Research and analysis

Water situation: March 2023 summary

Updated 11 January 2024

Applies to England

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

It was the wettest March across England since 1981 with monthly rainfall totals above average in all catchments across England. Soil moisture deficits remain low across England at the end of March as is expected at this time of year. River flows increased at more than four-fifths of the indicator sites, and most sites were normal or higher for the time of year. Groundwater levels increased at more than half of the indicator sites, at the end of March groundwater levels were normal at the majority of sites. Reservoir stocks in March increased at all but two of the reservoir and reservoir groups we report on and almost two-thirds were either normal or higher for the time of year.

1. Rainfall

The March rainfall total for England was 119.2mm which represents 180% of the 1961 to 1990 long term average (LTA) for the time of year (204% of the 1991 to 2020 LTA). All catchments across England received above average rainfall during March. The wettest hydrological area (relative to its LTA) was the Lower Bedford Ouse catchment in eastern England which received 256% of LTA rainfall for March. The driest hydrological area was the Tweed catchment in north east England with 105% of LTA rainfall.

March rainfall totals were classed as notably or exceptionally high at four fifths of catchments across England. Many catchments recorded their top ten wettest March on record since 1891 with Taw and North Devon and Lower Bristol Avon catchments in south west England and the Loddon catchment in south east England all recording their wettest March on records since 1891. At the regional scale, all areas across England received exceptionally high rainfall for the time of year with the exception of north west and north east England, which received notably high and above normal rainfall respectively. March rainfall across England as a whole was classed as exceptionally high and it was the wettest March since 1981.

The 3 month cumulative rainfall totals show that over four-fifths of catchments in England were classed as normal or above normal. The 6 month cumulative rainfall totals show a similar pattern, with all catchments classed normal or higher with more than a third of catchments notably high. The 12 month cumulative rainfall totals show the majority of catchments were classed as normal.

2. Soil moisture deficit

Soil moisture deficits (SMD) remain low across England at the end of March. Soil moisture deficits have decreased across central and eastern England and soils remain wet across the rest of the country for the time of year.

March SMD values across the majority of the country were close to the LTA for the time of year. The differences from the LTA have reduced across central, eastern and south eastern England with these areas now wetter than the LTA. At a regional scale, the end of March SMDs are lower than typical for the time of year.

3. River flows

March monthly mean river flows increased at over four-fifths of indicator sites we report on. All but two sites were normal or higher for the time of year, with more than half of sites either above normal or notably high for the time of year.

Monthly mean flows for all the regional index sites increased during March. Flows in, the Great Stour at Horton, the South Tyne at Haydon Bridge and the River Dove at Marston-on-Dove were above normal for the time of year. The Bedford Ouse at Offord and the River Lune at Caton were classed as notably high. Naturalised flows on the River Thames at Kingston was classed as normal and the River Exe at Thorverton in south west England recorded exceptionally high flows for the time of year.

4. Groundwater levels

At the end of March, groundwater levels increased at more than half of the reported indicator sites with many aquifers likely to benefit from end of season recharge. Nearly three quarters of end of month groundwater levels were classed as normal for the time of year. Four sites were classed as being below normal or lower for the time of year.

The major aquifer index sites showed a varied picture at the end of March, ranging from below normal to above normal levels. Normal groundwater levels were reported at Dalton Estate Well in the Hull and East Riding Chalk, at Redlands Hall in the Cam and Ely Ouse Chalk, at Skirwith in the Carlisle Basin and Eden Valley Sandstone and at Chilgrove in Chichester Chalk during March. Levels at Jackments Bottom in the Burford Jurassic Limestone increased to be classed normal. Stonor Park in the South West Chilterns Chalk remained at below normal levels. Little Bucket in the East Kent Stour Chalk decreased to normal levels in March and Weir Farm in the Bridgnorth Sandstone remained above normal for the time of year.

5. Reservoir storage

Reservoir stocks at the end of March increased at all but two of the reservoirs and reservoir groups that we report on. Eight reservoirs saw a stock increase of 10% or more compared to the end of February. The largest stock increase, 18%, was recorded at Hanningfield in east England. Two-thirds of the reservoirs or reservoir groups were classed as normal or higher for the time of year. Four reservoirs across England are classed as notably low.

At the regional scale, total reservoir stocks ranged from 81% in south-west England to 97% in south-east England. Total reservoir stocks for England were at 93% of total capacity at the end of March up 7% from the end of February.

6. Forward look

April began with a mix of generally settled conditions across the country bringing sunny spells and the occasional rain band crossing the country. The second week is likely to be unsettled with spells of wind and widespread rainfall. Towards the middle of the month conditions are likely to become more settled, particularly in the south and east, with warm sunshine by day but nights may still be cold. Confidence is lower in forecasts for the second half of the month, but in general settled weather is likely to dominate although the chance for changeable spells remains.

For the 3 month period for the UK from April to June there is an increased chance of warm conditions. There is an increased likelihood of the period being drier than usual but wet periods are still possible.

7. Projections for river flows at key sites

By the end of September 2023 river flows have a greater likelihood of being above normal or higher in all regions except the east of England. By the end of March 2024 river flows have a greater likelihood of being above normal or higher in south east, south west and north west England. In central England river flows have a greater chance of being below normal or lower.

8. Projections for groundwater levels in key aquifers

By the end of September 2023 groundwater levels have a greater likelihood of being above normal or higher in south west, central and east England. In the north east groundwater levels have a greater likelihood of being below normal or lower. By the end of March 2024 groundwater levels have a greater likelihood of being above normal or higher in south east, central and north west England.

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.