ABSTRACT

This chapter focuses on the Piddle catchment in Dorset in southern England, where surface/ groundwater interactions play a key role in determining the spatial distributions of water quality and availability in the catchment river systems and, hence, a fundamental control on the supply of water to dependent ecosystems. The hydrogeological controls on surface/groundwater interactions are identified and the spatial variation in surface water chemistry at individual sites and along the length of the river is discussed. It is found that, whilst there are numerous spring sources in the lower part of the Piddle catchment which contribute large volumes of water to river flow, the most significant spring sources are those in the Upper catchment. This is because there are very few sources, but these exert the main control on the quantity of water in the Upper Piddle and, consequently, control the water quality throughout the year.