Onboard and Online: Environment Agency Updates Flood Alerts For The Village

The Environment Agency updated the Flood Alert for the River Wylye and its tributaries (these include the River Till) at 11:52am on Sunday 29 December 2019.  Since then, with no rainfall, the river level has dropped a few inches and inundated land is now reappearing to the south of the village.

At

“Groundwater levels are rising in boreholes across Salisbury Plain in response to recent prolonged heavy rain. A few days of more settled weather is forecast though levels are continuing to rise further in response to recent rainfall. Reports indicate that properties are pumping and sewage systems could be impacted and roads affected. We encourage residents with pumps and other property resilience measures to put them in place and ensure they are working. We are continuing to monitor the situation and will update this message as the situation changes.”

We will provide further updates in due course.

Onboard and Online: Flood Alert in Force Now For River Wylye and Tributaries(ie the River Till)

The Environment Agency has just released the following:

Flooding is possible – be prepared

River levels have risen at the South Newton river gauge as a result of recent heavy rainfall and the ground being saturated. Consequently, flooding of roads and farmland is possible for the next few days. We believe there is a possibility of flooding for the tributaries between Norton Ferris and Wilton Flooding of properties is not forecast at this point. The next few days looks unsettled and further rainfall is expected. We are closely monitoring the situation and our incident response staff are clearing weed screens. Please stay aware in case further warnings are issued. This message will be updated when the situation changes.

This information was last updated at

Onboard and Online: Groundwater Flooding Alert for Winterbourne Stoke

The following flood alert was received from the Environment Agency this morning:

A Flood Alert has been issued by the Environment Agency.

Flood Alert in force: Groundwater flooding in the Salisbury Plain area.

Flooding is possible for: Boscombe, Cholderton, Collingbourne Ducis, Hanging Langford, Hindon, Hurdcott, Idmiston, Newton Tony, Orcheston, Porton, Salisbury, Shipton Bellinger, Shrewton, Stratford Sub Castle, Tidworth, Tilshead, Tisbury, Wilton, Winterbourne Stoke and Woodford.    

Be prepared.

Groundwater levels have risen in response to recent and prolonged rainfall. This morning’s level at the Terraces Borehole is 115.07 mAOD on the 19/12/19. Levels will continue to rise and flooding of fields and roads is expected. Following prolonged periods of heavy rain, groundwater levels have continued to respond. Levels are high and further rainfall is expected over the next few days and we would expect to see levels rise in response. Residents are advised to prepare property resilience measures and ensure that pumps are working where they have been installed.

We may start to see flooding on roads in these affected areas. We are continuing to monitor the situation and will update this message as the situation changes.

This morning, water levels in the Tilshead borehole reached 94.83mAOD against a flood level of 99mAOD:

The recharge rate has increased 6-fold over the last two or three days.  If the recharge of the aquifer continues at the same rate, the graph shows that we may have groundwater flooding in the village in less than a week.

No flood alert has yet been given for the River Till. However, water levels are rising rapidly and already the meadow to the south of the village is beginning to flood.  More rain is now being forecast over the next few days and the Environment Agency is advising those with properties prone to groundwater flooding take appropriate measures.

Wiltshire Council advise the following on their website:

As a property owner it is your responsibility to protect your property from flooding. The council is unable to supply sandbags in advance of any flood warnings and you should make your own arrangements to purchase and arrange for delivery to your home by local builders merchants (see yellow pages for suppliers)

If you are in imminent danger of flooding telephone 0300 456 0105.

Sandbags

Wiltshire Council  have a limited supply of sandbags and any requests for them during an emergency will be considered on a case by case basis and prioritised by level of need or vulnerability for example the elderly or infirm and the protection of commercial property to prevent environmental pollution.

Once delivered, sandbags are the responsibility of the householder and you will need to make arrangements for their disposal following the incident.

Locally, sandbags and sand can be obtained from the following suppliers identified by Wiltshire Council:

Please note that Winterbourne Stoke Parish Council is unable to provide householders with sandbags, sand, or gel sacs.

If you experience groundwater flooding, please let the Parish Clerk know.  Whilst we are unable to do do a great deal to assist, we can organise manpower, as we have done in the past.

Please can you ensure your neighbours, who may not have seen this article on the website, the link on Facebook, or the village noticeboard, are made aware of this flood alert.

Should the Environment Agency issue a flood alert for the River Till, or upgrade/downgrade the current groundwater alert, we will issue another notice here.

Onboard and Online: Flooding – Information from Wiltshire Council and the Environment Agency

Background

In the last 24 hours we have received two communications from the Environment Agency and Wiltshire Council regarding the grounwater situation across Wiltshire. Clearly, these have direct relevance for all of us living alongside the River Till.

