Water chemistry dynamics as affected by rainstorms in a high‐elevation stream, South Island, New Zealand

Abstract

The effects of rainstorms on water chemistry in a headwater stream in the Craigieburn Range were examined. Baseline chemical characteristics were determined from grab samples collected at two sites of differing elevation and catchment cover type, from 18 September 1990 to 16 May 1991. During this same period, samples were also collected before, during, and alter several rainstorms. Generally speaking, baseflow ion concentrations were quite low in the stream although significant differences in some chemical characteristics were noted between sample sites, most likely related to downstream changes in catchment characteristics. Water chemistry was affected by storm flow, with all ions monitored being diluted during periods of increased stream flow. Plots of element concentrations versus stream flow during storms produced clockwise‐negative trajectories, suggesting nutrient‐poor soils and refractory forms of elements present in the catchment basin.

Keywords:

• water chemistry
• trajectories
• rainstorms
• baseflow
• streams