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The density of roading in a region (e.g. catchments, and areas of karst type) (i.e. the length of roading in each area, divided by that area). This is an indicator of pressure. Roading provides access which gives rise to a range of pressures on the natural environment (e.g. ecosystems and fluvial and karst systems). It is often a precursor to changes in land use and land cover. In addition, the roads themselves have significant effects on runoff rates, slope drainage patterns and flow regimes, as well as soil erosion rates and runoff turbidity. Changes (which will normally be increases) in roading density within a region will imply a higher likelihood of adverse impacts on the natural environmental processes within that region. Environmental management systems in road design and construction can assist in protecting natural systems.
Road density per catchment Catchment Catchment Area (ha) Road Length (m) Road Density (m/ha) Derwent Estuary-Bruny 109,149.3 4,451,572 40.8 Tamar Estuary 107,439.0 2,828,090 26.3 Cam 28,859.5 744,390 25.8 Inglis 61,570.1 1,363,336 22.1 Rubicon 71,754.8 1,588,433 22.1 Little Forester 35,355.5 739,020 20.9 Emu 25,461.9 519,888 20.4 Blythe 37,718.3 751,897 19.9 Pitt Water-Coal 91,977.4 1,754,356 19.1 Great Forester-Brid 78,301.3 1,435,161 18.3 Leven 72,740.0 1,314,117 18.1 Duck 55,241.7 989,462 17.9 North Esk 106,549.8 1,896,269 17.8 Pipers 75,369.7 1,328,519 17.6 Tasman 92,706.3 1,576,871 17.0 Scamander-Douglas 68,655.9 1,164,067 17.0 Meander 156,863.2 2,576,699 16.4 Mersey 190,890.8 3,103,912 16.3 Jordan 125,324.7 1,898,003 15.1 Prosser 114,850.5 1,692,471 14.7 Black-Detention 64,615.7 947,753 14.7 Lower Derwent 160,374.4 2,348,487 14.6 George 61,499.9 872,307 14.2 South Esk 334,950.9 4,439,668 13.3 Brumbys-Lake 150,854.6 1,893,095 12.5 Swan-Aspley 136,032.1 1,701,225 12.5 Montagu 47,607.1 584,957 12.3 Ringarooma 98,284.5 1,175,906 12.0 Forth-Wilmot 117,960.7 1,359,951 11.5 King Island 109,400.1 1,201,717 11.0 Little Swanport 87,891.9 958,138 10.9 Welcome 67,480.3 671,818 10.0 Macquarie 273,243.5 2,532,784 9.3 Huon 380,790.4 3,470,977 9.1 Clyde 111,751.9 972,625 8.7 Arthur 250,541.9 2,115,557 8.4 Boobyalla-Tomahawk 65,219.2 544,713 8.4 Ouse 148,238.2 1,224,791 8.3 Upper Derwent 354,134.4 2,854,896 8.1 Musselroe-Ansons 97,209.3 782,874 8.1 Furneaux 188,791.4 1,457,252 7.7 King-Henty 179,271.3 1,305,253 7.3 Pieman 414,893.5 2,115,481 5.1 Nelson Bay 86,755.4 395,225 4.6 Great Lake 39,636.8 175,799 4.4 Wanderer-Giblin 175,638.1 295,173 1.7 Gordon-Franklin 589,357.0 801,821 1.4 Port Davey 284,321.4 167,416 0.6 The roads represented include all roads identified in the Road Infrastructure data set (DPIWE) at a 1:25,000 scale for 2002. Source: Road Infrastructure data (2002), and Planning and Management Catchment data (2000), DPIWE Road Density per area of karst type Karst type Karst type area (ha) Road length (m) Road density (m/ha) Permian limestone 21,640 382,305 17.7 Quaternary limestone 29,000 446,526 15.4 Ordovician limestone 135,405 1,090,296 8.1 Tertiary marine limestone 15,071 120,193 8.0 Precambrian-Cambrian dolomite 137,825 1,087,868 7.9 Silurian-Devonian limestone 30,748 80,898 2.6 The roads represented include all roads identified in the Road Infrastructure data (DPIWE) set at a 1:25,000 scale for 2002. The key karst types are represented, while some minor areas of karst are not represented because the carbonate rock type was extremely rare and highly dispersed, or because the area was too small. Source: Road Infrastructure data (2002) and the simplified lithological classification of karst from the Atlas data, v.2 (2002), Forestry Tasmania.
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