Sources and Flows
Managing contaminant pathways and attenuation to create headroom for productive land use
Challenge funding: $3,150,000
Research duration: October 2016 – June 2019
About half (55%) of agricultural contaminants (nitrogen, phosphorus, sediment, faecal microbes) are naturally removed as they flow from land to sea – but this percentage varies greatly for different soils and landscapes.
We require a more integrated understanding of the sources of these contaminants, their rate of transport to receiving waters, and how they are diluted while transported. This will enable the identification of critical source areas to target cost-effective mitigation interventions and contribute to our understanding of land use suitability.
Sources and Flows research brings together climate, soil, hydrology and water quality scientists to develop a framework that integrates existing national databases and knowledge of source, transport and attenuation processes of all 4 contaminants.
The framework will be tested in case study catchments in data-rich and data-poor regions of New Zealand. Researchers will evaluate where existing water quality models under-perform and explore methods to fill any key gaps in knowledge.
How Can The Research Be Used?
- The multi-component, modular framework developed by the Sources and Flows programme will allow landowners to pinpoint a location, identify the contaminants of concern, and select appropriate mitigations. It will also allow policy makers to set resource limits that more accurately reflect the likely risk of environmental impact.
- This research refined a ‘critical source area’ theory that explains that the majority of contaminants come from a minority of a farm or catchment. When targeted to these small but critical areas, mitigations are 6 to 7 times more cost-effective. This theory is now used in 77 guidelines, industry strategies and policy documents for environmental farm plans to improve water quality.
- Sources and Flows researchers looked at the likelihood of drought and found that 3 North Island sites experienced longer and more severe droughts than 3 South Island sites. Modelling of soil drainage at these sites indicated 35% to 80% more drainage peaks than expected, suggesting better monitoring of soil moisture and scheduling of irrigation is required. Because of this research the Northland Regional Council is refining drought intensity, duration and frequency curves for Northland to guide regional irrigation schemes and the allocation of water.
- Sources and Flows research used precision irrigation technologies, timed and matched to soil type at a location in Central Otago, to show that the loss of nitrogen and phosphorus in soil drainage was reduced by 70% to 80% compared to standard irrigation practice. Irrigation NZ highlighted this nationally.
- The Sources and Flows team is working with DairyNZ to develop geospatial data layers that capture the transport of N, P and faecal microbes from sources to water bodies. DairyNZ has been providing the research team with key data layer support as well as research questions that need to be answered.
- The Sources and Flows team is providing lookup tables of N and P losses that will support the assessment tool being developed by Land Use Suitability research. This research will also guide the development of catchment modelling tools.
In the Media
- Sources and Flows has a stakeholder advisory group to enable ongoing dialogue with industry groups including Pamu, Beef + Lamb NZ, DairyNZ and Rabobank regarding their needs from the Sources and Flows framework.
- Greater Wellington Regional Council, Waikato Regional Council, Tasman Regional Council and Environment Southland are collaborating with the Sources and Flows programme to test the accuracy of national-scale mapping of groundwater redox in their regions. The ECan chief scientist Dr Tim Davie actively participates in the Sources and Flows stakeholder adviser group.
- Environment Southland is working on development of the Sources and Flows framework. The next steps are to commence the application of the framework in Oreti and Aparima catchments.
- Sources and Flows have been working with Northland Regional Council to apply the drought risk component of their framework as a tool for the Northland region.
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