July 2014


Period: From July 2014      Issued on 14.07.2014 using data to the end of June

Summary

Although June was warm and dry across most of the country, June river flows were in the normal range or above in most areas except northern Scotland. The outlook for July is for normal flows to predominate, although above normal flows are likely to persist in the south and below normal flows are possible in western areas (the first ten days of July have seen some heavy rainfall in many areas of Britain, which suggests that the driest rainfall projections are unlikely to be realised). The three month outlook is for a broadly similar situation, with normal flows in most areas but above normal flows likely in parts of the south. The groundwater situation has changed very little over the last few months; levels have continued to decrease across most aquifers, as expected for the time of year, but are likely to remain in the normal range or above in most aquifers over the next three months. The water resources outlook up to early autumn is favourable.

Rainfall

Latest predictions for UK-mean precipitation favour near- to above-average rainfall for July. However, this is not the case for the July-August-September period as a whole, for which no particular category is favoured. The probability that UK precipitation for July-August-September will fall into the driest of five equal categories is around 20% and the probability that it will fall into the wettest of five equal categories is around 20% (the 1981-2010 probability for each of these categories is 20%).

River flows

River flows in June were mostly in the normal range or above (with above normal flows most prevalent in central and southern England), except in northern Scotland where some low flows were registered. The one-month outlook indicates July river flows are most likely to be in the normal range for much of the UK, but with an increased likelihood of below-normal flows in northern and western catchments and a high likelihood of above-normal flows persisting in parts of central southern England. The three-month outlook is for a broadly similar situation: flows are likely to be normal across much of the UK, but below normal flows are possible in western areas and above normal flows are likely to persist in parts of the south, particularly groundwater-dominated catchments in central southern England.

Groundwater

The groundwater level situation in June was similar to patterns of the last few months. Levels were above normal in much of the southern Chalk (notably so in some boreholes), the Permo-Triassic sandstone outcrops, and the Magnesian limestone of northern England, where levels increased in June. Elsewhere, levels were generally normal. The outlook for July is for similar patterns to continue, with levels in most aquifers staying within their current ranges. The broad spatial pattern of the three-month outlook is also similar. This continuity reflects the fact that at this time of year, significant groundwater recharge is unlikely and groundwater levels are not strongly influenced by variations in rainfall; levels are likely to recede through the next three months along a similar trajectory to recent months. There is unlikely to be any significant change to the groundwater situation until October, when evapotranspiration declines and rainfall will begin to dictate the groundwater outlook.