Research and analysis

Thames water situation report: November 2024 summary

Updated 13 December 2024

Applies to England

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

1. Summary

In November Thames area received 92mm of rainfall, 137% on the long term average (LTA). While total rainfall was normal for the time of year, two-thirds of the month’s rain fell over 3 days (23, 24, 26 November). River flows increased at 7 of our key indicator sites. Banbury recorded the third highest November flow since 1967, Bourne End (Hedsor) recorded the second highest flow since 1964, and Marlborough recorded its fourth highest flow since 1972. Groundwater levels increased at the majority of our indicator sites, while all but one are notably high or exceptionally high. Reservoir levels decreased in November, however they are still above average for the time of year. There were 52 flood alerts, and 37 flood warnings issued on rivers during November.

2. Rainfall

In November, Thames area received 92mm of rainfall, which was 137% of the LTA. There was an east-west split, with all the areal units in the west of Thames area receiving above normal rainfall, while the east of Thames area received normal rainfall for the time of year. Normal rainfall was received for the month, however two-thirds of the rain fell over 3 days: 23, 24, and 26 November. Total accumulated rainfall over the past 12 months remains exceptionally high across the entire area.

3. Soil moisture deficit and recharge

With the continued rain, soils remained saturated. In November, soil moisture deficits were 0mm or 1mm across all of Thames area, which is below the long term average of 38mm. This meant that the effective rainfall was 71mm which was 275% of what would be expected for November. 

4. River flows

Monthly mean flows increased at 7 of our key indicator sites, while 8 decreased. However, all were above normal of higher, with 2, Banbury on the Cherwell, and Bourne End (Hedsor) on the Wye, recording exceptionally high flow for the time of year. Banbury recorded its third highest November flow since 1967, Bourne End (Hedsor) recorded the second highest flow since 1964, and Marlborough recorded its fourth highest flow since 1972. Due to the majority of the November’s rain falling at the end of the month, just under half of our indicator rivers had exceptionally high daily mean flows by month end.

5. Groundwater levels   

Groundwater levels at all our indicator sites increased on last month, except for Jackaments Bottom in the Inferior Oolites, which slightly decreased but remained above normal for the time of year. Six sites, just over half, recorded exceptionally high levels, while all the rest but one (Jackaments Bottom) were notably high. Groundwater levels of the Chalk aquifer at Stonor remained exceptionally high for the tenth month in a row.

6. Reservoir stocks

Reservoir stocks continued to decline in the Lower Thames reservoir reservoirs and ended the month at 82.1%, compared to 86.9% at the end of October. Stocks in Farmoor reservoir also decreased slightly from 90.9% to 90.2% during November. However, both are above average for the time of year.

7. Environmental impact 

During November, there were 52 flood alerts, and 37 flood warnings issued in Thames area. At the end of the month no abstraction licences were being constrained in the area to protect water resources and the environment.

Author: Thames Area Groundwater Resources and Hydrology, [email protected]

Contact Details: 030708 506 506

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.