urban stream

File:Hobart Rivulet Underground.jpg in Tasmania, run underground for substantial distances]]

Governments may alter the flow or course of an urban stream to prevent localized flooding by river engineering: lining stream beds with concrete or other hardscape materials, diverting the stream into culverts and storm sewers, or other means. Some urban streams, such as the subterranean rivers of London, run completely underground. These modifications have often reduced habitat for fish and other species, caused downstream flooding due to alterations of flood plains, and worsened water quality.{{cite report |date=July 2007 |title=National Management Measures to Control Nonpoint Source Pollution from Hydromodification |url=https://www.epa.gov/nps/hydromodification-and-habitat-alteration-national-management-measures |publisher=U.S. Environmental Protection Agency (EPA) |location=Washington, DC |id=EPA 841-B-07-002}}

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Toxicants, ionic concentrations, available nutrients, temperature (and light), and dissolved oxygen are key stressors to urban streams.{{cite journal |last1=Wenger |first1=Seth J. |last2=Roy |first2=Allison H. |last3=Jackson |first3=C. Rhett |last4=Bernhardt |first4=Emily S. |last5=Carter |first5=Timothy L. |last6=Filoso |first6=Solange |last7=Gibson |first7=Catherine A. |last8=Hession |first8=W. Cully |last9=Kaushal |first9=Sujay S. |last10=Martí |first10=Eugenia |last11=Meyer |first11=Judy L. |last12=Palmer |first12=Margaret A. |last13=Paul |first13=Michael J. |last14=Purcell |first14=Alison H. |last15=Ramírez |first15=Alonso |last16=Rosemond |first16=Amy D. |last17=Schofield |first17=Kate A. |last18=Sudduth |first18=Elizabeth B. |last19=Walsh |first19=Christopher J. |title=Twenty-six key research questions in urban stream ecology: an assessment of the state of the science |journal=Journal of the North American Benthological Society |date=December 2009 |volume=28 |issue=4 |pages=1080–1098 |doi=10.1899/08-186.1|s2cid=23296920 |hdl=10919/80380 |hdl-access=free }}

Some communities have begun stream restoration projects in an attempt to correct the problems caused by alteration, using techniques such as daylighting and fixing stream bank erosion caused by heavy stormwater runoff.{{cite web |author=California Department of Water Resources|title=Urban Streams Restoration Program |url=http://www.watershedrestoration.water.ca.gov/urbanstreams/ |access-date=2009-07-11}}{{cite news |first= Andrew C. |last= Revkin |title= Rolling Back Pavement to Expose Watery Havens |url= https://www.nytimes.com/2009/07/17/world/asia/17daylight.html?_r=1 |work= New York Times |date=16 July 2009|access-date=19 July 2009 }}

Streamflow augmentation to restore habitat and aesthetics is also an option, and recycled water can be used for this purpose.{{cite journal |last1=Bischel |first1=Heather N. |last2=Lawrence |first2=Justin E. |last3=Halaburka |first3=Brian J. |last4=Plumlee |first4=Megan H. |last5=Bawazir |first5=A. Salim |last6=King |first6=J. Phillip |last7=McCray |first7=John E. |last8=Resh |first8=Vincent H. |last9=Luthy |first9=Richard G. |title=Renewing Urban Streams with Recycled Water for Streamflow Augmentation: Hydrologic, Water Quality, and Ecosystem Services Management |journal=Environmental Engineering Science |date=2013 |volume=30 |issue=8 |pages=455–479 |doi=10.1089/ees.2012.0201}}{{cite journal |last1=Halaburka |first1=Brian J. |last2=Lawrence |first2=Justin E. |last3=Bischel |first3=Heather N. |last4=Hsiao |first4=Janet |last5=Plumlee |first5=Megan H. |last6=Resh |first6=Vincent H. |last7=Luthy |first7=Richard G. |title=Economic and Ecological Costs and Benefits of Streamflow Augmentation Using Recycled Water in a California Coastal Stream |journal=Environmental Science & Technology |date=2013 |volume=47 |issue=19 |pages=10735–10743 |doi=10.1021/es305011z|pmid= 23688175 |bibcode=2013EnST...4710735H}}

Urban stream syndrome (USS) is a consistent observed ecological degradation of streams caused by urbanization. This kind of stream degradation is commonly found in areas near or in urban areas. USS also considers hydrogeomorphology changes which are characterized by a deeper, wider catchment, reduced living space for biota, and altered sediment transport rates. Keep in mind the status of water quality is difficult to assess in urban areas because of the complexity of the pollutions sources.{{Cite journal |last=Duda |first=Alfred M. |date=July 1982 |title=Water Quality in Urban Streams: What We Can Expect |url=http://www.jstor.org/stable/25041633 |journal=Water Pollution Control Federation |volume=54 |issue=7 |pages=1139–1147 |jstor=25041633 }} This could be from mining and deforestation, but the main cause can be attributed to urban and suburban development. This is because such land use has a domino effect that can be felt tens of kilometers away. Consistent decrease to ecological health of streams can be from many things, but most can be directly or indirectly attributed to human infrastructure and action. Urban streams tend to be "flashier" meaning they have more frequent and larger high flow events.{{cite journal |last1=Vietz |first1=Geoff J. |last2=Walsh |first2=Christopher J. |last3=Fletcher |first3=Tim D. |title=Urban hydrogeomorphology and the urban stream syndrome: Treating the symptoms and causes of geomorphic change |journal=Progress in Physical Geography: Earth and Environment |date=2016 |volume=40 |issue=3 |pages=480–492 |doi=10.1177/0309133315605048|s2cid=131397867 }}

