This report describes work to analyze runoff temperatures and runoff heat export rates for a
variety of terrestrial land covers and aquatic surfaces. Surface runoff temperatures and heat
export have been simulated for ten terrestrial covers, an unshaded wet detention pond, a
lake/reservoir, and a vegetated pond. A continuous simulation was run from April 1 to October
31, yielding a total of about 280 precipitation events for six years (1998-2000, 2003-2005). Six
years of 15-minute climate data from the weather station at the MnROAD facility in Albertville,
MN, were used as model input. In general, the variation in average runoff temperatures from
terrestrial land covers and open water surfaces was moderate, from 24.9 °C for concrete to 21.5
°C for a forest. Pavements, commercial rooftops, bare soil, wet detention ponds, and
lakes/reservoirs were all found to give runoff temperatures high enough to significantly impact
stream temperature. Vegetated surfaces gave substantially lower runoff temperature and heat
export than paved surfaces. Runoff temperatures from bare soils were consistently higher than
from vegetated surfaces, but lower than from pavements. Residential roofs gave, on average,
low runoff temperatures, due to very low thermal mass, while commercial roofs gave high runoff
temperatures in some cases. Large water bodies (lakes and reservoirs) generally give very high
runoff temperatures, but the quantity of runoff is highly dependent on the water level prior to the
storm event. Analysis of a vegetated pond indicates that shading from emergent vegetation can
reduce runoff temperature up to 6°C compared to an unshaded pond.
Verimillion River Watershed Joint Powers Organization, Dakota County, Minnesota; Minnesota Pollution Control Agency
Herb, William R.; Janke, Ben; Mohseni, Omid; Stefan, Heinz G..
Estimation of Runoff Temperatures and Heat Export from Different Land and Water Surfaces.
St. Anthony Falls Laboratory.
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