Landscape implications of coastal aggregate extraction

Abstract

New Zealand has more than 10, 000 kilometres of coastline. A large proportion of this coastline is made up of sand and gravel beaches. Wave and wind action transport the sand and gravel along the coastline. This forms a dynamic interlocking system of the rivers that supply the sand and gravel and the beaches along which it is moved.

On this system human settlement has developed. In New Zealand most large urban populations are based in cities that have expanded around harbours and ports.

Certain raw materials, including aggregate (sand and gravel) for roads and concrete manufacture, are required to service these cities. In overseas countries the majority of this aggregate is supplied from shallow pits that are located near the source of demand. A large amount of research and practical application has gone into the restoration and rehabilitation of these pits when extraction ceases. New Zealand is however different in its extraction and restoration techniques.

The coastlines surrounding New Zealand cities have been mined as though they contain an endless supply of aggregate. As the cities have increased in size so have the requirements for aggregate. As most cities are coastal based ever increasing demands have been placed on the coastal aggregate resource. This has lead to landscape destruction and coastal erosion.