Stuart Marshfield, Associate Hydraulic Modeller and Flood Risk Consultant with PJA
Introduction
Following on from this year’s Flood Modeller conference, I’m excited to share my collaboration with the Flood Modeller development team and Fathom to bring a user’s perspective on integrating Fathom’s cutting-edge flood mapping data within the Flood Modeller software.
PJA is a dynamic transport planning, placemaking, and engineering firm dedicated to providing bespoke planning and development advice to the private and public sectors. Flood Modeller is one of our go-to platforms for planning, schematising, analysing, and delivering robust hydraulic modelling assessments for our clients.
Navigating New Waters: The Updated Planning Policy Guidance
In August 2022, a significant update to the Planning Policy Guidance placed a spotlight on assessing flood risk from all sources. While the consultation for the updated National Planning Policy Framework is still underway, there’s already a clear shift towards a greater focus on surface water flood risk. This means we need to consider surface water flood risk earlier and more comprehensively as part of the Sequential Test when identifying suitable sites for sustainable development.
The Sequential Test: Steering Development to Safer Grounds
The Sequential Test is about directing new development to areas with the lowest flood risk. With the increased emphasis on flood risk from all sources, hydraulic modelling and comprehensive mapping are now more critical than ever. Detailed modelling not only helps us define flood extents and depths but also serves as a versatile tool for master planning, managing runoff rates, providing evidence for routing residual overland surface water and demonstrating improvements in local and downstream flood risk through mitigation options.
Building Confidence with Robust Evidence
Hydraulic modelling is essential for providing solid evidence. With robust evidence, we can instil confidence in our clients, potentially leading to investment and unlocking development opportunities. However, hydraulic modelling studies come with their own set of challenges, including time constraints, data availability, and technical complexities. These challenges can lead to increased costs, extended timelines, and uncertainty for our clients. In the private sector, delays can significantly impact planning application deadlines and appeals. By reducing delays, increasing confidence, and minimising uncertainty, we can facilitate cash flow, meet housing targets, and secure future sites for sustainable development.
Fathom’s Flood Mapping: A Seamless Integration
Since version 7.1, Flood Modeller users with Fathom accounts can access and automatically load Fathom’s online flood map datasets through the API. Fathom’s UK dataset offers a comprehensive selection of return periods and flood sources (fluvial, pluvial, coastal), considering climate change and flood defences. The data is fully interactive and integrates seamlessly with background mapping, existing published data, and model files within Flood Modeller.
In version 7.2, users can now directly import data into Flood Modeller, similar to loading raster information into GIS software, by submitting a data request directly to Fathom. This feature allows for specific requests for larger areas (>100km²) and enables users to store model output data for use at different project stages. This import procedure is specifically designed to process and visualise Fathom’s flood mapping data efficiently. Flood Modeller automatically applies appropriate symbology, allows for export to ASCII grids, specifies a custom suffix for imported files, and converts outputs from centimetres to metres, thereby promoting efficiency and saving time.
The Benefits of Using Fathom Flood Mapping for Project Initiation
Insight Ahead of Detailed Modelling: Gain early identification of potential issues with preliminary flood risk data.
Model Scoping and Schematisation: Define the scope and structure of the hydraulic model from the start.
Informing Decision Making at Early Stages: Support informed decision-making during the initial phases of a project.
Site Screening: Assess multiple sites to determine their suitability based on flood risk.
Adding Confidence Before Time/Spend Building a Model: Boost confidence in the project's feasibility with reliable data.
Tailor (and Potentially Reduce) Costs: Achieve more accurate cost estimation and potential savings by addressing flood risks early.
Mitigate Client Push Back, Alleviate Concerns: Reduce client concerns with clear, evidence-based flood risk assessments.
Unlock Client Spend: Encourage client investment by demonstrating thorough risk assessment and mitigation strategies.
Lower Commercial Risk: Minimize the risk of unforeseen flood-related issues, reducing overall commercial risk.
These benefits collectively enhance the efficiency, effectiveness, and financial viability of flood risk management projects.
The integration of Fathom’s flood mapping data within Flood Modeller provides further tools and efficiency savings for flood risk management. This collaboration enhances our ability to deliver comprehensive and reliable assessments, supporting sustainable development more effectively. By leveraging technology and robust data, we are well-positioned to meet the growing demands of flood risk management and deliver value to our clients.
Stuart Marshfield
Stuart is a chartered Associate Hydraulic Modeller and Flood Risk Consultant with PJA and has ten years of experience in the water and environmental management sector.
He is a technical specialist in the application of hydraulic models to derive fluvial and surface water design flood extents, and to inform sustainable river and natural flood management and the design of new development and infrastructure.
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