THE USE OF STREAMBED TEMPERATURE PROFILES TO ESTIMATE THE DEPTH, DURATION, AND RATE OF PERCOLATION BENEATH ARROYOS

Temporal variations in a streambed temperature profile between 30 and 300 cm beneath Tijeras Arroyo, New Mexico, were analyzed at 30-min int ervals for 1990 to estimate the depth, duration, and rate of percolati on during streamflows. The depth of percolation was clearly documented by the rapid response of the streambed temperature profile to streamf lows. Results indicate that the streambed possessed small thermal grad ients with significant diurnal variations from late November to late M ay, indicating that ephemeral streamflows created continuous, advectio n-dominated heat transport to depths below 300 cm during this period. Timing and duration of percolation suggested by temporal variations in the temperature profile were verified by comparison with measured str eamflow records for the study reach over 1990. Percolation rates were estimated using a technique based on the travel time of the daily maxi mum temperature into the streambed. Percolation rates were compared wi th streambed seepage rates determined from measurements of streamflow loss, stream surface area, and stream evaporative loss for the entire study reach. Travel time estimates of streambed percolation rates rang ed from 9 to 40 cm/hr, while streamflow estimates of streambed seepage rates ranged from 6 to 26 cm/hr during the study period. Discrepancie s between streambed percolation and seepage rates may be caused by dif ferences in the areal extent of measurements for percolation versus se epages rates. In summary, the depth, timing, and duration of streamflo w-induced percolation were well documented by temporal variations in a single streambed temperature profile, while rates of percolation base d on the temperature profile were about double the seepage rates based on streamflow records for the entire study reach.