Editing Water cycle (section)

==Changes caused by humans==

=== Land Cover and Land Use Changes ===
[[Image:Natural & impervious cover diagrams EPA.jpg|thumb|400px|Relationship between [[impervious surfaces]] and [[surface runoff]]]]
Human activities can alter the water cycle at the local or regional level. This happens due to [[Land development|changes in land use]] and [[land cover]]. Such changes affect "precipitation, evaporation, flooding, groundwater, and the availability of freshwater for a variety of uses".<ref name=":22">Douville, H., K. Raghavan, J. Renwick, R.P. Allan, P.A. Arias, M. Barlow, R. Cerezo-Mota, A. Cherchi, T.Y. Gan, J. Gergis, D.  Jiang, A.  Khan, W.  Pokam Mba, D.  Rosenfeld, J. Tierney, and O.  Zolina, 2021: [https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_Chapter08.pdf Water Cycle Changes]. In [https://www.ipcc.ch/report/ar6/wg1/ Climate Change 2021: The Physical Science Basis. Contribution of Working Group I  to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change] [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, US, pp. 1055–1210, doi:10.1017/9781009157896.010.</ref>{{rp|1153}}

Examples of common land use changes include urbanization, agricultural expansion, and deforestation. These changes can increase soil compaction and impervious surface cover which decrease the infiltration capacity of soils and result in greater surface runoff rates.<ref>{{Cite journal |last1=Sun |first1=Di |last2=Yang |first2=Hong |last3=Guan |first3=Dexin |last4=Yang |first4=Ming |last5=Wu |first5=Jiabing |last6=Yuan |first6=Fenghui |last7=Jin |first7=Changjie |last8=Wang |first8=Anzhi |last9=Zhang |first9=Yushu |date=2018-06-01 |title=The effects of land use change on soil infiltration capacity in China: A meta-analysis |url=https://linkinghub.elsevier.com/retrieve/pii/S0048969718301244 |journal=Science of the Total Environment |volume=626 |pages=1394–1401 |doi=10.1016/j.scitotenv.2018.01.104 |pmid=29898546 |bibcode=2018ScTEn.626.1394S |issn=0048-9697|url-access=subscription }}</ref> Deforestation has local and regional effects; at the local level it reduces soil moisture, evaporation, rainfall, and snowfall; at the regional level it can cause temperature changes that affect that affect rainfall patterns.<ref name=":22" />{{rp|1153}} 

Water management structures such as dams, stormwater drains, and sewage pipes can also alter local hydrologic conditions. Dams can alter natural flow rates, decrease water quality, and lead to a loss of habitat for aquatic species.<ref>{{Cite web |last=Fisheries |first=NOAA |date=2024-10-29 |title=How Dams Affect Water and Habitat on the West Coast {{!}} NOAA Fisheries |url=https://www.fisheries.noaa.gov/west-coast/endangered-species-conservation/how-dams-affect-water-and-habitat-west-coast |access-date=2025-05-01 |website=NOAA |language=en}}</ref> Stormwater drains function to decrease runoff rates, regulate flow rates, and increase groundwater recharge.<ref>{{Cite web |title=Overview of stormwater infiltration - Minnesota Stormwater Manual |url=https://stormwater.pca.state.mn.us/index.php/Overview_of_stormwater_infiltration |access-date=2025-05-01 |website=stormwater.pca.state.mn.us}}</ref> Leakage from sewage pipes may artificially contribute to groundwater recharge, resulting in higher stream baseflow conditions and groundwater contamination.<ref>{{Cite journal |last1=Fletcher |first1=T. D. |last2=Andrieu |first2=H. |last3=Hamel |first3=P. |date=2013-01-01 |title=Understanding, management and modelling of urban hydrology and its consequences for receiving waters: A state of the art |url=https://linkinghub.elsevier.com/retrieve/pii/S0309170812002412 |journal=Advances in Water Resources |series=35th Year Anniversary Issue |volume=51 |pages=261–279 |doi=10.1016/j.advwatres.2012.09.001 |bibcode=2013AdWR...51..261F |issn=0309-1708|url-access=subscription }}</ref> Groundwater depletion, however, remains an ongoing concern as groundwater is being pumped at unsustainable rates to meet municipal, industrial, and agricultural water demands.<ref>{{Cite journal |last1=Jasechko |first1=Scott |last2=Seybold |first2=Hansjörg |last3=Perrone |first3=Debra |last4=Fan |first4=Ying |last5=Shamsudduha |first5=Mohammad |last6=Taylor |first6=Richard G. |last7=Fallatah |first7=Othman |last8=Kirchner |first8=James W. |date=January 2024 |title=Rapid groundwater decline and some cases of recovery in aquifers globally |journal=Nature |language=en |volume=625 |issue=7996 |pages=715–721 |doi=10.1038/s41586-023-06879-8 |pmid=38267682 |pmc=10808077 |bibcode=2024Natur.625..715J |issn=1476-4687}}</ref>

