Taken from the official translation of the German Sustainable Development Strategy
Settlement density looks at the number of inhabitants in relation to the amount of settlement and transport area – in contrast to population density, which is based on the entire land area.
Apart from residential building land, settlement land includes areas of special functional character (such as hospitals and schools), industrial and commercial land, mixed-use land (such as shopping streets), and areas for sports, leisure and recreation. Changes in the number of inhabitants and changes in the extent of settlement and transport area both affect figures for the density of settlements.
Settlement density varies considerably between rural and non-rural areas, with the figures for 2018 showing an average of 3,344 people per square kilometre of settlement and transport area in non-rural districts but around 1,205 in rural districts. 2018). Residential building land in towns and cities is frequently much more densely developed, and with more multiple-floor buildings, than in rural regions, where more scattered development incorporating larger unsealed areas such as domestic gardens is prevalent.
From 2000 to 2009, there was a steady decline in settlement density in both rural and non-rural regions. The reduction in absolute terms is slightly smaller in non-rural areas than in rural regions. In relative terms, given the distinctly lower settlement density in rural areas, the reduction was considerably greater there, at 11%, than the 4% reduction observed in non-rural areas. Settlement density in non-rural regions been rising again since 2011. This shows that settlement and transport area in relatively urban areas is being used more efficiently than in previous years.
Looking at the trends in population numbers and settlement and transport area separately reveals marked differences between rural and non-rural regions. Between 2000 and 2018, the amount of settlement and transport area in both rural and non-rural regions increased, though to differing extents – by 15% and 8% respectively. After rising slightly at the beginning of the century, the rural population then shrank by approximately 2.3% before increasing again by 1.8% between 2010 and 2018. In contrast, the population in non-rural regions grew by 1.7% between 2000 and 2010 and again, by 5.4%, between 2011 and 2018. The effects that the development of additional settlement and transport area had on the indicator were therefore amplified in rural regions by the declining population numbers there.
The data sources for this indicator are the population figures and the area survey by type of actual use compiled by the Federal Statistical Office. In the population numbers, the 2011 census caused a jump in the time series. Some areas of land have moreover been reclassified in the official land register maintained by the Länder in recent years, without any actual change in the way they are used. Additionally, the switch from the old to the new land-use classification system was completed in 2016, which affected the official land-use statistics such that the data for 2016 are not directly comparable to those for previous years. So that comparisons can nevertheless be drawn, the relevant values were extrapolated on the basis of the 2011 census and the 2016 reform of the land-use survey.
The distinction between rural and non-rural is based on a classification used by the Thünen Institute. The institute ascribes a degree of rurality to districts and district-free cities on the basis of geographical characteristics such as settlement density and share of farmland and woodland. The classification is thus applied to whole districts rather than to smaller entities like towns or villages.