Classification of New Zealand hydrogeological systems

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Moreau M, White PA, Mourot F, Rawlinson ZJ, Tschritter C, Cameron SG, Westerhoff RS. 2019. Classification of New Zealand hydrogeological systems. Lower Hutt (NZ): GNS Science. 28 p. (GNS Science report; 2018/35). doi:10.21420/42QW-MC74.

Digital datasets of New Zealand hydrogeological systems and their boundaries have been developed using a nationally-consistent and transparent methodology. Here, we define hydrogeological systems as geographical areas with broadly-consistent hydrogeological properties, and similar resource pressures and management issues. These systems are represented in two Geographical Information System (GIS) datasets at the 1:250,000 scale, i.e., hydrogeological system polygons and system boundary polylines. The hydrogeological system polygons (1896 in total) include attributes corresponding to mapping levels, i.e.: unique names; unique identification numbers; system class; coastal information; aquifer overview; geology and age group; and description. The system boundary polylines have attributes identifying the data source and the type of each boundary line, providing transparency and traceability. These datasets were developed through an iterative process that used GNS Science’s QMAP (a national GIS database of surface geology) as the primary input dataset, supplemented by other national datasets (e.g., topographic contours, regional surface drainage and aquifer potential). A method to ‘translate’ QMAP data into the national map of hydrogeological systems was developed in a pilot region (Southland); validated in a second geologically-contrasting region (Waikato); and then applied nationally to the remaining on-shore New Zealand. (auth)