River Welland - Geography

Geography

The River Welland, with its tributaries, form a river system with a catchment area of 609 square miles (1,580 km2). Within this area, 257 miles (414 km) of waterway are designated as "main river", and are therefore managed for flood control by the Environment Agency. Of this total, the 14 miles (23 km) below Spalding are tidal, and have sea walls to protect the adjacent land from flooding, while 56 miles (90 km) are fresh water, but run through low-lying land, and are therefore embanked. Within the catchment area, 179 square miles (460 km2) are below sea level, and would be flooded without such defences.

The basin runs in a broadly south-west to north-east direction, with an extension to the north around the West Glen and East Glen rivers. The underlying geology consists of Lias clays at the western end of the catchment, with Lincolnshire limestone in the centre, including the valleys of the Glen. The eastern third is mostly alluvial soils, and it is this part that relies on artificial pumping to prevent flooding. Rainfall over the area varies between 26 and 30 inches (660 and 760 mm) per year, which is quite light, and because the land is efficiently drained during the winter months, there are few reserves, making the area prone to drought in the summer months.