Delineation of Localities (Densely Populated Areas)

The division of spatial structure to densely and sparsely populated areas is one of the most significant spatial classifications in the monitoring of spatial structure. The delineation of densely populated areas is an essential basis in planning, steering and monitoring of land use.

Formerly official densely populated areas were produced by Statistics Finland. This method followed the Nordic standard of densely populated areas ('tätort', 'byområde', 'tettsted', 'taajama'): buildings maximum 200 meters apart and at least 200 inhabitants in the area. The method how the delineation was carried out in practice however changed in time. Therefore comparable information since the year 1980 based on this Nordic method is not available.

Nowadays official densely populated areas are produced on the basis of the Monitoring System of Spatial Structure and Urban Form (YKR), which is a spatial grid-based information system maintained by the Finnish Environment institute. YKR is widely used in regional planning and research in Finland. The YKR-based delineation method of densely populated areas is comparable both in space and time, which makes it possible to monitor the expansion of densely populated areas without the errors brought on by the changes in the method used for delineation. The YKR method also results in a more compact delineation of the densely populated area than the one produced by using the Nordic standard. The delineation produced by this method is also used by Statistics Finland.

 

The method to delineate localities based on the Monitoring System of Spatial Structure and Urban Form (YKR)

The delineation of localities is based on the Monitoring System of Spatial Structure and Urban Form (YKR) and on the 250 x 250 meter statistical grid data and is implemented in several phases. First, the concentrations of buildings and population suggesting possible localities areas are sought. During the process, a series of generalization operations are carried out in order to implement a unified delineation of localities. The threshold values have been selected on the basis of examinations of several different sample areas and cross-sectional years so that regional differences are taken into account as well as possible.

The main datasets used in the delineation of localities have been:

  • the number of buildings (agriculture buildings and holiday homes excluded)
  • the floor area of buildings (agriculture buildings and holiday homes excluded)
  • population and
  • the relations between the variables mentioned above measured in distance

Through this delineation procedure, it is ensured that following characteristics of localities are paid attention to:

  • Single buildings with large floor areas that are located at an edge of a densely populated area and are functionally part of the area should be included in the delineation of densely populated areas
  • Elongated and narrow settlements along rivers, roads or shorelines that are sparsely populated and resemble rural areas should be excluded from the delineation of localities.
  • Large open areas inside localities should be excluded from the delineation (for example large unbuilt areas, sparsely built areas, fields, forests, waters).

Steps in the delineation method

The delineation of localities is carried out using the statistical grid (250 x 250 m) of building stock and population. The following steps generally describe the procedure of delineation:

  1. The nationwide grid is generalized with neighborhood analysis by counting to each single cell the sum of buildings that fall in cells within 1 km from that cell. Then the cells that have a sum of over 39 buildings are selected.
  2. After that a new generalization process is implemented by counting the floor area sum of eight neighboring cells using only the cells selected in the previous phase.
  3. From these only the ones having the floor area sum of over 1 499 are selected to form a grid.
  4. From this grid, the cells consisting of unbuilt or sparsely built areas are excluded.
  5. Then the cells from the original statistical grid that have a center point which falls within the grid formed in the phase 4 are selected.
  6. From this selection the cells with more than one building or floor area sum larger than 299 are selected.
  7. Those cells are then buffered outwards 250 meters and dissolved.
  8. This buffer is further buffered inwards 250 meters.
  9. The last buffer is used to select cells from the original grid.
  10. From this selection the cells that touch each other are then unified to a polygon.
  11. Population is then counted for the formed areas.
  12. Those areas with population over 199 are selected to be densely populated areas.

 

Further information from Finnish Enviroment Institute (SYKE)

E-mail: alu_tuki[at]ymparisto.fi

Published 2013-12-17 at 10:16, updated 2019-10-01 at 12:49