Geomorphic meanings of a resilient river

Abstract

In geomorphic terms, the concept of resilience is a useful metaphor to communicate various attributes of river morphodynamics, condition/health and evolutionary traits. However, the translation of this concept into management practice is fraught with difficulty and misinterpretation. Here, we present from the position that resilient rivers are not stable, nor do they need to be stabilised by fixed boundaries. Rather, rivers adjust, change and evolve, with different structures and functions in different settings. These differences are ‘expected’ characteristics and are fundamental to meanings of river resilience. Framed within this resilience context, river management accepts that rivers adjust and change, designing and implementing programmes that work with the river, not against it, enhancing self-healing and recovery traits. In this situated Antipodean account, we highlight differences in forms, rates and timeframes of geomorphic adjustment that underpin ‘expectations’ of a resilient river for a range of river types in Aotearoa New Zealand and Australia. We frame geomorphic meanings of a resilient river in relation to the expected range of variability and capacity of adjustment of any given river system. The ‘expected’ resilience for bedrock rivers is very different to that of a braided or wandering gravel bed river, a cut-and-fill river, a discontinuous watercourse (e.g., chains of ponds) or a fine-grained anastomosing river. The discussion relates resilience thinking upon evolutionary and emergent traits of riverscapes to Buddhist notions of impermanence.