Economic Assessment of Braided Rivers Management
Braided rivers provide the majority of groundwater recharge to Aotearoa’s main aquifer systems, and yet we do not know the amount of water they provide because of their size and complexity.
The Agribusiness and Economics Research Unit (AERU) contributed to a groundbreaking project examining how braided rivers work. The five-year MBIE-funded programme, led by Lincoln Agritech, enhanced our understanding of how much water is lost from braided river systems to groundwater, thereby helping regional councils to effectively manage their water resources and quantify the environmental and economic benefits of different river management strategies. The research focused on three rivers: The Wairau River in Marlborough, the Selwyn/Waikirikiri River near Christchurch, and the Ngaruroro River in Hawke’s Bay.
The AERU team led the economics component of the research programme that placed estimates of economic values alongside the management implications and recommendations developed by the broader research team. This contributed to understanding the benefits and costs to affected communities from the different braided river management options developed. The tradeoffs identified were assessed overall within a Benefit Cost Analysis. The approach was to form an integrated framework that captured both market and non-market benefit and cost values inherent in different management strategies. Farm systems models were used to assess the market effects on agricultural production such as forgone productive land along river margins, increased water security to irrigators, and levels of resource extraction such as gravel. Non-market valuation techniques including choice modelling were applied to value changes in environmental assets such as habitat for native biodiversity and aquatic species, and recreational use and access.