Modelling river response to environmental change
Morphodynamic simulation of Rees River, NZ, evolving through a series of consecutive high flow events
MBIE NZ, Endeavour
2021-2026
Team
Prof James Brasington, Justin Rogers with Jono Tonkin and Angus McIntosh (Biological Sciences at UC)
The Problem
The structure and diversity of river habitats is changing rapidly and unpredictably, fueled by the cumulative impacts of climate and land-use change. As we prepare for an unprecedented future, the evidence needed to support river management can no longer be found in historic analogues, nor our goals set in terms of unattainable reference conditions. An alternative approach is needed urgently to guide anticipatory, rather than reactive decision making in the face of such uncertainty. Our research seeks to addresses this goal by developing a process-based framework to predict how catchments and their rivers will adjust to these dynamic environmental pressures, shaping the physical habitat template that mediates species interactions and defines future ecological trajectories.
Research Goals
In this project we will develop multiscale geomorphological models to predict how the morphology, sedimentology and hydraulics of rivers and floodplains evolves over centennial timescales in response to changing climate and anthropogenic management. These modes aim to reveal how catchments filter environmental disturbances across space, reshaping fluvial habitats and the patterns of longitudinal and lateral connectivity that condition ecological response.
Using case studies from dynamic environments across the Southern Alps of New Zealand, we will develop ensemble forecasts of river flows and sediment transport that reflect climate and planning scenarios and use these to parameterize morphodynamic simulations that predict how rivers adjust at the reach-scale. This approach will reveal the processes that drive rivers to critical tipping points, resulting in fundamental shifts in their ecological function.
Validation of the numerical simulations will focus on mechanistic process representations over individual storm-scales (patterns and volumes of erosion and deposition, particle step-lengths) and the typological response of river networks over decadal timescales (using graph-theory). This will be supported by high resolution acoustic, airborne and satellite remote sensing (3D lidar, thermal imaging and archival image analysis) to characterize and quantify riverscape evolution.
Project Partners:
Cawthron Centre, Dr Robin Holmes and Joanne Clapcott
Relevant Publications
Connor‐Streich, G., Henshaw, A.J., Brasington, J., Bertoldi, W. and Harvey, G.L., 2018. Let's get connected. A new graph theory‐based approach and toolbox for understanding braided river morphodynamics. Wiley Interdisciplinary Reviews: Water, 5, p.e1296.
Richards, K., Brasington, J. and Hughes, F., 2002. Geomorphic dynamics of floodplains: ecological implications and a potential modelling strategy. Freshwater Biology, 47, 559-579.
Williams, R.D., Brasington, J. and Hicks, D.M., 2016. Numerical modelling of braided river morphodynamics: Review and future challenges. Geography Compass, 10, 102-127.
Williams, R.D., Measures, R., Hicks, D.M. and Brasington, J., 2016. Assessment of a numerical model to reproduce event‐scale erosion and deposition distributions in a braided river. Water Resources Research, 52, 6621-6642.
