Solent and South Downs water situation report: April 2024 summary
Updated 15 May 2024
Applies to England
© Crown copyright 2024
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1. Summary
Solent and South Downs (SSD) had above average rainfall in April, receiving 151% (81.6mm) of the long term average (LTA) rainfall (53.9mm). Monthly mean river flows and groundwater levels across SSD ranged from above normal to exceptionally high. Soils across SSD ended the month wetter than the average. End of month reservoir stocks at Ardingly Reservoir (Ouse) and at Arlington Reservoir (Cuckmere) were both above average.
2. Rainfall
SSD had above average rainfall in April, receiving 151% (81.6mm) of the LTA (53.9mm). The month started with a wet period from 1 to 4 April, when about 40% of the month total rain was recorded. The driest week of the month was from 17 to 23 April, with less than 3% of the month total rain. The most rain fell in the period from 24 to 27 April, with about 45% of the month total rain. The highest daily total of 43.8mm was recorded on 27 April at Duncton RG (Western Rother Greensand), which was the wettest day of the month.
During the last 3 month period, between February and April, SSD area and 11 of our 14 areal rainfall units received record amount of rainfall:
- Test Chalk
- East Hampshire Chalk
- West Sussex Chalk
- East Sussex Chalk
- Isle of Wight
- Western Rother Greensand
- Hampshire Tertiaries
- Lymington
- Sussex Coast
- Adur
- Ouse
Arun recorded the second highest, while Cuckmere recorded the third highest, and Pevensey Level the fourth highest rainfall totals in the last 3 month.
The last 9 months, 12 months and 15 months periods were the second wettest on record for SSD area, since 1871.
The last 18 months period was the wettest on record for SSD area, and 10 areal rainfall units in the western part of the area. On the eastern part of the area, Adur, Ouse, Cuckmere and Pevensey Level recorded the second highest rainfall totals in the last 18 months.
3. Soil moisture deficit and recharge
Soils across SSD ended the month wetter than the average for April, which means catchments are more responsive to run off.
4. River flows
Monthly mean river flows across SSD ranged from above normal to exceptionally high.
Flows were above normal:
- River Lymington at Brockenhurst
- River Arun at Alfoldean
- River Cuckmere at Cowbeech
Flows were notably high:
- River Ouse at Goldbridge
Flows were exceptionally high:
- River Test at Chilbolton
- River Test at Broadlands
- River Itchen at Allbrook&Highbridge
- River Meon at Mislingford
- River Wallington at North Fareham
- River Rother at Iping Mill
- River Adur at Sakeham
There was no data available for River Medina at Blackwater.
The monthly mean flows for April for the River Wallington at North Fareham were the highest on record since 1976.
The monthly mean flows were the second highest at Broadlands (Test), at Chilbolton (Test), at Allbrook&Highbridge (Itchen), at Iping Mill (Rother), and at Sakeham (Adur).
5. Groundwater levels
End of month groundwater levels ranged from above normal to exceptionally high.
Groundwater levels were above normal at:
- Cornish Farm (East Sussex Chalk)
Groundwater levels were notably high at:
- Carisbrooke Castle (Isle of Wight)
- Beeding Hill (West Sussex Chalk)
- Houndean Bottom (East Sussex Chalk)
Groundwater levels were exceptionally high at:
- Clanville Gate (Test Chalk)
- Lopcombe Corner (Test Chalk)
- Preston Candover (East Hampshire Chalk)
- West Meon (East Hampshire Chalk)
- Catherington (East Hampshire Chalk)
- Youngwoods Copse (Isle of Wight)
- Harting Common (Western Rother Greensand)
- Chilgrove (West Sussex Chalk)
Groundwater level for April was the highest on record at Harting Common since 1984. The groundwater levels were second highest on record at Clanville Gate, at Lopcombe Corner and at West Meon, since 1966, 1963 and 1986, respectively. The groundwater levels were third highest at Youngwoods Copse, at Catherington, at Cornish Farm and at Preston Candover since 1978, 1969, 1981, and 1975, respectively.
6. Reservoir stocks
End of month reservoir stocks were both above average. Ardingly Reservoir (Ouse) was at 100% of total capacity (LTA 98%) and Arlington Reservoir (Cuckmere) was at 97.7% of total capacity (LTA 97.16%).
7. Environmental impact
No licence restrictions were in force in April.
There were 12 Flood Alerts issued in April. In Hampshire 5, on the Isle of Wight 2, and in Sussex 5; all fluvial.
There were 3 Flood Warnings issued in April. In Hampshire 2 and on the Isle of Wight 1; all fluvial.
Author: HydrologySSD@environment-agency.gov.uk
Contact details: 03708 506 506
All data are provisional and may be subject to revision. The views expressed in this document are not necessarily those of the Environment Agency. Its officers, servants or agents accept no liability for any loss or damage arising from the interpretation or use of the information, or reliance upon views contained in this report.