THE SHAPE OF WATER

From Jason King’s Landscape+Urbanism site

 

sketch_2-e1528755612550-2000x974

“Rendering of Houston wetland channel showing ecological wetland, conservation areas, and recreation trails” p. 90-91

An amazing resource posted on ASLA’s The Dirt (here) focuses on Design Guidelines for Urban Wetlands, specifically what shapes are optimal for performance. Using simulations and physical testing to investigate hydraulic performance the team from the Norman B. Leventhal Center for Advanced Urbanism (LCAU) at MIT. Led by Heidi Nepf, Alan Berger and Celina Balderas Guzman along with a team including Tyler Swingle, Waishan Qiu, Manoel Xavier, Samantha Cohen, and Jonah Susskind, the project aims to have a practice application in design guidance informed by research. From their site:js_plan_typical-01

“Although constructed wetlands and detention basins have been built for stormwater management for a long time, their design has been largely driven by hydrologic performance. Bringing together fluid dynamics, landscape architecture, and urban planning, this research project explored how these natural treatment systems can be designed as multi-functional urban infrastructure to manage flooding, improve water quality, enhance biodiversity, and create amenities in cities.”
Starting in the beginning by outlining ‘The Stormwater Imperative’, the above goal is explained in more depth, and issues with how we’ve tackled these problems are also discussed, such as civil-focused problem solving or lack of scalability, but also explore the potential for how, through intentional design, these systems “can create novel urban ecosystems that offer recreation, aesthetic, and ecological benefits.” (1)

single_island

The evolution that has resulted in destruction of wetlands through urbanization, coupled with deficient infrastructure leads to issues like flooding, water pollution due to the loss of the natural holding and filtering capacity of these systems and the increased flows. However, as pointed out by the authors, this can be an opportunity, as constructed wetlands “can partially restore some lost ecosystem services, especially in locations where wetlands do not currently exist.” (5)

The modeled flow patterns are also interesting, showing the differentiation from fast, regular, slow flows, along with any Eddy’s that were shown in dye testing using the flumes.

Read More

Check it out and see what you think.  The report is available as a online version via ISSUU or via PDF download from the LCAU site, where there are also some additional resources.  All images in this post are from these reports and should be credited to the LCAU team.

sketch_1

MEDIA RELEASE: GARDENS ARE IMPORTANT

via Contact – Cape Resilient Landscaping Forum

As the City of Cape Town has just implemented water rationing, this media release  informs why we need  need to maintain resilient urban landscapes and gardens.

MEDIA RELEASE BACKGROUND:

image005

Wild green belt / city parkland. (Marijke Honig)

The water crisis is a major cause for concern and poses a serious threat to some businesses and people’s livelihoods.

On the positive side it has raised public awareness about the value of water, and highlighted the bad practice of using potable water for irrigation.

A workshop was held in August called ‘Water restrictions as an agent of positive change: how to create a resilient green industry’, attended by landscape architects, contractors, growers, compost and irrigation suppliers, retailers and others. One of the issues identified was the urgent need to educate people about the importance of the urban ecosystem and clear up confusion about the use of borehole water. Here is a communication from the newly formed Cape Resilient Landscaping Forum:

MEDIA RELEASE, FOR IMMEDIATE RELEASE – OCTOBER 2017

image006

Low maintenance road verge with no irrigation. (Marijke Honig)

GARDENS ARE IMPORTANT

ALL green areas – whether planted landscapes, wild areas, or a road verge with weeds – contribute to the urban ecosystem. They are vital to our well-being: green areas produce air for us to breathe, they filter pollution, absorb storm water and reduce flooding, purify water and maintain a pleasant temperature. Without sufficient planted areas and infiltration – due to the many tarred and paved areas, and reflective surfaces – the city heats up. This is known as the urban heat island effect: pollution levels rise and our quality of life decreases. On summer days, especially when there is no wind, the raised temperature is already evident in the City Bowl, which is a few degrees hotter than the suburbs.

Gardens form an important part of the urban ecosystem and are not a luxury: they are a necessity. Green areas provide habitat for wildlife and are good for our well-being. Please do not feel guilty about gardening! We encourage anyone with access to alternative water sources, such as borehole or grey water, to use it responsibly to help maintain the urban ecosystem. Furthermore help spread awareness of its value and the importance of permeable surfaces for infiltration of rain. This will make a positive difference

image004

Trees reduce air pollution in the urban environment, absorb CO2 and shade roads to decrease heat sink aspects. (Clare Burgess)

Some simple ways you can help preserve the urban ecosystem:

  1. Do not remove successful plants.Consider valuing plants for their resilience and ecological function, in addition to personal preference. A thriving common or weedy plant is better than nothing green at all!
  2. Mulch all planted areaswith a 5 to 10cm thick layer of mulch. This dramatically reduces water loss from the soil surface and keeps it cool. Organic mulches such as chipped wood and leaves are best, as they feed the soil and your plants.
  3. Keep areas planted, not paved. Consider how important it is for rainwater to infiltrate the soil: this is important for recharging groundwater (and good for trees) and keeps the ambient temperature down. Avoid hard surfaces where possible and usepermeable paving when a hard durable surface is required.
  4. If you do have a borehole, water deeply and infrequently. Mimic a good rainfall event of say 50mm and really saturate an area, with water penetrating at least 50-60cm into the soil. You may only need to do this every 3 to 4 weeks.
image007

Two local resilient plants species – Hermannia pinnata and Senecio crassulifolius. (Marijke Honig)

 

For more information on resilient landscaping and an educational quizz ‘How water-wise are you?’ please visit https://resilientlandscaping.wordpress.com/

Text by Marijke Honig

 

Design for Resilience – The Case of Flood Mitigation (via Praxis in Landscape Architecture)

More and more we hear about resilience in the face of the unknown rather than “big scale planning”

Design for Resilience - The Case of Flood Mitigation What do you do when historical data is no longer useful for predicting the future? Climate change is making the already-difficult proposition of predicting environmental phenomena even harder. Consider societal efforts to manage the flood system. The concept of a 100-year flood is based on the idea that history is useful indicator of future states and "most likely" scenarios. A 2010 paper by Gersonius et al.* tackles the question of how we might … Read More

via Praxis in Landscape Architecture