Canal Estates

Canal estates are developments where a network of waterways is artificially created through the excavation of land adjacent to the sea and the construction of seawalls. The surrounding land may be elevated by adding fill material. The area is then subdivided, with many properties having boundaries directly bordering onto the canals. The waterfront properties may be provided with floating pontoons where boats can be moored.

Such developments artificially extend the length of the coastal edge and therefore increase the number of waterfront properties which can be provided in a given area. They also increase the size of the marine area, potentially creating new habitat for marine creatures. However, the additional coastline which is created usually consists of unnaturally hard and straight edges which do not resemble natural coastline.

Canal estates can result in the destruction of natural features, particularly wetlands and estuarine areas. If not designed and managed properly, they can lead to increased stormwater runoff and sedimentation entering the marine area. In addition, bottom dwelling marine life may be disturbed during both construction and maintenance dredging of the canals and access channels. Such dredging can also lead to the suspension of sediment in the water column and may impact on other sites if the dredged material is disposed of at sea. Canal developments may reduce public access along the coastal edge, as the canal entrance often creates an impassable barrier for pedestrians, and frequently the canal edges are incorporated into the adjacent properties. These kinds of developments can be particularly vulnerable to changes in sea level.

One of the benefits of such developments is that they can draw development pressure away from more sensitive areas of the coastal environment and reduce the expansion of existing coastal settlements into more natural areas. If well-designed, with ample provision for public spaces and walkways along the coastal edge as well as public pontoons and jetties, such developments have the potential to increase public access to and enjoyment of the coast.

Development model	Potential negative effects from inappropriate development	Potential gains from sensitive development
Redevelopment of existing coastal settlements	✗ Reduces natural character and landscape values ✗ Detracts from “sense of place” ✗ Overloads existing infrastructure ✗ Increases sediment and pollutant flows into rivers and the marine area ✗ Increases risk from natural hazards ✗ Increases demand for hard protection structures ✗ Increases rates bills	✓Contains development within existing areas ✓ Keeps development away from undeveloped areas of coastline ✓ Retains individual character of settlements ✓ Promotes efficient use of existing infrastructure ✓ Enables communities to better adapt to future impacts of climate change
Expansion of coastal settlements	✗ Reduces natural character and landscape values ✗ Increases threats to biodiversity from weeds and pests ✗ Results in ribbon development along the coast ✗ Detracts from the natural setting ✗ Increases sediment and pollutant flows into rivers and the marine area ✗ Degrades or destroys historical or cultural sites ✗ Increases risk from natural hazards ✗ Increases demand for hard protection structures ✗ Changes population structure	✓ Contains development within existing locations ✓ Keeps development away from undeveloped areas of coastline ✓ Retains special values of the coast if done sensitively ✓ Increases public access to the coast
Establishment of new coastal settlements	✗ Reduces natural character and landscape values ✗ Results in sporadic and ribbon development along the coast ✗ Increases threats to biodiversity from weeds and pests ✗ Degrades and destroys historical and cultural sites ✗ Increases sediment and pollutant flows into rivers and the marine area ✗ Increases risk from natural hazards ✗ Increases demand for hard protection structures	✓ Avoids urban sprawl and ribbon development ✓ Provides coherent and appropriate building style ✓ Offers good balance between public and private spaces ✓ Presents a chance to incorporate sustainable design and green infrastructure ✓ Increases public access to the coast
Rural-residential development	✗ Detracts from the natural character and landscape values ✗ Results in houses dotted throughout the coastal landscape ✗ Creates cumulative effect of an urbanised rural landscape ✗ Reduces or excludes public access to the coast ✗ Degrades and destroys historical and cultural sites ✗ Increases threats to biodiversity from weeds and pests	✓ Protects important habitats ✓ Restores areas of native vegetation ✓ Restores natural systems such as wetlands and dunelands ✓ Enhances public access to the coast

Last updated at 2:12PM on February 25, 2015