The measurement of groundwater seepage into Catamaran Brook, New Brunswick

Abstract

Forest harvesting impacts on aquatic biota at Catamaran Brook (Central NB) has been a concern to many researchers over the past decade. This study is an attempt to quantify the groundwater seepage entering Catamaran Brook adjacent to a 1.5 km forest cut block zone. The contribution of groundwater to the brook was determined quite easily. Stream gauging was performed just upstream and just downstream of the cut block zone to measure the initial and final discharges of the brook, respectively. There are three small tributaries within the stream reach. Therefore, a portable RBC flume was set up in each tributary to measure discharge. Finally, the groundwater seepage was determined by finding the change in discharge from the lower site minus the upper site combined with the three tributaries. It appears that from the field tests, the seepage was 57.1 L/sec or 0.0571 m3/sec (32.2% increase in stream flow) on one day and 49.7 L/sec or 0.0497 m3/sec (18.8% increase in stream flow) during the second visit. This is an indication that the greater the stream flow, the lower the groundwater seepage contribution. The forest cut block zone adjacent to Catamaran Brook does contribute a relatively large quantity of groundwater to the brook. Therefore, changes to groundwater flow and temperatures, as a result of land clearing, may be more serious than previously thought. These small scale results may provide the basis for larger scale testing to gain more insight into the matter.