Blog by Alana Gaughan, GIS Data Lead for CJ Founds Associates
Let’s face it, Brits are used to dealing with rain. We just ‘Carry On’ as they say, not letting it ruin our picnics, festivals or bank holiday weekends.
And our resilience has stood us in good stead as according to the State of the UK Climate report the UK has become much wetter over the last few decades with evidence that 2011-2020 was 9% wetter than 1961-1990, not forgetting the extreme weather patterns due to climate change – remember the hail stones in the summer of 2021?
But with heavy rain, brings floods and that is a whole new challenge – some of which is well documented and causes huge damage to our road networks, leading to dire circumstances for people that live and work in or near flood zones and rely on transport systems for getting around.
There is also the added cost to the taxpayer for flood-related road repairs and maintenance and the broader economic impact to regions, Local Authorities, businesses and the wider community.
Under the Highways Act 1980, local authorities have a statutory duty relating to Highway drainage, including maintaining, cleansing and dealing with issues that could impact highway users. Quite often these are buried in Inspection and Maintenance Policies and Manuals but often manifest themselves through media – when flooding happens and worse when lives and safety are put at risk. But we can address this and be smarter in our approach to combating the effects of climate change through more pro-active and preventative approaches – saving time and resources.
This is where the clever use of GIS and data can help.
A simple desktop-based GIS approach can be designed to identify potential drainage and surface water flooding issues and uncover potential drainage issues by layering and interrogating existing data sources – and there are plenty of data sets held by LA’s – it’s just how they are captured and used.
Methodology
- Data Integration:
Cleaning up historic and real-time client-provided datasets, layering alongside Environment Agency’s National Flood Risk Assessment data.
- Spatial Analysis:
Conducted geoprocessing gives an ariel view of surface water features, ditch catchment locations, flow directions, and environmental variables (e.g. terrain gradient, flood risk zones). When overlaid with client areas of interest, such as highway networks or development sites, significant outfall and drainage vulnerability areas can be identified.
- Integrated Data Approach Provides Valuable Insights
The analysis uses reactive maintenance records, emergency callouts, and flood inquiries to identify critical drainage risks along road networks.
- Flow Direction Mapping Enhances Understanding of Road Risk Areas
Use of Digital Elevation Models (DEMs) to produce both high-level flow analysis across expanses of road networks, and more granular surface-flow estimates, to identify vulnerable outfall zones and pinpoint drainage issue areas.
- GIS-Led Resilience Scheme Supports Targeted Interventions
A resilience mapping layer highlights surface water flood risk zones that would benefit from strategic intervention and investment.
This layer can be used as a foundation for future planning when combined with internal datasets (e.g. utility data).
What this leads to is the ability to create a simple analysis tool which can help Highway Drainage and Asset Engineers identify and prioritise early interventions, whilst also addressing customer and resident enquiries. Whilst we have seen lots of proprietary systems on the market that will map gully locations, identify cleansing regimes and propose reactive solutions – these can often be expensive and very solution specific – not linking to open-source data sets, or wider asset information.
So, with a little logic planning and linking back to budgets we can produce something intelligent and representative – using existing data to drive forward programmes.
Tracking Challenges
One of the main challenges in quantifying flood-related repair costs, lies in the integration of these works into broader road maintenance programmes. Road repairs from flood damage are often not separately tracked, making it difficult to isolate their financial impact from general budgets. Quite often Local Authority Highways teams are faced with either delivering immediate repair and fix programmes using whatever funding is available from ever decreasing and squeezed revenue pots or trying to plan in-year and future year prevention programmes using capital funding.
So, what are the Key Takeaways
- Shifting away from traditional approaches to asset management and data driven use cases is critical if we are to maximise the value and impact of highway maintenance investments. Raising awareness of alternative methodologies, particularly the use of spatial and digital tools, can help unlock new levels of understanding across both technical and non-technical audiences.
- Geographic Information Systems (GIS) offer a powerful way to visualise and contextualise data. They translate technical problems into accessible, visual formats that support better-informed decision-making. This not only enhances understanding at all levels of an organisation but also provides a compelling platform to showcase evidence and justify investment. You don’t need to be an expert!
- With better use of data, we can prioritise and allocate funding more strategically targeting specific service areas and locations where the impact will be greatest. This approach maximises value for money by enabling decisions based on need, performance, and long-term benefits.
- The benefits extend beyond solving immediate issues. Strategic planning underpinned by robust data allows us to demonstrate wider environmental gains such as improved drainage or climate resilience downstream, as well as secondary outcomes like fewer reactive interventions and longer asset lifecycles.
- Adopting methodologies like this also creates stronger links between asset management systems, data capture, and technology integration across other service areas such as winter maintenance, reactive works, and inspections. In time, this enables a transition away from revenue-heavy reactive responses and toward a more efficient, planned maintenance model that delivers sustained value.
Key Considerations for Highway Authorities
- Start with the problem in-mind and know your problem points
- There isn’t any such thing as bad data – it’s just what you are collecting!
- Ensure your data is available and accessible ideally in a standard data format
- There is a lot of open-source data – make sure you have the right licences to access
- Analysis can depend on the accuracy and completeness of client-supplied data
- Large dataset size and study areas can introduce time constraints – ie regional plan
- Desktop-based assessments and results can provide an expert glimpse into immediate areas of prioritisation, but should always be validated through further field verification (ground-truthing)
- You don’t need to be an expert GIS “jockey” to harness the power of data integration – but good representative images and plans can talk a thousand words!
