1. Summary

Soils were saturated, reservoirs remained close to capacity and rivers were responsive to rainfall episodes. Groundwater levels rose in all aquifers. January did feature some settled periods and monthly precipitation totals in the normal range or above were influenced by a contribution from snowfall in the first week. Monthly mean river flows were in the normal to above normal range.

2. Rainfall

Monthly rainfall totals were in the normal range in most catchments, between 80% and 127% of the long term average (LTA). Rainfall was below the LTA in the northern Dales catchments of the Swale, Ure, Nidd and Wharfe. Precipitation in the Don catchment was notably high at 143% of the LTA, and above normal in the Hull and Humber at 130% of the LTA.

Snow and heavy rain on days 5 and 6 contributed 45% to 65% of the monthly total at many rain gauges in the Don, Ouse, Rye, Derwent and Hull catchments. This weather affected the northern Dales catchments to a lesser extent, accounting for the lower January totals as percentage of LTA in those areas. Other wet days occurred on 12 and 13 January in the Pennines and on days 23 and 26 throughout Yorkshire. Much of the second and third weeks of January featured settled conditions.

3. Soil moisture deficit

Soils throughout Yorkshire remained saturated and classified as wet all month. Even in settled periods, temperatures were too low for evaporation to increase soil moisture deficit.

4. River flows

Monthly mean river flows in most catchments were above the LTA and in the normal or above normal range for January. The monthly mean flow on the Don at Doncaster was notably high at 183% of the LTA, reflecting the higher snowfall and rainfall in this catchment.

The monthly mean flow on the West Beck in the upper Hull catchment was also notably high, at 186% of the LTA. This river sustained high flows all month, generated by strong spring flows from high Chalk groundwater levels and also a response to rainfall and snowmelt after day 5.

January began with high river flows across Yorkshire following a storm event on 31 December 2024 and the morning of New Year’s Day. Rainfall had been most intense in the Calder and particularly upper Colne catchments. The highest river level in the 45-year record occurred on the Colne at Huddersfield Longroyd Bridge, with significant peaks also recorded at other monitoring stations in the Calder catchment.

All the Pennine-fed rivers remained responsive to rainfall episodes through January, with moderate peaks on days 5 to 7, mid-month and on day 27. On the Don, Rother and the Esk in the north-east the highest flow of the month occurred on day 6 following rain and snowmelt. The Rye and Derwent showed a similar pattern, with a more moderate peak also building on the Derwent on days 28 to 30. Daily mean flows in most catchments fluctuated accordingly between the normal range for January and notably or exceptionally high. The Esk, upper Wharfe and upper Ure receded into below normal flows only for short periods within the settled second and third weeks. The geology of these catchments supports a low baseflow contribution in drier weather.

5. Groundwater levels   

5.1 Magnesian Limestone

The groundwater level within the Magnesium Limestone at Brick House Farm increased and remained notably high for the time of the year.

5.2 Millstone Grit

The groundwater level increased within the Millstone Grit at Hill Top Farm and was above normal for the time of the 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 subjected to the effects of this.

5.3 Sherwood Sandstone

The groundwater level in the Sherwood Sandstone decreased at Great Ouseburn but remained notably high for the time of year while groundwater levels increased at Riccal Approach Farm, remaining normal for the time of year.

5.4 Corallian Limestone

The groundwater level increased within the Corallian Limestone at Sproxton and was normal for the time of year.

5.5 Chalk

The groundwater level increased at Wetwang but moved into the upper part of the normal range for the time of year (northern Yorkshire Wolds chalk), while Dalton Estate (central Yorkshire Wolds chalk) increased and was above normal for the time of year.

6. Reservoir stocks

Total reservoir stocks increased marginally during January and were 6% above the LTA at the end of the month.

Author: Environment Agency, hydrology.northeast@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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