Australia’s island state, Hobart, is well known for its history of catastrophic fires, including the disastrous wildfires of 1897-98 and 1967. As the second-driest city in Australia, it’s easy to forget though that Hobart is also vulnerable to serious flooding. Until earlier this month that is, when a record 236.2mm of rain fell on Mount Wellington and 129.2mm fell in Hobart. The deluge flooded the city, with the Hobart Rivulet breaking its banks and flooding other lower lying areas in Sandy Bay, South Hobart, New Town, Lenah Valley and Kingston. In Hobart, cars were swept away in Collins St and Syme St and McRobies Rd in South Hobart.

Hobart’s closeness to nature and surrounding hilly terrain makes the city especially prone to wildfire and flash-flooding. But, the May 2018 flooding is also partly attributable to the city’s postwar planning. Like the rest of Australia, city planning in Hobart was dominated by, “a disconnection from nature. Creeks and streams were filled in, built over or walled off (taming nature), creating risks of catastrophic failure in unexpected conditions. This approach also overlooked the important ecological functions of watercourses.”

Unfortunately, the problem is only getting worst as Hobart expands, with houses, roads and buildings increasing the hardscaped area and decreasing green cover, which acts like a sponge. Planners now must apply water-sensitive urban design principles, including protecting floodplains from development, limiting the development of very steep land, and restricting land uses on flood-prone sites. Separately, thought must be given to the development of the urban forest – planting urban trees and carefully incorporating water sensitive urban design to better manage stormwater runoff. Good planning can help prevent future disasters and keep Hobart’s residents out of harm’s way.

Source: https://theconversation.com/lessons-in-resilience-what-city-planners-can-learn-from-hobarts-floods-96529

Citygreen at the 2015 NSW/WSUD/IECA Conference:

With our ongoing support of the stormwater industry, Citygreen® is proud to announce it’s involvement in this year’s NSW/WSUD/IECA Conference, on the 19th-23rd of October at Dockside Darling Harbour, NSW.

For more information please visit: www.wsud2015.org

With increasing urbanization, and more highly concentrated populations within cities, strengthening the green infrastructure is becoming increasingly important. One of the largest opportunities for impact is maintaining and enhancing the urban canopy. This is addressed most readily by advanced tree pit design, which refers to the subterranean structures put in place during planting.

In Minneapolis, the local government conducted research that revealed well-planted trees provide a strong financial incentive in addition to the ecosystem benefits. The research found a $2 million savings between a storm water conveyance system, or subterranean cell systems.

Peter MacDonagh, a landscape architect, said in an ASLA interview, “larger, older trees are far more valuable than younger ones, so work needs to be done to preserve these and use new techniques to enable younger trees to stay in place longer.”

As trees were planted in the past, the soil they were placed in was compacted, causing a lack of nutrients, storm water management, and root establishment. As a result, the trees struggle to thrive and provide their benefits to the local environment and infrastructure. Often, these struggling trees will either die, stop growing, or begin to push through and ruin sidewalks and roads.

“The Center for Urban Forest Research calculates that large-canopy trees …outperform small trees…and they do not start adding significant environmental performance until they reach 30 feet,” states Matthew Gordy, a landscape and urban design professional.

By utilizing cell systems, the strain put on the trees’ growth is almost completely eliminated, resulting in lower costs, and increased shade, stormwater management, and overall well being of the populaces and local infrastructure.

Get more information on advanced soil cell systems here.

The Future of Urban Water:

What would the state of urban water be in the next couple of years?

Well, the report The Future of Urban Water: Scenarios for Urban Water Utilities in 2040 by ARUP explores trends and future scenarios for the future of urban water utilities in 2040. It is the result of a jointly funded collaboration between Arup and Sydney Water.

“The programme has helped us gain a better understanding of possible pathways into the future, including implications for future infrastructure, governance and customer experiences.”

It depicts four plausible scenarios for the future of urban water utilities in 2040, using Sydney as a reference city. The report explores how a wide range of social, technological, economic, environmental and political trends could shape the urban water future.

