Spatial and temporal thermal patterns in the Spring Creek watershed

Elaine Langone, Forum

Water temperature is a critical physical property of stream ecosystems that influences nearly all in-stream biochemical processes. Atmospheric, physical and hydrologic conditions all influence a stream’s thermal regime, and anthropogenic effects on any of these actors, such as changes in land-use or natural flow patterns, can greatly impact stream temperature and ecosystem processes. The Spring Creek Watershed in Centre County, Pennsylvania is a small, headwaters watershed that exhibits wide variation in stream size, land-use, groundwater contribution, and industrial inputs and withdrawals. The Water Resources Monitoring Project has been observing stream temperature and discharge at locations throughout the catchment regularly since 1999. Both flow and thermal regimes vary substantially between monitoring locations with temperature ranging approximately 10-12°C during the winter and summer months and discharge rates ranging annually from 0-5.7 cms. This study aims to identify the most thermally influential environmental and/or anthropogenic factors for stream reaches within the Spring Creek watershed by analyzing spatial and temporal patterns of temperature data in the context of discharge rates, groundwater contribution from springs, locally contributing land cover, riparian cover, industrial inputs and withdrawals, and air temperature and precipitation patterns. Preliminary results indicate that groundwater contribution and discharge rates may be the most critical factors in maintaining stable thermal regimes in varying atmospheric, land-use and industrial conditions. Identifying areas that may be more susceptible to these conditions can help prioritize planning for streambank restoration, stormwater management and other innovative strategies to maintaining and/or restoring natural stream temperature regimes.