Ideas & catchment futures
Case study 3
Catchment-scale modelling utilises knowledge from all ICM research strands. It offers an opportunity to provide councils and sector groups with strategic advice that assesses impacts not only of future mixes of land and coastal uses, but also of other types of development such as population growth scenarios.
The first foundation for this research was an integrative triple-bottom-line modelling approach trialled using a participatory process with the ICM Community Reference Group. This Influence Matrix process identified three critical factors likely to affect the group’s vision for future sustainability of the catchment:
- Nature and extent of primary industries
- Measures of water quality and supply
- Available mix of policy–plans–rules–legislation.
The process and its results raised awareness of the value of modelling tools for informing long term council community plans, and for framing up ratepayers’ own perspectives on sustainability.
The second foundation was development of component models: catchment water yield and water quality, catchment transport of faecal pathogens and sediment, exchange of water between rivers and groundwater, coastal productivity and foodweb models, an ‘agent-based model’ which simulates people’s responses to policies, and the Motueka Futures economic input-output model with associated population growth module.
Together these models provide the third foundation, a large-scale modelling framework called IDEAS (Integrated Dynamic Environmental Assessment System). IDEAS is a scenario modelling system comprising a set of simplified linked models that allows us to assess cumulative effects of broad-scale development (e.g. land-use changes) over a 10–50 year time frame. It does this by looking not only at environmental outcomes (e.g. water quality) but also social (e.g. employment), economic (e.g. GDP) and cultural (e.g. biodiversity) consequences. IDEAS synthesises learning from all parts of the research programme to predict how the system would respond all the way out into Tasman Bay if major changes are made in the Motueka catchment or its offshore extension.
IDEAS has been applied to assess and compare the environmental and socio-economic impacts of different scenarios including present land use, present land use with best management practice, and continued present growth until 2020. IDEAS was developed as an integrative tool for adaptive management from catchment to regional scales, and to map trends that define acceptable vs non-sustainable land– water–coastal development options.
The research has included an ecological economics model of the whole catchment, beginning with an economic input-output model. Using benefit-transfer non-market valuation methods it was shown that natural ecosystem services annually contribute non-market (indirect) goods and services of $163 Milion, more than half the annual catchment gross product. This Motueka futures model, in conjunction with the agent-based model ENVISION, is part of the IDEAS framework, allowing a quadruple-bottom-line evaluation of various catchment-scale development scenarios.
John Dymond
Ben Knight
Cawthron Institute, Nelson
Ben.Knight@cawthron.org.nz