Evaluating the sustainability of impounded rivers: An ecosystem services approach

There has been increasing demand in Canterbury, New Zealand for the abstraction of water from rivers. This demand has led to the increased interest in dam projects. But, while river impoundment can result in significant benefits, it also can come at "cost", especially to river ecology. Given these benefits and costs, it is essential that impounded rivers are systematically evaluated for their sustainability. In this paper the ecosystem services approach is applied for the purposes of evaluating the sustainability of the Opihi River located in South Canterbury. Indicators are used to represent the set of ecosystem services provided by the river. Both the criteria of weak and strong sustainability are evaluated in a novel way. Weak and strong sustainability are operationalised through an ecosystem services index and the safe minimum standard concept, respectively. In applying these evaluation methods it is observed that since the construction of the Opuha Dam, the Opihi River has progressed towards weak and strong sustainability