Water Quality Control Options in Response to Catchment Urbanization: A Scenario Analysis by SWAT

Abstract

Urbanization poses a challenge to sustainable catchment management worldwide. This study compares streamflows and nutrient loads in the urbanized Torrens catchment in South Australia at present and future urbanization levels, and addresses possible mitigation of urbanization effects by means of the control measures: river bank stabilization, buffer strip expansion, and wetland construction. A scenario analysis by means of the Soil and Water Assessment Tool (SWAT) based on the anticipated urban population density growth in the Torrens catchment over the next 30 years predicted a remarkable increase of streamflow and Total Phosphorous loads but decreased Total Nitrogen loads. In contrast, minor changes of model outputs were predicted under the present urbanization scenario, i.e. urban area expansion on the grassland. Scenarios of three feasible control measures demonstrated best results for expanding buffer zone to sustain stream water quality. The construction of wetlands along the Torrens River resulted in the reduction of catchment runoff, but only slight decreases in TN and TP loads. Overall, the results of this study suggested that combining the three best management practices by the adaptive development of buffer zones, wetlands and stabilized river banks might help to control efficiently the increased run-off and TP loads by the projected urbanization of the River Torrens catchment.

Identifying Key Sites of Green Infrastructure to Support Ecological Restoration in the Urban Agglomeration

“…In view of this, they should be set up as water eco-logical conservation areas in regional and municipal land use planning policy [78]. Water mobility within these areas should be improved by optimizing the pattern of riparian green space patches and building multi-layered, less interventional symbiotic buffer zones [79,80]. Ecological fracture points are concentrated along cross-city railroads and highways, and the original wildlife migration corridors in these areas have been gradually disrupted by noise pollution and soil hardening [81].…”

Vegetated Buffer Zone Restoration Planning in Small Urban Watersheds

“…Complicated models like REMM (Riparian Ecosystem Management Model) [24,25], CREAMS (Chemical, Runoff and Erosion from Agricultural Management System Model) [26], and VFSMOD (Vegetative Filter Strips Model) [27] that are based on the whole physical process of sediment and pollutant deposition and migration can simulate the minimum width for specific removal efficiency of different riparian zones [28]. Some multi-functional hydrological models like SWAT also integrate a buffer width module [29]. Methods based on geographic Information Systems (GIS) and remote sensing techniques are also highlighted for the privilege in catchment scales and can delimit variable buffer zones for multiple needs [30].…”