Using Temperature Inferred Baseflow for Ground Water Modeling

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Heat has been shown to be an effective tracer of baseflow under certain hydrologic conditions.  In temperate climates, ground water is colder than surface water in the summer and warmer than surface water in the winter.  Using a heat balance, it is possible to quantify baseflow by measuring stream temperatures along with stream discharge measurements.  An advantage to this approach is that temperatures can be measured cheaply and rapidly, providing a better spatial resolution of baseflow than is practical using discharge measurements alone.  This approach was demonstrated in a stream that traverses a valley-fill aquifer in Western New York State. Streambed temperatures were collected along a 40 km stretch of the stream at multiple times during the Summer and Fall.    Under baseflow conditions, stream temperature appeared to correlate with gaining and losing sections of the stream. A heat balance on the stream was used to estimate ground-water fluxes at 14 reaches along the stream. These flux estimates were then used as observations, along with heads, in a ground-water flow model.  Measured and synthetic datasets were used to estimate the value of multiple baseflow estimates along a single stream for the calibration of ground-water models.  Although a single major stream drains the valley, baseflow estimates were the most influential observations in the model calibration.  These results suggest that, when shallow aquifers are hydraulically connected to streams, temperature surveys may provide a cost-effective dataset for ground-water model calibration.