Urban Ecology LIUDD Case Study
Land 7401 Urban Ecology Student ID: 1364497 Written by Andrea Reid
LIUDD Analysis LIUDD – Low Impact Urban Design and Development LIUDD is a design and development strategy that lowers the impact of the effects that human activities have on the environment. It uses new design initiatives that allow for different densities of urbanisation while maintaining ecological resources and protecting natural environmental cycles.
at implementing LIUDD approaches to effectively slow and filter stormwater at its source to minimise these detrimental effects. A specific focus on stream restoration, water supply, flood management and pollutant reduction are particular important within the Auckland area.
By implementing a range of ecological ideas, methods and practices, a range of devices can be integrated into new developments and existing systems to treat water, waste and air, harvest energy and food, and protect forest and fauna.
Currently the most utilised LIUDD initiatives reduce the quantity and increase the quality of the water by using a water treatment train that can include, but is not limited to; rainwater tanks, living roofs, rain gardens, swales, filter strips, ponds, wetlands and riparian planting.
These design interventions must maintain a balanced ecological carrying capacity so that the environment has time to regenerate the resources utilised and resulting waste is treated. The local ecology, geology, hydrology and catchment area of the site must be analysed so that a combination of appropriate LIUDD interventions can be made at different scales. LIUDD has the potential to help council meet many of its main objectives while providing environmental, social, economic and cultural well-being for residents. A New Zealand sustainable cities concept, LIUDD combines different strategies and ideas from America’s Low Impact Development (LID), Conservation SubDivisions (CSD), Integrated Catchment Management (ICM) and Sustainable Building/Green Architecture (SB). (World Wildlife Federation, 2012) The Auckland City Council will face major environmental difficulties with ongoing population growth and intensification, as an increase in impervious surface area will result and increase flood risk. The current underground stormwater system is not capable of handling this additional volume of run-off and is expensive to repair and maintain, so a variety of New Zealand Councils are looking
An example of a successful implementation of LIUDD principles would be to create green corridors throughout the Auckland region that generate infiltration zones and overland flow paths that facilitate complete flood protection in a 2-year storm event. This would result in Auckland’s social, ecological, economical and cultural resilience; creating recreational areas and walk/cycle transport connections for residents, protecting sensitive, marginal, ecological areas, increasing climate change resilience and reducing the urban heat Island effect. To make sure LIUDD schemes are working effectively, monitoring schemes can be used to identify existing statutory and non-statutory objectives, monitoring parameters, environmental values and pressures which could then be collated to prepare a monitoring strategy and action plan. (Land Care Research, 2009) By working with, rather than against nature and its natural cycles, LIUDD advocates for an alternative, cost-effective urban design and development strategy that creates community environments that respect, conserve and enhance natural processes and the wellbeing of those that live there.
Figure 1 .LIUDD Device Integration
Site Integration and Calculations A water treatment plan for an 88Ha subdivision development in the Karaka region, south of Auckland [Figure 2.] uses a range of LIUDD interventions to mitigate the rainwater and greywater produced within each complex [Figure 3]. The aim for this development is to create an area where residents can ‘grow, live, work and play’ in a community-focused, sustainable environment. This treatment plan was based on a conservation subdivision model and reflects these values and threads them into the everyday lives of the residents. The subdivision is situated within a single water catchment area that has water run from the ridge line on the western edge of the site to the coast on the eastern edge. The main impermeable areas on the site are the apartment roofs and the roads, which come to a total area of 119,740m2. The permeable areas include a coastal saline revegetation zone, wetland areas, vegetated slopes, permeable walk/cycle/ equestrian pathways, urban farming grassland and crops, parkland recreational zones and planting within the complex. This creates a total area of 760,260m2. Therefore 13.61% of the site is covered in impermeable surfaces and 86.39% is permeable. A variety of LIUDD stormwater mitigation devices will be put in place to increase the quality and decrease the quantity of the runoff before it enters the Manukau Harbour on the Eastern edge of the site. Below are calculations analysing the onsite stormwater for a 2-year rainfall event with an intensity of 70mm of rain per hour: The peak discharge for the total impermeable surfaces (with an average runoff coefficient of 0.98 for impermeable surfaces) within the site is 2.29m3 per second (p/s) and the peak discharge for all permeable surfaces (with an average runoff coefficient of 0.39 for urban landscapes) is 5.78m3 p/s.
By dividing the permeable areas into 3 zones, more accurate runoff coefficients can be used to get an accurate measure of runoff from these permeable areas, these three zones are Bush (revegetation area), Grass (urban farming and recreation) and Urban Landscape (outside area within the complex). Bush, total land area: Peak discharge: Grass, total land area: Peak discharge: Urban landscape, total land area: Peak discharge:
33.7Ha 4.59m3 p/s 17.6Ha 0.34m3 p/s 24.7Ha 1.87m3 p/s
This creates a more accurate permeable surface peak discharge total of 6.8m3 p/s. Therefore, the total site peak discharge is 9.09m3 p/s.
Figure 2. Plan view of 88Ha Karaka subdivision
This data can now be used to assess the total volume of storage required on the site for a 2-year storm event. The total onsite water storage needed will be 49,086m3. The storage needed for only impermeable surfaces is 12,366m3 and permeable surfaces 8,100m3. This breaks down into 24,786m3 storage needed in bush areas, 1,836m3 in grass areas, 10,098m3 within the open areas of the complex and 760m3 from the roofs of each complex (152m3 from each apartment).
with raingardens and swales at either side areas, growing areas and water filtration devices
By creating a treatment train that includes sand filters, water tanks, rain gardens, swales, vegetation and wetlands that connect to existing water flows, the water can be easily slowed and filtered before it reaches the harbour [Figure 1.]. Formulae and calculation processes comprise 3 A4 pages which are available on request.
