An assessment of the drainage quality and quantity associated with recycled wastewater irrigation in an urban park

Abstract : Quantification of drainage to remove excess water from the soil profile and provide a suitable environment for vegetation has been developed over the years. Drainage estimation is fairly challenging particularly in the heterogeneous urban environs. This research studied the temporal variation of drainage rate and nutrient leaching in Veale Gardens of Adelaide Parklands, Australia. A zero tension pan lysimeter was installed in an urban mixed vegetation park to study the quantity and quality of leachate solute. EM38 soil mapping and spatial analysis allowed mapping of two EC zones. Temporal changes of volume and characteristics of drained water were studied in the low EC zone for two seasons of summer and winter. The outcomes showed that the volume of drained water in the summer time was considerably less than in the winter time. This is likely to be the cause of the winter dormancy in most plants and evapotranspiration reduction in winter time. Chemical analyses of leachate solute showed a significant drop in the values of EC, potassium, total N, total P, and ionic balance from summer to winter despite a large increase in SAR. In terms of nutrient loading during the study period, this work has shown that there would be very little impact from using recycled waste water compared to conventional water sources.