urban flooding

File:Banks Street Kayakers - Mid-City New Orleans flooding July 2019.jpg

There are several types of urban flooding, each with a different cause:

• Pluvial (flooding caused by heavy rain),
• Fluvial (caused by a nearby river overflowing its banks), and
• Coastal flooding (often caused by storm surges).

Different types of urban flooding create different impacts and require different mitigation strategies.{{Cite web |date=2024-05-21 |title=Innovative Flood Mitigation Tactics For Urban Environments |url=https://urban-water.co.uk/innovative-flood-mitigation-tactics-for-urban-environments/ |access-date=2025-02-13 |language=en-US}}{{Cite book |url=https://www.iclr.org/wp-content/uploads/2021/04/ICLR_Flooding_2021.pdf |title=Focus on types of flooding |publisher=Institute for Catastrophic Loss Reduction |location=Canada |pages=2}}

Any activities that enlarge the impermeable surface areas in a city can increase the flood risk. Impermeable surface areas are generated through soil sealing as this reduces drainage options of floodwaters.Dodman, D., B. Hayward, M. Pelling, V. Castan Broto, W. Chow, E. Chu, R. Dawson, L. Khirfan, T. McPhearson, A. Prakash, Y. Zheng, and G. Ziervogel, 2022: [https://www.ipcc.ch/report/ar6/wg2/downloads/report/IPCC_AR6_WGII_Chapter06.pdf Chapter 6: Cities, Settlements and Key Infrastructure]. In: [https://www.ipcc.ch/report/ar6/wg2/ Climate Change 2022: Impacts, Adaptation and Vulnerability. Contribution of Working Group II to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change] [H.-O. Pörtner, D.C. Roberts, M. Tignor, E.S. Poloczanska, K. Mintenbeck, A. Alegría, M. Craig, S. Langsdorf, S. Löschke, V. Möller, A. Okem, B. Rama (eds.)]. Cambridge University Press, Cambridge, UK and New York, NY, USA, pp. 907–1040, doi:10.1017/9781009325844.008.{{rp|925}} As the pace of urbanization accelerates around the world, urban flooding has the potential to affect more people.{{rp|925}}

Some researchers have mentioned the storage effect in urban areas with transportation corridors created by cut and fill. Culverted fills may be converted to impoundments if the culverts become blocked by debris, and flow may be diverted along streets. Several studies have looked into the flow patterns and redistribution in streets during storm events and the implication on flood modelling.{{cite journal |last1=Werner |first1=MGF |last2=Hunter |first2=NM |last3=Bates |first3=PD |year=2006 |title=Identifiability of Distributed Floodplain Roughness Values in Flood Extent Estimation |journal=Journal of Hydrology |volume=314 |issue=1–4 |pages=139–157 |bibcode=2005JHyd..314..139W |doi=10.1016/j.jhydrol.2005.03.012}}

{{See also|Tropical cyclones and climate change}}

Many of the common causes of urban flooding, including storm surges, heavy precipitation, and river overflow, are expected to increase in frequency and severity as climate change intensifies and causes increases in ocean and river levels.{{Cite book |last=Intergovernmental Panel on Climate Change (IPCC) |url=https://www.cambridge.org/core/product/identifier/9781009157896/type/book |title=Climate Change 2021 – The Physical Science Basis: Working Group I Contribution to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. Summary for Policymakers. 31p. |date=2023-07-06 |publisher=Cambridge University Press |isbn=978-1-009-15789-6 |edition=1 |pages=25, 31 |doi=10.1017/9781009157896.001}} In particular, erratic rainfall patterns are expected to increase the frequency and severity of both pluvial flooding (as excessive amounts of rainfall in urban areas and cannot be adequately absorbed by existing drainage systems and pervious areas) and fluvial flooding (as excessive rainfall over a river can cause flooding and overflow, either where it occurs or downstream along the path of the river). The severity of extreme storm events, including hurricanes and other types of tropical cyclones, are also expected to increase.{{Cite journal|last1=Knutson|first1=Thomas R.|last2=McBride|first2=John L.|last3=Chan|first3=Johnny|last4=Emanuel|first4=Kerry|last5=Holland|first5=Greg|last6=Landsea|first6=Chris|last7=Held|first7=Isaac|last8=Kossin|first8=James P.|last9=Srivastava|first9=A. K.|last10=Sugi|first10=Masato|date=2010-02-21|title=Tropical cyclones and climate change|url=http://dx.doi.org/10.1038/ngeo779|journal=Nature Geoscience|volume=3|issue=3|pages=157–163|doi=10.1038/ngeo779|bibcode=2010NatGe...3..157K|issn=1752-0894|hdl=1721.1/62558|hdl-access=free}} Additionally, due to the geographic distribution of developing urban areas, the land area potentially exposed to climate change-related flooding is expected to increase significantly.{{Cite journal|last1=Anderson|first1=Tiffany R.|last2=Fletcher|first2=Charles H.|last3=Barbee|first3=Matthew M.|last4=Romine|first4=Bradley M.|last5=Lemmo|first5=Sam|last6=Delevaux|first6=Jade M.S.|date=2018-09-27|title=Modeling multiple sea level rise stresses reveals up to twice the land at risk compared to strictly passive flooding methods|url=http://dx.doi.org/10.1038/s41598-018-32658-x|journal=Scientific Reports|volume=8|issue=1|page=14484|doi=10.1038/s41598-018-32658-x|pmid=30262891|pmc=6160426|bibcode=2018NatSR...814484A|issn=2045-2322}}

