Drainage District Channels

Abstract: This data shows the watercourses forming part of Drainage Districts. Drainage Districts were carried out by the Commissioners of Public Works under a number of drainage and navigation acts from 1842 to the 1930s to improve land for agriculture and to mitigate flooding. Channels and lakes were deepened and widened, weirs removed, embankments constructed, bridges replaced or modified and various other work was carried out. The purpose of the schemes was to improve land for agriculture, by lowering water levels during the growing season to reduce waterlogging on the land beside watercourses known as callows.

Local authorities are charged with responsibility to maintain Drainage Districts. The Arterial Drainage Act, 1945 contains a number of provisions for the management of Drainage Districts in Part III and Part VIII of the act. The Act was amended on a number of occasions, e.g. to transpose EU Regulations and Directives such as the EIA, SEA, and Habitats Directives and the Aarhus Convention.

Lineage: The original sources for the information displayed in this dataset were the maps and descriptive documents, known as the Award, which were created when these schemes were completed to describe the work carried out. These maps were digitised between 2001-2004 from Ordnance Survey of Ireland 1:10,560 six-inch raster data in Irish Grid. Distortion arises from the historic Cassini map projection used in the original maps. Scale along the central meridian and at right angles to it is accurate, but everywhere else, scale, and therefore mapped objects, are distorted in a north-to-south direction.

The amount of distortion on the map increases with distance from the central meridian. In Ireland, the Cassini projection was applied on a county-by-county basis for six-inch mapping, with the central meridian passing through a point near the centre of the county. Therefore, distortion is most evident near county borders, and also in rivers, lakes and streams. Distortion and error inherent in the dataset are amplified during translation and re-projection using Irish Grid and Irish Transverse Mercator.

Purpose: This data has been developed to support the maintenance of Drainage Districts carried out under a number of drainage and navigation acts from 1842 to the 1930s. This work was initially carried out by the Commissioners of Public Works to improve land for agricultural purposes. Local authorities are now charged with the responsibility to maintain the Drainage Districts. Maps and descriptive documents, known as the Award, were created when these schemes were completed to describe the work carried out.