PREDICTING WATER TEMPERATURE VARIATIONS WHERE STREAMS START IN THE SOUTHERN APPALACHIAN MOUNTAINS

Previous studies have mapped and described stream heads, the initiation point of perennial surface water flow, and efforts have also been made to predict the stream water temperatures of headwater streams. Little work has attempted to predict the temperatures of stream heads in headwater streams. This project seeks to predict stream head temperature to learn more about the subsurface flow paths that potentially initiate streams. To do this, stream heads in four watersheds across an elevation range of 700 to 1600 m in Western North Carolina were mapped and field verified. iButton temperature loggers were installed in 3 streams in each watershed, for a total of 12 instrumented headwater streams. Sensors were installed and recorded the stream water temperature at the head, 200 m downstream, and the air temperature. The temperature was recorded every ten minutes for 25 days. Physical characteristics of the channel head were measured in the field such as width, slope, and the presence of discontinuous water upslope. Topographic analysis was conducted using a 1 meter, LiDAR-derived DEM. Preliminary analyses show that water temperatures at stream heads are almost constant through time. They have little to no relationship with air temperature, but strong relationships with several topographic metrics. Surprisingly, even at similar elevations, the temperature of the stream heads and down-stream warming varied between streams. These observed differences may indicate different groundwater flow paths or mechanisms for surface flow initiation. Our results suggest different surface flow generation mechanisms result in different topographic conditions leading to stream-initiation. These initiation processes are indicated by surface topography, which can then be used to remotely predict stream head temperature. This information could be used to inform headwater stream temperature predictive models for understanding responses to a changing climate. Modelling impacts of increasing air temperature in sensitive headwater systems is important because it has far reaching impacts for thermally sensitive species.