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Flood Risk Management

Protecting communities and increasing resilience

Devon Floods 20-21st October 2021


Published

Last Updated

Flood Investigation Report

A Downloadable PDF version of the report is available here.

 

This flood investigation report has been produced by Devon County Council as a Lead Local Flood Authority under Section 19 of the Flood and Water Management Act 2010.

Version Undertaken by Reviewed by Approved by Date
 Draft 1 Thomas Aldridge Martin Hutchings January 2022
 Final Thomas Aldridge Martin Hutchings Dave Black – Head of Planning, Transportation and Environment February 2022
Final V2 Thomas Aldridge Martin Hutchings March 2022

This report covers the flooding incident between 20th and 21st October 2021 and has identified all flooded properties within the County that we have been able to determine or brought to our attention. Based on the criteria set out in our Local Strategy this single report covers the requirement for 4 Section 19 Flood Investigation Reports.

 

1. Introduction

The Flood Risk Regulations 2009 and the Flood and Water Management Act 2010 (the Act) have established unitary and upper tier local authorities as the Lead Local Flood Authority (LLFA) for their area. This has placed a number of responsibilities on the LLFA in relation to flood risk management and in particular Section 19 of the Act which states:

Flood and Water Management Act 2010: Section 19 – Local Authorities: investigations

  • On becoming aware of a flood in its area, a lead local flood authority must, to the extent that it considers it necessary or appropriate, investigate –
    1. which risk management authorities have relevant flood risk management functions, and
    2. whether each of those risk management authorities has exercised, or is proposing to exercise, those functions in response to the flood.
  • Where an authority carries out an investigation under subsection (1) it must –
    1. publish the results of its investigation, and
    2. notify any relevant risk management authorities.

Flood and Water Management Act (2010), S.19, c.29, London: HMSO

A ‘Risk Management Authority’ (RMA) means:

(a) the Environment Agency (EA),

(b) a lead local flood authority,

(c) a district council for an area for which there is no unitary authority,

(d) an internal drainage board,

(e) a water company, and

(f) a highway authority.

When considering if it is necessary or appropriate to investigate a flood event Devon County Council (DCC) will review the severity of the incident, the number of properties affected and the frequency of such an occurrence. Devon’s Local Flood Risk Management Strategy clearly sets out the criteria to be used when considering a Flood Investigation Report.

Although not all of the locations in this report meet the significance threshold of 5 or more properties flooded, to ensure that the full extent of the flooding is appreciated and recorded it has been decided to include all locations brought to our attention which experienced any internal property flooding, and also other areas of particular concern.

In partnership with the other RMAs in Devon this report has been produced to comply with legislation and to determine the main causes of the flooding. It should be noted that in order to progress with their flood risk management function DCC has opted to develop this report further by considering the various actions that should be considered by the relevant RMA. DCC as the LLFA will continue to monitor the list of actions with all of the RMAs and will assist in the delivery where practical to do so.

Each affected area or group of smaller areas investigated within this report will have a number of recommended actions to be taken forward by the relevant RMAs or in some cases, by the landowner or local community action group. There are various levels of action that can be taken depending on the severity of the situation and the practical solutions available to reduce the risk of further flooding. The recommended actions will generally fall into one of the following categories:

Delivery of Quick win schemes: a solution that can be implemented quickly by the Risk Management Authorities or Local Authority at relatively low cost; some of these have already been completed as this report has been progressed.

Further investigation/research: Further investigations such as catchment studies and hydrological/hydraulic assessments to understand the flow rates and directional paths and evaluate the extent of flooding. These would provide evidence for future capital investment.

Development of future schemes: Where immediate action is not financially viable or a solution not readily available then a larger scale flood alleviation scheme may be required. In such cases national funding would need to be secured together with additional contributions from others, such as local levy, local authorities and other third parties.

Landowner action: Members of the public who own land adjacent to watercourses have riparian responsibilities and therefore have a duty to maintain their section of watercourse to ensure there is no impediment of flow. Other works to protect their property may also need to be funded by themselves to ensure delivery within their timescales.

Community action: In some cases it may be prudent for community groups to join forces and deliver and maintain their own local schemes. In some cases this may generate further contributions from local levy or the LLFA.

This investigation report will provide a starting point, with suggested actions being further refined in the light of further studies and where possible, through further dialog with the affected communities.