Urban streams also suffer from chemical alterations due to pollutants and waste being uncleanly dumped back into rivers and lakes. An example of this is Onondaga Lake. Historically one of the most polluted freshwater lakes in the world, its salinity and toxic constituents like mercury rose to unsafe levels as large corporations begun to set up shop around the lake. High levels of salinity would be disastrous for any native freshwater marine life and pollutants like mercury are dangerous to most organisms.{{Cite journal |last1=Rowell |first1=H. Chandler |last2=Enache |first2=Mihaela D. |last3=Quinlan |first3=Roberto |last4=Smith |first4=Alison J. |last5=Bloomfield |first5=Jay A. |last6=Charles |first6=Donald F. |last7=Effler |first7=Steven W. |date=2016|title=Quantitative paleolimnological inference models applied to a high-resolution biostratigraphic study of lake degradation and recovery, Onondaga Lake, New York (USA) |url= |journal=Journal of Paleolimnology |language=en |volume=55 |issue=3 |pages=241–258 |doi=10.1007/s10933-015-9877-8 |bibcode=2016JPall..55..241R |s2cid=130414481 }}

Higher levels of urbanization typically mean a greater presence of urban stream syndrome.{{Cite journal |last1=Brown |first1=Larry R. |last2=Cuffney |first2=Thomas F. |last3=Coles |first3=James F. |last4=Fitzpatrick |first4=Faith |last5=McMahon |first5=Gerard |last6=Steuer |first6=Jeffrey |last7=Bell |first7=Amanda H. |last8=May |first8=Jason T. |date=2009 |title=Urban streams across the USA: lessons learned from studies in 9 metropolitan areas |url= |journal=Journal of the North American Benthological Society |volume=28 |issue=4 |pages=1051–1069 |doi=10.1899/08-153.1 |s2cid=85861111 }}

Hydrology plays a key role in urban stream syndrome. As urbanization of these streams continue, there is in turn a decrease in the perviousness of the catchment to precipitation, which leads to a decrease in the infiltration and an increase in the surface runoff. This can cause problems during flood discharges. For example, flood discharges in urban catchments were at least 250% higher in urban catchments than in forested catchments in New York and Texas during similar storms.{{Cite journal |last=Paul |first=Michael J |date=2001 |title=Streams in the Urban Landscape |url=http://www.jstor.org/stable/2678644 |journal=Annual Review of Ecology and Systematics |volume=32 |pages=335 |doi=10.1146/annurev.ecolsys.32.081501.114040 |jstor=2678644 }}

Many water managers treat USS by directly addressing the symptoms, most commonly through channel reconfiguration that includes reshaping rock to address altered hydrology and sediment regimes. In spite of having ecological objectives, this approach has been criticized for addressing physical failures in the system without improving ecological conditions.{{cite journal |last1=Laub |first1=Brian G. |last2=Baker |first2=Daniel W. |last3=Bledsoe |first3=Brian P. |last4=Palmer |first4=Margaret A. |title=Range of variability of channel complexity in urban, restored and forested reference streams: Channel complexity and stream restoration |journal=Freshwater Biology |date=2012 |volume=57 |issue=5 |pages=1076–1095 |doi=10.1111/j.1365-2427.2012.02763.x}}

• Nationwide Urban Runoff Program (NURP) – US research program
• Nonpoint source pollution
• Subterranean river

• {{cite book |last1=Riley |first1=Ann L. |last2=Leopold |first2=Luna B. |title=Restoring Streams in Cities: A Guide for Planners, Policymakers, and Citizens |url=https://books.google.com/books?id=2NyTJHrDYpkC&q=Ann+Riley+restoring+streams |year=1998 |publisher=Island Press |location=Washington, DC |isbn=978-1-55963-042-9}}

• [https://www.epa.gov/urbanwaters Urban Waters Program] – U.S. Environmental Protection Agency (EPA)
• [http://cfpub.epa.gov/ncer_abstracts/index.cfm/fuseaction/display.abstractDetail/abstract/7711/report/0 Ecosystem Effects of Urban Stream Restoration] – EPA
• [https://www.geocities.ws/linwood/suds/ Suspended Sediment and Discharge in a West London River]

Category:Hydrology and urban planning

Category:Water pollution

Category:Environmental engineering

Category:Water streams

Category:Rivers

Category:Hydrology

Category:Fluvial landforms