Spatial and temporal variations in temperature of the West Branch Susquehanna River

Elaine Langone, Gallery Theater

A network of buoys and river bed temperature sensors were built and deployed on the West Branch of the Susquehanna between Muncy and Chillisquaque, Pennsylvania. The buoys were equipped with sensors collecting 15-minute measurements of solar radiation (W m-2), relative humidity, air temperature (°C), and water temperature (°C) at the water’s surface and at mid-depth. An additional temperature sensor was placed on the bed of the river. Flows during summer and fall were relatively normal, with channel widths averaging 200-220 m and depths 1-2 m. Downstream changes in temperatures were generally consistent, with .278 °C km-1 increase between Lewisburg and Chillisquaque. Cross-sectional variability in temperatures were much more complex. Temperatures in the middle of the channel showed only 1-2 °C warming from the water surface to the bed, with albedo and long-wave stream bed conduction effects warming waters along the bed of the river. In general, water temperatures are a subdued replica of air temperatures, with atmospheric and solar radiation effects dominating diurnal variability in water temperatures in the river. Peak diurnal water temperatures typically lag peak diurnal solar radiation by several hours each day. The buoys deployed approximately 10 m from banks of the channel indicate that shading from the riparian corridor dominate the temperature variability along the margins of the river, with the middle and west bank portions of the channel experiencing 600-800 W m-2 more solar radiation during morning hours and temperatures as much as 3.33 °C warmer than the left (shaded) portions of the channel. Turbidity, or water clarity, dominates light penetration in the water column and during clear water conditions.