Hurricane Harvey Warning: You are not logged in. Your IP address will be publicly visible if you make any edits. If you log in or create an account, your edits will be attributed to your username, along with other benefits.Anti-spam check. Do not fill this in! ==Environmental factors== [[File:Large Houston Landsat.jpg|thumb|Houston's very flat topography makes flooding a problem. (Simulated-color image)]] Houston is located in the [[Southeastern United States|southeastern]] United States on the [[Gulf Coastal Plain]], and its [[clay]]-based soils provide poor drainage.<ref name="Gabbatt 2808">{{cite news | author=Adam Gabbatt | title=What makes Houston so vulnerable to serious floods? | website=the Guardian | date=August 28, 2017 | url=https://www.theguardian.com/us-news/2017/aug/28/houston-harvey-risk-floods-analysis | access-date=August 30, 2017 | archive-url=https://web.archive.org/web/20170830012120/https://www.theguardian.com/us-news/2017/aug/28/houston-harvey-risk-floods-analysis | archive-date=August 30, 2017 | url-status=live }}</ref><ref name="Fox 29082017">{{cite news | author=Justin Fox | title=How to Make 500-Year Storms Happen Every Year | publisher=Bloomberg.com | date=August 29, 2017 | url=https://www.bloomberg.com/view/articles/2017-08-29/how-to-make-500-year-storms-happen-every-year | access-date=August 30, 2017 | archive-url=https://web.archive.org/web/20170830013602/https://www.bloomberg.com/view/articles/2017-08-29/how-to-make-500-year-storms-happen-every-year | archive-date=August 30, 2017 | url-status=live }}</ref> There is a tendency for storms to move very slowly over the region, allowing them to produce tremendous amounts of rain over an extended period, as occurred during [[Tropical Storm Claudette (1979)|Tropical Storm Claudette]] in 1979, and [[Tropical Storm Allison]] in 2001.<ref name="NPR.org 28 8 2017">{{cite news | title=How A Warmer Climate Helped Shape Harvey | website=NPR.org | date=August 28, 2017 | url=https://www.npr.org/sections/thetwo-way/2017/08/28/546748502/how-a-warmer-climate-helped-shape-harvey | access-date=August 30, 2017 | archive-url=https://web.archive.org/web/20170830014302/http://www.npr.org/sections/thetwo-way/2017/08/28/546748502/how-a-warmer-climate-helped-shape-harvey | archive-date=August 30, 2017 | url-status=live }}</ref> The area is a very flat flood plain at shallow gradient, slowly draining rainwater through an intricate network of channels and bayous to the sea. The main waterways, the [[San Jacinto River (Texas)|San Jacinto River]] and the [[Buffalo Bayou]], meander slowly, laden with mud, and have little capacity for carrying storm water.<ref name="Vartabedian 2017">{{cite news | author=Ralph Vartabedian | title=For years, engineers have warned that Houston was a flood disaster in the making. Why didn't somebody do something? | website=Los Angeles Times | date=August 29, 2017 | url=http://www.latimes.com/nation/la-na-harvey-engineering-20170828-story.html | access-date=August 31, 2017 | archive-url=https://web.archive.org/web/20170830224854/http://www.latimes.com/nation/la-na-harvey-engineering-20170828-story.html | archive-date=August 30, 2017 | url-status=live }}</ref> ===Urban development=== Houston has seen rapid urban development ([[urban sprawl]]), with absorbent prairie and wetlands replaced by hard surfaces which rapidly shed storm water, overwhelming the drainage capacity of the rivers and channels.<ref name="Fernandez Fausset 2017">{{cite news | author1=Manny Fernandez | author2=Richard Fausset | title=A Storm Forces Houston, the Limitless City, to Consider Its Limits | work=The New York Times | date=August 27, 2017 | url=https://www.nytimes.com/2017/08/30/us/houston-flooding-growth-regulation.html | access-date=August 31, 2017 | archive-url=https://web.archive.org/web/20170831025002/https://www.nytimes.com/2017/08/30/us/houston-flooding-growth-regulation.html | archive-date=August 31, 2017 | url-status=live }}</ref> Between 1992 and 2010, almost 25,000 acres of wetlands were lost, decreasing the detention capacity of the region by four billion gallons.