Development of an Integrated Spatial Planning Tool to support the co-management of estuaries in New Zealand

Estuaries worldwide face increasing challenges from multiple environmental pressures including: urban development, rural land use activities, and climate change. Managing the health of estuarine environments is a partnership between local government and the traditional inhabitants of the land; in Aotearoa New Zealand, Māori are tangata whenua (people of the land) with well-established approaches to environmental management - kaitiakitanga. As part of a broader Oranga Taiao, Oranga Tāngata research programme, local kaitiaki (guardians) highlighted the connectedness of system and the importance of considering not only impacts and changes in the harbour itself, but also how activities on land affect the ecological, economic, and cultural health of Tauranga Harbour and its catchment more broadly. To support this, we have developed an Integrated Spatial Planning Tool (ISPT) for the Tauranga Harbour and its catchment. This tool links detailed dynamic economic and land use change models to a model of contaminant flow through rivers, an estuary transport model, and finally to models of ecological health and species abundance in the estuary. This tool was developed with co-management partners and is spatially explicit and dynamic through time, meaning that it can show change at different points of time, as well as at different spatial scales of interest. A key use of the ISPT is for testing different management scenarios, in particular implementation of mitigation measures and increased regulations within the catchment. These local decisions (scenarios) are tested against multiple plausible worldwide economic futures, linked to different climate change trajectories. In this talk we will present the results of the initial scenarios that we have investigated, along with broader findings on the most important stressors in the estuary and the key management levers of change.