These are just some of the policies put in place in the latest Island Plan to stop homes being flooded, as Express explores in the wake of the Grands Vaux floods…
19 hours… and 6cm of rain
Overnight on 16 to 17 January, almost 6cm of rain fell over 19 hours, causing severe flooding in the Grands Vaux catchment, which covers about 10% of the island.
58 homes were evacuated on the day and 22 were left uninhabitable.
The Government says that new policies introduced in its latest Island Plan are designed to protect coastal and inland areas at risk of flooding.
Planning for flood-proofing
The Bridging Island Plan (BIP), which was shortened from its usual 10-year span to three because of the pandemic, is the first of Jersey’s key development blueprints to have specific rules around flooding.
It was passed by the previous Assembly last year but Environment Minister Jonathan Renouf has suggested that it is extended beyond 2025, when the BIP is due to expire.
CLICK TO ENLARGE: Flood risk categories have been established in the latest Island Plan, based on the probability of coastal flooding, and inland flooding.
Its flood-related polices were heavily influenced by a ‘Strategic Flood Risk Assessment’, which the Government commissioned to provide evidence for those drafting the plan.
Measuring risk
It identified areas most at risk of flooding, including Grands Vaux, and set out a ‘flood risk framework for development’ within them.
Policy ‘WER2’ in the plan is about managing flood risk.
It states:
Where possible, development which is vulnerable to flooding, or could increase the probability of flooding elsewhere, should be located away from areas at risk of flooding.
When a development is proposed to take place within an area at risk of flooding, the development will be assessed based on its location and subsequent exposure to inland and/or coastal flooding risk within a risk category (little or no risk, low, medium and high risk), and its vulnerability to flooding within a risk category, based on its vulnerability categorisation.
This assessment will determine if:
development is appropriate;
development is appropriate, subject to mitigation;
development will need to identify wider justification for its location; or
development should not be supported
All development proposals at low, medium or high risk of flooding will require a flood-risk assessment.
Development will only be supported where sufficient information has been provided in relation to a required flood-risk assessment, and when adequate steps have been taken to ensure:
the design and layout will locate the most vulnerable type of development on the site towards the areas at lowest risk of flooding within the site, where this is possible;
the development adopts all reasonable measures to ensure the development will be sufficiently resilient to current and future flood risk, including land raising, when this is appropriate;
the development will not adversely affect flood routeing and thereby increase flood risk elsewhere.
How vulnerable…?
The plan defines development by a ‘vulnerability classification’ with ‘essential civil infrastructure’ at the top of the scale and ‘water compatible’ development, such as football pitches, at the bottom.
Pictured: Table 3 (for built up areas) and Table 4 (for rural areas) in the BIP specifies the types of development that may or may not be acceptable in different flood risk categories, and defines the appropriate approach to planning decisions for each scenario.
‘Highly vulnerable’ developments include basement dwellings, care homes, pubs, schools, shops and restaurants.
Climate change consideration?
Kevin Pilley, a senior civil servant who helped draft the BIP, said that previous plans had included little consideration of flood risk but climate change and the consequential prediction of extreme weather had made it a necessity in the latest edition.
“Of course, we had been aware of the risk of flooding previously, but we now have the policy regime to back it up,” he said.
The Island Plan primarily relates to new development, although its policies also cover applications to extend and change the use of existing buildings.
In essence, any development in Grands Vaux – as well as other high-risk areas like Beaumont – will now have to have a flood-risk categorisation, and each application will have to prove that the building won’t flood, or cause other areas to flood.
Other Government documents and plans focus on responding to the type of rainfall and flooding that Grands Vaux experienced last month. These include the Grands Vaux Flood Plan, whose second edition was published in 2018 – but not updated, as scheduled, in March 2021.
Keeping the defences strong
This looked at how authorities and residents in Jersey should respond to flooding in the area. In light of the recent flooding, with 17 households still homeless, ministers have also promised action to strengthen defences.
This includes “reviewing alternative options for the remodelling of our drainage system, the reservoir and dam infrastructure and general water management”.
Practically, the Government says this means making sure all drains are properly maintained and possibly Jersey Water taking a greater role in flood management by varying the levels in its reservoirs when heavy rain is expected.
LISTEN…
Express spoke to Jersey Water’s Head of Production in the wake of the floods about the clean-up operation and the island’s defences – listen below or search ‘Bailiwick Podcasts’ via your favourite podcast provider…