Frequently Asked Questions

It is often believed that a 1 in 75 year flood refers to a flood event that would happen, on average, once every 75 years. In fact, the term refers to the probability of a major flood event occurring in any one year.   “1 in 75 years” actually means that, each year, there is a 1.3% chance of a flood of this magnitude happening.  This percentage is calculated on the basis of 1 divided by 75 times 100, a recognised formula for the calculation of annual flood risk. 

1 in 75 is the minimum standard of flood protection for which residential properties will be considered by insurance companies for insurance against flooding.  At present, there are several flood-prone properties in the town which cannot obtain affordable insurance against flooding.

The height of the flood walls is dictated by the flood levels predicted for a 1 in 75 year flood event.  The walls will actually vary in height along different sections of the river according to the risk of flooding in each particular area.  Throughout the Scheme, the walls will be built as low as possible in order to meet the overall protection criteria set by the planning authorities.

In some areas, that is possible and is an inevitable side-effect of building a flood protection scheme through the centre of a vulnerable town where flood walls are the only solution.  A priority has always been to allow pedestrians and residents to continue to enjoy views of the river from the riverside footpaths.  That’s why the Scheme has incorporated the installation of several large glass viewing panels to be built into the walls at intervals, allowing people views of the river.  Other measures include setting the flood protection walls back from the river’s edge wherever possible (at the Little Haugh, for example) so that existing riverside paths can be maintained with uninterrupted views along the river.  In other areas, footpaths will be raised and viewing areas created.

There will be a combination of finishes.  The design team has worked with Scottish Borders Council heritage and landscape teams to devise a range of wall finishes which complement and blend in with each locality along the area of the works.  Many design options were considered.  Where the wall face can be viewed by local residents, the finish will either be stone, reconstituted stone or patterned concrete, complimented by a stone and concrete coping detail. 

Whilst the removal of gravel from watercourses can be effective in certain circumstances, careful studies by experts have shown that it would not protect Hawick against a major flood event. Flooding comes from a variety of sources, for example, rivers, overland flow, sewers etc. In the case of Hawick, removing gravel could only have an impact on potential flooding arising from the local rivers but not flooding from other sources.  Analysis has shown that gravel removal on a large scale can provide a flood reduction benefit. However, this benefit will only be temporary due to the natural processes of the River Teviot washing more gravel downstream over time to take the place of any gravel which was cleared.  The flood defences being built in Hawick provide the only viable long-term protection. 

Dredging also has a number of major downsides, for example, undermining of existing bridges, damage to wildlife habitats and general environmental degradation of the river.

This has been considered in detail by the design team.  Currently, if heavy rainfall generates surface water volumes which are greater than the capacity of the road drainage network, then the excess water forms inconvenient ponds before eventually finding its way to the river, causing obstruction to pedestrians and traffic.  Once the Flood Protection Scheme is in place, the new walls could create a barrier to the escape of excess water.  That’s why the design includes provision of a high capacity drainage system along the back of the new walls to take excess water to a large underground chamber.  If the river levels are low (for example, the excess water is the result of a sudden summer thunderstorm), the water will discharge via gravity from the chamber into the river.   However, if river levels are high (as they often are, say, during the winter months) then the excess rain water will be pumped from the chamber into the river via an underground pumping station.

The construction works are scheduled to take 34 months.  The Flood Protection Scheme is planned to be operational and providing flood protection by the autumn of 2023 with final construction work due to be completed by the end of that year.

Regular updates on progress will be issued via the website, quarterly newsletters, public meetings and social media.

Consideration of wildlife and their habitats has been a major factor in the planning for the Scheme. Throughout the lifetime of the works, we will be working closely with a number of statutory environmental bodies - such as SEPA (Scottish Environment Protection Agency) and the Tweed Forum – to ensure that any impacts on wildlife are kept to a minimum.  A full Habitats Regulation Appraisal (HRA) has been carried out for the project.  This report identifies any potential impacts to wildlife habitats and recommends the constraints to be placed on the contractor to mitigate these impacts and protect wildlife.

Inevitably, any major construction project through the middle of a town will cause some significant disruption to traffic.  There’s no getting away from that fact.  This has been a major consideration from the inception of the Scheme.  Diversion routes and road closures are subject to consent by Scottish Borders Council and the Scottish Government’s transport agency Transport Scotland and will be announced in advance and clearly signposted when in operation.  We will do everything we can to keep any disruption to a minimum.

You can get the latest information in the Traffic Management section of this website. Information is also available on our Facebook and Twitter pages.

It is inevitable that some trees will have to come down in order to accommodate these vital flood defences.  The design of the Scheme ensures that the minimum number of trees is involved and any tree removal is subject to planning consent by Scottish Borders Council.  Some of the trees involved are reaching the end of their natural lifespans and would have been subject to removal in due course anyway.  We are committed to planting 2.5 trees for every one tree removed as well as undertaking a programme of enhanced landscaping measures tailored to each location affected by tree removal.

Scottish Borders Council operates a subsidised flood product scheme, whereby a number of flood protection products are available to households in the Scottish Borders to purchase at a discounted price. These include floodgates for doorways, air-brick covers and water-reactive sandless sandbags.  A subsidy up to the value of £650 is available to householders and businesses, with additional products available at cost price.  Go to www.scotborders.gov.uk/floodproducts for more details.

To access a PDF document of flood protection products available through the discount scheme, please click here.

