Evaluation of geospatial datasets and recognition of landscape gradients specific to water quality

This study evaluates the landscape relationships and suitability of existing geospatial datasets for the purposes of mapping physiographic water quality units for the Northland region. The physiographic method seeks to explain ‘how’ and ‘why’ water quality varies across a region by identifying the gradients driving key landscape processes that govern water quality outcomes and risk.

The importance of understanding the role of the landscape reflects the observation that whilst land use is a prerequisite for poor water quality outcomes, it is the inherent physical, chemical and biological characteristics (attributes) of a landscape that are often responsible for a larger proportion (>2 times) of the variation in water quality outcomes. This is particularly true for regions and/or countries, such as Northland and New Zealand, which are characterised by steep gradients in chemical, physical and biological landscape attributes.