Water catchment areas

This data includes Finland’s main river basins, water catchment areas and discharge points. The hierarchical catchment area includes up to 3 phases. The hierarchical character of the catchment area can be described by using the catchment lines associated with the material and the catchment area code. There are 74 main river basins, with an area of more than 200 km², and numbering starts in Ladoga’s descending river basins and passes around the coastal areas clockwise, ending with the waters entering the Viena sea. For each subdivision up to the third step, the area shall be divided into no more than 9 subdivisions, with a maximum of 729 sub-regions per river basin. This has been done with the main river basin over 10 000 km². The main river basins of 1 000 to 10 000 km² are divided into two subdivision stages, with a maximum of 81 sub-regions in the river basin. The main river basins of less than 1 000 km² are divided into up to nine subdivisions. The material is part of SYKE’s open data (CC BY 4.0). The data product INSPIRE has been published. Purpose: Water catchment areas are mainly for hydrological monitoring purposes.Demolition points may be located not only at the side-row or the skeleton of the lake, but also at, for example, a power plant or other hydrological measurement site. The size of the catchment areas can vary considerably (approximately 2 km² to approx. 3 500 km²) due to the chosen identification system and the specific nature of Finland’s natural geography (e.g. lake-based areas). The Water Framework Directive’s water management planning system is based on a water catchment approach, e.g. the river basin management areas under the Directive are made up of the main river basins. For more information: https://geoportal.ymparisto.fi/meta/julkinen/dokumentit/valuma-aluejako.pdf Catchment Areas The spatial dataset of Finnish catchment areas includes main river basins, river basins’ delineation and discharge points. The hierarchical river basin/delineation has 3 levels. The structure of the hierarchy is described using catchment area boundaries together with the river basin codes attached to the features. The database has 74 main river basins with an area over 200 km². The code numbering starts from the south-eastern river basins flowing to the Lake Ladoga, and continues clockwise along the Baltic coast, ending to the rivers flowing into the Arctic Ocean and the White Sea. All the river basin hierarchy levels have maximum 9 sub-basins. Besides the main river basins, the boundaries are determined for 177 small coastal basins, smaller than 200 km²; they are not further divided into sub-basins. This SYKE’s dataset can be used according to open data license (CC BY 4.0). Inspire compatible dataset has been published. The first river basin delimitation covering the whole of Finland was completed in 1863 and published by Senior Counsellor Cl. By W. Gylden in the Imperial Road and Watercourses Administration under the name “Finland rivers and lakes”. In 1936, a book by T. V. Olini, entitled “Regions and Lakes of Finnish Watercourses”, was published by the Hydrographic Office. The work compiled data on all “rain areas” with an area of at least 200 square kilometres in Finland. The delimitation was carried out on the general map of Finland (1: 400 000). The river basin numbering currently used in Finland was carried out in 1968 at the Engineering Department of the Government of Agriculture under the leadership of Senior Engineer Matti Väreen. The process, led by DI Pertti Seuna, was completed for the so-called second phase of the division in 1971, when a study entitled “Finland’s river basins” was published in the series “Publications of the Water Board”. The completion of the baseline survey (major 1:20 000) in 1978 and the completion of the reduction of the baseline map (may be 1:50 000) between 1983 and 1987 made it possible to demarcate the catchment areas more accurately and with smaller subdivisions. The demarcation of the catchment areas was carried out on the basis of topography and water bodies of 1:50 000 scale paper maps, from which the areas were digitised by the FINGIS programme as blind digitisation at the Hydrology Office of the Institute of Water and Environment from 1984 to 1990 under the direction of hydrologist Matti Ekholm. The numerical river basin register was completed in 1991 and integrated into the environmental management information system in the same year. The lists of water basins with their names, water code, area and lakes were also published in printed form as the work on Finnish river basins (Matti Ekholm: Finland’s river basins 1993, Publications of the Water and Environment Administration, Series A 126). The 1:400 000 scale river basin and demolition point maps related to the publication were printed between 1989 and 1991.