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Auckland’s Catchments
The Auckland Region spans from just beyond Wellsford in the north to Pukekohe in the south. The mainland area of the region covers around 16,140 square kilometres and has 1,613 kilometres of coastline. It is comprised of three districts (Franklin, Papakura and Rodney) and four cities (Auckland, Manukau, North Shore, and Waitakere).
The landscape of the region is extremely diverse, ranging from volcanic cones and native forest clad ranges, through freshwater wetlands, estuaries, harbours to coastal seas and offshore islands. The natural environment is highly valued by the people of the region, whether it is enjoying the beaches, sailing, fishing or just enjoying the view. Aucklanders also value our extensive network of local or regional parks, whether to play organised sport, go tramping, mountain biking or just kick back and relax.
The Auckland Region makes up just 2% of New Zealand’s land area, but has 30% of the population and 34% of the economic activity. The Region is now home to 1.2 million people (June 1999) from a wide range of cultures and ethnicity.
The total length of streams in the Auckland Region is estimated to be 10,000 km. Most are small (less than 2 metres wide) with a few tributaries, much like the finger-tips of your hand. The small size of streams is due to the catchments of the Auckland isthmus being small and short. This makes them sensitive to low summer flows and the taking of water.
Streams may be perennial, meaning they flow all year, or ephemeral, which means they dry up in summer. Waterways in the Auckland region are typically soft bottomed due to the underlying clay material on which they are formed.
A lot of the urban waterways in Auckland fall into the small category, with catchments only several hundred hectares in area. Many are less than 3 kilometres in length and are small enough that you could easily jump across them. We have about 9,500 kilometres of these types of streams in the region, about 90% of the total. Even the large catchments are made up of many smaller sub-catchments. Whatever happens in the smaller feeder streams affects the overall well being of the main waterway lower down.
The urban part of the Auckland Region is spread over a very large and ever expanding area. As the boundaries of urbanisation spread out over time, catchments or parts of them become modified further and further. In the larger urbanised catchments there is very likely to be a range of land uses occurring from bush or forestry through rural and urban fringe/lifestyle blocks to fully urbanised. Each of these land uses has a characteristic set of effects, or impacts on streams.
What is a catchment
A catchment is described as an area of land, bounded by hills or mountains from which surface and groundwater flow into streams that meet the sea. Everybody lives in a catchment. In New Zealand catchments vary in size from large, such as the Waikato River stretching from Taupo to Pukekohe, to tiny areas of only a few hectares.
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