Many members will have noticed, unlike the photograph, the very low water level in the River Misbourne in recent weeks, and the fact that it has completely dried up in the area around Tesco. The Chiltern Chalk Streams Project Officer of the Chilterns Conservation Board has provided us with the following explanation:-
In contrast to many rivers elsewhere in the country, the R. Misbourne is currently experiencing a period of very low flows as a result of exceptionally low groundwater levels. The chalk streams like the Misbourne rely on groundwater for their flow (more than 90% of the total flow in the Misbourne is derived from groundwater) rather than surface runoff. Groundwater levels vary according to season with the main period for recharge being between October and March. Groundwater levels reach their peak in March/April (the timing differs from river to river) and then decline again throughout the summer and autumn until December/January (in a normal year) when the winter rainfall begins to reach the aquifer to start the recharge process again. Last winter provided just 63% of average recharge to the aquifer which, on top of two previous years of lack lustre recharge, meant that groundwater levels peaked below normal levels and have declined ever since. The Misbourne is not the only river affected. The chalk streams to the North are also suffering. The Ver, in particular is dry for long sections of its course. Groundwater levels are at their lowest level on record for the time of year. Lower even than in the major drought of 1997. Whilst the water companies have not declared a water resources drought, there is no doubt that the Chilterns rivers are in the grip of a serious environmental drought. Without above average recharge this winter the rivers will be worse off next year.