Characterisation of Urban Stormwater Quality in the Auckland Region(New Zealand)

摘要

This paper describes characterisation of urban sediment and stormwater quality derived from a range of field studies undertaken over the last 10-years in the Auckland region, New Zealand. The most comprehensive field work involved monitoring of eight sub-catchments in the Auckland City in 2000-1. The monitoring included three single land-use control sub-catchments: (1) commercial, (2) industrial and (3) residential, while the remaining five sub-catchments were of mixed land use. Other sampling involved monitoring runoff components within sub-catchments: roads and motorways; carparks and industrial sites Urban sediment and stormwater quality yields by land use, material (principally roof runoff) and activity level (principally traffic volume) were derived. Stormwater contaminants characterised included three heavy metals of concern in the Auckland region: zinc, copper and lead; and polycyclic aromatic hydrocarbons. Nutrients (total nitrogen and total phosphorus) and enterococci were characterised from the sub-catchment monitoring. Particle size distributions (PSD) were generated from available data and distilled into 'typical' PSDs for (1) urban streams, (2) urban pipe networks and (3) construction (earth work) sites. Auckland regional yields generally are similar to United States and Australia studies. Zinc yields generally are high owing to runoff from a large quantum of older, galvanized roof material yet lower than some northern hemisphere studies. The PSDs of sediment in the Auckland region lie between the United States (which has a larger fraction of larger sized particles) and Australia (which has a larger fraction of smaller sized particles).