=== Water cycle intensification due to climate change ===
{{Main|Effects of climate change on the water cycle|Effects of climate change on oceans}}
[[File:20211109_Frequency_of_extreme_weather_for_different_degrees_of_global_warming_-_bar_chart_IPCC_AR6_WG1_SPM.svg|thumb|[[Extreme weather]] (heavy rains, [[Drought|droughts]], [[Heat wave|heat waves]]) is one consequence of a [[Effects of climate change on the water cycle|changing water cycle due to global warming]]. These events will be progressively more common as the Earth warms more and more.<ref>IPCC, 2021: [https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_SPM.pdf Summary for Policymakers]. In: [https://www.ipcc.ch/report/ar6/wg1/ Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change] [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, US, pp. 3−32, doi:10.1017/9781009157896.001.</ref>{{rp|Figure SPM.6}}]]
[[File:Soil_moisture_and_climate_change.svg|thumb|Predicted changes in average soil moisture for a scenario of 2°C global warming. This can disrupt agriculture and ecosystems. A reduction in soil moisture by one [[standard deviation]] means that average soil moisture will approximately match the ninth driest year between 1850 and 1900 at that location.]]
Since the middle of the 20th century, human-caused [[climate change]] has resulted in observable changes in the global water cycle.<ref name=":0">Arias, P.A., N. Bellouin, E. Coppola, R.G. Jones, G. Krinner, J. Marotzke, V. Naik, M.D. Palmer, G.-K. Plattner, J. Rogelj, M. Rojas, J. Sillmann, T. Storelvmo, P.W. Thorne, B. Trewin, K. Achuta Rao, B. Adhikary, R.P. Allan, K. Armour, G. Bala, R. Barimalala, S. Berger, J.G. Canadell, C. Cassou, A. Cherchi, W. Collins, W.D. Collins, S.L. Connors, S. Corti, F. Cruz, F.J. Dentener, C. Dereczynski, A. Di Luca, A. Diongue Niang, F.J. Doblas-Reyes, A. Dosio, H. Douville, F. Engelbrecht, V.  Eyring, E. Fischer, P. Forster, B. Fox-Kemper, J.S. Fuglestvedt, J.C. Fyfe, et al., 2021: [https://www.ipcc.ch/report/ar6/wg1/downloads/report/IPCC_AR6_WGI_TS.pdf Technical Summary]. In [https://www.ipcc.ch/report/ar6/wg1/ Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change] [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, US, pp. 33−144. doi:10.1017/9781009157896.002.</ref>{{rp|85}} The [[IPCC Sixth Assessment Report]] in 2021 predicted that these changes will continue to grow significantly at the global and regional level.<ref name=":0" />{{rp|85}} These findings are a continuation of scientific consensus expressed in the [[IPCC Fifth Assessment Report]] from 2007 and other special reports by the [[Intergovernmental Panel on Climate Change]] which had already stated that the water cycle will continue to intensify throughout the 21st century.<ref name=":22" />

{{excerpt|Effects of climate change on the water cycle|paragraphs=1-3|file=no}}