Coastal cities may be particularly affected by sea level rise and higher rainfall intensity.{{rp|925}}

{{excerpt|Effects of climate change#Floods|paragraphs=1-2}}

{{See also|Flood#Negative impacts}}

File:Trapped woman on a car roof during flash flooding in Toowoomba 2.jpg, Queensland, Australia]]

Some of the most obvious impacts of urban flooding are those to human life and to property damage. In 2020, floods caused an estimated 6,000 deaths and caused US$51.3B in damages globally.{{Cite web |date=2021-04-21 |title=2020: the non-COVID Year in Disasters - Global Trends and Perspectives - World {{!}} ReliefWeb |url=https://reliefweb.int/report/world/2020-non-covid-year-disasters-global-trends-and-perspectives |access-date=2024-07-30 |website=reliefweb.int |language=en}} Residents at low-elevated regions are often at risk of inundation, financial loss, and even the loss of lives.

Urban flooding also impacts critical public services, including public transportation systems.{{Cite journal|last1=Suarez|first1=Pablo|last2=Anderson|first2=William|last3=Mahal|first3=Vijay|last4=Lakshmanan|first4=T.R.|date=May 2005|title=Impacts of flooding and climate change on urban transportation: A systemwide performance assessment of the Boston Metro Area|url=http://dx.doi.org/10.1016/j.trd.2005.04.007|journal=Transportation Research Part D: Transport and Environment|volume=10|issue=3|pages=231–244|doi=10.1016/j.trd.2005.04.007|bibcode=2005TRPD...10..231S |issn=1361-9209|url-access=subscription}}{{Cite journal|last1=Chang|first1=Heejun|last2=Lafrenz|first2=Martin|last3=Jung|first3=Il-Won|last4=Figliozzi|first4=Miguel|last5=Platman|first5=Deena|last6=Pederson|first6=Cindy|date=2010-08-31|title=Potential Impacts of Climate Change on Flood-Induced Travel Disruptions: A Case Study of Portland, Oregon, USA|url=http://dx.doi.org/10.1080/00045608.2010.497110|journal=Annals of the Association of American Geographers|volume=100|issue=4|pages=938–952|doi=10.1080/00045608.2010.497110|s2cid=16751304|issn=0004-5608|url-access=subscription}} Traffic congestion can be worsened by urban flood events.{{Cite journal|last1=Zhu|first1=Jingxuan|last2=Dai|first2=Qiang|last3=Deng|first3=Yinghui|last4=Zhang|first4=Aorui|last5=Zhang|first5=Yingzhe|last6=Zhang|first6=Shuliang|date=2018-05-10|title=Indirect Damage of Urban Flooding: Investigation of Flood-Induced Traffic Congestion Using Dynamic Modeling|journal=Water|volume=10|issue=5|pages=622|doi=10.3390/w10050622|issn=2073-4441|doi-access=free|bibcode=2018Water..10..622Z |hdl=1983/a361dcd5-80d9-4033-a831-59f916bbe1a2|hdl-access=free}}

{{See also|Flood#Economic impacts}}

File:Houses in Corinda flooded during 2022 Brisbane flood, 05.jpg flooded during 2022 eastern Australia floods]]

