Solent and South Downs water situation report: April 2025 summary
Updated 14 May 2025
Applies to England
© Crown copyright 2025
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1. Summary
Solent and South Downs (SSD) had below average rainfall in April, receiving 49% (26.4mm) of the long term average (LTA of 53.9mm). Monthly mean river flows across SSD ranged from notably low to above normal and the end of month groundwater levels ranged from notably low to notably high. Soils across SSD ended the month much drier than the average for April. End of month reservoir stocks were above average at Ardingly Reservoir (Ouse) and were below average at Arlington Reservoir (Cuckmere).
2. Rainfall
After the exceptionally low rainfall in March, SSD had below average rainfall in April, receiving 49% (26.4mm) of the long term average (LTA of 53.9mm). The East Sussex Chalk, Pevensey Levels and Cuckmere areal units on the east received the highest rainfalls, above 30mm. The Test Chalk areal unit on the west received the lowest rainfall with only 17.6mm for the whole month, which represents 34% of LTA (51.7mm).
There were only 3 days with widespread rain, 14, 18 and 22 April. The majority of the month’s rain fell on these 3 days. The rest of April was mostly dry with over 20 dry days.
The highest daily totals were recorded on 22 April, 22.2mm at Plumpton RG (East Sussex Chalk) and 20.8mm at Storrington (Western Rother Greensand).
The last 2 months have been the seventh driest on record for SSD, while it was the fourth driest on record for the Test Chalk areal unit. The exceptionally low 3-months rainfall total for the Sussex Coast areal unit were the seventh driest on record.
In contrast, over the longer time periods, the 15-month, 18-month and 24 month running totals remain high. Figures for the 15-month period (starting February 2024) were the eighth highest total for the Test Chalk and the East Sussex Chalk areal units. Figures for the 18-month period (starting November 2023) were the tenth highest total for SSD and the fifth highest for the Test Chalk areal units. For the 24-month period (starting May 2023) it was the fifth highest total for SSD and the second highest for the Test Chalk areal unit.
All these statistics are based on records going back to 1871.
3. Soil moisture deficit and recharge
Soils across SSD ended the month much drier than the LTA for April.
4. River flows
Monthly mean river flows for April ranged from notably low to above normal across SSD.
Flows were notably low on the:
- River Wallington at North Fareham
- River Arun at Alfoldean
Flows were below normal on the:
- River Lymington at Brockenhurst
- River Adur at Sakeham
- River Ouse at Goldbridge
- River Cuckmere at Cowbeech
Flows were normal on the:
- River Test at Chilbolton
- River Meon at Mislingford
- River Medina at Blackwater
- River Rother at Iping Mill
Flows were above normal on the:
- River Test at Broadlands
- River Itchen at Allbrook and Highbridge
The notably low monthly mean flows for the River Arun at Alfoldean were the fifth lowest on record for April since 1970.
The notably low monthly mean flows for the River Wallington at North Fareham were the sixth lowest on record going back to 1976.
5. Groundwater levels
End of month groundwater levels for April ranged from notably low to notably high across SSD.
Groundwater levels were notably low at:
- Carisbrooke Castle (Isle of Wight)
Groundwater levels were below normal at:
- Beeding Hill (West Sussex Chalk)
Groundwater levels were normal at:
- Lopcombe Corner (Test Chalk)
- Catherington (East Hampshire Chalk)
- Harting Common (Western Rother Greensand)
- Chilgrove (West Sussex Chalk)
- Houndean Bottom (East Sussex Chalk)
- Cornish Farm (East Sussex Chalk)
Groundwater levels were above normal at:
- Clanville Gate (Test Chalk)
- West Meon (East Hampshire Chalk)
- Youngwoods Copse (Isle of Wight)
Groundwater levels were notably high at:
- Preston Candover (East Hampshire Chalk)
The notably high groundwater level at Preston Candover (East Hampshire Chalk) was the fourth highest on record for April since 1975. In contrast, the notably low groundwater level at Carisbrooke Castle (Isle of Wight) was the fourth lowest for April on a record going back to 1975.
6. Reservoir stocks
End of month reservoir stocks were above average at Ardingly Reservoir (Ouse) and were below average at Arlington Reservoir (Cuckmere).
Ardingly Reservoir (Ouse) was at 99% of total capacity (LTA 98%) and Arlington Reservoir (Cuckmere) was at 96.1% of total capacity (LTA 97.16%).
7. Environmental impact
Abstraction licence restrictions:
During April there was one licence restriction in force, a reduced abstraction rate restriction on the River Meon, East Hampshire.
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.