As Autumn begins, it seems like a good time to reflect on the differences in the weather between the summer of 2018 and the one just passed. What do the differences mean for our water resources?
A comparison of two summers
Looking back, the summer of 2018 started early with prolonged dry weather in May. As the summer progressed through June and July the hot, dry weather prevailed leading to increased soil moisture deficits and river flows becoming notably low, putting pressure on water resources across the country. August brought much-needed rainfall, but soil moisture deficits were still significantly above average – resulting in the agricultural drought we reported on last year. All eyes were on the weather as 2018 drew to a close, to see if there would be enough rainfall to alleviate the agricultural drought and prevent a water resources drought.
As the groundwater recharge period finished in April 2019, poor recharge had left groundwater levels remaining low with soil moisture deficit. Groundwater-fed catchments (particularly in the south east and south) had notably low river flow, due to a reduced baseflow.
The summer of 2019 presented a different situation to that of 2018. The 2019 weather has been more unsettled with near-average rainfall at a national level, but a more variable story on a regional level. There was exceptionally high rainfall in central England and north Wales, with Lincolnshire experiencing flooding of over 100 properties. There was also flash flooding in North Yorkshire. As a result of the significant rainfall seen in parts of the UK, summer recharge to groundwater was seen partially in areas underlain by Jurassic limestone areas such as the Cotswolds. In contrast, groundwater levels in many other areas (most notably the south east Chalk aquifers) were ‘well below normal’ to ‘exceptionally low’ by the end of June despite the near average rainfall.
Whilst extremes have been seen around the country there were also more usual falls in the groundwater levels in areas such as the Permo-Triassic Sandstone in Wales, where levels generally fell but remained within the normal range. The result of the disparity in rainfall across the UK has been flooding in some areas and migration of emergence points within chalk stream headwaters down the catchment, as groundwater levels fall.
Where does this leave us now?
In short, the UK, (overall) is better-off than this time last year.
Catchments within central and northern England which have received high rainfall and summer recharge to groundwaters are in a more stable position than last year. Water resources pressures in these catchments have been eased for now soil moisture deficits leading into autumn 2019 at normal levels which will assist recharge.
However, catchments at the other end of the scale such as the Chalk aquifer in East Anglia and the South and South East, the water resources future is less certain. A strong recharge season is required to restore levels back to normal to prevent a drought in 2020. When considered in the context that these regions are populous and have a high density of water-reliant business, such as agriculture, planning for 2020 is important.
At a national and regional scale, choices may have to be made between using hosepipes and growing food. At a local and business scale, monitoring local and river and groundwater levels allow you to observe trends and make decisions about your water use.
How can Envireau Water Help?
The team at Envireau Water have a great range of knowledge and expertise in water resource management. We can provide help and guidance on monitoring and decision making. We are helping our clients make plans to mitigate against impacts of low rainfall, and uncertain water availability, now and in the future. Get in touch with us on 01332 871882 or at info@envireauwater.co.uk.
Reference
1. Centre for Ecology and Hydrology (2019). Monthly Hydrological Summaries. https://nrfa.ceh.ac.uk/monthly-hydrological-summary-uk
