Use of urban lakes for managing stormwater, improving community benefits and property values

Abstract

As urban development needs to be designed in a manner that takes into consideration the maintaining the harmony of water cycle, it is important to understand the effectiveness of existing water bodies in urban landscapes. This study aimed to explore the use of urban lakes for stormwater storage and treatment whilst considering the property price impact and community benefits. To explore this, it was necessary to understand how water quality of urban lakes varies, the impact catchment characteristics have on the water quality, and the impacts of the systems on community and property prices. Water quality monitoring was done in the following locations: Wattle Grove Lake, and Woodcroft Lake and Wetland system. Parameters such as temperature, pH, dissolved oxygen, electrical conductivity, nitrite N, nitrate N, ammonium N, phosphate P, total nitrogen and phosphorus, chlorophyll a, and dissolved organic carbon were monitored fortnightly. The water quality data were analysed to understand the quality of the water and the impacts on the water quality due to rainfall and other seasonal changes. In conjunction with fortnightly monitoring, autosamplers were installed to obtain water samples immediately after a rain event to understand the quality of stormwater flowing into the lakes and the quality of water leaving the lakes. Water samples using autosamplers were collected for over a period one year. Soil samples from the study area were also collected to understand the chemical and physical composition of the soil in each catchment area. On seasonal basis, a number of sediment samples were collected at both lakes and the various nutrients and cations were analysed. The two sites also vary in design: one has a constructed wetland that acts as a pretreatment for the stormwater, and one does not. By comparing the water quality of the two sites, the impact of the constructed wetland on the water quality was investigated. The design of the two lake and wetland systems along with catchment area properties was also explored to understand the efficiency and applicability of these systems in other urban areas. Inlet and outlet water quality analysis revealed that catchment size and characteristics have considerable impact on the water quality of lake and wetland systems. Soil samples in both areas indicated high levels of nutrients and iron. As such, this affected the water and sediment characteristics of the wetland and lake system studied. Results of this study show that constructed wetlands do improve stormwater quality. However, even with the inclusion of this system, the nutrient levels in water are still higher than the allowable range for such systems. It was found that the integrated system of wetland and lake performed better with respect to parameters such as turbidity, total suspended solids (TSS) and nutrients. There was about 50% removal of turbidity and TSS between the inlet and outlet of Woodcroft Lake. A community survey was conducted to understand the impact of the lakes on residents around the wetland/lake sites. The survey explored aspects such as wellbeing, local environment and property value benefits. Responses from community show that there is an overall positive perception of the lake and associated parkland. When asked, over 70% of the respondents stated that there is a positive impact of the lake on the property prices. Further, 50% of residents found that there was moderate to significant impact of the lake on both mental and physical wellbeing of people. Approximately, 20% of respondents stated that they would not exercise if the local lake system did not exist. Also, 60% of the respondents stated that the lake improved their quality of life. . In general, wetlands and urban lakes can greatly contribute to the well-being of the community by acting as urban recreational spaces that provide aesthetic appeal, landscape diversity and health lifestyle opportunities. The property price analysis, using hedonic regression, was conducted to understand the impact of the lakes on surrounding properties. The output of the regression modelling showed significant positive impact (p

Date of Award	2019
Original language	English