The 1988/1993 drought, which extended across large parts of Europe, was very protracted, featured notable regional and temporal variations in intensity and was punctuated by several wet interludes.
The River Kennet near Avebury © Neil Campbell-Sharp
Generalising, the western and northern parts of the UK were worst affected in the early phases of the drought whilst during 1991 and 1992 groundwater levels – and flows in spring-fed streams across the English Lowlands were exceptionally depressed. The 1988/1993 drought lead to widespread hosepipe bans and the temporary loss of aquatic habitats. It also highlighted the vulnerability of parts of the UK to long-term rainfall deficiencies, particularly against a backdrop of higher water demand, and media and public speculation concerning the impact of global warming.
Audio: Recollections from the newly formed National Rivers Authority during the 1988-1993 Drought
From mid-1988 to mid-1992 there was a preponderance of drier-than-average months (with the notable exception of the wet winter (1989/1990)). Over its full span, the rainfall deficiency was most severe in eastern Britain (see map) but the winters of 1988/1989 and 1991/1992 were particularly dry across southern England. Well above average temperatures, particularly in 1989 and 1990, contributed to seasonally high evaporative demands; correspondingly soils were notably dry for extended periods.
The plot below shows the monthly North Atlantic Oscillation (NAO) Index for the periods before, during and after the drought. The NAO is a prominent teleconnection pattern in all seasons, and strong positive phases tend to be associationed with above-average temperatures in northern Europe, whilst negative phases of the NAO tend to be associated with below-average temperatures. There is more information available here.
Click images to enlarge
The 1988/1992 drought embraced several extended periods of notable runoff deficiency; these varied substantially in magnitude across the country. By contrast, the notably wet winter of 1989/90 resulted in significant flooding in many parts of the UK. Across most of southern Britain, the runoff deficiencies began to build through the autumn of 1988 and by the summer of 1989 depressed flows characterised most of the country. Following sustained rainfall through the winter of 1989/90 flow recessions were once again steep and over the period from September 1990 to August 1992 runoff in many rivers, including the Trent, Great Stour, Itchen and Tone, was exceptionally depressed. For some Chalk rivers and stream (including the Itchen and Mimram) flows remained close to the lowest on record for the spring and early summer.
The event began in December 1988 predominantly affecting the south-west of England and Wales. There was a brief recovery in March-April before a period of more widespread and intense drought occurred in 1989/1990. During this period, significant deficits were seen across the UK, with the exception of West Scotland.
This was then followed by another brief recovery over winter-spring of 1990 before a further wave of drought intensity hit, this time focused on the south and eastern parts of the UK. This part of the event lasted through to mid-summer 1992, particularly affecting the southern England, Anglian and Severn Trent regions, but with some deficits also extending to south-west England, south Wales and north-eastern England. When considering this event from a shorter term 3-month perspective, the initial wave of the event in 1989 had the widest extent, reaching into to the north and east of England and eastern Scotland. However, from a longer-term 12-month perspective, the peak coverage was during 1992, when all of the southern and central parts of the UK, as well as north-eastern England, were affected.
The location and timing of the period of maximum severity are difficult to determine due to the multi-faceted nature of this event. However, two distinct periods, 1989 and 1991/1992 are evident in the hydrological drought characterisations, with the latter more focused on the central and southern parts of the UK. Over late 1991 and early 1992, the northern parts of the UK recovered, followed by the southern parts leading to the drought ending by autumn 1992.
The duration of this event ranks quite highly when considering both 3-month and 12-month accumulation periods. For 3-month, the earlier 1989 part of the event ranks within the top 3 events for 1891-2015 in many catchments of eastern Scotland. The latter part of the event features highly in duration rankings for catchments in Anglian and south-eastern England. Over a 12-month accumulation, the same regions stand out, but over the 1988-1992 event as a whole, rather than for the two distinct timings. In terms of the mean deficit, east Scotland, Anglian and south-eastern England regions show the highest rankings. This event is not as notable as the 1975/76 event but is one of the most prominent events since the 1940s in the south-east, where most catchments rank it within the top ten events and many ranking it within the top five. This event shows more spatial inconsistency than some other events, with scattered catchments within the regions ranking the event highly, rather than a homogeneous regional response. The picture for maximum intensity is much the same as the mean deficit.
Despite near average rainfall condition over the four year period 1988-1992 as a whole, the heavy rain-bearing weather systems tracked over the north and west of the UK. Together with exceptionally warm temperatures the prolonged period of below average rainfall, with only short wet interludes, resulted in this significant drought event that predominantly affected the south and east of the UK. The inconsistencies of response across catchments in the south and east are likely due to localised differences in hydrological storage capacities (e.g. reservoirs and groundwater aquifers), as well as variations in local demand for water resources.
Overall groundwater storage was exceptionally healthy in the spring of 1988 but, the 1989/1990 winter aside, aquifer replenishment was very meagre thereafter and across much of the country groundwater levels remained seasonally depressed until the winter of 1992/1993 – and longer in some slow-responding aquifer units. As a consequence, many springs were dry and streams sustained by groundwater ceased to flow throughout much of their length. The relatively long period of groundwater drought between 1988 and 1993 was driven by a series of short winter recharge seasons that particularly affected the Chalk aquifer of eastern and southern England. Its spatial effects varied due to spatial variations in recharge and also on the nature of the aquifers it affected.
