This article discusses how the management of storm water in urban areas has evolved over time and possible approaches for the future in creating better urban environments.
Urban development can create conflicts with stormwater and flooding. The construction of new buildings and roads increases stormwater runoff compared to the natural environment. Flooding can be incompatible with the use of buildings and roads. The management of stormwater is therefore an important issue in the development of cities.
In the early 20th century, urban stormwater management in NSW primarily focused on flood control. The approach was largely reactive, involving the construction of drainage networks to divert water away from urban areas. These networks, often consisting of concrete channels and pipes, were designed to address immediate flooding risks by transferring water quickly from one place to another, but paid little attention to environmental impacts.
This "conveyance-focused" strategy reflected the priorities of the time, where urban expansion and infrastructure development often overshadowed environmental concerns. However, as cities grew and impermeable surfaces increased, the limitations of this approach became evident. Problems such as water pollution, downstream effects, habitat degradation, and urban heat islands began to surface, prompting a shift in thinking.
The below images of Johnstons Creek at Annandale and the Cooks River at Campsie show approaches to dealing with storm water and flooding from the late 19th to mid 20th century. These formerly natural water courses have been lined with concrete in order to move water faster from upstream in the catchment to downstream areas ie. Sydney Harbour for Johnstons Creek and Botany Bay for the Cooks River.
While these engineered environments are highly effective in making water move quickly from one place to another and thus reducing flooding upstream, they add very little to urban amenity or the environment compared to the natural waterways that they replaced. They must also be surrounded by safety fencing due to the hazard of very fast moving water during storm events. Despite this, they are often subject to unauthorised access, vandalism and other anti-social behaviour, as evidenced in the images.
The above approaches were somewhat necessary at the time, as a result of increased urban development in their catchments ie. concreting/asphalting over surfaces for roads and constructing buildings increasing runoff and therefore creating localised flooding. Development often occurred in an un-orderly manner, therefore creating knock-on affects.
By later in the 20th century, some efforts were being made by Council's and developers to consider the broader effects of stormwater as part of new developments.
The below reserve constructed by Landcom in the 1980s at Rosemeadow is designed to temporarily detain stormwater during a large storm event in order to prevent flooding downstream. While it relies on constructed pits and pipes underground, it also provides a reserve with fairly good amenity for the local community, unlike the previous solutions.
An even more evolved approach can be seen at Landcom's Park Central Development at Campbelltown, developed around 20 years ago.
Here, stormwater drains to a wetland, which provides habitat for various wildlife as well as a recreational area for the local community. Plants in the wetland also absorb nutrients/pollution from upstream in the catchment, before the water ultimately discharges to the Georges River and Botany Bay. This approach comes to the closest to mimicking nature and reduces impacts on wildlife.
With regard to streets, the vast majority of areas continue to rely on a kerb and gutter at the edge of the road collecting and draining stormwater, often draining to pits and a pipe underneath the kerb.
Another Landcom development in recent years, "Bunya" in Blacktown has sought to provide a more sustainable approach, with many roads draining to specially constructed raingardens in the middle of the road, that absorb nutrients/pollution from water before discharge into local waterways. See example below. The trees and green space also improve the amenity of the local area.
Some Council's, especially those with more financial resources, have sought to retrofit raingardens onto streets within their areas, to improve local water quality and amenity. See example below in Rosebery (City of Sydney Council).
While in some respects, approaches to managing storm water in urban areas has improved with regard to impacts on the environment and the appearance of infrastructure, a desire for people to live in larger and larger houses offsets much of the improvement in public drainage. See the below images of a new suburb developed in the past 10 years (Oran Park), versus one over 50 years old (Yagoona). Modern houses occupy a much larger footprint, with far less garden/pervious area than in previous generations.
All images are courtesy of Google Maps.
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