The IPCC summarized the current research regarding economic impacts as follows (as of 2022): "economic risks associated with future surface water flooding in towns and cities are considerable."{{rp|925}} This is explained as part of the dynamic Interaction of urban systems with climate.{{rp|922}}

Urban flooding has significant economic implications. In the US, industry experts estimate that wet basements can lower property values by 10%-25% and are cited among the top reasons for not purchasing a home.{{cite web |url=http://www.cnt.org/media/CNT_PrevalenceAndCostOfUrbanFlooding.pdf |title=The Prevalence and Cost of Urban Flooding |date=May 2013 |publisher=Center for Neighborhood Technology |location=Chicago, Illinois}}. According to the U.S Federal Emergency Management Agency (FEMA), almost 40% of small businesses never reopen their doors following a flooding disaster.{{cite web |publisher=Federal Emergency Management Agency (U.S.). |title=Protecting Your Businesses |date=March 2013 |url=http://www.fema.gov/protecting-yourbusinesses |url-status=dead |archive-url=https://archive.today/20130917193030/http://www.fema.gov/protecting-yourbusinesses|archive-date=2013-09-17}} In the UK, urban flooding is estimated to cost £270 million a year in England and Wales; 80,000 homes are at risk.Parliamentary Office of Science and Technology, London, UK. [http://www.parliament.uk/documents/post/postpn289.pdf "Urban Flooding."] Postnote 289, July 2007

A study of Cook County, Illinois, identified 177,000 property damage insurance claims made across 96% of the county's ZIP codes over a five-year period from 2007 to 2011. This is the equivalent of one in six properties in the County making a claim. Average payouts per claim were $3,733 across all types of claims, with total claims amounting to $660 million over the five years examined.

Urban flooding can also create far-reaching supply chain issues,{{Cite journal |last1=Ohmori |first1=Shunichi |last2=Yoshimoto |first2=Kazuho |date=2013-06-30 |title=A Framework of Managing Supply Chain Disruption Risks Using Network Reliability |journal=Industrial Engineering and Management Systems |volume=12 |issue=2 |pages=103–111 |doi=10.7232/iems.2013.12.2.103 |issn=1598-7248 |s2cid=167979543 |doi-access=free}}{{Cite journal |last=Jongman |first=Brenden |date=2018-05-29 |title=Effective adaptation to rising flood risk |url=http://dx.doi.org/10.1038/s41467-018-04396-1 |journal=Nature Communications |volume=9 |issue=1 |page=1986 |bibcode=2018NatCo...9.1986J |doi=10.1038/s41467-018-04396-1 |issn=2041-1723 |pmc=5974412 |pmid=29844334}} which can create significant interruptions in the availability of goods and services, as well as financial losses for businesses.

Between 1961 and 2020, nearly 10,000 cases were reported with 1.3 million deaths and a minimum of US$3.3 trillion of financial losses at an equivalent loss rate of almost US$1800 per second. On average, the total reported deaths worldwide were around 23,000/year for the past 6 decades at an equivalent rate of one death every 24 min.{{Cite journal |last1=Ling |first1=Lloyd |last2=Lai |first2=Sai Hin |last3=Yusop |first3=Zulkifli |last4=Chin |first4=Ren Jie |last5=Ling |first5=Joan Lucille |date=Jan 2022 |title=Formulation of Parsimonious Urban Flash Flood Predictive Model with Inferential Statistics |journal=Mathematics |language=en |volume=10 |issue=2 |pages=175 |doi=10.3390/math10020175 |doi-access=free}}

{{See also|Flood#Mathematical models and computer tools}}

Flood modeling is often conducted in a very localized fashion, with hydrological models created for individual municipalities and incorporating details about buildings, infrastructure, vegetation, land use, and drainage systems.{{Cite journal|last1=Rosenzweig|first1=B. R.|last2=Cantis|first2=P. Herreros|last3=Kim|first3=Y.|last4=Cohn|first4=A.|last5=Grove|first5=K.|last6=Brock|first6=J.|last7=Yesuf|first7=J.|last8=Mistry|first8=P.|last9=Welty|first9=C.|last10=McPhearson|first10=T.|last11=Sauer|first11=J.|date=2021|title=The Value of Urban Flood Modeling|journal=Earth's Future|language=en|volume=9|issue=1|pages=e2020EF001739|doi=10.1029/2020EF001739|bibcode=2021EaFut...901739R|s2cid=234311646|issn=2328-4277|doi-access=free|hdl=11603/20943|hdl-access=free}} This localized modeling can be very useful, especially when paired with historical data, in predicting which specific locations (e.g. streets or intersections) will be the most impacted during a flood event and can be helpful in designing effective mitigation systems specific to local needs.

