Assessment of Thermal Pollution Associated with Riparian Canopy Clearning

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Master of Natural Resources Professional Papers (North Carolina State University. College of Natural Resources)

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North Carolina State University. College of Natural Resources


Abstract Blackwell, James and Daniel E. Line PE. Master of Natural Resources Geographic Information Systems Technical Option. Assessment of Thermal Pollution Associated With Riparian Canopy Clearing This report summarizes the results of monitoring water temperatures at 5 stream sites for 2+ years. The sites encompassed varying stream sizes and lengths, tree canopies, and road improvement activities. This study was designed to document water temperature in mountain streams that have had limited tree removal in the riparian corridor as a result of road improvement. Results showed that for a large stream (drainage area >10,000 ac) the temperature increase from upstream to downstream was <0.09 F, even though the stream had a reach of 650ft without any tree canopy. Monitoring on 2 of the 4 smaller streams (drainage areas <1,000 ac) documented a decrease in temperature from upstream to downstream of a reach where road improvements had occurred. The reason for the decrease was not known, but clearly road improvements were not causing increases in stream temperatures. For the 2 small streams with increases in temperature, the greatest increase (0.61 F) from upstream to downstream occurred for a stream reach of >3100ft with essentially no tree canopy. Altogether the data suggested that: 1) for larger streams (drainage area >10,000 ac), removing trees outside a 20ft stream buffer did not result in a measurable increase in temperature, 2) for larger streams (drainage area >10,000 ac), with all tree canopy up to a 650ft reach removed, the increase in temperature was <0.10 F, 3) tree canopy is not the only factor influencing whether stream temperature increased in a monitored stream reach, 4) additional research is needed where stream temperature is monitored before during and after road improvement to more definitively document the effects of riparian canopy reductions on stream temperatures.



canopy clearing, riparian thermal pollution