Temporal and spatial variability in North Carolina piedmont stream temperature
Understanding temporal and spatial patterns of in-stream temperature can provide useful information to managing future impacts of climate change on these systems. This study will compare temporal patterns and spatial variability of headwater in-stream temperature in six catchments in the piedmont of North Carolina in two different geological regions, Carolina slate belt and Triassic basin. The NC Neuse River Buffer Rules were established in the 1990s to protect nutrient sensitive waters through maintaining and protecting existing buffers. These buffers can also moderate diurnal fluctuations and stream temperature maximums. In October 2007 six catchments ranging from 12 to 46 hectares (i.e., four on Hill Demonstration Forest and two on Umstead Research Farm) with perennial stream channels were outfitted with stream discharge, meteorological and water temperature monitoring equipment. There were similarities in winter and summer daily maximum stream temperature and mean diurnal fluctuations within the paired and larger watersheds. However, the winter and summer water temperature patterns varied significantly between geological regions. There were smaller ranges in summer diurnal fluctuations (e.g., 0.4 oC to 2.0 oC) compared to winter fluctuations (e.g., 0.3 oC to 4.7 oC) in all watersheds, suggesting that the trees along the riparian buffers are moderating the affects of air temperature on water temperature by reducing wide fluctuations in temperature. A regression model predicted that a 2 oC increase in daily maximum air temperature would increase daily maximum water temperature 0.6 oC to 1.0 oC in the winter and 0.2 oC to 0.8 oC in the summer between watersheds.