The bottom line of both these documents is to urge town parish councils to be aware of the current situation and to adopt such measures as they can. In turn, we are now asking parishioners, particularly those of you owning/living in properties known to be susceptible to groundwater flooding, to be aware of the situation and take appropriate measures for your own properties; for instance by checking that water pumps are functioning and that other measures you have adopted in the past, sandbags, moving furniture and carpets to higher parts of the property, etc., can be initiated at short notice and carried out quickly.

The Current Regional Situation

“We have noticed the recharge (the aquifer starts to refill) season started earlier this year due to the wetter autumn that we have experienced, in fact bore hole levels across Dorset and Wiltshire are recording levels considerably above average for this time of year.

Below is a graph of the Groundwater level at Woodyates (on the Dorset / Wiltshire / Hampshire border) the dotted blue line is the mean October 31st level. This site is used as a national indicator for groundwater levels as it is fairly central and has a long period of recorded data.

As you can see, we ended the first month of the traditional re-charge period in October at around 91.0 mAOD (Ordnance datum (mAOD) is based on the mean sea level at Newlyn in Cornwall) compared to a twenty year mean of 76.0 mAOD. It is the second highest level on record after 2012 which was a bit of an anomaly as there was almost no recession that summer due to a Groundwater flooding event. As you can see we are at a level that is already higher than average for this time of year.


The Flood Alert level at this site is 98m mAOD and we would consider issuing a Flood Warning at 102 mAOD.

The Current Local Situation

As of 9:15 this morning, the water level in the Tilshead borehole stands at 90.24m mAOD. Levels have been rising for the last three weeks, but it is fair to say that the rate of increase over the last few days, with less rain, has begun to slow. The graph looks as follows:

The red arrow indicates the level this morning. We are only 4 metres below the 6-year average MAXIMUM winter level and in a credible worst-case scenario, less than two weeks/9 metres from possible groundwater flooding. If that looks scary, don’t forget that the average winter maximum is 94m. The good news is that we should have several days of dry weather over the next week and the rate of increase should fall and may even reverse. That said, the Environment Agency make the following point: “With Groundwater levels currently higher than average for this time of year, if we continue to have heavy rainfall events across Dorset and Wiltshire we anticipate issuing Groundwater Flood Alerts across Dorset and Wiltshire before Christmas”. Even then, it is far from certain we will have flooding here.

Winterbourne Stoke Parish Council will continue to monitor groundwater levels in the aquifer and publish weekly updates with the first due to appear on Sunday 8th December showing data collected for the first week. Keep an eye-out here for any interim bulletins or on the village Facebook page.

Please let the Parish Clerk (or any Councillor) know if you have concerns about specific properties, are seeking further help, or believe that a flooding event is imminent or underway.

Further Information

The Environment Agency and Wiltshire Council are holding two drop in sessions to enable town and parish councils and residents an opportunity to discuss groundwater issues in your area, share flood maps that maybe helpful for you to identify areas at risk of flooding and share knowledge on what to look for in your area. We can also give you more information on the Groundwater flood warning service available for your community.

We would also like to hear about your observations and feedback
If you have not made or updated your flood or emergency plan it’s not to late! If you need assistance, help or advice contact: drainage@wiltshire.gov.uk

Drop-in Sessions
Tuesday 10th December 2019 – Amesbury
Shears Dr, Amesbury, Salisbury SP4 7XT
10 – 6

Tuesday 17th December 2019 – Wilton
Castle Meadow Pavilion
SP2 0HG


To sign up for flood and groundwater warnings, click here https://www.gov.uk/sign-up-for-flood-warnings
or
FloodlineTelephone: 0345 988 1188 24-hour service

It’s Still Raining

Although we are not reporting weekly water levels in the aquifer, we are keeping an eye on them and the rainfall. Some of you will have noticed that some of the springs have broken and that the river is flowing again.

The reason for the latest update is that Autumn has arrived with a vengeance and whilst the colours of the trees are glorious, they are no longer taking up as much water as they were only a week ago. That has had a huge impact on the water levels in the aquifer which have risen 3 metres in the course of just a few days. To put that into context, as of this morning, the water level in the Tilshead borehole stands at 84.17 metres. That’s some way short of the flood level of 99 metres, but as we’ve said in previous years, once we get close to the 85 metre mark, the aquifer becomes very sensitive to small changes in rainfall.

So, how do we stand in comparison with previous years:

Season Date levels passed 84 metres

2013-14 04/01/14 (The last flood year)

2014-15 25/12/15

2015-16 07/01/16

2016-17 09/02/17

2017-18 10/01/18

2018-19 19/01/19

That means we’ve hit the 84 metre mark some 6 to 8 weeks before we would have in an “average” year. Given we have what is “normally” the rainiest part of the year (December and January) yet to come, that doesn’t mean we are going to have a flood this year. The rains may have come early, or we may have a particularly dry end to this year and start of the next. We will be keeping a close eye on the situation and produce another bulletin if things change markedly before the start of December. If there is any other information we can let you have in relation to floods and flooding in the village, please contact us.