Recommended Actions:

The purpose of this report is to act as a tool for all of the relevant RMAs to understand and appreciate the extent of flooding in their area and to consider and prioritise those actions relevant to their authority. Due to the extent of flooding, not only from the events covered in this report, the level of recommended actions far exceeds the budgets and resources available to enable them to be delivered immediately. Although we take all flooding issues seriously it should therefore be appreciated that some actions may not be progressed within the timescales expected by some residents or communities. Every effort will be made to progress the actions if and when suitable funding is obtained.

The recommended actions highlighted in this report will be used by the LLFA to monitor progress achieved by the RMAs.

 

2. Risk Management Authority Responsibilities

2.1 Recording Flood Incidents

LLFAs must record flood incidents as part of their duties under the Flood and Water Management Act. The information below shows the national guidance given as part of the Preliminary Flood Risk Assessment Spreadsheet submission to the EA, which outlines information to be collected by LLFAs.

Information the LLFA must record

Devon County Council (DCC) will record this on the DCC flood incident database:

  • Start Date
  • Days duration
  • Probability
  • Main source: Surface water runoff; Groundwater; Ordinary watercourses; Artificial infrastructure; Main rivers; The sea; No data
  • Main mechanism: Natural exceedance; Defence exceedance; Failure; Blockage or restriction; or No data
  • Main characteristics: Natural flood; Flash flood; Deep flood; Snow melt flood; No data
  • Significant consequences:
    • To human health (residential properties)
    • To economy (non-residential properties)
    • To the environment (designated sites flooded)

2.2 Key Responsibilities

RMAs in Devon all have their own roles and responsibilities. The general RMA responsibilities in relation to flood risk and surface water management are outlined below:

The Environment Agency is responsible for managing the risk from the sea, Main Rivers and reservoirs and has a strategic overview role for all flood risk management, making it a key local partner for DCC, especially when managing the risk from combined sources and in the event of a large flood incident. The EA also provides a flood warning service throughout England and Wales in areas at risk of flooding from rivers or the sea.

Devon County Council as the Lead Local Flood Authority is responsible for overseeing the flood risk from Ordinary Watercourses, groundwater and surface water runoff. They are also responsible for consenting to works on Ordinary Watercourses and enforcing the removal of any unlawful structure or obstruction within the watercourse. And, as previously stated they must ensure that a flooding investigation is carried out by the relevant authority and publish a report. DCC must also prepare a Local Flood Risk Management Strategy and maintain a register of flood risk assets.

Local District Councils are classified as land drainage authorities with discretionary powers under the Land Drainage Act, such as the implementation and maintenance of flood defences on ordinary watercourses. They also have powers under the Public Health Act to ensure the removal of any blockage within an Ordinary watercourse that is considered a nuisance. As a planning authority they are responsible for the preparation of development plans and making decisions based on planning policy.

Devon County Council as the Highway Authority maintains the highway drainage system to reduce the amount of standing water on the highway. This is achieved by limiting the water on the roads and ensuring that they are kept clear of rainwater; including the maintenance of highway gullies and culverts.

National Highways is responsible for managing, maintaining and improving the Motorway and trunk roads across England and any associated drainage and flood risk.

Land/Property Owners that have a watercourse in or adjacent to their land have riparian responsibilities on that watercourse. This means the landowner must:

  • Let water flow through their land without any obstruction, pollution or diversion which affects the rights of others.
  • Accept flood flows through their land, even if these are caused by inadequate capacity downstream.
  • Keep the banks clear of anything that could cause an obstruction and increase flood risk, either on their land or downstream if it is washed away.
  • Maintain the bed and banks of the watercourse and the trees and shrubs growing on the banks and should also clear any litter or debris from the channel and banks, even if it did not come from their land.
  • Keep any structures, such as culverts, trash screens and debris grills, weirs and mill gates, clear of debris.

The LLFA must also take an overseeing role to ensure that all flood risk is being managed appropriately.

In small, localised groundwater and surface water flooding incidents which do not reach the threshold level to trigger a flood investigation by the LLFA under Section 19, the Local Authorities will work in partnership to consider the appropriate action.

All RMAs have a duty to co-operate and to share information in relation to their flood risk management functions.

