Research and analysis

Lincolnshire and Northamptonshire water situation: August 2024 summary

Updated 13 September 2024

Applies to England

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

1. Summary

August was a dry month across Lincolnshire and Northamptonshire, particularly in the first half of the month. August rainfall totals were well below average, ranging from 18mm to 29mm (30% to 50%) of the long term average (LTA) and as such were banded as notably low. The dry end to July and the dry August since then has led to a rapid rise in soil moisture deficits (SMD) in all 6 hydrological areas. The area as a whole ended the month with SMD of 120mm. Despite August rainfall being classified as notably low for the time of year, most of river sites across the area are showing normal levels because of the healthy recharge season during last winter and the wet spring. Following the notably low levels of rainfall and normal to above normal SMD across the area in August, groundwater levels still remained normal or higher at all sites with data, but trends showed a slight decline at all indicator sites. With the exception of Covenham and Rutland, reservoirs in the area ended the month above their normal operating curves.

2. Rainfall

On average, the Lincolnshire and Northamptonshire area received 24mm of rainfall during August, which is 40% of the LTA. August rainfall totals ranged from 30% to 50% of the LTA (18mm to 29mm) and as such were banded as notably low in all 6 hydrological areas. Throughout the month frontal system did not give hydrological area rainfall totals higher than 9mm during any single event. Following August’s rainfall, the 3-month total is now showing that the hydrological areas have received below normal to normal levels of rainfall. This is a decrease from July’s report which showed normal level to above normal levels of rainfall in all hydrological areas. As a result of these low levels of rainfall in August, the last 6 months’ totals displayed normal levels in all 6 hydrological areas. The record-breaking rainfall totals over winter are still having an impact on the long-term analysis with the last 12 months rainfall totals in all hydrological areas still being exceptionally high during these periods.

3. Soil moisture deficit and recharge

SMD responded in line with the rainfall received across August. SMD has increased in all 6 hydrological areas. The dry end to July and the dry August since then has led to a rapid rise in deficit. Four of the 6 hydrological areas are now showing above normal levels of SMD for the time of year, whereas in July’s report all hydrological areas were at normal levels. The area as a whole ended the month with SMD of 120mm, in comparison to 101mm at the end of July.

4. River flows

Despite August rainfall being classified as notably low for the time of year, most of river sites across the area are showing normal levels because of the strong base flows caused by the wet winter. The only site not classified as normal is the Glen. The Glen is showing above normal levels (a decrease from notably high levels in July). Although all river flows receded during August, Barlings Eau and Witham levels show no change in banding since July. Hence, mean monthly flows ranged from 34% to 114% of the LTA, and from normal to above normal classification.

5. Groundwater levels   

Following the notably low levels of rainfall and above normal SMD across the area in August, groundwater levels still remained normal or higher at all sites, but trend showed a slight decline at all indicator sites. Most groundwater level shows no change in banding since July 2024, except Leasingham Exploratory and Grange Farm Aswarby sites. Overall, at all sites with data, groundwater levels were classified as normal to notably high for the time of year.

6. Reservoir stocks

With the exception of Covenham and Rutland, reservoirs in the area ended the month above their normal operating curves. The levels at Covenham were 3% below target curve and Rutland was 4% below target curve in August, however levels are not alarmingly low (around the 1995 to 1996 operational curve).

7. Environmental impact 

The Trent-Witham–Ancholme (TWA) transfer scheme has been in use during August. During August water has been pumped into the Ancholme from the Witham at Short Ferry while transfer from the Trent into Witham at Torksey started on 3 August. Both the Gwash-Glen and Slea augmentation schemes remained off in August. There were 7 ‘hands off flow’ active:

• 4 in the Witham catchment
• 2 in the Steeping catchment
• 1 in the Ancholme catchment.

There were 2 flood alerts, and no flood warnings issued.

8. Forward look

8.1 Probabilistic ensemble projections for river flows at key sites

September 2024: All sites are showing an increased probability of below normal flows.

December 2024: There is an increased probability of lower-than normal flow at North Brook and a decreased probability of normal flows at Nene Northampton and Nene Wanford.

8.2 Probabilistic ensemble projections for groundwater levels in key aquifers

September 2024: All sites are showing an increased probability of groundwater levels being normal or higher with none of modelled rainfall scenarios showing below normal to exceptionally low levels.

March 2025: All sites are showing a slightly increased probability of groundwater levels being higher than normal.

Author: Pan 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

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