East Anglia water situation: September 2024 summary
Updated 11 October 2024
Applies to England
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Following a dry August, the rainfall for September 2024 was above average for all of East Anglia, with exceptionally high month totals recorded in the Bedford Ouse catchment. Most of this rainfall occurred over the last 9 days of September and led to flooding within the Great Ouse catchment. Groundwater levels continued to recede at most report sites across September, although levels remain elevated for the time of year. Most public water supply reservoirs have levels above their respective normal operating curves.
1. Rainfall
September 2024 was a wet month across East Anglia, with all reporting catchments having above average rainfall totals for the month. The largest rainfall month totals were seen in the Upper Bedford and Lower Bedford Ouse catchments, which respectively had 203mm and 153mm of rainfall across September. These totals are the highest September totals on record for these catchments, based on the long term record dating back to 1871. Most of this rainfall occurred over the last 9 days of September and led to flooding within the Great Ouse catchment. Over the last 12 months, East Anglia has received 878mm of rainfall, which is 252mm greater the long term average. This value ranks as the third highest October to September 12 month total on record going back to 1871.
2. Soil moisture deficit and recharge
Cooler temperatures and a wet end to the September resulted in a reduction in the soil moisture deficit value for East Anglia. The largest reductions in SMD were seen in the west of the area, reflecting the distribution of rainfall for the month.
3. River flows
With a wet September following a dry August, the majority of river report sites showed an increase in runoff relative to August. This was largely in response to the heavy rainfall seen towards the end of September. Rivers with a significant baseflow component, such as the Burn and Heacham, showed a small reduction in month mean flows, reflecting the continued recession in local groundwater levels. Exceptionally high day mean flows were recorded at gauging stations on the Ouse, such as Offord and Roxton, as well as on upstream tributaries, such as the Ivel, Ouzel and Tove. These flows should be viewed with caution since it is common for gauging stations, such as Roxton, to drown at very high flows resulting in reduced accuracy of flow measurement.
4. Groundwater levels
Groundwater levels at the majority of report sites continued to recede across September 2024. Two report sites, Fringford and Biggleswade, recorded increasing groundwater levels from August to September. This is indicative of aquifer recharge within the Upper Bedford Ouse catchment, which has seen exceptional rainfall totals for September 2024. Groundwater levels at the majority of report sites are above normal to exceptionally high for the time of year.
5. Reservoir stocks
At the end of September 2024, the majority of water company reservoirs showed levels greater than their respective normal operating curves. Reservoir capacities ranged between 75% to 87% of maximum storage capacities. Only Grafham reservoir ended the month with a level marginally below its normal operating curve.
6. Forward look
6.1 Probabilistic ensemble projections for river flows at key sites
For all surface water forecast sites there is a high probability of flows being above normal or higher for December 2024, with a continued high probability of flows remaining in the normal or higher range for March 2025.
6.2 Probabilistic ensemble projections for groundwater levels in key aquifers
Groundwater levels at the majority of report sites are above normal to exceptionally high for the time of year. A wet September has led to wetter than average soils for the time of year. Consequently, there is a high probability of groundwater levels remaining at normal or higher levels by March 2025 and September 2025.
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.