3. Incident Summary

3.1 Incident Summary

On the evening of the 20th October and early hours of 21st October 2021, significant flooding was experienced in Devon as a result of some intense and very localised rainfall events. Watercourses overtopped and drainage systems became overwhelmed which led to multiple properties flooding in East Devon, South Hams and Teignbridge. The areas worst affected were Axminster and Seaton; other areas affected include Kenton, Woodbury, Slapton, Kingsbridge and Modbury. In total, 101 properties suffered internal flooding (88 residential and 13 commercial).

Flood alerts were issued for the following rivers; Axe, Otter, Sid, Teign, Torridge, Dart, Clyst, Culm and Tributaries, Erme, Avon, Yealm, South Devon Coast.

Table 3.1 lists the towns and villages affected on this date together with the reported number of properties flooded in each location. These have been identified on Figure 3.1 to show the geographical extent of flooding across Devon. Rainfall data for the event is visualised in Figure 3.1. It should be noted that the flooded locations have been reported alphabetically and not in any order of priority.

Table 3.1 List of towns and villages affected

Location Number of properties flooded Source of flooding
East Devon
Axminster 42 Ordinary Watercourse/Surface Water
Seaton 31 Sewer/Ordinary Watercourse/Surface Water
Woodbury 6 Surface Water/Ordinary Watercourse
Broadhembury 3 Main River
Musbury 3 Surface Water
Exmouth 2 Surface Water
Feniton 1 Surface Water
Kilmington 1 Surface Water
Sidmouth 1 Surface Water
Stockland 1 Surface Water/Ordinary Watercourse
Tipton St John 1 Surface Water/Ordinary Watercourse
Whitford 1 Main River
Teignbridge
Kenton 5 Ordinary Watercourse
Bovey Tracey 1 Surface Water
Dawlish 1 Surface Water
Dunsford 1 Surface Water
Newton Abbot 1 Surface Water
South Hams
Kingsbridge 2 Surface Water
Slapton 2 Sewer/Surface Water
Modbury 2 Surface Water
Stoke Gabriel 1 Surface Water
Mid Devon
Hemyock 1 Surface Water
Torridge
Holsworthy 1 Surface Water
West Devon
Buckland Monachorum 1 Surface Water
Total properties flooded: 112
A colour map of Devon showing the locations that were flooded on 20th and 21st October 2021
Figure 3.1 Devon wide map showing locations that were flooded on 20th and 21st October 2021.
A heatmap showing the extent of rainfall over East Devon, Dorset and Somerset at 11pm on 20th October 2021
Figure 3.2 The extent of rainfall over East Devon, Dorset and Somerset at 11pm, 20 October 2021.

 

 

3.2 Data and Information Collation

It should be noted that this report is only based on the information brought to the attention of DCC through its professional partners, the media and the public and where further investigation by the authorities have identified additional flooded properties. Therefore, it cannot be guaranteed to contain an exact or exhaustive list of individual properties or affected communities on the 20 October 2021 event.

3.3 Highway Drainage and Sewerage Impacts

During this event on 20 October and early hours of 21 October 2021, significant surface water flooding affected the Highway network across Devon. Highway drainage systems in several areas particularly South and East Devon struggled to cope with the drastically increased flows, sometimes causing them to overflow onto the highway. Typically, these highway drainage and sewer systems are not designed to cope with such high intensity, short duration rainfall events. As part of the investigation, it will be recommended that Devon County Council Highways review the highway gullies and consider whether any maintenance issues require attention.

The A30 between Honiton and Ilminster had serious flooding and in parts had to be closed to traffic with cars stuck in the verges. This road is maintained by National Highways and is not considered in detail in this report. The Council will write and ask what their action plan is.

Notable areas of the highway affected are detailed in the following list:

  • Flooding to Station Road/A376 in Exton due to flooding.
  • Weycroft Bridge in Axminster closed.
  • A30 closed in sections by the police due to crashes associated with surface water flooding.
  • Patteson’s Cross between Ottery St Mary and Feniton flooded.
  • A3052 White Hart Inn to Axmouth, ordinary watercourse overtopping and surface water flooding caused several vehicles to get stuck in floodwaters.
  • Significant Highway flooding in and around Hemyock and Stockland
  • Overtopping of watercourse at Stoney Lane/Chard Road roundabout in Axminster causing significant flooding to road
  • Landslide reported between Colyton and Whitford
  • Overtopping and debris deposited on Wyke Lane between Axminster and Wyke Green
  • Road flooding in East Devon including Holcombe, Shute, Whitford, Uplyme
  • Road flooding in Church Street and Mill Street, Kingsbridge with some areas half a metre deep.