Flood flows in urban environments have been investigated relatively recently despite many centuries of flood events.{{cite book |last1=Brown |first1=Richard |url=http://espace.library.uq.edu.au/view/UQ:243550 |title=Turbulent Velocity and Suspended Sediment Concentration Measurements in an Urban Environment of the Brisbane River Flood Plain at Gardens Point on 12–13 January 2011 |last2=Chanson |first2=Hubert |author-link2=Hubert Chanson |last3=McIntosh |first3=Dave |last4=Madhani |first4=Jay |publisher=The University of Queensland, School of Civil Engineering |year=2011 |isbn=978-1-74272-027-2 |series=Hydraulic Model Report No. CH83/11 |location=Brisbane, Australia |pages=4}} Some researchers mentioned the storage effect in urban areas. Several studies looked into the flow patterns and redistribution in streets during storm events and the implication in terms of flood modelling.{{cite journal |last1=Werner |first1=M.G.F. |last2=Hunter |first2=N.M. |last3=Bates |first3=P.D. |date=November 2005 |title=Identifiability of distributed floodplain roughness values in flood extent estimation |journal=Journal of Hydrology |volume=314 |issue=1–4 |pages=139–157 |bibcode=2005JHyd..314..139W |doi=10.1016/j.jhydrol.2005.03.012}} Some recent research considered the criteria for safe evacuation of individuals in flooded areas.{{cite book |last1=Chanson |first1=Hubert |title=Hydraulic structures and society - Engineering challenges and extremes |last2=Brown |first2=R. |last3=McIntosh |first3=D. |year=2014 |isbn=978-1-74272-115-6 |pages=1–9 |chapter=Human body stability in floodwaters: The 2011 flood in Brisbane CBD |doi=10.14264/uql.2014.48 |chapter-url=https://eprints.qut.edu.au/88693/1/88693.pdf}} But some recent field measurements during the 2010–2011 Queensland floods showed that any criterion solely based upon the flow velocity, water depth or specific momentum cannot account for the hazards caused by the velocity and water depth fluctuations. These considerations ignore further the risks associated with large debris entrained by the flow motion.

The curve number (CN) rainfall–runoff model is widely adopted. However, it had been reported to repeatedly fail in consistently predicting runoff results worldwide. Unlike the existing antecedent moisture condition concept, one of the recent studies preserved the parsimonious curve number runoff predictive basic framework for model calibration according to different watershed's saturation conditions under guidance from inferential statistics. The study also showed that the existing CN runoff predictive model was not statistically significant without recalibration. CN runoff predictive model can be calibrated according to regional rainfall-runoff dataset for urban flash flood prediction.

Climate change has intensified extreme weather events across the globe, including unseasonal and heavy rainfall during months traditionally considered dry or pre-monsoon. For instance, cities worldwide are increasingly experiencing intense downpours in months like April and May, contributing to overwhelmed drainage systems and localized urban flooding. Urban infrastructure in many regions remains ill-equipped to handle such unpredictability, leading to frequent waterlogging and damage in densely populated areas.{{Cite web |title=UPSC Coaching in Delhi, IAS Coaching in Delhi - SRIRAMs IAS |url=https://www.sriramsias.com/upsc-daily-current-affairs/urban-floods-causes-and-policy-response-in-india/ |access-date=2025-05-31 |website=www.sriramsias.com}}

Modeling of climate change impacts, on the other hand, is often done from a "top-down", global perspective. While these models can be helpful in predicting worldwide effects of global warming and in raising awareness about large-scale impacts, their spatial resolution is often limited to 25 km or more, making them less helpful for local planners in mitigating the effects of climate change on a street-by-street scale.{{Cite web|last=Setzer|first=Maria|title=Climate Modeling|url=https://www.gfdl.noaa.gov/climate-modeling/|access-date=2021-11-07|website=www.gfdl.noaa.gov|language=en-US}}

