Fatemeh Kazemi

A review of ET measurement techniques for estimating the water requirements of urban landscape vegetation

Increasing urbanisation combined with population growth places greater demands on dwindling water supplies. This is especially the case in arid and semi-arid areas like Australia, which is known as the driest inhabited continent on earth. Sustainable irrigation management necessitates better understanding of water requirements in order to decrease environmental risks and increase water use efficiency. Although the water requirements of agricultural crops are well established in field and laboratory studies, little research has been conducted to investigate the water requirements of urban green spaces. In addition, most previous research investigations have focused on the water requirements of turf grasses and not on other landscape plant species. Landscape plants can include various species of trees, shrubs and turf grasses with different planting densities and microclimates. Such complicated environments make measuring the water requirements of urban landscapes difficult.  This paper reviews previous studies and techniques for measuring the water requirements of urban landscapes and describes how optimum irrigation management strategies for urban landscape vegetation can assist in better water conservation, improved landscape quality and reduced water costs. The authors conclude that WUCOLS is a practical approach that can provide an initial estimate of urban landscape water demand but ideally this should be further refined based on the health and aesthetic condition of the urban vegetation. The authors recommend calibration of the WUCOLS estimates with an in-situ method such as a soil water balance.

Impact of green roofs on stormwater quality in a South Australian urban environment.

Green roofs are an increasingly important component of water sensitive urban design systems and can potentially improve the quality of urban runoff. However, there is evidence that they can occasionally act as a source rather than a sink for pollutants. In this study, the water quality of the outflow from both intensive and extensive green roof systems were studied in the city of Adelaide, South Australia over a period of nine months. The aim was to examine the effects of different green roof configurations on stormwater quality and to compare this with runoff from aluminium and asphalt roofs as control surfaces. The contaminant concentrations in runoff from both intensive and extensive green roofs generally decreased during the study period. A comparison between the two types of green roof showed that except for some events for EC, TDS and chloride, the values of the parameters such as pH, turbidity, nitrate, phosphate and potassium in intensive green roof outflows were higher than in the outflows from the extensive green roofs. These concentrations were compared to local, state, national and international water quality guidelines in order to investigate the potential for outflow runoff from green roofs to be reused for potable and non-potable purposes. The study found that green roof outflow can provide an alternative water source for non-potable purposes such as urban landscape irrigation and toilet flushing.