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Residential Density is used as a measurement of the spatial concentration of populations. There are a number of definitions of residential density within urban areas. Definitions used in the analysis of settlement densities in Sydney's urban areas (Cardew 1996) range from site density to metropolitan density. National State of the Environment reporting defines the concept as the area of land within urban centres designated 'residential land use' divided by total population resident in those centres (Newton et al. 1998). This report adopts the definition provided by ANZEC (ANZECC 2000) - the total resident population divided by the area of land within built residential zones - and includes both urban residential and rural residential areas as 'built residential zones' within the statistical subdivisions of greater Hobart and greater Launceston (NGGIC 1996). The human settlement environment is strongly influenced by settlement density. Both high density and the high per capita land consumption rates associated with low density development can have negative environmental consequences. Higher settlement densities can concentrate pollutants within the urban environment, but can reduce the impact of residential development on surrounding ecosystems and productive agricultural resources, and reduce energy and resource use. The low density settlement typical of urban fringe or peri-urban areas may result in the removal of remnant vegetation and consequent loss of biodiversity, convert agriculturally productive areas to less productive residential development, exacerbate the spread of weed and animal pests and increase energy consumption and infrastructure provision costs. The calculation of residential density for this report relies on two source digital datasets - Census Collector District (CCD) population statistics from the 2001 census (Australian Bureau of Statistics 2001), and Tasmanian land use mapping data to provide areas of urban and rural residential development (Drenen 2003). For the greater Hobart region, rural residential areas were mapped from recent (2001) aerial photography to more accurately delineate existing development within rural residential zones. The combination of these digital datasets produces output that combines population values with residential areas for each CCD, using the assumption that the majority of residents live in residential zones. Residential density can then be calculated and averaged across identified residential areas within each CCD, and mapped to display density ranges across the entire statistical subdivision For this report, the connection between Census Collector District boundaries and the size of residential populations has advantages and disadvantages when using CCDs to estimate residential densities. More densely populated areas result in smaller CCDs that are indicative of urban areas and more likely to contain urban residential zones; larger, comparatively sparsely populated CCDs are more likely to represent peri-urban and rural areas characterized by lower density residential development. CCDs are therefore more likely to contain relatively homogeneous residential densities than many larger statistical units with more permanent boundaries (such as postcode or municipal areas). This can minimize distortions resulting from density averaging across a CCD's residential zones and provide a more accurate localised density estimate. However, CCD boundaries are impermanent, which makes census-by-census density trend analysis difficult for these statistical boundaries. Residential densities have also been calculated for the locality/postcode areas of the greater Hobart and Launceston regions (DPIWE 2003), using the average of CCD density values contained within each of these boundaries. The data are displayed in the following tables together with distances from city center (GPO location) to the central points of each locality/postcode area. While more generalized than the CCD data, the boundaries of this spatial unit are more permanent and therefore the data is better suited to spatio-temporal density trend analysis. Residential denstities for the Greater Hobart and Greater Launceston region Census Collector Districts
Residential densities for the locality/postcode areas within the two regions are summarised in the tables below. Residential densities for Greater Hobart region localities. Residential densities for Greater Launceston region localities. Core Land Indicator HS 5 (ANZECC 2000). |
