Using treated wastewater to save wetlands impacted by climate change and pumping

摘要

Wetlands occur where the watertable which underlies much of Perth intersects the land surface.nRegional groundwater levels have been falling since the 1970s as a result of lower rainfall andnincreased extraction causing a loss of environmental and social values. This paper examinesna scheme to add almost 2 GL/yr of treated wastewater to infiltration galleries immediatelyndown-gradient of Perry Lakes so that the wetlands may be restored. Modelling suggest thatngroundwater levels would be raised up-gradient of the galleries, increasing both lake levelsnand groundwater supplies in the vicinity. It is not envisaged that wastewater will enter the lakes.nAdding treated wastewater to nearby trial galleries has shown that phosphorus, pathogensnand organic carbon are greatly reduced within 5 to 50m. Nitrogen levels are less reducednbut are similar to those in the lakes and nearby aquifer. It is estimated that the wetlandsnadd about $54m to land prices near the lakes and would add more than $24M to the salenprice of proposed nearby land if they contain water. If successful, the proposal could be antest case for the use of treated wastewater to create hydraulic barriers against salt waternintrusion into coastal areas.