<ref>{{cite web | url=https://qz.com/1064364/hurricane-harvey-houstons-flooding-made-worse-by-unchecked-urban-development-and-wetland-destruction/ | first1=Ana | last1=Campoy | first2=David | last2=Yanofsky | title=Houston's flooding shows what happens when you ignore science and let developers run rampant | date=August 29, 2017 | access-date=September 12, 2017 | archive-url=https://web.archive.org/web/20170912080708/https://qz.com/1064364/hurricane-harvey-houstons-flooding-made-worse-by-unchecked-urban-development-and-wetland-destruction/ | archive-date=September 12, 2017 | url-status=live }}</ref> However, Harvey was estimated to have dropped more than fifteen trillion gallons of water in the area.<ref>{{cite web | url=https://www.strongtowns.org/journal/2017/8/30/houston-hurricane-harvey-land-use | first1=Daniel | last1=Herriges | title=Houston isn't flooded because of its land use planning | date=August 30, 2017 | access-date=September 12, 2017 | archive-url=https://web.archive.org/web/20170912234548/https://www.strongtowns.org/journal/2017/8/30/houston-hurricane-harvey-land-use | archive-date=September 12, 2017 | url-status=live }}</ref> The Katy Prairie in western Harris County, which once helped to absorb floodwaters in the region, has been reduced to one quarter of its previous size in the last several decades due to [[Urban sprawl|suburban development]], and one analysis discovered that more than 7,000 housing units have been built within the 100-year floodplain in Harris County since 2010.<ref>{{cite web |url=http://www.slate.com/articles/business/metropolis/2017/08/houston_wasn_t_built_to_withstand_a_storm_like_harvey.html |title=Houston Wasn't Built for a Storm Like This |author=Henry Grabar |work=[[Slate (magazine)|Slate]] |date=August 27, 2017 |access-date=August 29, 2017 |archive-url=https://web.archive.org/web/20170829025120/http://www.slate.com/articles/business/metropolis/2017/08/houston_wasn_t_built_to_withstand_a_storm_like_harvey.html |archive-date=August 29, 2017 |url-status=live }}</ref> ===Subsidence=== As Houston has expanded, rainwater infiltration in the region has lessened and [[aquifer]] extraction increased, causing the depletion of underground aquifers. When the saturated ground dries, the soil can be compressed and the land surface elevation decreases in a process called [[subsidence]]. Subsidence can also occur due to sediment settling. Specifically, regions to the north and west of the Houston metro have seen {{convert|10|mm|in}} to {{convert|25|mm|in}} of subsidence per year.<ref name="Jiangbo Yu et al">{{cite journal|author = Jiangbo Yu|display-authors=etal|title=Is There Deep-Seated Subsidence in the Houston-Galveston Area?|journal=International Journal of Geophysics|volume=2014|pages=1–11|date=July 2, 2014|doi=10.1155/2014/942834|doi-access=free}}</ref> While oil extraction can cause subsidence, in the Houston-Galveston area, most oil has been extracted from sandstone that has relatively negligible ability to compress once oil has been removed. Thus, oil extraction has not resulted in significant subsidence.<ref name="Jiangbo Yu et al"/> Further, the volume of oil extraction in the Houston area is too low to cause significant subsidence.<ref>{{cite web|title=Oil Wells and Production in Harris County, Texas|url=http://www.texas-drilling.com/harris-county|access-date=December 14, 2017|archive-url=https://web.archive.org/web/20171215111431/http://www.texas-drilling.com/harris-county|archive-date=December 15, 2017|url-status=live}}</ref> ===Climate change=== {{See also|Tropical cyclones and climate change}} The [[Gulf of Mexico]] is known for hurricanes in August, so their incidence alone cannot be attributed to [[global warming]], but the warming climate does influence certain attributes of storms. Studies in this regard show that storms tend to intensify more rapidly prior to landfall.<ref name="Wapo Aug27" /> Weather events are due to multiple factors, and so cannot be said to be caused by one precondition, but climate change affects aspects of extreme events, and very likely worsened some of the impacts of Harvey.<ref name="PIK Research Portal 31 Aug">{{cite web | author=Stefan Rahmstorf | author-link=Stefan Rahmstorf | title=Storm Harvey: impacts likely worsened due to global warming | website=[[Potsdam Institute for Climate Impact Research]] Research Portal | url=https://www.pik-potsdam.de/news/in-short/storm-harvey-impacts-worsened-due-to-global-warming | access-date=August 31, 2017 | archive-url=https://web.archive.org/web/20170831070041/https://www.pik-potsdam.de/news/in-short/storm-harvey-impacts-worsened-due-to-global-warming | archive-date=August 31, 2017 | url-status=live }}</ref> In a briefing, the [[World Meteorological Organization]] stated that the quantity of rainfall from Harvey had very likely been increased by climate change.