Tracks and roads provide access routes for people, vehicles, equipment and stock.
Their construction and maintenance has significant impact on the rural environment.
Environmental significance of roads
Roads intercept, accumulate and transmit water within a catchment. If they are well designed, constructed and maintained the effects of this can be minimised. However, if this is done poorly, erosion and stream contamination result.
A road must, necessarily:
This creates a risk of sedimentation and erosion, which must be controlled through good design, careful construction and effective maintenance.
Principles for erosion control
Erosion will invariably occur from the surface of earthen or gravel roads. Hence, table drains, culverts and offshoot drains must be designed to cope with its. They need some capacity to transport water with small quantities of sediment to discharge positions where the sediment can be readily and safely trapped.
The key point in minimising the impact of roads is to reduce the accumulation and channelling of water by dispersing it back into the normal catchment system at as many points as possible. This means:
- expose mineral soil and
- channel the flow of water.
- minimising accumulated water flows to keep velocities below that which causes scouring (velocity is dependent on channel cross section, shape and slope, and the volume of water).
- minimising the exposure of mineral soil, especially on non-trafficked areas such as batters and drains.
- discharging run-off so that it does not have direct access to drainage lines or streams.Tracks and roads provide access routes for people, vehicles, equipment and stock.