Application of HEC-RAS 4.0 temperature model to estimate groundwater contributions to Swan Creek, Ontario, Canada

摘要

The HEC-RAS 4.0 model has been expanded to include a water quality component which can simulate water temperatures and the movement of contaminants in rivers. Stream temperature is often considered a critical habitat parameter because it affects in stream chemical and biological processes. For streams where groundwater discharge is present, the thermal regime of the surface water system is influenced by the distribution and rate of groundwater discharge. Groundwater provides a source of thermally stable water that can mitigate the effects of diurnal variations and sustain refugia and spawning habitat. In the field, heterogeneous groundwater-surface water interactions can make it very difficult to estimate the amount of groundwater entering a stream. Reach-level stream gains can be highly uncertain when groundwater discharge represents a moderate to small percentage of the total stream flow. In this paper a small southern Ontario creek is modelled in HEC-RAS 4.0 to explore the temperature modelling capabilities of HEC-RAS 4.0. Specifically, the ability to use HEC-RAS 4.0 as a secondary means of estimating groundwater discharge during low-flow conditions is examined using measured stream temperature data.