Catchment processes and management
(Dis)connectivity in geomorphology: From basic research to managing fluxes at source and at scale
Dr Ronald Poeppl1, Prof Tony Parsons2, Prof Kirstie Fryirs3, Prof Gary Brierley4
1University of Vienna, Vienna, Austria, 2University of Sheffield, Sheffield, United Kingdom, 3Macquarie University, Sydney, Australia, 4University of Auckland, Auckland, New Zealand
In geomorphology, connectivity has emerged as a significant conceptual framework for understanding the transfer of sediments through landscapes. The concept of connectivity has had particular success in the fields of fluvial and hillslope geomorphology, but has also been widely applied in (peri)glacial, aeolian, and marine contexts. Recent research highlights that not all systems are connected and widespread disconnectivity can be a natural and expected part of landscape function that drives fluxes in sediment, hydrological, biogeochemical and ecological processes. To manage (dis)connectivity in practice requires that scientists and practitioners have a baseline understanding of the natural or expected (dis)connectivity patterns and linkages in the landscape they are managing, and how (dis)connectivity functions vary in space and time. This then forms the basis for determining the extent to which anthropogenic activities have altered the operation of (eco)system fluxes and the extent to which (dis)connectivity ‘needs’ to be managed at source and at scale. We aim to create a diverse session that illustrates the role of (dis)connectivity in landscape systems. We particularly welcome both case studies where (dis)connectivity principles have been applied and used in management and more theoretical contributions to understanding how (dis)connectivity shapes landscape responses to disturbance events. We hope to use the session to promote the importance of understanding (dis)connectivity as a basis for managing fluxes at source and at scale.
(Mis)USLE: towards better practices in soil erosion and sediment budget modelling
Dr Maarten Wynants1,2, Prof Andrew Brooks2, Dr Pedro Batista3, Prof. David Dunkerley4
1Ghent University, Ghent, Belgium, 2Griffith University, Gold Coast, Australia, 3University of Augsburg, Augsburg, Germany, 4Monash University, Melbourne, Australia
Soil erosion models, like the USLE, are increasingly popular with scientists and practitioners. This is in part due their ease-of-use with the increasing availability of remote imagery, but also due to the easily-digestible mapping outputs they produce. However, erosion models are constrained by locally representative relationships and specific assumptions. Empirical field data for understanding soil erosion, sediment connectivity, and geomorphological processes are still lacking in many parts of the world, particularly in the Global South. Despite that, USLE-based erosion models are increasingly applied around the globe, often integrated within sediment budget models relying on coarse resolution spatial data and with little attention to uncertainty analysis and model testing. Nevertheless, the increasing reliance of resource managers on erosion models ultimately impacts the lives of stakeholders and conservation efforts. With this interactive session, we aim to foster a discussion on the perils of misusing soil erosion models and proposing ways to increase model reliability in support of decision making. Specifically, we encourage contributions pertaining to:
(i) perspectives and reviews on the current application of soil erosion modelling;
(ii) best scientific practices for improving the representativeness of USLE-based models and their integration in catchment sediment budgets;
(iii) case studies of model (in)validation, e.g. where and when do models (not) work;
(iv) improved methods for model parameterisation, testing, and uncertainty quantification;
(v) ethical ways for translating modelled erosion rates and sediment budgets into risk assessments and recommendations that impact stakeholders and environmental quality.
We encourage applications from the Global South and welcome interdisciplinary contributions bridging the gap between mathematical modelling and policy making. Contributions can be both in oral and poster format, and the session will be followed by a discussion session with the aim to provide a community perspective with best practices for the application of soil erosion models.
Advancing Theory and Modelling of River Systems
Professor He Qing Huang1
1China University of Geosciences (Wuhan)/Chinese Academy of Sciences, Chaoyang District, Beijing, China
A fundamental contribution of earth scientists is to make convincing predictions about river channel change that are useful to the public and to decision makers. This is particularly important in developing areas of the world, where human impact has not yet radically altered river morphologies, but where development pressures are mounting. It is also critical in the face of climate change, and the probable increase in extreme events. Unnatural channel change contributes to degradation in aquatic habitats, extinction of riverine species, loss of flood-retaining areas etc. The purpose of this session is to communicate recent advances in theory and modelling of how river systems change at all scales and consequently, to identify complex self-organised models of river systems. We welcome studies conducted in a wide range of geographical areas, using a broad range of methodologies.
Please note that this session is organised by a working group of the International Association of Geomorphologists, and Prof. He-Qing Huang (China), Prof. Ian Rutherfurd (Australia) and Prof. Paul Carling (UK) are the co-chairs.
Predicting and responding to geomorphic change: case studies from Aotearoa New Zealand
Dr Richard Measures1, Dr Sophie Horton2
1National Institute of Water & Atmospheric Research Ltd, Christchurch, New Zealand, 2School of Earth and Environment, University of Canterbury, Christchurch, New Zealand
Like many countries, hazard management in Aotearoa New Zealand faces significant challenges in balancing the social, environmental, cultural and economic pressures placed on the rivers and coastlines.
Recent significant events such as the Auckland Anniversary floods and the impacts of Cyclone Gabrielle have highlighted the urgency of many of the problems hazard managers must contend with: legacy flood and coastal protection infrastructure in need of renewal and/or upgrade, post- event recovery works, increases in the magnitude and frequency of inundation and erosion due to climate change and changes in societal expectations regarding acceptable levels of risk and the role of various agencies in managing that risk. Tackling these challenges has been undertaken against a backdrop of significant policy change and the need to continue to manage existing geomorphic hazards of avulsion, rapid channel migration, coastal erosion and the degradation of coastlines and waterways.
