East Anglia water situation: May 2024 summary
Updated 21 June 2024
Applies to England
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1. Rainfall
May 2024 was another significantly wet month, ranging between 128% and 203% of the long term average (LTA) for May, and following the trend of wet weather experienced over the past 12 months in the region. The last 3-month, 6-month and 12-month rainfall totals have consistently been notably or exceptionally high across the region. Rainfall totals across the region have not dropped below 120% of the LTA, across any of the observed timeframes.
2. Soil moisture deficit and recharge
Soil moisture deficit (SMD) saw a sharp change through May as it continued to increase, due to the warmer temperatures and higher evapotranspiration rates, before this increase was impeded due to the high rainfall received in the middle of the month, causing the SMD to decline. It has since however, continued its rise as rainfall reduced. Overall, the deficit is lower than average for this time of year and May to June usually sees a sharp increase in SMD as rainfall totals drop with warmer, drier days.
3. River flows
Monthly river flows ranged between 109% and 275% of the LTA for May. While the month began with rivers at baseflow for much of the region, the periods of intense rainfall led to a sharp peak in flows towards the beginning of the month before receding. River flows remain above average for the region due to high groundwater levels and soil moisture supporting baseflow and high runoff volumes. Catchments in the south and east of the region, the Chelmer, Gipping and Waveney saw flows closest to average for the time of year, reflecting the lower rainfall totals.
4. Groundwater levels
Groundwater levels remain high across East Anglia, with all catchments with data demonstrating above average, notably or exceptionally high levels compared to the LTA. The continued high levels of rainfall continue to recharge groundwater; however, a number of sites are now trending down from exceptionally high. Despite this trend, it is likely groundwater levels will remain above normal at many locations through the summer months.
5. Reservoir stocks
Reservoir stocks for the month were in a good position, Abberton, Alton and Hanningfield stocks were all 95% or above, and running above normal operating curve for this time of year. Ardleigh and Grafham are slightly below their normal operating curve, but still have around 90% of normal capacity stored.
6. Forward look
6.1 Probabilistic ensemble projections for river flows at key sites
Projecting forward, the simulations suggest, based on the current starting conditions, there is roughly a 25% probability flows will be below average or notably low by September 2024, while average conditions are predominately expected. However, it is expected that flows will increase later in the year and by December it is likely flows will be above normal to notable high.
6.2 Probabilistic ensemble projections for groundwater levels in key aquifers
None of the models run for the groundwater levels suggest levels to reduce below normal, with sites Kenninghall, Smeetham and Therfield Rectory simulating at least notably high groundwater levels, by September 2024. This highlights the significance of the wet winter experienced in enabling groundwater recharge, as well as the continued above average rainfall totals supplementing the groundwater levels. March 2025 projections show a reduction in groundwater levels with roughly a 25% chance of levels falling below average, this suggests the influence of the previous wet winter will have subsided and projected average rainfall for the region will drive the groundwater levels.
Author: Hydrology Team, hydrology-ean-and-lna@environemnt-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.