Research and analysis

Water situation: July 2023 summary

Updated 11 January 2024

Applies to England

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

July was a very wet month, the wettest July in England since 2009, with all catchments receiving above average rainfall and the north-west recording the wettest July on record, using data from 1891. Soil moisture deficits (SMD) decreased across England, with soils across much of the country wetter than would be expected for the end of July. River flows were above normal or higher at more than half of reported sites, particularly those in the north-west as they responded to the wet weather. By the end of July, groundwater levels had decreased at more than three-quarters as is expected at this time of year, and two-thirds of sites were classed as normal for the time of year. Reservoir stocks at the end of July were classed as normal at almost all reservoirs or reservoir groups we report on.

1. Rainfall

The July rainfall total for England was 120mm which represents 207% of the 1961 to 1990 long term average (LTA) for July (181% of the 1991 to 2020 LTA). For north-west England it was the wettest July on record (using records since 1891), and for England as a whole it was the sixth wettest (using records since 1891) and the wettest since July 2009. All catchments in England received above average rainfall during July, with two thirds receiving more than double the average amount of rainfall. Six catchments recorded their wettest July on record, including the Douglas catchment in Lancashire in north-west England which received 314% of LTA rainfall, making it the wettest hydrological area. The driest hydrological area was North West Grain in Kent in south-east England which received 119% of the LTA rainfall for the time of year.

After such a wet month, July rainfall totals were classed as normal for the time of year for just fifteen catchments in England which was only in 11% of the total number. The remaining catchments were all classed as above normal or higher, with the majority being notably high for the time of year. At a regional scale, south-east and east England were above normal for the time of year, while central England was notably high. North-west, north-east and south-west England all received exceptionally high rainfall during July. Across England as a whole, rainfall in July was exceptionally high for the time of year.

With 2 drier than average months being followed by a much wetter July, the 3 month cumulative rainfall totals reflect a mixed period for England. Much of the country saw normal rainfall totals over the 3 month period. In contrast Kent saw below normal rainfall totals for the 3 months. The north-west received above normal or higher rainfall totals, and parts of north-east, central and south-west England also saw above normal rainfall totals. The 6 month cumulative rainfall totals show the majority of the country received above normal or higher rainfall. The south-east, Welsh borders and north-east received normal rainfall. Twelve month cumulative rainfall totals show a similar pattern, although much of the south coast saw exceptionally high rainfall totals.

2. Soil moisture deficit

SMD decreased across England by the end of July following the above average rainfall received during the month. In the south-east and east SMDs reduced slightly from their higher levels at the end of June. Meanwhile, in the south-west, central, north-west and north-east deficits were reduced significantly by the rainfall throughout the month, with some areas having little to no deficit at the end of July.

At the end of July SMD values in the south-east and east remained around or only slightly larger than average for the time of year, meaning soils were as dry as expected for the time of year. In contrast the SMDs in south-west, central, north-west and north-east England were smaller than average, with wetter soils than would be expected for the time of year, marking a rapid change since the end of June when all soils were drier than average.

3. River flows

Monthly mean river flows increased at more than half of the indicator sites we report on. More than half of sites were above normal or higher for the time of year, with the remaining sites recording normal monthly mean river flows for July. Just one site was below normal, the River Burn at Burnham which has now remained below normal since October 2022. All sites in the north-west were above normal or higher for the time of year.

Monthly mean river flows increased at all except two regional index sites in July. The naturalised flows on the River Thames at Kingston and gauged flows on the Great Stour at Horton both saw a small decrease in flows, leaving them above normal and normal respectively. The most notable increases in monthly mean river flows were recorded at Caton on the River Lune in the north-west, Haydon Bridge on the South Tyne in the north-east and Marston-on-Dove on the River Dove in central England. All 3 of these sites had above normal or notably high flows in July having been below normal or lower in June.

4. Groundwater levels

By the end of July, groundwater levels had decreased at more than three-quarters of reported indicator sites compared to the end of June, as is expected at this time of year. Two-thirds of sites were classed as normal for the time of year, and all remaining sites were classed as above normal or higher.

All except two major aquifer index sites were classed as normal at the end of July. The only exceptions were both in the south-east, Chilgrove in the Chichester Chalk and Little Bucket in the East Kent Stour Chalk, which were both above normal for the time of year. Redlands Hall in the Cam and Ely Ouse Chalk was the only site classed as normal to have changed band since June, having changed from above normal levels.

5. Reservoir storage

Reservoir storage during July decreased at two-thirds of the reservoirs or reservoir groups that we report upon. The largest storage changes occurred at Clatworthy, Stithians and Wimbleball in the south-west and Ardingly in the south-east with all four seeing a decrease of more than 10%. The biggest increase was seen in the Pennines Group where levels rose by 17%. These changes in storage resulted in almost all reservoirs or reservoir groups being classed as normal or higher for the time of year. Storage at four reservoirs was classed as below normal or lower.

At a regional scale total reservoir storage increased during July in the north-east, north-west and central England, while all other regions saw levels decline. England as a whole saw levels remain around the same as at the end of June. Total reservoir storage ranged from 68% in the south-west to 95% in south-east England. By the end of July the total reservoir storage for England was 82%.

6. Forward look

Although average rainfall is forecast, the mid-August period is likely to experience unsettled conditions with scattered showers across the country, north-west England is expected to experience heavier and more frequent showers than the south-east. Conditions are likely to remain changeable for the rest of August with occasional bands of rain and showers most likely.

For the UK for the 3 month period from August to October there is a higher chance than usual for warmer weather although near average temperatures are most likely. The chances of either a wet or dry period are similar to expected for the time of year.

7. Projections for river flows at key sites

By the end of September 2023, rivers throughout England have a greater likelihood of experiencing either above normal or normal flows, Stiffkey in east England, is the only river where projections shows a high likelihood of below normal flows. September projections show a split with a greater chance of lower flows throughout east England and higher flows in the west. A similar trend can be observed in the projections through to March 2024; where the majority of rivers across England are likely to experience normal flows or greater, while rivers in the east and south east have an increased chance of experiencing below normal flows compared to the rest of the country.

8. Projections for groundwater levels in key aquifers

By the end of September 2023, groundwater in south-west and south-east England has a greater likelihood of experiencing above normal or higher levels. Groundwater levels are most likely to be in their expected range across the rest of England. By the end of March 2024, groundwater levels throughout England are expected to be normal. With sites located along the east coast more likely to experience below normal levels, whereas sites supported by the Chalk aquifer in south and east England are likely to experience above normal or greater levels. Skirwith in the north-west is the only location with a high likelihood of notably high groundwater levels.

Author: National Water Resources Hydrology Team, [email protected]

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.