Water situation for Upper Ivel – February 2023
All data presented courtesy of the Environment Agency and Met Office (Crown copy right
2023)
Rainfall:
February was exceptionally dry with only 20% of the long-term average (LTA), classified as exceptionally low. The 3-month average (Jan- March) has fallen to 72% of the long-term average.
The worsening rainfall situation in February sees the continuation of drought conditions in Upper Bedford Ouse catchment. Overall East Anglia experienced the driest February since 1959 (3rd driest on record).
Soil Moisture Deficit (SMD)
Due to the exceptional low levels of rainfall in February and the milder than normal temperature, soil moisture
deficit (SMD) increased across the whole of East Anglia. The area surrounding the Ivel increased to 10-20mm SMD,
meaning that recharge stopped and effective the aquifer started to empty… SMD ended the month at 21 mm. SMD
in the northern and eastern areas of the region deteriorated even more.
Definitions:
Soil Moisture deficit (SMD) – The difference between the amount of water in the soil and the amount of water that the soil can hold (field capacity).
Ground Water (GW):
Looking at the regional picture across the East Anglian chalk, Ground Water levels are now ranging between normal to notably low compared to historic February levels. Affinity Water confirmed to RevIvel that by the end of February Ground Water levels were in decline in the upper Ivel catchment.
It is worth noting that if an augmentation scheme was up and running for the Ivel it would have to be deployed now!
This is a frightening thought when you realise that such measures are mean to only be deployed at the end of the summer / early autumn when GW level would naturally be in decline.
Springs and River flows:
The main spring at Ivel Springs in Baldock started to flow on 14 th January 2023.
The second spring at the Ivel Springs nature reserve (upstream of culvert) in Baldock started to flow on 1st January 2023.
Flow at Blackhorse Mill was seen by the end of the first week in January 2023.
Three springs now flow in Radwell meadows at very low levels.
River flow is low through Stotfold.
The river Ivel flows are officially measured at Blunham. The river had been low to notable low through the summer but returned to normal (green zone) during October- January responding directly to significant rainfall events. The significant lack of rain fail in February has resulting in river levels falling to below normal.
Reservoir Stocks:
Water from the Ouse is transferred at Offord into Grafham Water.
Recovery of reservoir stocks in Grafham Water remains slow with the reservoir currently only 80% full (blue line on graph) (Notably Low). The current stock levels are a long way from the normal operating level of 90%+.
End of February Grafham Water reservoir stock compared to the Normal operating Curve, Drought Curve and 1995-1996 stock levels.
Looking forward:
Recharge of the chalk aquifer relies on the amount of rainfall through the autumn and winter months. The autumn and early winter (Oct- Nov – Dec 2022) were wet months with 150% of LTA.
Whist January rainfall was 103% of the LTA, February has been exceptionally dry and this is already having a negative effect on the aquifer and recharge has stopped.
Significant rain is needed in March 2023 to support the return to aquifer recharge and to improve the chances of flow of the chalk springs in Baldock, Norton and Radwell in the spring and summer months 2023.
The Upper Bedford Ouse catchment has been in official drought since end June 2022.Over this time Affinity Water has applied its drought management plan with the local area being in Drought Level 1 and Drought Level 2 (4 levels in total). The focus of the drought management to date has been to reduce customer demand and reduce leakages…. Pumping of the groundwater from the boreholes around Baldock and Letchworth continued throughout July 22 to February 23. Affinity Water abstracted all the water they could within legal and physical limits irrespective of rainfall / aquifer recharge. Throughout this time no temporary drought orders were applied (no hosepipe ban). In line with their drought management plan Affinity Water fully accept their actions will see chalk stream dry up for
long periods of time……….
Since 2019, when RevIvel have been highlighting the plight of the chalk headwaters of the Ivel and Affinity Water have been making all the right noises, more water has been taken from the aquifer than ever before!
Consequently, the river Ivel and its associated flora and fauna continues to suffer……..