Land-use Contaminant Loads and Mitigation Costs

A great deal of research has been carried out to quantify the processes, transformations and effects of contaminant loss from land to water, as well as to identify strategies to mitigate contaminant losses to freshwater (e.g. Monaghan et al. 2007; McDowell & Nash, 2012; McDowell et al 2014). However, less research has been undertaken to assess the unintended impacts of the NPS-FM on New Zealand’s greenhouse gas emissions (GHG).

This is a technical paper related to Motu Working Paper 17-10: Modelling the potential impact of New Zealand’s freshwater reforms on land-based greenhouse gas emissions.

The aim of this component of the study was to use the existing catchment model CLUES (Catchment Model for Land use and Environmental Sustainability) (Woods et al. 2006; Semadeni-Davies et al. 2011, 2012) (to assess the loads of contaminants entering streams, summarised by Freshwater Management Unit (FMU). This involved running CLUES for a ‘current’ land use, extracting loads for each land-use by REC subcatchment, and then summarising the results by the larger FMU polygons.