4. Flood Incident Extent and Impact

4.1 Axminster

4.1.1 Flood Incident Extent and Impact

Axminster experienced significant surface water and ordinary watercourse flooding right across the town. Figure 4.1 shows the significant locations in Axminster where ordinary watercourses are known to have overtopped, highlighting the widespread nature of the flooding within the town.

A map marking the areas where watercourses are known to have overtopped and caused internal flooding in Axminster on 20/21st October 2021.
Figure 4.1 A map marking the areas where watercourses are known to have overtopped and caused internal flooding in Axminster on 20/21st October 2021.
Millbrook Stream

At least 15 properties internally flooded from the overtopping of the Millbrook stream and this was enhanced by surface runoff on 20th October 2021.  At least 10 properties were primarily affected by the overtopping of the stream at the Willhay Lane culvert with many more experiencing flood damage to their gardens and outbuildings.

The overtopping of the culvert occurred during peak flows which alongside surface runoff led to some flooding on the parcels of land north of the Millbrook, including the cricket club at Cloakham Lawns, see Figure 4.2. The primary impact however was through a significant flowpath from the overtopping Millbrook conveying south down Willhay Lane toward the lowest lying properties via footpaths and the road network, as well as through the allotments. Some of the properties affected lay more than 300m from the Millbrook Stream. Properties in Lynch Close and North Street were also impacted by the out of bank flows.

Previously a culvert in this location acted as the mechanism for flooding as it only had the ability to convey approximately 2m3/s which equates to less than the flow generated in a 1 in 5-year event, with everything over and above that spilling into Willhay Lane. This last happened in 2012 when 31 properties flooded up to 900mm in depth from a rainfall event less significant than was experienced in the most recent event. As a result of the flooding that occurred in 2012, DCC replaced the old restrictive culvert with one that has the ability to convey over 7m3/s as well as constructing a new flood wall upstream to direct flows away from the properties at risk. This work was completed in 2017 and can be seen in figures 4.3 and 4.4.

The new culvert installed was shown by monitoring data in Figure 4.7, to be functioning during the event, and with a capacity of almost three times what it replaced, it is clear the scheme helped ensure that a significant amount of flooding and damage was avoided. Especially noteworthy given the event experienced on the 20th of October was more extreme than in 2012, with less properties being impacted to a much lesser depth. The mechanism for this flooding is attributed to surface water generated locally being exacerbated by a short period of overtopping of the new culvert structure as can be seen in the monitoring data in Figure 4.7.  Anecdotally the peak in flows experienced at the new culvert structure aligns with timing of a blockage clearing on a culvert structure upstream on Chard Road, releasing a wave of water toward Willhay Lane.

In a separate incident along the Millbrook there were 3 properties flooded by the backing up of flows due to a blockage at the Chard Road/Stoney Lane Culvert, see Figure 4.5. The Millbrook during peak flows was reported as being out of bank over 1km upstream of the Willhay Lane Culvert. This brought bank material down into the watercourse and there was significant flooding associated with the blockage of the Chard Road/Stoney Lane Roundabout culvert which was blocked by an upstream flood victim’s outbuilding that had been washed into the culvert, see Figure 4.6. One property saw their ground floor flood up to 2m deep as the peak Millbrook flows had no alternative route due to the blocked culvert. Public open space and adjacent footpaths were also damaged.

The blockage and then flooding at Chard Road/Stoney Lane Culvert occurred prior to 9pm coinciding with the peaks shown downstream. A 15ft deep ‘sinkhole’ was created due to the significant erosion to the downstream end of the culvert and there was flooding and large deposits of material along the public open space that Charter Road fronts onto.

Flooding was reported upstream on the Millbrook beyond the urban extent of Axminster in Sector Lane, highlighting that the sheer amount of rainfall was the primary cause for flooding.

Mud and silt deposition showing flooding in areas around Cloakham Lawns, Axminster
Figure 4.2 Mud and silt deposition showing flooding in areas around Cloakham Lawns, Axminster (credit: Environment Agency Reconnaissance Team)
Two images side by side. On the Left Looking downstream at the improved Willhayes Lane culvert on 29 October 2021 with EA river level sensor, on the right looking downstream at the pre-improvement works Willhayes Lane culvert in circa 2014.
Figure 4.3 On the Left Looking downstream at the improved Willhayes Lane culvert on 29 October 2021 with EA river level sensor, on the right looking downstream at the pre-improvement works Willhayes Lane culvert in circa 2014.

