All data presented courtesy of the Environment Agency and Met Office (Crown copy right 2023)
April was a relatively wet month with rainfall in our catchment reaching 110% of the expected long-term-average (LTA).Rainfall across East Anglia was classified as normal to notably high in all hydrological areas.Following the exceptionally high March rainfall and above average April figures, the 3-month average for our catchment is now 136% (notably high) and the six-month average through the autumn and winter is at 132% of LTA.
Monthly rainfall totals for the past 12 months as a percentage of the 1961-1990 LTA.
Soil Moisture Deficit (SMD)
The heavy rainfall in March and above average rainfall in April resulted in the area surrounding the Ivel maintaining 0-10mm SMD. Groundwater recharge season has been unusually extended into April and this has improved groundwater conditions in our catchment, with Upper Bedford Ouse catchment continuing in ‘Recovering Drought’
As a result, we are seeing improvements in surface water flows, groundwater levels and ecology recovery.
Soil Moisture deficits for week ending 30 April 2023. Data based on weekly MORECS data for real land use and compared to an analysis of historic 1961 – 1990 LTA dataset.
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 continued to improve during April.The west of the region (including the upper Ivel) has seen the greatest improvement in GW levels with resulting in noticeable improvements in spring flows, ending the month as “normal”. The North Norfolk chalk streams remain in a poor situation being “notable low”.
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.Thanks to the exceptionally high rainfall in March and above average rainfall in April, the springs in Baldock, and Radwell are all looking good. There is currently good flow, but at the Ivel Springs there are no invertebrates (water insect larvae) due to the drying up of the river between June 2022 –Dec 202. Chalk stream ecology is adapted to a constant environment and is high intolerant of repeated episode of drying up. Where the Ivel has managed to keep a constant flow of water (below Radwell Mill), aquatic life is flourishing and the RiverFlies team recorded their best ever sample including hundreds of Mayfy larvae. This is a clear indication of the potential of our chalk stream if we can establish a healthy flow regime year-round.
The river Ivel flows are officially measured at Blunham. The river had been low to notable low through the summer but returned to normal during October- January responding directly to significant rainfall events. Heavy rain events throughout March resulted in “exceptional high water levels recorded but during April this returned to normal levels
Water from the Ouse is transferred at Offord into Grafham Water reservoir. Recovery of reservoir stocks in Grafham Water remains slow with the reservoir currently at 87% full (blue line on graph) (Below normal). Despite the rainfall over the last six-month having reached 132% of LTA, the current stock levels remain below the normal operating level of 90%+.
End of April 2023 Grafham Water reservoir stock compared to the Normal operating Curve, Drought Curve and 1995-1996 stock levels.
Recharge of the chalk aquifer relies on the amount of rainfall through the autumn and winter months. Overall, the last 6 months has seen good recharge conditions with overall 132% of Long Term Average (LTA).
The Upper Bedford Ouse catchment has been in official drought since end June 2022. The exceptional rain fall in March and above average levels in April 2023 has thankfully resulted in a change in status to “Recovering Drought, much to the relief of the Affinity Water and the Environment Agency.
Affinity Water has recently changed Ivel catchment classification from drought zone 1 to average. Sadly, Affinity Water seem to rely on such exceptional “GET OUT OF JAIL CARDS”, without any real plan other than continuing to abstract ground water (GW) as much as is legally and / or physically possible every month. For the nine months period of drought experienced in 2022/ 2023 Affinity did not instigate any hosepipe bans instead they continued to pump water from the ground and allowed the river to dry all the way from Baldock to Radwell (acknowledged result of their Drought Plan).
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……..