1998 was an exceptionally warm and, in most parts of the UK, a notably wet year. The high temperatures, combined with unusually moist soil conditions in the summer encouraged high transpiration rates and annual evaporation losses were close to the maximum on record over wide areas. Entering 1998, groundwater levels remained depressed in a few eastern outcrop areas - the consequence of long term rainfall deficiencies and limited opportunities for recharge since the winter of 1994/95. Following a dry February there was some concern regarding the water resources outlook in such areas.  However, the spring was remarkably wet and the focus of hydrological concern switched rapidly to the threat of flooding. A major flood event in April heralded well above average river flows through most of the summer half-year. Unsettled weather patterns, in June and July especially, helped contain the normal seasonal increase in water demand and water supply stress was minimal. Seasonal recoveries in runoff and recharge rates began earlier than usual and further widespread flooding occurred in October. Spate conditions were more subdued thereafter but overall reservoir stocks remained close to the seasonal maxima as they did throughout most of 1998 (Figure 1) and, in most aquifers, groundwater recoveries in the early winter were brisk and sustained. By year-end the water resources outlook was very healthy.

1998 continued a sequence of notably warm years, most being characterised by persistent and significant departures of monthly runoff and recharge rates from the seasonal average. However, the recent tendency for an increase in the proportion of overall rainfall falling during the winter half-year did not continue in 1998 and the arid soil conditions, which have been a common feature of the eastern lowlands during the summers of the early 1990s, were also absent.  In water resources terms 1998 served to emphasise the very different recovery rates of surface water resources and groundwater resources following a lengthy drought episode (that of 1995-97). It also underlined the importance of spring rainfall in determining the water resources outlook for the summer and autumn. Taking a broader hydrological perspective, 1998 - together with much of the last decade - demonstrated the complexity of the interplay between rainfall patterns, evaporative demands and soil moisture conditions in determining runoff and recharge rates. This underpins the need for continuing careful monitoring of river flows and groundwater levels to identify any significant hydrological trends.