 

An image showing tree catcher upstream on the Millbrook of Willhayes Lane culvert which enabled it to continue to convey flows for much of the October flood event. Picture taken circa 2017/18.
Figure 4.4 Showing tree catcher upstream on the Millbrook of Willhayes Lane culvert which enabled it to continue to convey flows for much of the October flood event. Picture taken circa 2017/18.
A photo looking downstream at the Chard Road/Stoney Lane Culvert on the Millbrook. Picture taken November 2021.
Figure 4.5 Looking downstream at the Chard Road/Stoney Lane Culvert on the Millbrook. Picture taken November 2021.
A photo showing an outbuilding that was washed out by the Millbrook and a major contributing factor to the blocking of the Chard Road/Stoney Lane Culvert.
Figure 4.6 Outbuilding that was washed out by the Millbrook and a major contributing factor to the blocking of the Chard Road/Stoney Lane Culvert (credit: Axminster Nub News).
Purzebrook Stream

There was overtopping of multiple watercourses where they are culverted under the A358 in Axminster causing numerous properties to flood internally across the town. This was particularly significant for the Purzebrook which along with surface water runoff caused 10 properties to flood internally. Blocking of the grill at the inlet to the culvert in Lea Combe is recognised as a factor enhancing the issue on the Purzebrook leading to the worst affected properties receiving over 1m deep of internal flooding and runoff through the footpath link onto the A358. The area has a long history of similar flooding including in November 2009, December 2008, 1998 and 1985. Works were undertaken in 2013 to address some of the historic causes for blockages of the culvert.

Weycroft

The Weycroft area of Axminster saw 9 properties flood. 3 of which were associated with the main river Axe flooding and 6 associated primarily with ordinary watercourse and surface runoff.  At least three of the properties flooding internally by surface water experienced up to 18 inches (45cm) of internal flooding. The flood bank upstream of Stoney Bridges was overtopped. Local reports suggest that surface water runoff from adjacent farmland into Lodge Lane and possible overtopping of an unnamed ordinary watercourse led to significant flooding in Weycroft around 20:30 to 21:00 hours which was then exacerbated by the Axe overtopping around 23:30 hours, with peak conditions on the Axe at 00:05 and 03:00 on 21 October 2021. Residents were issued a flood warning for the River Axe by the Environment Agency at 22:46 however, as the primary impact was due to the surface runoff and ordinary watercourse many had already flooded.

Others areas of Axminster

At least two other ordinary watercourses are known to have overtopped on the southern urban extent of Axminster, at the points in which they are culverted under the A358, during peak flows which led to property flooding. This includes a shop and property at Abbey Gate which were also affected similarly in 2012, and a property in Dukes Way.

There were individual cases of surface water flooding distributed across Axminster including a local school and church. Garden and road flooding was also reported in Musbury Road, Fairy Lane, Lyme Road and Stoney Lane.   There were also reports of watercourses overtopping further south along the A358 out at Musbury, near Boshill Cross. As well as surface water flooding reported south-east of Axminster on Harcombe Road and Red Lane, Raymonds Hill, Woodbury Lane and along Cooks Lane.

4.1.2 Historic Flooding

There has been previous flooding experienced in Axminster, with the following incidents recorded

23/12/2013: 1 property flooded

21/11/2012: 1 property flooded from the Purzebrook

07/07/2012: 67 properties internally flooded

13/11/2009: 9 Properties flooded

13/12/2008: Flooding of at least one property

31/12/2000: 11 properties affected

07/12/2000: At least one property affected

05/11/2000: 1 property flooded

31/10/2000: 1 property flooded

05/01/2000: 1 property flooded

18/09/1999: 1 property flooded

05/12/1994: 3 properties on Castle Street flooded

03/02/1988: Number of properties flooded unknown

25/08/1986: 3 properties flooded around Weycroft Bridge area

27/12/1979: 2 properties flooded due to Millbrook Culvert blockage

30/05/1979: 5 properties flooded due to Millbrook Culvert blockage

Newspaper archival reports suggest significant flooding in October 1882, July 1926, June 1931 and July 1968 in Axminster.