Some advocate for an integration of localized hydrological modeling with larger-scale climate modeling, claiming that such integration allows the benefits of both forms of modeling to be realized simultaneously and creates the potential for modeling flooding due to climate change in a way that allows planners to design specific strategies to mitigate it at the local level.{{Cite journal|last1=Cheng|first1=Chingwen|last2=Yang|first2=Y.C. Ethan|last3=Ryan|first3=Robert|last4=Yu|first4=Qian|last5=Brabec|first5=Elizabeth|date=November 2017|title=Assessing climate change-induced flooding mitigation for adaptation in Boston's Charles River watershed, USA|journal=Landscape and Urban Planning|volume=167|pages=25–36|doi=10.1016/j.landurbplan.2017.05.019|issn=0169-2046|doi-access=free|bibcode=2017LUrbP.167...25C }}

Scientists investigate climate change scenarios and their impacts on urban flooding and found that: "For example in the UK, expected annual damages from surface water may increase by £60–200 million for projected 2–4°C warming scenarios; enhanced adaptation actions could manage flooding up to a 2°C scenario but will be insufficient beyond that.{{rp|926}}

{{See also|Flood control|Flood#Protections against floods and associated hazards}}

Flood flows in urban environments have been studied relatively recently despite many centuries of flood events.{{Cite book |last1=Brown |first1=Richard |url=http://espace.library.uq.edu.au/view/UQ:243550 |title=Turbulent Velocity and Suspended Sediment Concentration Measurements in an Urban Environment of the Brisbane River Flood Plain at Gardens Point on 12–13 January 2011 |last2=Chanson |first2=Hubert |last3=McIntosh |first3=Dave |last4=Madhani |first4=Jay |journal=Hydraulic Model Report No. CH83/11 |year=2011 |isbn=978-1-74272-027-2 |page=120 |author-link2=Hubert Chanson |issue=CH83/11}} Some recent research has considered the criteria for safe evacuation of individuals in flooded areas.{{cite book |last1=Chanson |first1=H. |url=https://eprints.qut.edu.au/88693/1/88693.pdf |title=Hydraulic structures and society - Engineering challenges and extremes |last2=Brown |first2=R. |last3=McIntosh |first3=D. |date=26 June 2014 |publisher=Proceedings of the 5th IAHR International Symposium on Hydraulic Structures (ISHS2014) |isbn=978-1-74272-115-6 |editor-last=Toombes |editor-first=L. |location=Brisbane, Australia |pages=1–9 |chapter=Human body stability in floodwaters: The 2011 flood in Brisbane CBD |doi=10.14264/uql.2014.48 |author-link1=Hubert Chanson}}

{{See also|Levee}}

One traditional urban flooding management strategy is building gray infrastructure, which is a set of infrastructure types (including dams and seawalls) traditionally constructed of concrete or other impervious materials and designed to prevent the flow of water. While gray infrastructure can be effective in preventing flooding-related damage{{Cite journal|date=2015-08-07|title=Water security: Gray or green?|url=http://dx.doi.org/10.1126/science.349.6248.584-a|journal=Science|volume=349|issue=6248|pages=584|doi=10.1126/science.349.6248.584-a|pmid=26250669|issn=0036-8075|url-access=subscription}} and can be economically valuable,{{Cite journal|last1=Davlasheridze|first1=Meri|last2=Fan|first2=Qin|date=2019-08-07|title=Valuing Seawall Protection in the Wake of Hurricane Ike|url=http://dx.doi.org/10.1007/s41885-019-00045-z|journal=Economics of Disasters and Climate Change|volume=3|issue=3|pages=257–279|doi=10.1007/s41885-019-00045-z|bibcode=2019EDCC....3..257D |s2cid=201297569|issn=2511-1280}} some models suggest that gray infrastructure may become less effective at preventing flood-related impacts in urban areas in the future as climate change causes flooding intensity and frequency to increase.{{Cite journal|last1=Kim|first1=Yeowon|last2=Eisenberg|first2=Daniel A.|last3=Bondank|first3=Emily N.|last4=Chester|first4=Mikhail V.|last5=Mascaro|first5=Giuseppe|last6=Underwood|first6=B. Shane|date=2017-10-26|title=Fail-safe and safe-to-fail adaptation: decision-making for urban flooding under climate change|url=http://dx.doi.org/10.1007/s10584-017-2090-1|journal=Climatic Change|volume=145|issue=3–4|pages=397–412|doi=10.1007/s10584-017-2090-1|bibcode=2017ClCh..145..397K|s2cid=158494951|issn=0165-0009}}