Vegetation and trees were removed along the line of the flood defences to ensure the safe construction of the Scheme. The vegetation that remains will be left as it is and there will be additional planting as part of the landscaping. This vegetation is required to help stabilise the bank and reduce erosion.

Some pumps do need to run at all times as they are pumping water out of excavations to allow the construction works, in these instances silent generators will be used. Generators are also required for providing power to site compounds and tower lighting to allow works to continue in the winter when it is dark.

Despite extensive ground investigation being carried out, there will be unforeseen ground conditions encountered during a project of this size. Along the riverbank at this location, high rock head meant that the sheet piles could not be driven to the required depth. To counteract this, rock armour was placed on the engineered bank to prevent erosion.

A controlled partial demolition of Bridgehouse Guesthouse was carried out in 2021 following previous damage to the structure. The remaining building has been left intact.  The Scheme is programmed to be constructed in this area in 2022. Once flood protection is in place, discussions will be held on the future use of the building and area.

The Scheme contains many features to reduce the risk of flooding to the town.  Direct defences reduce the risk of the river overtopping, sheet pile foundations to the wall reduce the risk of seepage related ground water flooding and pumping stations reduce the risk of surface water flooding.  All of these measures are designed to provide a degree of protection, rather than removing the risk altogether.  At no point in the scheme design or public consultation was it deemed possible to prevent these risks, as the economic and environmental impacts would have left the Scheme undeliverable.

The plethora of mill lades and the exceptionally permeable ground conditions which are present beneath the surface mean reducing the seepage risk was very challenging.  The sheet piles are designed to increase the time it takes for the ground water to rise in response to a rising river level.   With time, the water levels will equalise and the effects of the seepage protection become redundant.  Under “normal” flood event circumstances, the River Teviot will rise very quickly and fall relatively quickly thereafter, giving the seepage protection the best chance of working to its full potential.  In the case of the 28th October 2021 event, the river remained above 2.0m on the gauge for 26 hours which is an extremely unusual situation  – this is a level at or above many basements and, the equalising of the water levels on each side of the sheet piles will have caused the observed flooding.

The only way to further reduce seepage / groundwater flooding would be to seal the sheet piles along the clutches where they join together, and run a line of piles away from the river up into the hillside at the upstream end of the town at huge economic and environmental costs. This would also run the risk of trapping natural groundwater flow on the dry side of the piles, increasing the risk of permanent basement flooding.  Infiltration of ground water into the new surface water pumping station pipework will assist in reducing the groundwater level.

During the initial stages of the Hawick FPS, the inclusion of the Slitrig Water was assessed.  At that point, the process for scheme development and funding was slightly different than it is now and the main driver behind approval was an economic decision based on the Benefit Cost Ratio (BCR) – which basically is the return the scheme would provide, against the cost of the scheme.  Hawick FPS received 80% Scottish Government (SG) grant funding and to fulfil the funding criteria to receive this, the scheme required a BCR above 1 (for every £1 spent, the benefits were at least £1).  Including flood protection along the Slitrig Water dropped this figure below 1 for the Hawick FPS as a whole and was deemed to be non-viable as we would not receive the SG funding required to complete the scheme.  Therefore, at that stage a decision was made not to include protection along the Slitrig Water due to the lack of feasibility.

We do, however, understand that properties on the South side of Hawick, and in the upper Slitrig catchment are affected by flooding from the Slitrig Water and assisting these properties is of upmost importance to Scottish Borders Council (SBC).  In 2019, considering that the assessment of potential flood protection schemes now includes more factors than purely economics, a flood study was carried out to explore flood risk management options in the Crowbyres/Whitlaw area.  In December 2019, Scottish Borders Council put forward five potential flood protection schemes to SEPA for delivery within the 2022-28 Flood Risk Management Plans; this included a potential flood protection scheme for the Whitlaw and Crowbyres areas of Hawick.  The prioritisation of flood protection schemes by SEPA has not yet been finalised and SBC are currently awaiting the results of this process.

SBC are undertaking a set of targeted, small-scale, short-term flood risk management measures in the Whitlaw and Crowbyres areas of Hawick; these are programmed to be delivered between December 2021 and February 2022 and will provide increased flood protection to some of the highest risk properties in these areas.

The new footbridges constructed in the town have been raised to ensure flood events protected by the Scheme pass under them and they do not become blocked and cause backing up of the river that we have seen in the past when large trees gets washed downstream. If the footbridges were lower, this would impact on the 1 in 75 year level of protection the Scheme will provide once fully constructed.  All footbridges can be accessed by a ramp with the addition of steps in some locations and have appropriate level handrails and lighting. The footbridges and their approaches will be coated with specialist non-slip surfacing. The camber of the footbridges have been designed to be compliant with the relevant Disability Discrimination Act requirements. It should be noted that the previous footbridges did have a camber which is required for drainage. The new footbridge do have more of a camber which improves the flood resilience of the structure as well as the aesthetic appearance.

Access is provided along this stretch of the river bank by a flood gate on Commercial Road so this will allow access to clear debris from this area should it be required. Smaller rocks are to be placed between the boulders as part of the works and longer term the spaces in between the rock armour will likely naturally start to fill with gravel and silt.

Vegetation and trees were removed along the line of the flood defences to ensure the safe construction of the Scheme. The vegetation that remains will be left as it is and there will be additional planting as part of the landscaping. This vegetation is required to help stabilise the bank and reduce erosion.