The World Economic Forum’s Global Risks 2014 report said water crises is one of the top five global risks posing the highest concern. “Despite this, water issues are often overlooked or misunderstood, and there is a need for better awareness of their social, economic and environmental impacts.”

The Arup report said aside from the increasing water scarcity and pollution, rapid population growth and urbanisation are “major factors posing fundamental challenges to the global water cycle, with a particular pressure on the urban water supply”.

Australia utilises over 50 percent of its water consumption for agricultural purposes. The rest is for household, industrial and commercial use. But in urban areas, “the main driver for demand remains the population, and thus population growth”.

One of the key drivers for water conservation is smart infrastructure. It responds intelligently to changes in its environment to improve performance. “It is estimated that the market size for smart grid technologies will almost triple by 2030. Smart water networks could save the industry US$12.5 billion a year.”

Another is the change to a more digital lifestyle where people will be able to monitor the consumption and cost of water in real time. “More awareness of the issues could lead to increased scrutiny of water utilities and pricing of services. The availability of data provides an opportunity to educate customers about consumption and managing resource use.”

The report also mentioned new solutions for water supply such as the extensive use of desalination. About 96 percent of the earth’s total water supply is found in oceans. “Worldwide, desalination plants are producing over 32 million cubic metres of fresh water per day. However, energy costs are currently the principal barrier to its greater use.”

Finally, the report also said green infrastructure is part of the plan. “Benefits of increased green infrastructure include the reduction of flood risk, improved health and wellbeing as well as providing a habitat for wildlife. Extensive green networks can be formed over time to create an encompassing city ecosystem that can support the sustainable movement of people, rebuild biodiversity and provide substantial climate change adaptation.”

For more of the report, you can check this out.

A Water Sensitive Urban Environment:

Water Sensitive Urban Design (WSUD) is also known as Low Impact Development (LID) in the United States, and Sustainable Urban Drainage Systems (SUDS) in the United Kingdom.

It all refers to the land planning and engineering design approach that integrates the urban water cycle, including stormwater, groundwater, and wastewater management and water supply, into urban design. This is done to minimise the environmental degradation as well as improve the look of the area.

Why use WSUD? According to the guidelines released by the South Eastern Councils in Melbourne Victoria, WSUD has been identified as a “means to control flows and filter stormwater to remove pollutants”.

Stormwater is the water that runs off urban surfaces after heavy rainfall. The report said it has been identified as the key cause of pollution and declining health of waterways.

“With increased urban development, the proportion of impervious surfaces in our catchments increases. This increases the velocity and amount of water running into our waterways, creating problems of erosion and flooding and changing natural flow regimes, with associated ecological damage. It also washes more pollutants into our streams, further impacting river health.”

Victoria councils, like other councils in Australia, have recognised the importance of sustainable water management such as WSUD. The release of various guidelines enables organisations to have a first point of reference for their projects.

The design “integrates urban water cycle management with urban planning and design, with the aim of mimicking natural systems to minimise negative impacts on the natural water cycle and receiving waterways and bays”.

Some of the key principles of WSUD as stated in the Urban Stormwater: Best Practice Environmental Management Guidelines (BPEMG) include:

• Protect and enhance natural water systems within urban environments.
• Integrate stormwater treatment into the landscape, maximizing the visual and recreational amenity of developments.
• Improve the quality of water draining from urban developments into receiving environments.
• Reduce runoff and peak flows from urban developments by increasing local detention times and minimising impervious areas.
• Minimise drainage infrastructure costs of development due to reduced runoff and peak flows.

Australian states started to release WSUD guidelines based on the federal government’s foundational research in the 1990s. Western Australia first released theirs in 1994 followed by other states like Victoria, New South Wales, Queensland and so on.

The Citygreen® products are designed to ensure it supports the effort for a sustainable water management. The Stratavell’s™ octagonal modules leave over 94 percent of its total volume for root growth and storm water harvesting. Find out more about the products here.

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