The Kendal Flood Risk Management Scheme and Integrated Flood Risk Management

The Kendal Flood Risk Management Scheme (FRMS) is a phased programme designed to reduce flood risk in Kendal and nearby settlements after severe flooding, including Storm Desmond. An important lesson from Using the CityCAT Hydrodynamic Model to Assess Fluvial and Pluvial Flood Risk in Kendal (MSc Dissertation, Newcastle University, 2019) is that Kendal’s flooding is not caused by a single source. The town is affected by fluvial flooding from the River Kent, the River Mint and Stock Beck, as well as pluvial flooding and overland flow. This makes the scheme a useful example of integrated flood risk management (FRM), because it combines structural measures in the town with interventions upstream and on tributaries.

Why Kendal needed an integrated scheme

The CityCAT study explains that Storm Desmond caused major impacts in Kendal, where about 2,150 residential and business properties were affected. It also notes that flooding came from several pathways, including overtopping of river banks, surface runoff from fields, and overflow linked to Stock Beck and its culvert. The study therefore shows that flood risk in Kendal is a whole-catchment problem rather than just a problem of one river channel.

The same study also highlights two wider issues that support an integrated approach:

• standard flood mapping may not fully represent changing future risks, especially because the Flood Map for Planning does not include climate change impacts;
• flood defences and drainage systems cannot be treated as fail-safe during extreme events.

These points link directly to non-stationarity and resilience. Non-stationarity means that past flood behaviour may no longer be a reliable guide to future flood probability or magnitude, especially under climate change. Resilience means designing a system that can still perform, adapt or recover when conditions exceed expectations.

The three phases of the Kendal FRMS

Phase 1: Linear defences through Kendal and the Stock Beck pumping station

According to Kendal Flood Risk Management Scheme: Catchment Map with Scheme Details, Phase 1 contains two main elements.

• Linear defences through Kendal: 6 km of linear defences, made up of flood walls and earth embankments, tied into areas of existing high ground. These have an average height of 1.1 m and a maximum height of 2 m. Because these defences cross access points in the town, 14 flood gates are included.
• Stock Beck pumping station: a 1 m3/s pumping station at the confluence of Stock Beck and the River Kent in central Kendal. Its role is to help maintain discharge from Stock Beck when levels in the Kent are high.

This phase mainly strengthens protection in the urban area itself. It addresses the problem that, during high water levels in the Kent, tributary drainage from Stock Beck can become constrained.

Phase 2: Linear defences in Burneside, Staveley and Ings

Kendal Flood Risk Management Scheme: Catchment Map with Scheme Details shows that Phase 2 extends protection to nearby settlements:

• 0.6 km of linear defence in Burneside, with an average height of 0.8 m and a maximum height of 1.4 m;
• 0.7 km of linear defence in Staveley and Ings, with an average height of 0.7 m and a maximum height of 1.2 m.

This phase broadens the scheme beyond central Kendal, but it remains focused on local structural defences.

Phase 3: Upstream storage and the Stock Beck catchment drain

Phase 3 introduces larger-scale catchment interventions, again described in Kendal Flood Risk Management Scheme: Catchment Map with Scheme Details.

• Flood storage at Kentmere Tarn: storage of about 1.2 million m3, with a control structure restricting pass-forward flow to about 41 m3/s. The embankment is about 160 m long, with average height 1.9 m and maximum height 4.3 m.
• Flood storage at Kentrigg: storage of about 1.7 million m3, with pass-forward flow restricted to about 183 m3/s. This involves a series of embankments or walls totalling 2000 m in length, with average height 3.6 m and maximum height 6.5 m, plus walls up to 1.8 m and a designated spillway.
• Stock Beck catchment drain: a drain up to 2 km long taking excess flow from Stock Beck East and Stock Beck North into the River Mint to reduce downstream flows. This phase also includes repairs to the existing Stock Beck culvert.

Phase 3 is the clearest expression of integrated FRM because it works at catchment scale rather than only defending the town centre. It aims to store water upstream, reduce downstream peak flows, and alter the way tributary flows are routed.

What the CityCAT study suggests about benefits

Using the CityCAT Hydrodynamic Model to Assess Fluvial and Pluvial Flood Risk in Kendal (MSc Dissertation, Newcastle University, 2019) provides evidence that multiple mechanisms contributed to flooding in Kendal. The study identified important impacts from:

• overtopping on the River Kent;
• significant impact from overtopping of the left bank of the River Mint;
• surface runoff from fields east of Kendal;
• rainfall-driven flooding in streets before peak river flooding;
• overflow associated with Stock Beck and its culvert.

This evidence supports the logic of having several components in the FRMS rather than a single defence line. In particular:

• the urban linear defences may reduce direct river flooding in central Kendal;
• the pumping station may help where high River Kent levels prevent Stock Beck from discharging efficiently;
• the upstream storage areas may reduce downstream flood peaks by holding back water before it reaches vulnerable urban areas;
• the Stock Beck drain and culvert repairs target a specific tributary mechanism that the CityCAT model reproduced with high accuracy.