<ref name="Miles Aug 29 2017">{{cite news | author=Tom Miles | title=Storm Harvey's rainfall likely linked to climate change: U.N. | agency=Reuters U.K. | date=August 29, 2017 | url=https://uk.reuters.com/article/us-storm-harvey-un-idUKKCN1B919O | access-date=August 31, 2017 | archive-url=https://web.archive.org/web/20170831072346/https://uk.reuters.com/article/us-storm-harvey-un-idUKKCN1B919O | archive-date=August 31, 2017 | url-status=live }}</ref> Harvey approached Houston over sea-surface waters which were significantly above average temperatures. Warm waters provide the main source of energy for hurricanes, and increased ocean heat can result in storms being larger, more intense and longer lasting, in particular bringing greatly increased rainfall.<ref name="Atlantic2717">{{cite news|url=https://www.theatlantic.com/science/archive/2017/08/did-climate-change-intensify-hurricane-harvey/538158|date=August 27, 2017|work=The Atlantic|title=Did Climate Change Intensify Hurricane Harvey?|access-date=August 28, 2017|archive-url=https://web.archive.org/web/20170828193702/https://www.theatlantic.com/science/archive/2017/08/did-climate-change-intensify-hurricane-harvey/538158/|archive-date=August 28, 2017|url-status=live}}</ref><ref name="Wapo Aug27">{{cite news|url=https://www.washingtonpost.com/news/energy-environment/wp/2017/08/25/what-you-can-and-cant-say-about-climate-change-and-hurricane-harvey|title=What you can and can't say about climate change and Hurricane Harvey|date=August 27, 2017|newspaper=The Washington Post|access-date=August 30, 2017|archive-url=https://web.archive.org/web/20170830230225/https://www.washingtonpost.com/news/energy-environment/wp/2017/08/25/what-you-can-and-cant-say-about-climate-change-and-hurricane-harvey/|archive-date=August 30, 2017|url-status=live}}</ref> [[Sea level rise]] added to the resulting problems.<ref name="PIK Research Portal 31 Aug" /> According to officials from the Harris County Flood Control District, Harvey caused the third '500-year' flood in three years.<ref name="Wapo30Aug3rd500Event">{{cite news|url=https://www.washingtonpost.com/news/wonk/wp/2017/08/29/houston-is-experiencing-its-third-500-year-flood-in-3-years-how-is-that-possible|title=Houston is experiencing its third '500-year' flood in 3 years. How is that possible?|date=August 30, 2017|newspaper=The Washington Post|access-date=August 30, 2017|archive-url=https://web.archive.org/web/20170831044940/https://www.washingtonpost.com/news/wonk/wp/2017/08/29/houston-is-experiencing-its-third-500-year-flood-in-3-years-how-is-that-possible/|archive-date=August 31, 2017|url-status=live}}</ref><ref>{{cite news|url=https://www.npr.org/sections/thetwo-way/2017/09/08/549280066/hurricanes-are-sweeping-the-atlantic-whats-the-role-of-climate-change|title=Hurricanes Are Sweeping The Atlantic. What's The Role Of Climate Change?|first=Christpher|last=Joyce|work=[[NPR]]|publisher=National Public Radio|location=Washington, D.C.|date=September 8, 2017|access-date=September 9, 2017|archive-url=https://web.archive.org/web/20170909052329/http://www.npr.org/sections/thetwo-way/2017/09/08/549280066/hurricanes-are-sweeping-the-atlantic-whats-the-role-of-climate-change|archive-date=September 9, 2017|url-status=live}}</ref><ref>{{cite news|url=https://www.theatlantic.com/science/archive/2017/08/did-climate-change-intensify-hurricane-harvey/538158/|title=Did Climate Change Intensify Hurricane Harvey?|first=Robinson|last=Meyer|work=[[The Atlantic]]|location=Washington, D.C.|date=August 27, 2017|access-date=September 9, 2017|archive-url=https://web.archive.org/web/20170911154824/https://www.theatlantic.com/science/archive/2017/08/did-climate-change-intensify-hurricane-harvey/538158/|archive-date=September 11, 2017|url-status=live}}</ref> The [[National Climate Assessment]] states:{{blockquote|The recent increases in activity are linked, in part, to higher sea surface temperatures in the region that Atlantic hurricanes form in and move through. Numerous factors have been shown to influence these local sea surface temperatures, including natural variability, human-induced emissions of heat-trapping gases, and particulate pollution. Quantifying the relative contributions of natural and human-caused factors is an active focus of research.