Research and analysis

East Anglia water situation: July 2024 summary

Updated 14 August 2024

Applies to England

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

1. Summary

After a dry June, July continued the trend of the past 12 months with high rainfall volumes across the East Anglian region. This rainfall continued to exert influence over the groundwater volumes and river flows which remained healthy, despite a dry second half of the month. The soil moisture deficit increased significantly towards the end of the month and is now within normal range for the Area.

2. Rainfall

High rainfall at the start of July was above normal compared to the long-term average for the month. The past 3 months have also produced rainfall totals above normal, despite a below average rainfall in June. Over the longer time periods, the 6-month and 12-month running totals remain exceptionally high for the region overall. The highest rainfall total since records began, in 1871, have been recorded for 8 catchments in the Area, as well as for East Anglia as a whole, over the last 12-month period of rainfall. June remains the outlier as the only month to have produced below average rainfall totals over the past 12 months.

3. Soil moisture deficit and recharge

The soil moisture deficit significantly increased towards the end of the month with the warmer temperatures and significant reduction in rainfall. The Area’s soil moisture deficit remains normal for this time of year.

4. River flows

River flows ranged between 131% and 220% of the long-term average for July. Groundwater levels remain very high due to the months of continuous recharge, consequently, base-flow contributions to rivers have been high. Flows are notably high to exceptionally high for all but 2 rivers, the Waveney and Yare, which are above normal, due to the lower rainfall totals to the east of East Anglia and the lower runoff responses.

5. Groundwater levels   

Groundwater levels remain high across East Anglia. All catchments with available data demonstrated above normal, to notably or exceptionally high levels compared to the long-term averages. The warm, dry weather in the second half of this month will have provided little recharge to groundwater stores, and a continued downward trend is noticeable at all groundwater sites, as expected, given the time of year. However, due to the wet winter, groundwater levels remain healthy.

6. Reservoir stocks

Reservoir stocks are healthy this month and above the normal operating curve for July. Abberton and Ardleigh are filled just below 90% capacity, while Alton, Grafham and Hanningfield are filled over 90% of capacity. There are currently no concerns with public water supply reservoirs as we approach the end of the summer.

7. Forward look

7.1 Probabilistic ensemble projections for river flows at key sites

The projections show that the majority of the model runs using current starting conditions and historic rainfall and potential evapotranspiration simulate flows for September 2024 being at least categorised as normal. The only exception to this is the Ely Ouse that is projected to have a 10% chance of below normal flows. By December 2024, model runs suggest a 25% likelihood of flows being below normal or notably low across the rivers.

7.2 Probabilistic ensemble projections for groundwater levels in key aquifers

For September 2024, no models suggest groundwater levels could be anything below above average, while Smeetham is unlikely to be below notably high and Therfield Rectory was modelled at exceptionally high through all simulated runs. They show the dominant influence of the winter recharge season in determining groundwater levels throughout the following summer, as well as the continued above average rainfall into the spring and summer months. By March 2025, all boreholes are forecasted to have some probability of normal to below normal groundwater levels, suggesting a decline in the influence of the wet 2023 winter.

Author: Hydrology Team, hydrology-ean-and-lna@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.