Water balance at Ainsdale National Nature Reserve 1975-2100

Groundwater levels at Ainsdale Sand Dunes National Nature Reserve rise and fall by about 0.5m between winter and summer. There have been several periods where water table levels were considerably lower than average, which caused the dune floors to dry up, with undesirable environmental effects. However these dry periods have been interspersed by occasional wet years where the water table has risen to above average levels. This paper explains a physically based model of the water balance in the dune system and describes how the model was tested against observed water table levels. The model is sensitive to the timing of rainfall events. The effects of expected climate change published by the UK Climate Impact Programme (UKCIP) are simulated in the model. Results suggest that the average water table level in the open dunes will fall by about 1.2m between the years 1990 and 210