Published online by Cambridge University Press: 05 December 2011
The River Tay, which drains a dominantly metamorphic catchment, has the largest freshwater discharge of any British river. Direct methods of determining the solute, suspension and bed loads at six gauging stations have enabled the river transport to be assessed at 375,000 and 997,000 tonnes annually for dry and average wet years respectively. Added to estimates of loads from the Earn and Isla rivers the load entering the head of the Tay Estuary varies from 646,000 tonnes to 1,648,000 tonnes annually. This corresponds to total losses of 100 t/km2/year to 255 t/km2 year, which equates with an average lowering of the basin surface by 4–5 cm to 11.6 cm per thousand years of dry and average conditions respectively.