Year 11 Preliminary Geography Assessment Task 2Biophysical & Human Interactions at Bombo Beach & Headland, Kiama

LOCATION OF THE STUDY AREA

The annotated satellite image above gives an overview of the study area. Biophysical features, such as Bombo Beach and Headland, and human features, such as the Princes Highway and Bombo Quarry, are both displayed above.

KIAMA

KIAMA DOWNS

BOMBO

Bombo Headland

Spring Creek

Bom

bo B

each

Primrose Hill Creek

Princes Highway

Bombo Quarry

Railway

Sewage Treatment Plant

Bombo Railway Station

The Boneyard

BIOPHYSICAL PROCESSES AND LANDFORMS

1. BOMBO HEADLANDThe aerial photograph of Bombo Headland above shows that it is made up of several lobes of ancient volcanic rock protruding into the sea. This is a result of a series of lava flows that date from the Permian geological period, over 250 million years ago. These flows resulted from intense volcanic activity in eastern Australia during that period. The lava would have covered the existing sedimentary sandstone rock, rapidly and uniformly cooled into basalt rock, and subsequently been covered by other sediments that were compressed into rock. The structure of the basalt is one of hexagonal columns, with deep vertical jointing and horizontal fractures. These cracks have been exposed to weathering processes and marine erosion, slowly breaking down the rock. The junction between the lighter, horizontally-bedded sedimentary rocks, and the darker, vertical basalt columns is evident around the headland.

2. BOMBO BEACH/DUNE SYSTEMThe erosion of rock or the dead remains of plants and animals form sand. The size and shape of sandy beaches varies between seasons. Generally, larger winter waves erode beaches by washing sand out to form offshore sand banks. Gentler summer waves then

move the sand back on shore to rebuild the beach. The dunes therefore provide a reserve of sand in winter, and prevent sand blowing inland during summer. The dune system also acts as a buffer between the land and the sea, and contains many plant and animal species specifically adapted to this harsh environment.Bombo Beach is currently an intermediate type beach, with fine to medium sand grain size, and moderate wave energy (0.5-2.5m). Many other examples of intermediate beaches can be found in southern Australia.

Land and sea breezes result from the differential heating of the sea and the adjacent land surface (Bombo Beach). The resulting differences in atmospheric pressure are significant enough to generate a movement of air. Sea breezes build up in the late morning, and die off in the evening, and land breezes begin soon after sunset, and die off at sunrise.

3. SPRING CREEK/PRIMROSE HILL CREEKBoth creeks flowing towards Bombo Beach are small in volume, but are important ecosystems. When the creeks are open to the ocean, they are affected by the tides and flushed out regularly. In times of little rain, the sand builds up at the entrance of the creeks, stopping the salt water mixing with the fresh water. Once this occurs, it takes heavy rain, often accompanied by large seas, to allow the creeks to flow into the ocean once again.

HUMAN IMPACTS ON TERRESTRIAL & AQUATIC ECOSYSTEMS

1. QUARRYINGLike many other man-made activities, quarrying causes a significant impact on the environment. In particular, it is often necessary to blast rocks with explosives in order to extract materials for processing, but this method of extraction gives rise to air pollution, damage to biodiversity, and habitat destruction.Dust from quarry sites is a major source of air pollution, and dust particles can impact on the hydrosphere by increasing silt and making water turbid, for example.Dust can also have physical effects on the surrounding plants, such as blocking and damaging their internal structures and abrasion of leaves and cuticles, as well as chemical effects which may affect long-term survival.

Quarrying also carries the potential of destroying habitats and the species they support. Even if the habitats are not directly removed by excavation, they can be indirectly affected and damaged by environmental impacts, such as changes to ground water or surface water, which causes some habitats to dry out, and/or others to become flooded.

2. URBAN DEVELOPMENTUrban development can lead to water pollution. Some water pollution sources include treated effluents discharged from sewage treatment plants and untreated effluents that bypass sewage treatment plants, treated and untreated storm water runoff, and combined sewer overflows that carry a mixture of untreated sewage and storm water.Urban development can also lead to an increase in erosion by disturbing both soil structure and plant roots that would otherwise hold the soil in place, through unmanaged construction activity, and the clearing of vegetation. The clearing of vegetation can also destroy entire ecosystems.

3. TRANSPORTThe impacts of transport are very similar to the impacts of urban development: road run-off contributes to water pollution, the construction of roads/railway can increase erosion, and may destroy ecosystems through the clearing of habitats.

Transport is also becoming an increasing source of air pollution. The motor vehicle engine emits many types of pollutants including nitrogen oxides, carbon monoxide, particulates, sulphur dioxide, lead (in some cases) and carbon dioxide. Collectively, vehicles represent a major source of air pollution throughout the world.

MANAGEMENT STATEGIES

1. RE-VEGETATIONBombo Headland was once used for basalt quarrying, and became a dumping ground for rubble, and subsequently fell into a bad state of disrepair. Later it was filled in and turned over to grassland for grazing, and the result is a devastated site devoid of native vegetation. It finished up covered with lantana, blackberries and kikuyu grass infesting the whole area, and rabbits flourished in this environment.

In 1989, a landcare group was established, and began pulling out lantana in sections and gradually replanting with native rainforest species such as Casuarinas, Acacias, Banksias, and Myoporum. There has been a definite change in the landscape over the past 20 years: the forest canopy has started to be reinstated, and as a result, many native birds have returned to the area.The project is ongoing, because landcare members have to re-spray and hand weed the areas they have previously worked in.

The Bombo Headland Landcare Group has averaged about 1000 successfully established native trees, shrubs and plants per year.

2. VISITOR INFRASTRUCTUREBefore the establishment of the Bombo Headland Landcare Group in 1989, abusive activities such as trail bike riding, vehicular access and acts of vandalism on the remnants of vegetation were generally accepted.

Since 1989, many different types of visitor infrastructure have been constructed:• Walkways: provide a specific route for visitors, minimalising damage to vegetation• Signage: provides information for visitors, eg. opening/closing times• Rubbish Bins: provides an outlet for waste disposal; no negative impact on

environment• Other general amenities: eg. picnic areas, water outlets, public toilets

An example of the construction of visitor infrastructure:The concrete walkway linking with the board walk leading onto Boneyard Beach was a joint Green Corp/Kiama Council effort; overseen and funded by Kiama Council, who supplied machinery, materials and a concreter; labour was supplied by Green Corp.

3. FENCING/SIGNAGE/WALKWAYSRecreational uses of the coastal environment can be organised in a way that does not concentrate the impact on vulnerable parts of the environment, such as dune systems. Fencing off dunes and ʻfunnellingʼ beach-goers into walkways is a highly effective and cheap means of reducing damage to dune systems and the fragile vegetation that stabilises them. Signage may also inform beach-goers of the damage they may cause if they donʼt adhere to the boundaries created by walkways or fencing, and/or any consequences for their actions.