4.1.3 Data Gathered

Rainfall data from the top of the Millbrook catchment, see Figure 4.8, shows that more than 30mm of rain fell in a two hour period between 19:00 and 21:00 hours on the 20 October 2021. This then coincides with the river gauge on the Millbrook culvert which shows peak flows above the base of the sensor situated on the culvert from 20:30 until 21:15 hours, which is taken to indicate overtopping of the culvert on Willhay lane during this period. This is shown in Figure 4.3.1 where it flatlines at 20:30 hours as the water has submerged the sensor at the top of the culvert on Willhay Lane. In a 31 hour period, from 16:30 hours on 19 October 2021 until 23:00 hours on 20 October 2021, the rainfall gauge recorded a rainfall total of 81.63mm rainfall. This was significantly higher than the event in 2012 which affected more properties.

A graph displaying EA sensor data showing river levels on the Millbrook at the inlet to the Willhay Lane Culvert on the evening of October 20th 2021.
Figure 4.7 EA sensor data showing river levels on the Millbrook at the inlet to the Willhay Lane Culvert on the evening of October 20th 2021.
A graph displaying rainfall radar data from EA gauge in East Devon.
Figure 4.8 Rainfall Radar data from EA gauge in East Devon.

 

4.2 Seaton

A photo of Seaton Fire Crew in attendance of a car stranded in flood water.
Figure 4.9: Seaton Fire Crew in attendance of a car stranded in flood water (photo credit: Seaton Fire Station)

4.2.1 Flood Incident Extent and Impact

Flooding was primarily caused by the sheer amount of rainfall which led to multiple watercourses overtopping at the allotments on Barnards Hill Lane, adjacent to the cricket club on Valley View and at the junction between Harepath Road and Valley View. The combination of these overtopping watercourses along with surface water runoff from neighbouring roads caused substantial amounts of water to reach lower lying areas of Seaton during peak flows particularly affecting Mead Way, Valley View and Summersby Close where at least 5 properties, a hospital and a primary school internally flooded by up to 100mm.

The floodwaters drained away within a short period of time, enabling most residents to stay within their homes following the event. Queen Street, Scalwell Lane and Colyford Road also saw considerable surface water flows with at least five properties flooding internally on Scalwell Lane and a couple of properties in Colyford Road. Dozens of properties in these areas experienced garden and/or garage flooding. It was noted that the highways and car parking areas were key areas for storing surface water during the event. Sandbags were widely used by residents during and post event utilising a sandbag store that the Town Council has available 24/7.

There were no reports of tidal or main river flooding with all property flooding associated with the ordinary watercourses and surface water runoff which locally attributed to sewerage flooding as well.

Five properties were also flooded on Marlpit Lane from surface water runoff and locals referred to incidents of ‘sewer water’ entering properties. Sewerage flooding was also locally referenced as a cause of flooding along Colyford Road. South West Water have reported no recorded hydraulic overload events in Seaton for this event.

Four properties were reported internally flooding due to the overtopping of an ordinary watercourse where it is culverted to the rear of Primrose Way/Buttercup Close. Many other properties reported rear garden flooding associated with this event as well.

Commercial and residential properties along Beer Road and Harbour Road were internally flooded and the highway network received significant areas of pooling, see Figure 4.10.

A sinkhole was also reported on the footpath along Clapps Lane attributed locally to the surface water sewer network.

A photo of surface water flooding of Harbour Road.
Figure 4.10 Surface water flooding of Harbour Road (Credit: County Councillor Marcus Hartnoll)

4.2.2 Historic Flooding

There has been previous flooding experienced in Seaton, with the following incidents recorded.

24/10/2016:         Tidal flooding of 3 properties

January 2016:     Fluvial (Ordinary Watercourse) flooding of at least 1 property

February 2014:    Surface runoff flooding at least 9 properties including commercial property on Harbour Road

21/11/2012:         Fluvial (Ordinary Watercourse) flooding of at least 1 property

December 1989: Tidal Flooding of at least 2 properties

June 1981:          Surface runoff/Sewerage flooding of at least 2 properties

February 1979:   Widespread tidal flooding of properties of at least 80 properties

4.3 Kenton

4.3.1 Flood Incident Extent and Impact

Properties along Mamhead Road, Kenton were affected by surface water and ordinary watercourse flooding on the evening of 20 October 2021. Overtopping of the watercourse occurred when the capacity of the culvert under Mamhead road was exceeded around 8.30pm to 9.30pm on 20 October 2021. Four properties and the Primary School were internally flooded with floodwaters receding within 2 hours. Properties reported internal flooding up to 50cm. High water levels on Mamhead Road reached the bumper level on parked cars.  Primary School students lost multiple school days due to the flood incident. The same properties were impacted by a similar flood event on 30 May 2008.

