Infrared Thermography and Geochemistry to Identify Ground Water Discharge Locations for Fish Habit Assessments

Monday, April 20, 2009: 10:50 a.m.
Joshua Tree (Hilton Tucson El Conquistador Golf & Tennis Resort )
Brewster Conant Jr., Ph.D. , Department of Earth and Environmental Sciences, University of Waterloo, Waterloo, ON, Canada
Neil J. Mochnacz , Arctic Science Division, Fisheries and Oceans Canada, Winnipeg, MB, Canada
Nicholas C. Utting , Department of Earth Science, University of Ottawa, Ottawa, ON, Canada
An innovative approach combining infrared thermography and geochemical analyses has been used to identify and characterize groundwater discharge to several tributaries of the Mackenzie River in the Northwest Territories, Canada to better characterize fish habitat for salmonids.  Groundwater discharge (especially originating from deep in the ground) provides thermal refugia for fish by preventing river reaches from freezing in winter and creates areas of stable riverbed temperatures conducive to spawning. Despite groundwater discharge being extremely variable spatially and temporally, identifying high groundwater discharge areas in rivers is important for habitat assessments. Infrared thermography can locate groundwater discharge where temperature contrasts exist between surface water and groundwater, but conventional methods of acquiring thermal images from satellites and airplanes tend to be expensive, often lacks the resolution necessary to identify small discharge locations, and do not allow real time decisions to investigate and ground truth identified temperature anomalies. Geochemical differences between surface water and deep groundwater can also be used to indicate groundwater inputs to rivers, but it can be difficult, time consuming and expensive to accurately locate and sample groundwater springs and surface waters. This study developed a solution to these problems that uses an infrared thermography system to provide a relatively inexpensive, high resolution, real-time way of locating groundwater discharge and help pinpoint geochemical sampling, thereby improving data quality and making field work more efficient.  A handheld FLIR ThermaCam P25 infrared camera, visual video camera, infrared video capture system, and GPS were used in a low flying helicopter and on the ground to characterize several kilometer long reaches of river and identify springs and seeps along the rivers on a submeter scale.  Locations were immediately sampled for major dissolved ions and isotopes. Preliminary results suggest that this multidisciplinary approach is a practical method to locate key fish habitat for northern fishes.