Research and analysis

Wessex water situation: June 2024 summary

Updated 12 July 2024

Applies to England

• Publication for Northern Ireland
• Publication for Scotland
• Publication for Wales

Summary

In June there was considerably less rainfall across Wessex making it the driest June in 6 years and the driest month since February 2023. An average of 21mm of rain fell across Wessex, 35% of the long term average (LTA). Although June was a drier month, it remained the second wettest 6 months, and the wettest 12 month period since records began in 1871. Soil moisture deficit (SMD) increased in June with the majority of areas reporting between 41mm and 70mm. The majority of monthly mean flows across the north of Wessex were normal, with sites to the south of Wessex reporting above normal and notably high flows. The groundwater sites across Wessex all reported normal or higher levels in June, with the sites monitoring the chalk aquifer reporting above notably high levels to the south of Wessex, and the northern Wessex sites reporting as above normal. Throughout June, reservoir levels decreased with Wessex Water ending the month at approximately 89% capacity and Bristol Water ending June at approximately 86% capacity.

1. Rainfall

An average of 21mm of rain fell across Wessex in June (35% of the LTA) with 77% of the monthly total rainfall, falling on just 3 days, 25 to 18 June. The low levels of rainfall made it the 16th driest June since our records began in 1871. Most hydrological areas across Wessex received notably low levels of rainfall in June, with a few areas to the northeast of Wessex receiving slighter higher amounts of rainfall and recording as below normal, while one area to the east of Wessex received the least rainfall with levels recorded as exceptionally low. The longer-term outlook shows a different picture, with the past 3 months recording majority normal levels, with a few above normal levels recorded in the south of the patch, while the past 6 and 12 month recorded exceptionally high rainfall across all hydrological areas. Despite the drier weather in May, the heavy rainfall in the previous months makes it the eighth wettest 3-month period (March to June), the second wettest 6-month period (December to June) and the wettest 12-month period (June to June) since records began in 1871.

Rainfall ranged from 15% to 54% of LTA for the month with the highest levels of rainfall being recorded as 34mm at Grove Farm rain gauge in the Bristol Avon Tributaries catchment. The lowest levels of total monthly rainfall being recorded as 8mm at the Winterbourne Stoke rain gauge, within the Hampshire Avon catchment.

2. Soil moisture

The majority of areas across Wessex recorded a range of 41mm to 70mm, with areas to the south-east of the patch recording 71mm to 100mm, and a very small area at the most western point of Wessex recorded 11mm to 40mm. The southern and eastern hydrological areas were recording a SMD between 6% and 25% above the LTA. The north-western hydrological areas recorded a SMD of 6% and 25% lower than the LTA with central areas recording a SMD range of 5% below to 5% above the LTA.

3. River flows

The majority of sites to the north and west of Wessex reported normal flows in June 2024, with the exception of Frenchay, on the Bristol Frome, which recorded below normal flows. The sites within the chalk aquifer reported above normal and notably high flows, the remainder of sites in the south of Wessex also recorded above normal and notably high flows.

Across Wessex all sites were recording lower flows at the end of June in comparison to the end of May, and at the end of the month most daily mean flows were decreasing following the little precipitation the area received over the month.

4. Groundwater levels   

The groundwater levels varied across Wessex in June from normal to exceptionally high. Didmarton 1 (monitoring the Inferior Oolite formation) recording the exceptionally high levels, and Oakley Industrial Estate monitoring the Chalk recording normal levels. Amongst the sites monitoring the Chalk aquifer, the most southern 2 sites Kingston Russell Road and Delcombe recorded notably high levels, whereas the more northern sites, Tilshead, Chitternedown and Woodyates, all recorded above normal levels.

5. Reservoir stocks

Reservoir levels in Wessex decreased over the month of June, with Wessex Water reporting reservoirs at approximately 89% capacity by the end of the month, which is similar to this time last year. Bristol Water reported reservoirs levels at approximately 86% capacity by the end of June, which is also similar to this time last year.

Author: Wessex Hydrology, hydrologywessex@environment-agency.gov.uk

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.