The sandy coasts of Glenelg

Introduction

Coasts range from the rocky shores and sandy beaches to extensive calm water mud flats, seagrass and mangrove habitats. Coastal and marine environments are a valuable community resource and are of great biological and economic value to the area. Coastal areas are very complex eco-systems which rely on a number of different processes and systems. Humans are constantly disrupting these processes by developing and taking part in recreation in coastal areas. Alterations can have harmful results and disturb the dynamic equilibrium of the natural processes that occur there.

The constant human input into coastal systems

Therefore there is now a need for constant human input into coastal systems in order to artificially maintain them. This creates a lot of conflicts of interest between groups about what should be done about the problem in terms of the sustainability of the environment versus our societal need. Examples of coastal areas where there is a lot of conflict of interests are the sandy coasts of Glenelg, and also the Port Adelaide Estuaries.

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The Adelaide coastline is highly developed with houses and roads occupying a large proportion of the original dune system.

Development along the coastline, particularly in Glenelg, has had many detrimental effects on the coastal system. Coastal dunes have been leveled and covered with roads, houses and buildings and these developments have removed the valuable source of land, allowing for severe wave erosion to occur. To protect the houses and other structures that were built in the coast, concrete walls were put in place at the back of the beach.

However, this made the situation worse as the sea wall often caused the beach infront of it to erode.

The dynamic equilibrium of the coast

There is conflict about whether development should be ceased in Glenelg to reduce the human interference with the dynamic equilibrium of the coast. This would have many environmental gains, but the tourism, recreation, local shops etc. will suffer. Along the Adelaide coast sand gradually drifts northwards, eroding the southern metropolitan beaches such as Glenelg, due to the north-south alignment of the beach and the predominance of south-westerly winds. There is little sand input to the beach through natural processes, which is causing sand and dune levels to drop.

Maintaining beach levels is currently the responsibility of the Coast and Marine Section, Environment Protection Authority of the Department of Environment, Heritage and Aboriginal Affairs (DEHAA), which is a government funded organisation. They are responsible for putting a number of management strategies in place and for the construction of artificial structures (eg. riprap rock walls, groynes, and netting etc). Sand replenishment in Glenelg is carried out both with sand relocated within the littoral cell and with sand dredged from offshore sources outside the cell.

The management strategies

Sand dredging is an expensive technique which involves sand being pumped from offshore (eg from sandbars) to the beach, and then carted and dumped where it is needed. This process is being used on a regular basis in the Glenelg foreshore area and is funded by the SA government (with the help of tax-payers money! ). This strategy is also used in other highly developed coastal areas such as the Gold Coast and the South Carolina Coast, where beachfront development has disrupted the natural processes. These management strategies are maintaining the environmental sustainability of the Glenelg coast, while still satisfying the needs of the society.

However, sand replenishment processes are very expensive, and the need for maintenance is increasing. Therefore this may prove to be an unrealistic management strategy in the near future. Another coastal area where there are conflicts of interest is the Port Adelaide esturay/mangrove forest. As humans, our life style is creating problems for these areas due to industrialisation and pollution. This has an impact on the eco-systems within the mangrove area, and effects the health of plants and animals in the food chain.

Litter from rivers, creek and roads can get into the water ways and cause pollution and also block water flow in tight areas such as within the mangrove forest. The issue of conflict in this area is whether Port Adelaide should remain a mangrove swamp, or whether it should become a tourist attraction, by constructing new housing and dolphin sanctuary. Management is currently under control of the Coast and Marine Branch of the Department for Environment and Heritage and the Information and Data Analysis Branch of Planning SA. These departments are undertaking a project, which is aiming to conserve the mangrove and saltmarsh habitats in SA.

Trash racks and floating netting have already been put in place to filter out litter that comes from the water ways leading to the esturay. The floating netting moves up and down as the water height differs, meaning litter cannot escape over the top or underneath the net. Coastal acid sulphate soils (CASS) are present throughout most low-lying coastal regions in South Australia, and these chemicals are filtered out partially by the mangroves. The mangrove swamp is functioning well and improving the health of the environment.

However, there is now big a difference in the way this area is percieved compared to a few years ago. The port river area was once a rubbish tip and industrial area and now conservation techniques have been put in place as there may be an opportunity for tourism and in this area eg. the dolphin santuary and modern housing as mentioned earlier. These management strategies should minimise the negative impact of human activities in the area, by decreasing the amount of pollution entering the estuaries from industrial areas, and by increasing the community awareness of the issue.

Conclusion

Our coasts are extremely important resources. Human intervention has threatened the existence of the dynamic equilibrium of natural processes in coastal areas, so our coastal systems rely on constant artificial management practices in order to be sustained. It is important to maintain these coastal areas so that they are able to be enjoyed by people now, without compromising the environment for future generations. This causes conflicts of interest, but with good management practices and funding, the needs of the society and the environment can both be satisfied.