This session is co-convened by the New Zealand Rivers Group and New Zealand Coastal Society. It will draw on case studies from those who are managing rivers and coasts around Aotearoa. We welcome contributions that focus on recovery efforts and insights they provide for future preparedness, the investigation and management of vulnerability in the face of climate change and examples where mana whenua and community engagement has been used to achieve more sustainable and lower cost outcomes for Aotearoa.
River and catchment evolution, processes, and management
Dr Karen Gran1, Dr. Lisa Ely2, Dr. Karl Wegmann3, Dr. Takashi Oguchi4
1University Of Minnesota Duluth, Duluth, United States, 2Central Washington University, Ellensburg, United States, 3North Carolina State University, Raleigh, United States, 4University of Tokyo, Tokyo, Japan
Rivers are constantly changing and evolving in response to external perturbations ranging from tectonic and volcanic disturbances to glaciation to modern climate change and anthropogenic impacts. Geomorphology plays a key role in helping resource managers understand how rivers are responding to past and present perturbations, and thus how they may respond to future changes. This session invites a range of scientific contributions that use geomorphology to improve management and restoration of rivers and catchments. We also welcome general contributions on river and catchment evolution and river management. This session is supported by the Quaternary Geology and Geomorphology Division of the Geological Society of America.
Urban Streams: From Long Trajectories to Restoration Issues and Hazard Management
Professor Laurent Lespez1, Professor Peter Ashmore2, Assistant Professor Frédéric Gob3, Assistant Professor Corey Dawson4
1Univ. Paris-Est-Créteil & LGP - CNRS, Thiais, France, 2University of Western Ontario, London, Canada, 3University of Paris 1 Pantheon-Sorbonne & LGP CNRS, Thiais, France, 4Dalhousie University, Halifax, Canada
Today's urban streams face a double challenge: improving their hydrogeomorphological and ecological functioning and managing increasing hydrological risks. In addition, cities have to cope with climate change, which has implications such as an increase in the magnitude and frequency of floods and their geomorphological consequences. New research is needed to take into account the characteristics of urbanisation and the diversity of bioclimatic contexts specific to each hydrosystem. This remains a challenge because urban sprawl is discontinuous and multiform, and because changes in biophysical processes occur simultaneously with urban development. The current functioning of urban streams is the result of the urbanisation of catchments, which can be very old and has left many legacies that are not fully understood. Distinguishing the effects of urbanisation from more ancient alterations raises the question of the hydrogeomorphic equilibrium of these river systems. In addition, cities and the rivers that flow through them are subject to climatic phenomena specific to the bioclimatic regions of the world. Thus, the increase in the number of storms and typhoons raises new issues for the sustainable hydrogeomorphic management of these streams.
To discuss these issues, we are looking for papers that focus on streams flowing through cities and that address one or more of these issues:
- Current processes governing the hydrogeomorphic function of urban rivers and streams in different regional biophysical contexts, from temperate to tropical, in a changing climate.
- Understanding the role of urban development (forms, processes, chronology) and the impact of historical legacies on the past and future evolution of urban streams in different socio-cultural contexts.
- Innovative techniques and methods to monitor the hydromorphological dynamics of urban rivers, from regular functioning to major flood events, and from field work to remote sensing and modelling.
- Management and restoration of urban streams.
Using geomorphology in river management: From science to action
Dr Alex Sims1, Josie McGushin2
1Alluvium Consulting, Dunedin, New Zealand, 2Melbourne Water, Melbourne, Australia
Geomorphology provides a critical framework for understanding and managing rivers. Geomorphologists are increasingly required to reconstruct and explain past river behaviour, map and interpret contemporary forms and processes, to make predictions about future river behaviour and to apply these skills to projects aimed at rehabilitating degraded ecosystems, reducing flood hazards, preparing for droughts and climate extremes, and protecting natural and human made assets. The increased use of geomorphology in such projects has been accompanied by a revolution in the tools and methods employed by geomorphologists, enabled by the explosion in the availability and resolution of remote sensing data, dating techniques, repeat high-resolution surveys and increased computing power.
Advances in measurement and modelling methods, and the technology deployed during fieldwork have occurred while the field of applied fluvial geomorphology is increasingly shifting away from the traditional ‘command and control’ paradigm of river management, towards more holistic and process-based modes of thinking. Contemporary river management is increasingly focused on accelerating natural river recovery, using nature-based solutions and prioritising low-cost interventions that work with river processes to shape geomorphic trajectories. When used appropriately these new approaches have the potential to deliver multiple benefits including increased habitat provision, lower overall maintenance costs, decreased natural hazard impacts and carbon sequestration.
This session is co-convened by the Australian River Basin Management Society and The New Zealand Rivers Group. We welcome studies that explore how recent advancements in fluvial geomorphology are being used to drive more sustainable river management practices. We seek contributions that synthesise the many examples of innovative rehabilitation techniques and case studies to identify how actions can be up scaled and implemented. We also welcome studies that provide guidance on how to communicate applied geomorphology in river management practice, and thoughts towards professional development needs and development of communities of practice for applied geomorphologists.