File:Planning approach of blue-green infrastructure.jpg

An alternative to gray infrastructure is green infrastructure, which refers to a set of strategies for absorbing and storing stormwater at or close to the location where it falls. Green infrastructure includes many types of vegetation, large open areas with pervious surfaces, and even rainwater collection devices.{{Cite web |last=US EPA |first=OW |date=2015-09-30 |title=What is Green Infrastructure? |url=https://www.epa.gov/green-infrastructure/what-green-infrastructure |url-status=dead |archive-url=https://web.archive.org/web/20160216081120/https://www.epa.gov/green-infrastructure/what-green-infrastructure |archive-date=2016-02-16 |access-date=2021-11-07 |website=www.epa.gov |language=en}} Green infrastructure may prove to be an effective and cost-efficient way to reduce the extent of urban flooding.{{Cite journal|last1=Chen|first1=Jingqiu|last2=Liu|first2=Yaoze|last3=Gitau|first3=Margaret W.|last4=Engel|first4=Bernard A.|last5=Flanagan|first5=Dennis C.|last6=Harbor|first6=Jonathan M.|date=2019-05-15|title=Evaluation of the effectiveness of green infrastructure on hydrology and water quality in a combined sewer overflow community|journal=Science of the Total Environment|language=en|volume=665|pages=69–79|doi=10.1016/j.scitotenv.2019.01.416|pmid=30772580|bibcode=2019ScTEn.665...69C|s2cid=73457016|issn=0048-9697|doi-access=free}}

One way urban flooding is commonly mitigated is via urban drainage systems, which transport storm water away from streets and businesses and into appropriate storage and drainage areas. While urban drainage systems help municipalities manage flooding and can be scaled up as population and urban extent increase, these systems may not be sufficient to mitigate additional future flooding due to climate change.{{Cite journal|last1=Skougaard Kaspersen|first1=Per|last2=Høegh Ravn|first2=Nanna|last3=Arnbjerg-Nielsen|first3=Karsten|last4=Madsen|first4=Henrik|last5=Drews|first5=Martin|date=2017-08-18|title=Comparison of the impacts of urban development and climate change on exposing European cities to pluvial flooding|journal=Hydrology and Earth System Sciences|volume=21|issue=8|pages=4131–4147|doi=10.5194/hess-21-4131-2017|bibcode=2017HESS...21.4131S|s2cid=54025209 |issn=1607-7938|doi-access=free}}

{{excerpt|Sustainable drainage system}}

Since the ratio of pervious to impervious surfaces across an area is important in flooding management, understanding and altering land use and the proportion of land allocated to different purposes/use types is important in flood management planning.{{Cite journal|last1=Neupane|first1=Barsha|last2=Vu|first2=Tue M.|last3=Mishra|first3=Ashok K.|date=2021-09-07|title=Evaluation of land-use, climate change, and low-impact development practices on urban flooding|journal=Hydrological Sciences Journal|volume=66|issue=12|pages=1729–1742|doi=10.1080/02626667.2021.1954650|s2cid=238241352|issn=0262-6667|doi-access=free|bibcode=2021HydSJ..66.1729N }}{{Cite journal|last1=Dammalage|first1=T. L.|last2=Jayasinghe|first2=N. T.|date=2019-04-10|title=Land-Use Change and Its Impact on Urban Flooding: A Case Study on Colombo District Flood on May 2016|journal=Engineering, Technology & Applied Science Research|volume=9|issue=2|pages=3887–3891|doi=10.48084/etasr.2578|s2cid=155967894|issn=1792-8036|doi-access=free}} In particular, increasing the percent of land dedicated to open, vegetated space can be helpful in providing an absorption and storage area for storm runoff.{{Cite journal|last1=Kim|first1=Hyomin|last2=Lee|first2=Dong-Kun|last3=Sung|first3=Sunyong|date=2016-01-30|title=Effect of Urban Green Spaces and Flooded Area Type on Flooding Probability|journal=Sustainability|volume=8|issue=2|pages=134|doi=10.3390/su8020134|issn=2071-1050|doi-access=free|bibcode=2016Sust....8..134K }} These areas can often be integrated with existing urban amenities, such as parks and golf courses. Increasing the pervious surface fraction of an urban area (e.g. by planting green walls/roofs or using alternative pervious construction materials) can also help de-risk climate-linked flood events.{{Cite journal|last1=BOYD|first1=M. J.|last2=BUFILL|first2=M. C.|last3=KNEE|first3=R. M.|date=December 1993|title=Pervious and impervious runoff in urban catchments|journal=Hydrological Sciences Journal|volume=38|issue=6|pages=463–478|doi=10.1080/02626669309492699|issn=0262-6667|doi-access=free|bibcode=1993HydSJ..38..463B }}{{Cite journal|last1=Liu|first1=Wen|last2=Chen|first2=Weiping|last3=Peng|first3=Chi|date=November 2014|title=Assessing the effectiveness of green infrastructures on urban flooding reduction: A community scale study|url=http://dx.doi.org/10.1016/j.ecolmodel.2014.07.012|journal=Ecological Modelling|volume=291|pages=6–14|doi=10.1016/j.ecolmodel.2014.07.012|bibcode=2014EcMod.291....6L |s2cid=83502965 |issn=0304-3800|url-access=subscription}}