The groundwater drought began in the north-east Chalk following a long groundwater recession in 1988. This left groundwater levels relatively low at the end of the summer of 1988. This was followed by very limited groundwater recharge during the winter of 1988/1989 (e.g. Dalton). The groundwater drought deepened in the north and spread south-eastwards through the Chalk of Lincolnshire to Norfolk during 1989 and 1990 due to a second winter with very limited groundwater recharge. Groundwater levels in the Chalk of the north and east briefly rose, in some cases to near normal levels, during the spring of 1991 when there was good recharge season, only to rapidly fall during the hot summer of 1991 and throughout the summer of 1992 due to severely limited recharge during the spring of 1992.
In contrast to the Chalk of the north and east, groundwater levels in the Chalk of southern England were at average levels at the end of 1988 due to relatively high antecedent groundwater levels in the winter of 1987/1988. Limited groundwater recharge during the winter of 1988/1989 led to groundwater drought in the southern Chalk during the summer of 1989. Unlike the northern Chalk, near normal recharge took place over large parts of the southern Chalk during the spring of 1990 and broke the initial groundwater drought. However, the drought returned due to a combination of a long groundwater recession during the hot summer of 1990 and two subsequent consecutive winters of low groundwater recharge, 1990/1991 and 1991/1992, such that the groundwater drought was most widespread and most intense by the end of the spring of 1992.
The groundwater drought of 1988-1993 was slightly less severe in the Permo-Triassic aquifer of the English Midlands and north-west, in part due to the relatively slow response of the sandstone aquifer to changes in recharge and the attenuating effect that this has on meteorological drought signals. Consequently, the groundwater drought was relatively slow to appear in the sandstones, and although it also typically peaked in 1992 groundwater levels remained relatively low in some observation boreholes in the sandstones (e.g. Heathlanes) throughout 1993 and into early 1994.
There was a significant reduction in the length of groundwater supported streams, particularly on the Chalk (Marsh et al. 1994; Peters et al. 2006). The magnitude of the shrinkage in groundwater-fed stream length was very exceptional and more extensive than in 1976 (Marsh et al. 1994). The widespread failure of winterbournes was, in some areas, exacerbated by groundwater abstraction (Marsh et al. 1994).
Short-term impacts on Chalk ecosystems were noted (Wood & Petts, 1999; Boulton, 2003). Due to the low flows elevated levels of phosphorous was reported to have had an impact on local biological communities in groundwater-fed streams (Boar et al. 1995), and intermittent high nitrate concentrations in streams - due to mobilisation during large fluctuations in groundwater levels during the dry summer of 1989 were reported (Reynolds & Edwards, 1995).
Several measures were implemented over the course of the drought period to tackle groundwater supply issues, including the drilling of exploratory boreholes and bringing old public supply boreholes back into service (Marsh et al. 1994). There was also use of groundwater augmentation schemes (such as those on the Itchen and Little Ouse) and regional transfers between the Ely and Ouse (Marsh et al. 1994). The dry winter and autumn of 1988 also triggered the development of the National Hydrological Monitoring Programme in January 1989.
High soil moisture deficits in late summer across the country each year during the drought. The drought increased pest and disease pressures on crops. Abstraction restrictions were widely imposed, leading to the creation of the first Water Abstractor Groups. Mild weather conditions during the winter of 1989 increased the risk of pest and disease, like take-all, virus yellow and aphids. There was a widespread yield loss in winter and spring barley. Scotland's spring barley harvest was one of the worst ever, with 30% of the crop not meeting the required standards for malting for whisky and beer production.
The unusually hot, dry weather also impacted the manufactures of grain driers in 1990 due to cereals’ low moisture content.
“A combination of drought and barley yellow dwarf virus have knocked barley yields by 10%. Generally quality is poor” Yields down in south-east, Farmers Weekly, 28 Jul 1989, Vol 111 (4), p 35
Farmers had to adapt their feeding and management routines after the very hot, dry summer of 1989. Milk producers who maintained milk production targets either introduced early buffer feeding or have very low stocking rates.
“Stock farmers whose feeding systems depend heavily on home-grown fodder must beware the possible impact of prolonged dry weather. […] So producers must start planning ahead now to avoid buying expensive feed next spring when home-grown supplies could run out” Home-grown feeders at risk in heat, Farmers Weekly, 4 Aug 1989, vol 111(5), p 42
Not since 1976 were agricultural abstraction suspensions so widely imposed. In 1990, the National Rivers Authority (NRA) banned irrigation in parts of the Cambridgeshire Fens, Severn Trent area, Yorkshire, Wales and many other parts of the country. Groundwater abstraction licences were revoked in limestone aquifers in Yorkshire. Salad vegetable growers were particularly hard hit by the irrigation bans, and potato and sugar beet crops suffered too. In spring 1991, growers in East Anglia were advised to plan irrigation and cropping programmes on the basis of expected shortages as water supplies were severely limited after another abnormally dry winter. These restrictions materialised - farmers in parts of Lincolnshire had a total ban on spray irrigation in the summer of 1991 while others had their daily water allowance halved; at least 200 growers in Norfolk and Suffolk were operating under similar restrictions and 885 farmers were on amber alert that licences could be suspended. In 1992, more restrictions came into place. The Lark Abstractors Committee was formed in October 1991 by a group of 72 licensed abstractors in the Lark Valley who had water difficulties during this drought.
Audio: Recollections from the newly formed National Rivers Authority during the 1988-1993 Drought
Wood PJ, and Petts GE. 1999. The influence of drought on Chalk stream macroinvertebrates. Hydrological Processes, 13(3), 387-399