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Morphodynamic research challenges for braided river environments: Lessons from the iconic case of New Zealand

journal contribution
posted on 16.10.2020, 09:54 by DM Hicks, Edwin BaynesEdwin Baynes, R Measures, G Stecca, J Tunnicliffe, H Friedrich
Pressures on braided river systems in New Zealand are increasing due to anthropogenic stresses such as demand for irrigation water, braidplain conversion to farmland and invasive vegetation, as well as extreme natural events associated with earthquakes and climate change. These pressures create issues around preserving braided river physical environments and associated ecosystems and managing hazards such as floods, aggradation and erosion. A need for more robust understanding and quantification of braided river morphodynamic processes underpins many of these issues. Here, we present eight morphodynamic research challenges to service this need. The first four research challenges relate to managing aggradation‐related flooding hazards; the last four address issues stemming largely from recent dairy expansion, which has created huge pressure to take land and irrigation water from the alp‐fed braided rivers and to alter flow regimes at their mouths. Hāpua, the freshwater lagoons found where most braided rivers meet the coast, show complex morphodynamic behaviour in response to the interplay of river and coastal processes, and their special ecosystems are sensitive to river flow and sediment load changes. We discuss how physical laboratory experiments and novel numerical modelling can help to understand the morphological processes braided rivers undergo, and we show how those research advances could inform planning and legal decisions to regulate land rights and irrigation water allocation on New Zealand’s braidplains. We illustrate these environmental and engineering issues and research challenges with examples from the Kowhai, Waiho, Waiau, Rangitata and Hurunui Rivers.

Funding

Marsden Fast-Start Grant no. 18-NIW-002 (Marsden Fund, Royal Society of New Zealand)

Smart Ideas no. CONT807 61471-ENDSI-NIW (Endeavour Fund, Ministry of Business, Innovation and Employment 808 of New Zealand)

History

School

  • Social Sciences and Humanities

Department

  • Geography and Environment

Published in

Earth Surface Processes and Landforms

Volume

46

Issue

1

Pages

188 - 204

Citation

Hicks, D.M. ... et al. (2021). Morphodynamic research challenges for braided river environments: Lessons from the iconic case of New Zealand. Earth Surface Processes and Landforms, 46 (1), pp.188-204.

Publisher

Wiley

Version

AM (Accepted Manuscript)

Rights holder

© Wiley

Publisher statement

This is the peer reviewed version of the following article: Hicks, D.M. ... et al. (2021). Morphodynamic research challenges for braided river environments: Lessons from the iconic case of New Zealand. Earth Surface Processes and Landforms, 46 (1), pp.188-204, which has been published in final form at https://doi.org/10.1002/esp.5014. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions.

Acceptance date

03/10/2020

Publication date

2020-11-10

Copyright date

2020

ISSN

0197-9337

eISSN

1096-9837

Language

en

Depositor

Dr Edwin Baynes Deposit date: 13 October 2020