New Computer Programs Using Diurnal Temperature Time Series to Determine Streambed Percolation Velocities

Streambed percolation is one of the most important routes for groundwater recharge. Among many methods, using diurnal temperature in the streambed to determine percolation velocity is one the most frequently used methods. Several numerical codes, VS2DH, SUTRA, and TOUGH2, have been developed primarily for 2D or 3D heat transport simulation and also for use in streambed percolation velocity calculation, but, with great complexity. This research simplifies percolation velocity calculation by developing new computer codes that solve the 1D heat transfer equation. Using diurnal temperature data, percolation velocity can be determined easily to each day of the monitoring period. More percolation velocity data will enable more understanding for the river/groundwater interaction. This work also conducts a field test for studying streambed percolation in the Choshui stream, Central Taiwan. The data show the average percolation velocity at approximately 6.8×10-6 m/s.