual processing of satellite data. This data is usually used to fill in gaps outside of areas covered by confirmed flood observations. Note that this flood extent data was prepared by the SCC Mapping Team for operational use only. It may have missing or incomplete data that could lead to gaps in analysis or visualisations. The dataset does not capture the peak flood extent in all areas. The dataset does not capture the extent of flash flooding. Past and future layers may be added as the data becomes available. List of events included in Supplemental Information

Floods that hit Thailand between June and December 2011 were the most expensive flood disaster recorded since 1900, with economic losses surpassing 60 billion U.S. dollars. Three of the 10 costliest floods in recent history all happened since 2020. China was the country most hit by economic damage in the past century, registering six of the top 10 floods in terms of economic loss.

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. 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 development and generation of the datasets that are published in this data release, were based on the methods and findings of the report: Kohn, M.S. and Patton, T.T., 2018, Flood-Inundation Maps for the South Platte River at Fort Morgan, Colorado, 2018: U.S. Geological Survey Scientific Investigations Report 2018-5114, 14 p., https://doi.org/10.3133/sir20185114. The geospatial datasets contain final versions of the raster and vector geospatial data and related metadata, and the model archive dataset contains all relevant files to document and re-run the surface-water hydraulic model that are discussed in the report. Digital flood-inundation maps for a 4.5-mile reach of the South Platte River at Fort Morgan, Colorado from Morgan County Road 16 to Morgan County 20.5, were created by the U.S. Geological Survey (USGS) in cooperation with the Colorado Water Conservation Board. The flood-inundation maps, which can be accessed through the USGS Flood Inundation Mapping Science web site (https://water.usgs.gov/osw/flood_inundation/), depict estimates of the areal extent and depth of flooding corresponding to select water levels (stages) at USGS streamgage 06759500, South Platte River at Fort Morgan. Current conditions for estimating near-real-time areas of inundation using USGS streamgage information are available through the National Water Information System web interface or the National Weather Service (NWS) Advanced Hydrologic Prediction Service (http:/water.weather.gov/ahps/). Water-profiles were computed for the stream reach by means of a one-dimensional, step-backwater model. The September 15, 2013 and May 20, 2017 floods were used to calibrate the model, and the June 15, 2015 and May 29, 2017 floods were used to independently validate the model. Nine pressure transducers were deployed to record the stage at nine different locations along the reach and to document the floods of May 20 and 29, 2017 at the South Platte River at Fort Morgan streamgage. The calibrated hydraulic model was then used to determine 16 water-surface profiles for flood stages at 1-foot intervals referenced to the streamgage datum and ranging from 12 ft (3.66 m) or below bankfull to 27 ft (8.23 m), which is 1 ft (0.3 m) greater than the highest recorded water level (25.73 ft [7.84 m] on September 15, 2013) at the South Platte River at Fort Morgan streamgage during its period of record and the 2013 flood exceeds the major flood stage of 21.5 ft (6.55 m) by more than 4 ft (1.2 m) as defined by the National Weather Service. The simulated water-surface profiles were then combined with a geographic information system digital elevation model (derived from light detection and ranging) to delineate the area flooded at stages ranging from 12-ft to 27-ft. The availability of these inundation maps, along with internet information regarding the current stage from the USGS streamgage 06759500, South Platte River at Fort Morgan, Colorado, and forecast river stages from the NWS Advanced Hydrologic Prediction Service, provides emergency management personnel and residents with information that is critical for flood response activities such as evacuations and road closures, as well as for post-flood recovery efforts.

Causing economic losses of over 45 billion U.S. dollars (CPI-adjusted), the Great Flood of 1993 was one of the most devastating in U.S. history. With the Midwest frequently flooded, the incidence of flooding events in the North American country is expected to worsen over the next century. In 2023 alone, there were four billion-dollar flooding events across the United States.

In 2023, there were 170 flood disaster events recorded worldwide. This marks a slight decrease from the 176 disasters in 2022 but remains significantly higher than the average 86 floods per year reported in the 1990s. The peak in the past three decades occurred in 2006, with 226 flood disasters.

Devastating human and economic toll Floods continue to take a heavy toll on human lives and economies worldwide. In 2023, approximately 32 million people were impacted by flooding, including injuries and displacement. Although the number of people affected by floods has decreased since the beginning of the century, due in large part to an improvement in flood protection, better warning systems, and forecasting, the economic burden they cause has increased. Economic loss caused by floods amounted to 453 billion U.S. dollars in the past decade, the highest since the 1970s. Five of the ten costliest floods since 1900 have occurred after 2010, underscoring the increasing financial burden of these events.

Regional disparities in flood impact The impact of floods varies significantly across regions. In 2023, Africa bore the brunt of flood-related fatalities, accounting for over 50 percent of global flood deaths. Asia also suffered severely, with over 2,000 casualties in 2023. Southeast Asian countries, including Bangladesh, Vietnam, and Thailand, are among the most exposed to river flood risk worldwide due to factors such as low elevations, frequent tropical cyclones, and prolonged monsoons.