<ref>{{cite web|url=http://nca2014.globalchange.gov/highlights/report-findings/extreme-weather#intro-section-2|title=Extreme Weather|publisher=National Climate Assessment|access-date=August 30, 2017|archive-url=https://web.archive.org/web/20170830052059/http://nca2014.globalchange.gov/highlights/report-findings/extreme-weather#intro-section-2|archive-date=August 30, 2017|url-status=live}}</ref>}} Warmer air can hold more water vapor, in accordance with the [[Clausius–Clapeyron relation]], and there has been a global increase of daily rainfall records.<ref name="PIK Research Portal 31 Aug" /> Regional [[sea surface temperature]]s around Houston have risen around 0.5 °C (0.9 °F) in recent decades, which caused a 3–5% increase in moisture in the atmosphere. This had the effect of allowing Harvey to strengthen more than expected.<ref name="Mann2817">{{cite news | author=Michael E. Mann | author-link=Michael E. Mann | title=It's a fact: climate change made Hurricane Harvey more deadly | website=the Guardian | date=August 28, 2017 | url=https://www.theguardian.com/commentisfree/2017/aug/28/climate-change-hurricane-harvey-more-deadly | access-date=August 28, 2017 | archive-url=https://web.archive.org/web/20170828142032/https://www.theguardian.com/commentisfree/2017/aug/28/climate-change-hurricane-harvey-more-deadly | archive-date=August 28, 2017 | url-status=live }}</ref> The water temperature of the Gulf of Mexico was above average for this time of the year, and likely to be a factor in Harvey's impact.<ref>{{cite news|url=https://www.nytimes.com/2017/08/28/climate/how-hurricane-harvey-became-so-destructive.html|date=August 28, 2017|title=How Hurricane Harvey Became So Destructive|work=The New York Times|access-date=August 28, 2017|archive-url=https://web.archive.org/web/20170828192049/https://www.nytimes.com/2017/08/28/climate/how-hurricane-harvey-became-so-destructive.html|archive-date=August 28, 2017|url-status=live}}</ref> Within a week of Harvey, [[Hurricane Irma]] formed in the eastern Atlantic, due to the similar conditions involving unusually warm seawater. Some scientists fear this may be becoming a 'new normal'. Also higher sea-water temperatures can make hurricanes more devastating.<ref>{{cite news|url=https://www.theguardian.com/world/2017/sep/06/twin-megastorms-irma-harvey-scientists-fear-new-normal|title=Twin megastorms have scientists fearing this may be the new normal|first=Jonathan|last=Watts|work=[[The Guardian]]|location=[[Kings Place]], London|date=September 6, 2017|access-date=September 9, 2017|archive-url=https://web.archive.org/web/20170909022026/https://www.theguardian.com/world/2017/sep/06/twin-megastorms-irma-harvey-scientists-fear-new-normal|archive-date=September 9, 2017|url-status=live}}</ref> The slow movement of Harvey over Texas allowed the storm to drop prolonged heavy rains on the state, as has also happened with earlier storms.<ref name="NPR.org 28 8 2017" /> Harvey's stalled position was due to weak prevailing winds linked to a greatly expanded subtropical high pressure system over much of the US at the time, which had pushed the jet stream to the north. Research and model simulations have indicated an association between this pattern and human-caused climate change.<ref name="Mann2817" /><ref name="Mann Rahmstorf Kornhuber Steinman p=45242">{{cite journal | author1=Michael E. Mann | author2=Stefan Rahmstorf | author3=Kai Kornhuber | author4=Byron A. Steinman | author5=Sonya K. Miller | author6=Dim Coumou | title=Influence of Anthropogenic Climate Change on Planetary Wave Resonance and Extreme Weather Events | journal=Scientific Reports | publisher=Springer Nature | volume=7 | date=March 27, 2017 | issn=2045-2322 | doi=10.1038/srep45242 | page=45242| bibcode=2017NatSR...745242M | pmc=5366916 | pmid=28345645 }}</ref> Summary: Please note that all contributions to Christianpedia may be edited, altered, or removed by other contributors. If you do not want your writing to be edited mercilessly, then do not submit it here. 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