Using Fieldwork, GIS and DEA to Guide Management of Urban Stream Health

Aquatic ecosystems are vulnerable to threats from human activity. Urban stream ecosystems are especially vulnerable to urbanisation of surrounding land use, and interest continues to grow in improving the health of urban streams. We study 30 sites along two highly urbanised streams in Brisbane, Australia. Field research generated a suite of stream health indicators at each site. Spatially explicit geographic information system (GIS) techniques were used to determine metrics of nearby land use that put stress on stream health at each site. Population density is also considered as a stressor. Data Envelopment Analysis (DEA) is applied to individual health indicators (one at a time) and multiple stress indicators to construct a suite of best-practice frontiers, from which ecological efficiencies and response elasticities are calculated at each site. DEA is also used to aggregate stream health indicators into a stream health index for each site, and to aggregate land use stress indicators into a land use stress index for each site. A second round of DEA is then applied to the stream health index and multiple stress indicators, and a third round of DEA is then applied to the stream health and land-use stress indices to create an overall ecological performance index for urban streams (EPIUS). Empirical findings show significant deviations beneath best practice, wide variation in response elasticities, and numerous dominance relationships in all three exercises. Each of these findings can provide guidance to those responsible for allocating scarce resources in an effort to improve the management of the health of Brisbane’s urban streams.