Assessing a Land-Use Conflict at the Urban Fringe
A city of 900,000 people is expanding westward. A 600-hectare area of peri-urban land is contested. It contains: 210 ha of prime agricultural soil (class 1–2) growing vegetables for the city; 180 ha of remnant eucalypt woodland containing a listed threatened bird; 120 ha of low-density housing on large lots; and 90 ha of former quarry land, degraded but zoned industrial. The city's projected housing need is 4,500 dwellings over 15 years. Density assumptions: greenfield development at 15 dwellings/ha; infill redevelopment of the low-density lots at 40 dwellings/ha; quarry land at 25 dwellings/ha. The state government requires 60% of new dwellings to be infill.
1. Calculate the dwelling capacity of each land-use option and determine whether the 60% infill target can be met within this area.
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Step 1 - Capacity of each option.
- Greenfield on agricultural land: 210 ha × 15 dwellings/ha = 3,150 dwellings. (Note: developing the woodland is not an option because of the threatened bird, so only the agricultural land is counted as greenfield.)
- Infill of low-density housing: 120 ha × 40 dwellings/ha = 4,800 dwellings - but this is the gross figure. Redevelopment replaces existing dwellings, so the net gain is lower. If the 120 ha currently holds about 1,200 dwellings (10 dwellings/ha on large lots), the net gain is 4,800 − 1,200 = 3,600 dwellings.
- Quarry land: 90 ha × 25 dwellings/ha = 2,250 dwellings.
Step 2 - Apply the 60% infill target.
- Total need = 4,500 dwellings.
- Required infill = 60% × 4,500 = 2,700 dwellings.
- Required greenfield = 1,800 dwellings.
Step 3 - Test feasibility.
- Infill supply (3,600 net, or 4,800 gross) comfortably exceeds the 2,700 required - target achievable on infill alone.
- Greenfield requirement of 1,800 dwellings needs 1,800 ÷ 15 = 120 ha of the 210 ha of agricultural land - leaving 90 ha of prime soil in production.
- The quarry land (2,250) could substitute for greenfield entirely, meaning no agricultural land need be lost.
Conclusion: the 60% infill target can be met and exceeded. The arithmetic shows the conflict is not a simple housing-versus-farming trade-off; the quarry land and infill together can meet the entire need. A strong answer distinguishes gross from net infill capacity - a common error is to use 4,800 without subtracting existing dwellings.
2. Recommend a land-use allocation and justify it, addressing the competing values of food security, biodiversity and housing supply.
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Recommended allocation:
- Quarry land (90 ha): develop at 25 dwellings/ha for 2,250 dwellings. This is the least contested land - already degraded, zoned industrial, and close to services. It should be prioritised before any greenfield release.
- Low-density lots (120 ha): allow staged infill to a net gain of about 3,600 dwellings, phased over 15 years to let infrastructure (schools, transport, drainage) keep pace.
- Agricultural land (210 ha): retain in production. With quarry and infill supplying 5,850 dwellings against a need of 4,500, there is no requirement to convert prime soil.
- Woodland (180 ha): protect as a conservation reserve with a buffer, because the listed bird's habitat cannot be replaced and offsets elsewhere would not compensate.
Justification:
- Housing supply: the need (4,500) is exceeded by the quarry + infill capacity (5,850), so the target is met with a buffer for market lag.
- Food security: class 1–2 soil is a finite, non-renewable resource; once sealed it is effectively lost. Retaining 210 ha near a city of 900,000 supports local vegetable supply and reduces food miles.
- Biodiversity: the woodland is irreplaceable habitat for a listed species; the precautionary principle favours protection over offsetting.
- Equity and infrastructure: concentrating growth on the quarry and infill sites uses existing services, reducing the per-dwelling cost of roads and pipes compared with dispersed greenfield development.
Caveats: infill at 40 dwellings/ha may meet community resistance and require design controls; the quarry needs remediation (contamination, slope stability) before development. A strong answer sequences the options (quarry first, then infill, agricultural land last) and shows the recommendation is driven by the capacity figures, not preference alone.