Nature's Resistance: Quantifying ecological roughness for enhanced flow prediction in rivers

Context. Rivers are fundamental to our landscapes, ecosystems, and communities, yet their natural flow is interrupted by both human-made and ecological features - including aquatic vegetation, trees and roots, and woody debris. These living or once-living elements, termed ecological roughness, alter water flow through river channels, affecting the flow depth, velocity, and turbulence. These processes underpin socio-ecological factors, including flood risk, particulate transport, and biodiversity. Amid accelerating climate change, rising extreme rainfall, evolving management priorities toward ecological restoration, and the spread of invasive plant species - the physical character of rivers is undergoing transformation from the conditions observed in recent decades. Despite this, current flood prediction models largely overlook the complexity of these ecological roughness features, creating a critical blind spot undermining both scientific understanding and practical flood management. Hence, there is an urgent need to quantify the diversity of ecological roughness to develop up-to-date models incorporating their dynamic, multi-scale influence on flow to enhance flood resilience while supporting river ecosystem health.
Challenge. My Fellowship addresses four critical knowledge gaps that will transform how we conceptualise, measure, and model river systems:

The diversity and extent of ecological roughness elements remain undocumented.
Conventional assessments consider roughness components in isolation, neglecting combined effects of multiple obstructions and underlying bed topography.
The effect of roughness porosity (water passage through structures) on flow remains difficult to quantify.
Flood models inadequately represent the dynamic nature of ecological roughness that changes over multiple timescales.

Research Aims and Objectives. This Fellowship has two interconnected aims: (1) comprehensively quantify the diversity of ecological roughness in rivers and develop a new conceptual framework to improve flow modelling via field observations, flume experiments, and numerical simulations; and (2) apply this framework to tackle environmental and societal issues related to flood prediction and management in a changing climate.
These aims are addressed through four research objectives:
RO1: Establish a database documenting the location and spatiotemporal diversity of riverine ecological roughness.
RO2: Evaluate the multi-component contributions of ecological roughness to flow resistance using high-resolution field data.
RO3: Develop a universal empirical formula for flow resistance through physical modelling of ecological roughness coupled with bed roughness.
RO4: Integrate refined ecological roughness parameters into hydraulic flood models to improve predictions of flood extent.
Applications and benefits. This research will deliver wide-reaching transformative impacts across science and policy sectors - bridging river science, hydraulic engineering, and ecology.
The work will generate a novel, integrative framework for identifying, quantifying, and modelling ecological roughness across scales, reshaping how flow processes are represented in predictive models - enabling more realistic flow predictions, improving flood modelling accuracy, and potentially reducing damage costs. An open-access database and empirically derived tools will support flood risk managers, environmental agencies, and river restoration practitioners in making evidence-based decisions that balance flood mitigation with ecological restoration. Citizen science engagement will empower the public to contribute data and deepen their understanding of river systems, strengthening links between science and society. These contributions will also inform broader applications such as habitat assessments, sediment transport analysis, and landscape change modelling, key to building climate-resilient river environments.
Finally, this fellowship will accelerate my trajectory toward research independence – developing my leadership, project management, and stakeholder engagement capabilities, while creating opportunities for international collaboration and follow-on funding at the critical interface between hydraulics and ecology.