{{Excerpt|Integrated urban water management|paragraphs=1}}

• Worldwide: List of floods
• Africa: Floods in Africa
• Australia: Floods in Australia
• The Netherlands: Floods in the Netherlands
• United States: Lists of floods in the United States
• North Sea: Storm tides of the North Sea

{{Further|Lists of floods in the United States}}

One of the most well known at-risk urban areas in the United States is New Orleans. Because of its coastal location and low elevation, the city is prone to flooding due to tropical storms, including cyclones and hurricanes and is particularly vulnerable to changes in sea level or storm frequency. In 2005, Hurricane Katrina caused more than 1800 deaths and US$170B in damages.{{Cite web |title=Natural Disasters: Economic Effects of Hurricanes Katrina, Sandy, Harvey, and Irma |url=https://www.gao.gov/products/gao-20-633r |access-date=2021-11-07 |publisher=U. S. Government Accountability Office}} After Katrina, additional flood protections were built with a changing climate in mind; these protections have proved effective in reducing damages due to subsequent extreme weather events, such as Hurricane Ida.{{Cite magazine |last=De La Garza |first=Alejandro |title=Engineers Bent the Rules, and May Have Saved New Orleans |url=https://time.com/6094221/hurricane-ida-engineering-protection/ |access-date=2021-11-07 |magazine=Time}}

During the summer of 2021, Hurricanes Henri and Ida caused significant flooding in many cities along the east coast of the United States.{{Cite web |last1=Alfonso III |first1=Fernando |last2=Hayes |first2=Mike |last3=Jones |first3=Judson |last4=Wagner |first4=Meg |date=2021-08-22 |title=Tropical Storm Henri makes landfall in the Northeast |url=https://www.cnn.com/us/live-news/henri-storm-updates/index.html |access-date=2021-11-07 |website=CNN}}{{Cite web |last=Dewan |first=Angela |date=2 September 2021 |title=Analysis: Ida turns New York City into a front line of climate change-supercharged weather |url=https://www.cnn.com/2021/09/02/world/ida-climate-change-floods-rain-intl/index.html |access-date=2021-11-07 |website=CNN}} In particular, New York City experienced record levels of rainfall, prompting many to question whether the city should implement additional flood protection measures in anticipation of potential future flood events.{{Cite news |last1=McKinley |first1=Jesse |last2=Rubinstein |first2=Dana |last3=Mays |first3=Jeffery C. |date=2021-09-03 |title=The Storm Warnings Were Dire. Why Couldn't New York Be Protected? |url=https://www.nytimes.com/2021/09/03/nyregion/nyc-ida.html |access-date=2021-11-07 |work=The New York Times |issn=0362-4331}} In September 2021, the New York City mayoral office released a new rainfall preparedness plan.{{Cite news |date=2021-09-04 |title=Video: New York's Mayor Outlines Rain-Preparedness Plan |url=https://www.nytimes.com/video/nyregion/100000007956663/new-york-flood-rain-preparedness-ida-de-blasio.html |access-date=2021-11-07 |work=The New York Times |issn=0362-4331}}

{{Portal|Architecture|Engineering|Environment|Water}}

• Climate change adaptation#Flooding
• {{annotated link|Nature-based solutions}}

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Category:Flood control

Category:Stormwater management

Category:Drainage