Research and analysis

East Anglia water situation: April 2024 summary

Updated 15 May 2024

Applies to England

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

1. Summary

Hydrologically, the extremely wet autumn and winter across East Anglia will continue to exert an influence on both groundwater levels and river flows in those parts of the Area where groundwater is important and the rivers have significant baseflow components. April itself was slightly wetter than average, with the most notable rainfall event occurring on 27 April. The west of East Anglia had the heaviest rainfall on 27 April, with 20mm to 25mm widely, and was the wetter side of the Area overall throughout the month.

2. Rainfall

Rainfall this April across East Anglia was higher than the long-term average for the month. The 3-month, 6-month and 12-month running totals continue to be exceptionally high in almost all catchments. The highest rainfall total since records began in 1871 has been recorded in each of those accumulation periods in at least two catchments across East Anglia. Not only have there been some exceptionally wet months during the past year, most notably October and February, but there have been very few dry months. There has not been a month with rainfall significantly less than average across East Anglia since June 2023.

3. Soil moisture deficit and recharge

A soil moisture deficit began to build through April, mainly due to increasing day length. The low temperatures during the second half of the month suppressed the deficit slightly, and the widespread rainfall on 27 April led to a temporary reduction. Overall, the deficit is lower than average for the time of year. The recharge season might now have ended, at it usually has by the end of April.

4. River flows

As a soil moisture deficit built up throughout the month, most river flows receded to baseflows. The heaviest rainfall on 27 April in the western and southern catchments brought significant increases in flow there, while the lower totals to the east and north led to much more muted responses. Overall, the catchments in the west of East Anglia were generally in the above normal or notably high categories, due to both high baseflows and the responses to rainfall. The catchments in the east were generally in the normal range, reflecting the lower rainfall totals for the month and the lower runoff responses. 

5. Groundwater levels   

Groundwater levels are high across most of East Anglia, reflecting the high rainfall totals across the autumn and winter. Groundwater levels in the west of the Chalk across East Anglia peaked at particularly high levels over the winter. Several borehole groundwater levels are exceptionally high and some have exceeded their previous highest recorded levels over the past winter. All are in the above normal range or higher except Rook Hall, Braiseworth, which is very close to the above normal range. 

6. Reservoir stocks

Public water supply reservoirs are generally at healthy levels for the time of year. Grafham is slightly below its control curve for operational reasons, but healthy flows in the Bedford Ouse give little cause for concern for the prospects this summer.

7. Forward look

7.1 Probabilistic ensemble projections for river flows at key sites

The projections show that none of the model runs using current starting conditions and historic rainfall and potential evapotranspiration simulate flows for June 2024 lower than those categorised as normal. By September, only the projections for Denver show some simulations reaching the below normal category. That could be due to the fenland areas in the Denver catchment not showing as much persistence of the wet conditions from the winter as the other forecast locations as we go through the summer. 

7.2 Probabilistic ensemble projections for groundwater levels in key aquifers

None of the model runs using current groundwater levels and historic rainfall and potential evapotranspiration simulate groundwater levels for September 2024 lower than the normal category. Two sites, Kenninghall and Therfield Rectory, simulate all model runs as remaining exceptionally high. They show the dominant influence of the winter recharge season in determining groundwater levels throughout the following summer.  The projections for March 2025 show the possibility of some lower categories being recorded by then, indicating the declining influence of this wet winter as we go through another year. 

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 within.