The CityCAT study is especially valuable because it reproduced several observed flood mechanisms from Storm Desmond, including the Stock Beck culvert overflow. That gives weight to the idea that targeted intervention on Stock Beck could produce real benefits.

Costs and cost-related concerns

The clearest cost evidence in the supplied sources comes from the CityCAT dissertation, which states that the scheme was estimated at £56 million and that Stage 1 costs £16 million. The dissertation argues that this creates an important phasing issue: Phase 1 delivers only limited flood protection relative to the total scheme, yet requires a substantial share of spending up front.

From this evidence, the main cost-related evaluation points are:

• the total scheme is expensive, so benefits depend on later phases being delivered as well as the first;
• Phase 1 absorbs a large portion of total funding;
• if later phases are delayed or cancelled, value for money may be reduced because the full integrated benefit would not be realised.

Phasing risks identified by the CityCAT study

The CityCAT dissertation raises several important risks about how the scheme is sequenced.

• Risk of incomplete delivery: it states that Phase 1 offers very little in terms of flood protection compared with the completed scheme, yet already costs £16 million out of the estimated £56 million. Proceeding without certainty that all phases will follow is therefore described as a major risk.
• Risk of under-addressing the River Mint: the dissertation notes concern that upstream storage is being implemented on the Kent while options for upstream storage on both the Mint and Kent had been identified for investigation. This matters because both the report and the CityCAT simulation showed that overtopping of the left bank of the Mint had significant effects on flooded extent.
• Risk of limited protection standard: the dissertation notes that the scheme is not intended to protect against an event with Storm Desmond’s approximate recurrence interval of 1 in 150 years. This means residual risk remains even after construction.

These are classic integrated FRM issues. A scheme can be technically sound in parts but still vulnerable if delivery is partial, if one major source of risk receives less attention than another, or if the protection standard is below the most damaging plausible events.

Link to non-stationarity

Non-stationarity is highly relevant in Kendal. The CityCAT dissertation notes that the Flood Map for Planning does not account for climate change. This means that future flood hazard may differ from the historical patterns on which many planning assumptions are based. The same source also refers to research showing important climate-related changes in flood frequency and intensity.

For the Kendal FRMS, this has two implications:

• a scheme designed around historical estimates may face conditions more severe than those originally expected;
• phasing delays increase exposure, because later components may be delivered into a climate context that is already changing.

In other words, non-stationarity strengthens the case for catchment-scale measures and adaptive planning, but it also makes under-designed or incomplete schemes more problematic.

Link to resilience

Resilience is not just about preventing all floods. It is about reducing damage, managing exceedance, and coping when systems are stressed or fail. The CityCAT dissertation notes that floodplain mapping often excludes defences because there is always a risk of failure during extreme flooding. It also argues that urban drainage infrastructure can be thought of as part of the flood defence system.

This helps us see Kendal’s scheme as a resilience strategy with several layers:

• resistance: walls, embankments and gates aim to keep water out of vulnerable places;
• conveyance and drainage support: the pumping station and Stock Beck drain help water move through or away from the system when river levels are high;
• attenuation: upstream storage reduces the size of downstream flood peaks;
• residual risk management: because extreme events can exceed design standards, resilience still requires preparedness for flooding beyond the scheme’s protection level.

The CityCAT evidence suggests that resilience in Kendal depends on not relying on a single line of defence. Because flooding can begin from rainfall, field runoff, tributary overflow and main-river overtopping, a resilient system must combine measures across the whole catchment and urban network.

Overall evaluation

The Kendal FRMS is a strong example of integrated FRM because it combines:

• urban linear defences;
• a pumping station at a critical confluence;
• upstream flood storage at Kentmere and Kentrigg;
• a catchment drain and culvert works on Stock Beck.

Using evidence from Using the CityCAT Hydrodynamic Model to Assess Fluvial and Pluvial Flood Risk in Kendal (MSc Dissertation, Newcastle University, 2019), its main strengths are that it recognises multiple flood mechanisms and includes targeted action on Stock Beck as well as broader upstream storage. Its main weaknesses are the risks created by phasing, the high up-front cost of Phase 1 relative to its limited standalone protection, concern that the River Mint may be less fully addressed than the River Kent, and the fact that the scheme does not eliminate risk from very extreme events such as a Storm Desmond-scale flood.

Viewed through non-stationarity and resilience, the key lesson is that Kendal needs more than fixed defences. It needs a flexible, catchment-wide approach that can cope with changing flood behaviour, incomplete certainty, and residual risk. The scheme moves in that direction, especially in Phase 3, but the CityCAT study shows that its success depends on full delivery and continued attention to all major flood pathways.