Identifying leakage to groundwater from LakeRerewhakaaitu using isotopic and water quality data

摘要

Stable isotopes (~(18)O, ~2H), water dating, andmajor anion and cation water chemistryof springs, groundwater bores, a streamand a lake have been used to identify areasof discharge from Lake Rerewhakaaitu.Groundwater aquifers and spring dischargesto the north and west of Lake Rerewhakaaituare found to contain up to 79% lake water. Hierarchical cluster analysis is used togroup sites into three clusters based onthe major anion/cation water chemistry.Defining meaningful hierarchical clusters wasdifficult due to the similarity of the chemicalcompositions between sites. The threeclusters defined in this study do not clearlyidentify the sites containing lake water.However, the hierarchical cluster analyses canbe used to infer sites that are likely to containproportions of lake water in the groundwater,and therefore provides a method to identifysites that may contain lake water. The groundwater and spring discharges tothe north and west of Lake Rerewhakaaituflow into a different surface water catchment,thus providing a hydrological link betweentwo different surface water catchments. Thishas implications for catchment managementin the greater Rerewhakaaitu area.