Longitudinal effects of seep water on stream water discharge and chemistry in a headwater catchment in Hubbard Brook Experimental Forest, New Hampshire

Abstract

This research was conducted in the Hubbard Brook Experimental Forest in New Hampshire, USA, and focuses on water chemistry and discharge of stream water. The aim of this research is to find out if there is an effect of seep water on stream water. A seep is a groundwater upwelling area that is perennial wet. Seep water has a distinct chemical composition that leads to typical vegetation in that specific area. This research uses two methods to look at the influence of seep water on stream water. One method is the tracer injection method to measure discharge. With this method sodiumchloride (NaCl) was injected into the stream with a near-instantaneous ' slug' and the electrical conductivity (EC) was measured downstream of this injection point. To see if the stream had a gain or loss of water the EC was measured at several reaches whereby the change in discharge (Î Q) could be calculated. The discharge results did not show a significant change that could be caused by the input of seep water. The second method in this research consisted of collecting water samples in spring and summer to see if the distinct chemistry of seep water had an influence on the water chemistry of a stream. Supplementary data from Zimmer et al. (2012) was used to show changes in chemistry over time and making this research complete. Also the chemical composition of stream water was not significantly influenced by the chemistry of seep water indicating that there is no connection.