Use of stable isotopes of water (d and o-18) in hydrological studies in the Jonkershoek valley

Abstract

Stable isotopes of water in rainfall and streams in the Jonkershoek Valley were used to determine the relative contribution of new water (i.e. rain) during storm flow conditions. Significant differences between rain and stream isotopic signatures which facilitated the use of a mass balance equation to calculate the components of storm flow were found. Analyses indicated that < 5% of the storm flow comprised direct runoff. This suggests that the rapid response of these streams to rainfall is mainly due to displaced groundwater.