Abstract:
Catchment characteristics that if present concurrently support improvement in stream ecosystem health following urban development include riparian vegetation, stormwater treatment via raingardens, ponds elevated above the riparian corridor and forest trickle irrigation of pond or raingarden overflows. Water Sensitive Urban Design has much in common with the New Zealand (NZ) practice, Low Impact Urban Design and Development (LIUDD). In New Zealand, both terrestrial and aquatic ecosystem protection and re-creation are essential elements of LIUDD. This paper reports on comparative NZ catchment studies over 7 years for conventional and LIUDD subdivision at low/countryside and average/urban residential densities. Catchment characteristics are related to the health of in-stream macro-invertebrate communities as indicators of stream and catchment condition. Results for in-stream indicators are compared to region-wide values and show the ecological superiority of WSUD/LIUDD catchments. Indicators of stream ecological health in treatment catchments have improved for two urban streams and up to three countryside residential streams during the subdivision and house construction period contrary to normal expectations for conventional urban development.
