Rebecca Thirkell

Principal Modeller and Manager | MSc, BSc (Hons), MCIWEM C.WEM

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Rebecca Thirkell Aegaea

I am a Principal Modeller and Manager at Aegaea. As a Chartered Member of the Chartered Institute of Water and Environmental Management (CIWEM), I have been working in the flood risk sector for over 10 years. I specialise in hydraulic modelling and hydrology but also have experience in flood risk assessment and drainage design. I manage Aegaea’s modelling team. My experience is broad, covering everything from surface water and river hydraulic modelling to surface water drainage strategies and complex river restoration projects. I genuinely enjoy the technical challenge of redefining flood risks to help projects move forward that might otherwise be held back by generic mapping.

How I Can Help You

  • Hydraulic and Hydrology Expert: I can provide insight into proportionate modelling to support a development, restoration or master planning. Each site is unique and I am able to take your objectives and identify the appropriate approach to move it forwards with a strong evidence base.
  • Independent Model Review: I lead third-party reviews of flood studies, hydraulic models and hydrological studies providing clients and regulators with independent assurance of technical quality.
  • Project Management: I manage projects from enquiry through to delivery, with clear client communication at every stage. I take care of the organisation – scoping, programming, resourcing and budget control – and coordinate technical reviews so projects are delivered right and on time.
  • Driving Innovation: I unlock sites for development by going back to first principles and thinking beyond standard approaches – adapting available models and applying them to the specific challenges of a site to build the evidence base where conventional methods fall short.
  • Expert Policy Knowledge: I draw on a robust knowledge of UK National Flood Risk Planning Policies to ensure every report is fully compliant and stands up to regulatory scrutiny.

 

Expertise in Action

  1. Redefining Flood Extents (Scotland): For an industrial development, I undertook 10km of detailed hydraulic modelling that successfully proved the site was not at risk. This led to the removal of a holding objection from SEPA and allowed the client to receive planning permission.
  2. Complex River Restoration (South England): Working with a rivers trust, I modelled a highly sensitive reach involving multiple weirs and historic bridges. My work evidenced that the proposed channel reprofiling and gravel bar installation would actually reduce flood risk for local residents.
  3. Third-Party Review (Quarry Extension, Edinburgh): I provided an independent third-party review and certification of the flood risk assessment and surface water management plan supporting a planning application for a major quarry extension. My review scrutinised the water balance modelling and surface water management proposals, giving the client and the local authority independent assurance that the assessment was technically robust ahead of submission.
  4. NSIP-Compliant Flood Modelling (Lincolnshire Fens): I led application-compliant modelling for a Nationally Significant Infrastructure Project, combining three legacy Environment Agency models into a single large-scale model rebuilt in approved software, covering both defended and undefended scenarios. This involved extensive collaboration with the EA to agree bespoke methods beyond standard approaches, ensuring the assessment was robust and acceptable to all parties. Following detailed EA technical review, the modelling – including breach and extreme event assessments – was accepted with no further modelling required.
  5. Complex Wetland System Modelling (East England): I modelled a complex wetland habitat creation scheme of 22 cells served by high level and low level carriers, with automated controls including penstocks and gated weirs operating on logical rules. The model informed the operating regime and design of the wetland, balancing abstraction, water levels and flood resilience across the system.
  6. Masterplan Re-design (North West England): I used breach and fluvial modelling to recommend alterations to a residential masterplan. By adapting the layout to work with existing overland flow routes, we removed homes from high-risk areas without increasing risk elsewhere.
  7. Protecting a School from Surface Water Flooding: I managed a detailed surface water model build for a small catchment to assess the risk to a school from overland flow, examining flood depths, extents and hazard for the post-development site. Working closely with the Lead Local Flood Authority, I translated complicated technical assessments for non-technical audiences and contributed to design meetings – identifying the layout changes needed, alongside other on-site constraints, to ensure no vulnerable persons were at risk and no increase in flood risk off-site.
  8. Complex Fluvial Modelling in an Upper Fenland Catchment: I delivered complex fluvial modelling for a site in an upper catchment within a fenland environment. This included detailed catchment analysis and an EA-compliant hydrological assessment with a full Flood Estimation Report, justifying a non-standard approach that was agreed with the EA as the most appropriate for this unusual catchment. I constructed and extensively tested a hydraulic model using rain-on-grid methods to simulate fluvial flood risk across the catchment, with post-processing agreed in collaboration with the EA to separate the different sources of flood risk from the model outputs.

A Bit About Me

I hold an MSc in River Environments and their Management from the University of Birmingham. When I’m not diving into survey specifications and model stability, I stay active by playing netball and hiking. I also love spending as much time as possible outdoors walking my dog.

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