Aanleiding van het project
A comprehensive hydrological-water quality modelling framework was developed for the Waituna Catchment in 2014. The farm-scale spatial resolution of this model represents a major improvement over other catchment models currently being applied across New Zealand. The water quality model was developed in parallel with a farm system modelling study aimed at evaluating different options for reducing farm nutrient losses while minimising the impacts on profitability. This study found that the response of individual farms to different nutrient reduction strategies is highly variable due to differences in system type, existing leaching rates, soil type, stage of development and farmer practices and philosophies. A limit setting approach which grandparents existing nutrient loss rates but requires a uniform reduction across all farms irrespective of system type would heavily penalise low intensity farms. An alternative approach to achieve nutrient loss reduction targets while minimising the economic impacts could be to spatially optimise the implementation of different strategies across the catchment.
The long term objective of this study is to integrate the existing water quality modelling framework with farm system-economic algorithm routines to provide a framework for running optimisation scenarios at the catchment scale. While similar economic models have been set up and applied to other catchments across the country (i.e. Waikato), the proposed Waituna approach goes a step further by having actual information for all farms in the catchment as well as fully integrating the water quality model component.
This is also considered an important project for Deltares (the Contractor), who intends to realise financial matching to
complement this project through the Knowledge and Innovation Program on Delta technology of the Dutch Ministry of
Economy (TKI program). Both the ecomonic model and the optimisation module are also interesting for other clients in the
Doel van het project
The overall research project has the following four key objectives:
1. Integrate existing information on the economic impacts of farm-scale system changes to reduce nutrient leaching rates
with the existing Waituna WFD-Explorer water quality model to provide a common framework for the simulation of water
quality and economic scenarios at the catchment-scale.
2. Implement a framework for modelling the implementation of farm-scale edge of field mitigation strategies (e.g.
constructed and natural wetlands, tile drain filter systems, riparian plantings) on catchment nutrient loading and economics.
3. Develop and integrate a process for undertaking environmental and economic optimisation of farm-scale nutrient load
reduction targets at the catchment scale into the water quality modelling framework.
4. Develop a conceptual framework for the further expansion of the Waituna catchment water quality modelling framework,
including integration of the developed financial mitigation tool with the DDV.
Omschrijving van de activiteiten
1. Provide a memo on the matrix-based implementation of the DDV water quality model applications.
2. Review and elaborate on proposed DairyNZ approach for the development and coding of the financial mitigation tool
(farm system mitigations, edge of field mitigations, forcing of mitigations on farm input file and representation of the
environmental and economic cost benefit results).
3. Deliver support on Python coding of the financial mitigation tool modules (farm system mitigations, edge of field
mitigations, forcing of mitigations on farm input file and representation of the environmental and economic cost benefit results).
4. Review on the validity of the environmental and economic optimisation module design.
5. Deliver support on Python coding of the environmental and economic optimisation module
6. Design and implement the financial mitigation tool in the Waituna DDV application.