USE OF INSTREAM HEAT BUDGETS AND SUPPORTING DATA FOR PREDICTING SURFACE AND SUBSURFACE TRANSIENT STORAGE INFLUENCES

The recent use of instream heat budgets that incorporate the influences of surface and subsurface transient storage have provided a promising method to complement solute tracer studies for quantifying transient storage effects on reach scale transport. Challenges with uncertainty in ensuring individual heat transfer processes are well represented arise due to the additional number and type of processes that must be included in heat budgets. This has led to the need for specific data collection techniques to support instream temperature predictions and resulted in questions regarding the spatial resolution of information necessary to capture the influences of transient storage. Recent efforts have identified data types necessary for accurate solute and temperature predictions within the main channel and individual transient storage zones. Within the context of the Virgin River, Utah, we have found that one temperature time series and one solute curve collected at two different locations longitudinally in the main channel provides much of the information necessary to predict responses within each zone at both locations. Additionally, we have found that temperature data collected within surface and subsurface transient storage zones supply necessary information to validate transient storage zone predictions with efficient investment of time and resources. Subsurface temperature data collected using unique installation methods also provides information to separate out the conductive and advective influences within the stream sediments. Further, the use of high resolution thermal imagery has proven to be a promising method to set specific parameters and investigate the appropriate spatial resolution of data. Together, these findings provide more confidence in transient storage predictions as well as the foundations for incorporating larger scale groundwater influences necessary to understand the importance of subsurface exchange at a reach scale.