Research and analysis

Yorkshire water situation: May 2024 summary

Updated 21 June 2024

Applies to England

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

1. Summary

May was a much drier month, although included wet spells in the second part of the month. River flows declined from the previous month and most monthly mean flows were above normal. Reservoir stocks remained near capacity. Groundwater levels declined. Soils started to drain but due to soils returned to wet by the end of the month.

2. Rainfall

May was a month of two parts, it began with dry conditions and then was followed by short intense episodes of rain that affected the majority of Yorkshire. The monthly mean rainfall was within above normal range for most catchments, with the exception of the Don, Rye and Derwent, which were within normal range and the Aire and Wharfe classified as notably high.  The highest rainfall totals were captured in the Aire, which recorded 166% of the long term average (LTA). Other catchments recorded between 108% and 160% of the LTA, with wetter conditions in the west than in the east of Yorkshire.

Early in the month many rain gauges recorded minimal to no rain until around day 11. The Pennine catchments were affected by moderately heavy rain on 12 May. During the second fortnight of the month there were 2 short intense periods of rainfall across Yorkshire, the first on day 21 to 22 and the other around day 26 to 28. Skipton Snaygill rain gauge recorded 80% of the monthly LTA on day 22 and at least 42% of the LTA on days 26 and 28.

3. Soil moisture deficit

Yorkshire’s soils started the month fully saturated. Soil moisture deficit (SMD) gradually increased in the east and by week 3 soils in the mid and east of Yorkshire were classified as normal. By the end of week 4 all soils were again classified as wet and at month end only the lower Hull and Holderness had SMD just within the normal range.

4.  River flows

The monthly mean flows were above normal for the Swale, Ure, Nidd, Ouse Wharfe, Derwent and upper Hull, mostly between 130% and 180% of the LTA. Similarly in the Calder, Don and Rother flows for the month were above normal at 112% to 143% of the LTA. May flow values were notably high in the Aire and to the east in the Esk and Rye. Overall in comparison to the previous month, the monthly mean flows across Yorkshire have all reduced considerably.

In the Pennine catchments flows started the month within normal range, which was maintained until around day 22, when in response to heavy rainfall flows increased to exceptionally high. The multiple rain events from day 21 onwards ensured that the flows remained in a high state from day 22 until month end. Flows were most elevated in the Aire, reflecting the high rainfall, and monthly mean flow was 240% of the LTA.

Flows followed a similar pattern in the Don and Rother catchments to the south. For the first three weeks of May these rivers were classified within the normal range and then reached exceptionally high on day 22 in response to the widespread rainfall event. Flows receded towards month end.

Daily mean flows in the Rye and Derwent were above normal or notably high for the majority of May, supported by strong inflows from groundwater sources after the wet spring. Flows were receding gradually but increased again on day 22 to 24 in response to the widespread rainfall event.

In the east of the Area in the Chalk-fed West Beck flows continued to decline, but remained in the above normal range with a monthly mean 144% of the LTA for May.

5. Groundwater levels   

5.1 Magnesian Limestone

The groundwater level within the Magnesian Limestone at Brick House Farm continues to decrease but remains exceptionally high for the time of year.

5.2 Millstone Grit

The groundwater level has decreased within the Millstone Grit at Hill Top Farm and is back to normal for the time of year. It should be noted that this observation borehole is used for water abstraction by means of a pump. Therefore, the groundwater level recorded here may be subject to the effects of this.

5.3 Sherwood Sandstone

The groundwater level in the Sherwood Sandstone remained constant at Great Ouseburn (exceptionally high) but decreased in Riccall Approach Farm. Riccall Approach Farm remains notably high.

5.4  Corallian Limestone

The groundwater level decreased within the Corallian Limestone at Sproxton but is now notably high for the time of year.

5.5 Chalk

The groundwater level decreased at both Wetwang (northern Yorkshire Wolds chalk) and Dalton Estate (central Yorkshire Wolds chalk). Wetwang is now in the normal range but Dalton Estate remains within the notably high range.

6.  Reservoir stocks

A small 2.6% decline of overall reservoir stocks occurred throughout the month. The rain that occurred within the month kept the reservoir stocks replenished and 5% above average at the end of May.

 

Author: Yorkshire Hydrology, northeast.hydrology@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.