Solent and South Downs water situation report: March 2026 summary
Updated 14 April 2026
Applies to England
© Crown copyright 2026
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1. Summary
Solent and South Downs (SSD) had below average rainfall in March, receiving 58% (33mm) of long term average (LTA) of 57mm. Monthly mean river flows for March ranged from normal to notably high across SSD. End of month groundwater levels for March ranged from normal to notably high. Soils across SSD ended the month drier than the LTA for March. End of month reservoir stocks were above average at Ardingly Reservoir (Ouse) and average at Arlington Reservoir (Cuckmere).
2. Rainfall
SSD had below average rainfall in March, receiving 58% (33mm) of LTA (57mm). The East Hampshire Chalk areal unit received the highest monthly rainfall total with 68% (42mm) of LTA (63mm). This was followed closely by 67% (41mm) of LTA in the Western Rother Greensand unit. The majority of the SSD areal units were within the normal range with many of the coastal units below normal. The lowest rainfall total was received by the Pevensey Levels with 46% (23mm) of LTA (50mm). The Cuckmere (51% of LTA), Sussex Coast (52%), Lymington (52%) and Isle of Wight (54%) units also received below normal rainfall.
The highest rainfall was recorded throughout the River Test catchment (Test Chalk and Hampshire Tertiaries areal unit) and River Itchen catchment (East Hampshire Chalk unit). The highest daily totals were recorded on 12 March and represented around a third of the month’s total rainfall. The highest daily total of 18 mm was recorded on 12 March at Broughton RG (Test Chalk), Testwood RG (Hampshire Tertiaries) and Otterbourne RG (East Hampshire Chalk). Romsey RG (Hampshire Tertiaries) recorded a total of 17mm on the same day.
Rainfall was concentrated into the first half of the month with around 80% of the month rain recorded between 1 and 15 March. The three wettest days (12, 6 and 10 March respectively) represented on average 60% of the total monthly rainfall. There were only seven wet days over the whole month.
March rainfall was not notable, but the January to March 3-month period has been the third wettest on record for these areal units:
- Test Chalk
- East Hampshire Chalk
- Hampshire Tertiaries
- Lymington
- Adur
The remaining areal units also ranked in the top 10 for the same period. SSD ranked the sixth wettest January to March on record.
October to March represents the winter recharge period in the hydrological calendar. Those six months have recorded exceptionally high rainfall totals over the whole of Hampshire and IOW and notably high rainfall over the majority of Sussex. The exceptions in Sussex where the Cuckmere and Pevensey Levels units which, while having lower rainfall, had rainfall totals in the above normal range. The October to March winter period ranks the:
- third wettest on record for the Adur areal unit
- fifth wettest on record for Lymington and East Hampshire Chalk units
- sixth wettest on record for the Hampshire Tertiaries unit
All these statistics are based on records going back to 1871.
3. Soil moisture deficit and recharge
The soil moisture deficits (SMDs) across SSD are now occurring due to the below average rainfall in March and the start of the growing season. Soils across SSD ended the month drier than the LTA for March.
4. River flows
Monthly mean river flows for March ranged from normal to notably high across SSD.
Flows were normal on the:
- River Lymington at Brockenhurst
- River Wallington at North Fareham
- River Rother at Iping Mill
- River Arun at Alfoldean
- River Adur at Sakeham
- River Ouse at Goldbridge
- River Cuckmere at Cowbeech
- River Medina at Blackwater
Flows were above normal on the:
- River Test at Chilbolton
Flows were notably high on the:
- River Test at Broadlands
- River Itchen at Allbrook and Highbridge
- River Meon at Mislingford
The monthly mean flows for March ranked the:
- fifth highest for the River Itchen at Allbrook and Highbridge since 1959
- sixth highest for the River Test at Chilbolton since 1989
- ninth highest for River Test at Broadlands and River Meon at Mislingford both since 1958
5. Groundwater levels
End of month groundwater levels for March ranged from normal to notably high.
Groundwater levels were normal at:
- Carisbrooke Castle (Isle of Wight)
- Harting Common (Western Rother Greensand)
Groundwater levels were above normal at:
- Youngwoods Copse (Isle of Wight)
- Catherington (East Hampshire Chalk)
- Preston Candover (East Hampshire Chalk)
- Beeding Hill (West Sussex Chalk)
- Cornish Farm (East Sussex Chalk)
Groundwater levels were notably high at:
- Lopcombe Corner (Test Chalk)
- Clanville Gate (Test Chalk)
- West Meon (East Hampshire Chalk)
- Chilgrove (West Sussex Chalk)
- Houndean Bottom (East Sussex Chalk)
The groundwater levels for March were the:
- sixth highest on record at West Meon Hut (1986)
- seventh highest on record at Houndean Bottom (1977)
- eighth highest on record at Lopcombe Corner (1963)
- ninth highest on record at Catherington (1969) and Preston Candover (1975)
6. Reservoir stocks
End of month reservoir stocks were above average at Ardingly Reservoir (Ouse) and average at Arlington Reservoir (Cuckmere). Ardingly Reservoir was at 100% of total capacity (LTA 97%), and Arlington Reservoir was at 99.1% of total capacity (LTA 99.0%).
7. Environmental impact
At the start of March there were no licence restrictions in force. By the end of the month two licence restrictions were in place. These included:
- cessation of abstraction for one licence on the River Lymington
- restriction on abstraction rates for one licence on the River Meon
No new groundwater flood alerts were issued in March. At the start of March there were 19 groundwater alerts in force, all issued during the previous two months. However, throughout March alerts were removed as the situation improved. At the end of March only six groundwater flood alerts remained in force.
See full report for details.
Author: HydrologySSD@environment-agency.gov.uk
Contact Details: 03708 506506
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.