muriwai coastal process
Comprehensively analyse how the operation and integration of natural processes within your chosen New Zealand geographic environment have led to the formation of one significant feature.
New Zealand geographic environment – Muriwai Coastal Environment
Feature – Sand dunes situated at the back of Muriwai beach
Introduction
Muriwai Coastal Environment is located on the west coast of the North Island. It is located west of Auckland, midway between the entrances to the he Manukau and Kaipara Harbour. It is located between Woodhill Forest and Waitakere Ranges. It’s nearest settlements are Kumeu to the east and Helensville to the south. It is a 3km area stretching from Okiritoto stream in the north to Māori Bay in the south. The area comprises of two beaches, Muriwai beach and Māori Bay. The two beaches are separated by a headland (Otakamiro Point). Beaches face out toward the Tasman sea. This essay is going to look at the natural processes that interact to form the sand dunes, located toward the back of Muriwai beach. These processes are Long shore drift (LSD), saltation, interception by vegetation and dune accumulation.
Long shore drift
LSD has provided the sand to form dunes. Sand was transported to the Muriwai area by L.S.D.
Diagram 1.
As a result of LSD sand along the west coast (including the black titanium magnatite sands from Waikato Heads) was transported to Muriwai and brought to shore by constructive waves (i.e. less than 10 waves per minute break). These waves have a greater swash than backwash and therefore depositing more sediment on to the beach than they remove. This sand at the beach provides the source of sand to form dunes.
Saltation
Saltation is wind transporting the grains of sand. If beach sediment is between 0.25 and 0.5mm and winds are relatively strong (+16kph) sand moves up on to the beach. As sand bounces along the beach its impact causes more sand to ‘explode’ and get carried by the wind up the beach.
Diagram 2
New Zealand geographic environment – Muriwai Coastal Environment
Feature – Sand dunes situated at the back of Muriwai beach
Introduction
Muriwai Coastal Environment is located on the west coast of the North Island. It is located west of Auckland, midway between the entrances to the he Manukau and Kaipara Harbour. It is located between Woodhill Forest and Waitakere Ranges. It’s nearest settlements are Kumeu to the east and Helensville to the south. It is a 3km area stretching from Okiritoto stream in the north to Māori Bay in the south. The area comprises of two beaches, Muriwai beach and Māori Bay. The two beaches are separated by a headland (Otakamiro Point). Beaches face out toward the Tasman sea. This essay is going to look at the natural processes that interact to form the sand dunes, located toward the back of Muriwai beach. These processes are Long shore drift (LSD), saltation, interception by vegetation and dune accumulation.
Long shore drift
LSD has provided the sand to form dunes. Sand was transported to the Muriwai area by L.S.D.
Diagram 1.
As a result of LSD sand along the west coast (including the black titanium magnatite sands from Waikato Heads) was transported to Muriwai and brought to shore by constructive waves (i.e. less than 10 waves per minute break). These waves have a greater swash than backwash and therefore depositing more sediment on to the beach than they remove. This sand at the beach provides the source of sand to form dunes.
Saltation
Saltation is wind transporting the grains of sand. If beach sediment is between 0.25 and 0.5mm and winds are relatively strong (+16kph) sand moves up on to the beach. As sand bounces along the beach its impact causes more sand to ‘explode’ and get carried by the wind up the beach.
Diagram 2