4.3.2 Historic Flooding

There has been previous flooding experienced in Kenton, with the following incidents recorded

19/09/2014:  Surface water flooding of 2 properties

09/06/2009:  widespread surface water flooding, at least 1 property known to flood internally

30/05/2008:  4 properties along Mamhead Road and the school flooded. Up to 12 in total affected.

22/06/2007:  Local School and another property flooded from surface water runoff

24/10/2006:  Surface water flooding of 1 property

19/10/2006:  Several properties flooded from surface water runoff

07/12/2000:  4 properties flooded

4.4 Woodbury

4.4.1 Flood Incident Extent and Impact

Five properties in Woodbury were flooded along Castle Lane from the overtopping of a surface water drainage system.

Highway flooding of 300mm was reported near to the watercourses at the western end of Stoney Lane, on the B3179 at the eastern edge of Woodbury village and adjacent to Woodbury Business Park. A single property was reported as flooding adjacent to the B3180.

4.4.2 Historic Flooding

There has been previous surface water flooding experienced in Woodbury, with the following incidents recorded.

30/12/2015:  2 properties flooded from surface runoff

07/12/2000: 1 property flooded from surface runoff

4.4.3 Data Gathered

Residents had a CCTV survey undertaken which has shown blockages in a 12’ concrete land drain which caused the backing up of surface water runoff until it overspilled onto Castle Lane.

Devon County Council have supported further investigation and the clearance works associated with the land drain flooding in Woodbury. Any additional works required are the responsibility of the riparian owners to address, however DCC will continue to support the community as required to help expedite matters.

4.5 Other Affected Areas in East Devon

4.5.1 Broadhembury

In Broadhembury, surface runoff from surrounding agricultural land, which had just been harvested for maize, as well as overtopping of the River Tale contributed to the flooding to property. Capacity within the Tale, classified as a main river, is believed to have been reduced significantly due to a pre-existing build-up of silt, stone and mud in the channel and underneath the bridge over the River Tale which acted as a pinch point for flows (See Figure).

Three properties were internally flooded. Many others avoided flooding due to the installation of Property Flood Resilience measures.

A photo showing the build-up material post event under the Bridge over the River Tale, Broadhembury.
Figure 4.11 Showing the build-up material post event under the Bridge over the River Tale, Broadhembury (Credit: Poppy Millar, Environment Agency).

4.5.2 Exmouth

Surface water flooding of commercial property and many garages was reported in Victoria Way/Victoria Road with the highway inundated with approximately 250mm of water. Flooding to property was also reported in Raddenstile Lane.

4.5.3 Tipton St John

The primary school at Tipton St John was affected by surface water and ordinary watercourse flooding with store areas and all outside spaces flooded.

Photo of floodwaters surrounding Tipton St John School buildings following the flood incident on 20/21st October 2021.
Figure 4.12 Photo of floodwaters surrounding Tipton St John School buildings following the flood incident on 20/21st October 2021 (Credit: Colin Butler, Headteacher at Tipton St John Primary School).

4.5.4 Other East Devon villages/towns

Individual property flooding from surface runoff was reported in Kilmington, Sidmouth, Stockland and Whitford. A number of outbuildings, gardens and local roads, as well as three properties were reported to have flooded in Musbury.

In Feniton, a single property was reported as flooding. Reports from local residents and the parish council praising the actions of the community flood group and property flood resilience measures, see Figure 4.13, in significantly limiting the impacts and preventing further properties from flooding.

A photo of floodwaters in Station Road on October 20th 2021.
Figure 4.13 Floodwaters in Station Road on October 20th 2021 (Credit: Feniton Parish Council)

 

4.6 Rest of Devon

In Teignbridge District area, internal property flooding from surface water runoff was reported in four Teignbridge District towns/villages with an individual property reported flooding in Bovey Tracey, Dawlish, Dunsford and Newton Abbot.

In the South Hams, two commercial properties were reported flooding from surface water in Kingsbridge, whilst Modbury recorded two residential properties flooding. Two properties in Slapton were locally reported as flooding from sewerage and surface water. In Stoke Gabriel, one property flooded from surface water runoff.

