The effects of urban land use on stream temperatures

Angela Perez-Toro, Delyn Martinez, Evan Portier, Angela Perez-Toro, Delyn Martinez, Evan Portier,

Jennifer Daugherty, Jian Ang andJennifer Daugherty, Jian Ang andKendyl CrawfordKendyl Crawford

Natural causes of stream temperature rising

• Air temperatures •Physical aspects of a stream (location, i.e. glacier, lake, spring, wetland, etc.)

•Physical characteristics (shading shoreline, depth)

•Watershed Elevation & Tributaries (mix velocity)

Various impacts on watersheds

Temperatures are changing in stream and rivers in the U.S.

•Annual mean increased by 0.009-0.077°C

•More rapid in, but not confined to, urbanizing areas.

•Typically correlated with increases in air temperatures, which could be caused by global warming and urbanization.

(Source: Sujay S Kaushal, Gene E Likens, Norbert A Jaworski, Michael L Pace, Ashley M Sides, David Seekell, Kenneth T Belt, David H Secor, and Rebecca L Wingate)

Causes of stream temperature rising

• Streamside trees are usually removed.

• Drainage from hot paved surfaces increase stream temperatures.

• Exposed irrigation channels are also another source of heat.

• Shading of streams by vegetation can reduce stream temperatures by as much as 10°C.

Streams in urban landscape expected to be higher in temperatures

Forested Landscape Urban Landscape

Hogue Creek

Flat Lick Branch above Frog

Branch

Elevation and temperature are not correlated

The effects of rising water temperatures

• Could have important effects on eutrophication, ecosystem processes, contaminant toxicity and loss of aquatic biodiversity.

Why do we care?• Increased water temperatures = decreased

dissolved oxygen.• Some species of fish have high oxygen

demands, such as trout & salmon.

• Temperature also influences the rate of photosynthesis by algae.

• Increases metabolic rate (fish) = need more food and release more waste.

• Recreational fishing• Commercial fishing• Crabbing• Oystering• Clamming

Potomac River uses

Mitigation can decrease negative human impact

•Pavement coloration

•Storm water treatment ponds

•Streamside buffers

Shading

•Green infrastructure planning

Pervious surfaces

Pipe materials

Socioeconomic factors

•Improve air quality

•Increased fishery yield

•Enhance appearance of a community

•Increased property values

Recap of experience

•http://www.bluecrab.info/forum/index.php?topic=28253.0

•http://www.waterencyclopedia.com

•http://files.dep.state.pa.us/Water/Watershed%20Management/lib/watershedmgmt/state_water_plan/regional_committees/potomac/may08/potomacregion-31-45.pdf

•www.esajournals.org/joi.abs/10.1890/090037

Sources

Questions???