In Mid Devon, the local church in Hemyock was reported as flooding internally from surface water runoff.

Elsewhere in the district, the River Culm came out of bank and flooded the railway line in the vicinity of Hele & Bradninch level crossing. The flooding closed the railway for approximately 6 hours and delayed 203 trains resulting in 1,940 delay minutes at a total direct cost to Network Rail of £434,917.00. There were no reports of internal property flooding.

A aerial photo of a flooded valley with farmland and buildings.
(photo credit: William Radmore from Aerial Dimensions on 21 October 2021)

In Torridge, a property in Holsworthy was reported as flooding from surface water runoff.

In West Devon, a property near Buckland Monachorum was reported as flooding from surface water runoff.

As a result of this investigation report, several recommendations have been made for actions to be taken in specific locations. These are either as a result of initial site or desktop investigations, or the continuation of works or investigations already in progress. DCC as the LLFA will continue to monitor and record all flood incidents that come to our attention and consider this within our action plan and future investment programme. The current action plan can be found on the DCC Flood Risk Management Website at https://www.devon.gov.uk/floodriskmanagement/. Table 5.1 below summarises the recommended actions for this flood incident.

Table 5.1. Recommended actions for the affected communities in Devon.

Action By Recommended Action How
General actions recommended for the areas featured in this chapter:
EA /LLFA / Local communities Increase community resilience to all affected communities. Where applicable assist with the development of community emergency/flood action plans. Advice and possible funding available from Devon Community Resilience Forum.
DCC Highways / National Highways To ensure efficient operation of highway drains and culverts. Review and carry out maintenance in problem areas
District Council / EA / LLFA To ensure flood risk is managed from new development. Encourage sustainable drainage practices for new developments.
Property Owners / LLFA / EA Consider flood risk to own properties. To install property level protection where necessary in liaison with appropriate Risk Management Authorities.
SWW Ensure efficient operation of public combined and surface water sewers. Continue maintenance regime and consider storm separation where appropriate.
In addition to the general actions the following should be considered at specific locations:
Axminster
LLFA To consider any opportunities to increase culvert capacities where watercourses cross the A358 Review condition of existing culverts and investigate possible funding opportunities
LLFA Pursue opportunities for funding to provide additional PFR measures to properties Submit a business case for Defra Grant in Aid
LLFA Investigate the risk associated with those properties that suffered internal flooding and communicate with the property owners Carry out surveys of those properties affected by the Millbrook stream and consider the Property Flood Resilience measures that would be suitable to reduce the risk
LLFA Understand the performance of the recently completed flood improvement scheme Carry out an assessment of the event in relation to the Millbrook flood improvements and consider any further enhancements that could be delivered
Kenton
LLFA To understand risks associated with potential unconsented structures within the watercourse Carry out site visit to investigate and take appropriate action on any unconsented structures in the watercourse upstream of Kenton village
LLFA Consider feasibility for Property Flood Resilience measures Advise affected property owners of DCC’s PFR funding scheme and encourage them to apply
Seaton
LLFA To gain a better understanding of the risk of ordinary watercourse and surface water flooding and work with other Risk Management Authorities to ensure opportunities to reduce this risk long term are investigated. There is already an ongoing investigation into the local flood risk in Seaton. Information from the recent flooding will help inform the decisions and recommendations detailed in the study. Further actions will be derived from the report.
Woodbury
LLFA/Riparian Owners To investigate further the cause of the blockage and ascertain responsibilities for historic land drain for maintenance LLFA to share results of CCTV and clearance works with riparian owners

 

6. Next Steps

The next steps following this report will be for DCC as the LLFA to ensure that the recommended action tables in each chapter are presented to the responsible Risk Management Authority. DCC will consider their actions in line with other priorities and monitor delivery through regular reviews, whilst working in partnership with the EA, District Councils, South West Water and the local communities affected.

There is an expectation from DCC of itself and its partners that all authorities involved will cooperate and work together to improve the flood risk in the vulnerable areas identified in this report by completing the recommended actions. As the LLFA, DCC has a responsibility to oversee the delivery of these actions.

Where minor works and quick win schemes have been identified, these will be prioritised and subject to available funding and resources will be carried out as soon as possible by the relevant authority or landowner. Any major works requiring capital investment will be considered through the EA’s Medium-Term Plan process.

A review of the actions will be carried out by DCC as the LLFA to monitor progress and encourage delivery of recommended actions.