Figure 3. Complex layout example
LIUDD Application Water management Applications The water enters a series of rain gardens from the living roof and is used to irrigate the vegetables growing on each tier [Figure 5]. The top tiers are sheltered by glass to encourage growth of exotic highdemand fruit and vegetables such as bananas. Each tier is constructed from native timbers and holds a variety of productive edible plants that are cared for by, and shared between, residents in the complex. The timber frame is faced with haphazard stones and bits of timber with small holes in them, creating spaces for a variety of native geckos, skinks and bees to hide from predators and stay warm. The plants filter the water as it travels through the system and joins the algae pond at the bottom that is part of the grey water filtration system [Figures 7,8 and 9]. Any excess stormwater that would otherwise flood the vegetable gardens is stored in a rainwater collection tank under the structure to utilise during droughts. To avoid flooding the filtration system, an overflow pipe leads from the watertanks to the swales to mitigate flooding during large storm events. The greywater passes through an underground settling tank beneath the rainwater mitigation system. It will then run through a series of filters; large scoria, algae filtration pond, small scoria and sand. The permeable boardwalk (native timber) is raised above water level and runs along the large scoria filter and parts of the sand filter. A treatment train connects the water from each complex to the coast [Figures 4 and 6]. A series of rain gardens spiral out of the complex, running into swales that carry the water out to the existing water table. These existing water flows will be enhanced with riparian planting and lead the water down the bank to the wetland system at the bottom of the
slope. The wetland will then release the clean filtered water into the Manukau harbour, enhancing its environmental integrity.
swales to filter any remaining pollutants in the water.
This system should effectively protect residents from flooding, damage to forest and fauna and unfiltered pollution and sewage entering the harbour by slowing and filtering the rainwater and greywater before it reaches the coast.
Old stones, drilled timber, corrugated iron and other recycled materials will be used to create artistic insect walls on the urban farming rainwater system to increase the indigenous biodiversity within the urban area. To encourage native insects and reptiles to use the insect wall, native vegetation will be planted in the dry areas parallel to the pathways. Plants that encourage native lizards flower close to the ground, bring insects and flies within reach, provide berries and nectar that can supplement their diets and create bundles of dead material at their base to provide camouflage. These plants include selections of Coprosma, Muehlenbeckia, Melicytus, and Gaultheria.
System Effectiveness
Urban Farming and Recreation Area:
Large scale urban farming, mixed use areas and high density developments are positioned behind and buffered by the medium and low density apartment complexes before their runoff can enter the coastal system.
Complex area: Every complex (high, medium, low and mixed use density models) has a filtering system at its centre to filter all greywater and rainwater runoff within the complex. This also acts as an aesthetically pleasing outdoor social area and has community garden space to maintain the ‘grow, live work, play’ philosophy of the site. Composting toilets will be used within the complex so that sewage does not need to be filtered through the water filtration system as it could result in hygiene issues. The complex is designed to have minimal impact on the existing urban systems that surround it and be as self sustaining as possible by providing its own water treatment, sewage, power and major food sources. A native tree will be featured in the centre of each complex. A variety of coastal and wetland plants will be used within the sand filters, rain gardens and
All waterways and existing waterflow areas that move through urban farming or recreational areas will be buffered with a minimum of 15m of native riparian planting either side. This will filter the runoff of sediment, nutrients and harmful faecal bacteria contaminants. Stock will also be excluded from riparian margins, to minimise bank erosion and nitrification of waterways. Natural crop farming methods will be employed to avoid harmful chemical sprays entering the natural biofabric of the site. The riparian margins will contribute to urban indigenous biodiversity by acting as native wildlife corridors, helping link larger bush areas and providing walk/cycle/equestrian connection pathways between complexes, recreation, farming and mixed use areas. Riparian margins provide food and habitat for a range of birds, frogs, lizards, invertebrates and freshwater life. Shading waterways by edging them with native Carex grasses and planting large shade trees reduces water temperature and creates areas for sensitive native species to shelter, spawn, feed and breed. Undercut banks and stump and tree root retention will also be encouraged as they provide habitat for native kokopu, eels and ducks. Some of
these riparian plants will include, but are not limited to, species of Carex, Caprosma, Phormium and Cordyline. Native forest area: This large patch of core vegetation will be planted with natives and contain a large area of wetland. The bank will be planted with a collection of robust trees that can cope with sloping conditions and that attract pollinators. These species may include Sophora microphylla -kowhai, Kunzea ericoides –kānuka, Leptospermum scoparium -mānuka, Melicytus ramiflorus –mahoe, Metrosiderous excelsa –pohutukawa and Corynocarpus laevigatus -karaka. Core vegetation creates a strong resilient ecological area with fewer exotic pests and weeds. An abundant habitat for native wildlife will result, which cannot otherwise be provided at the edge of a vegetation patch. The walk/cycle/equestrian tracks that weave through this forest are an urban amenity for residents and visitors and provide social, ecological and cultural well-being.
Wetland area: The wetland is threaded through the forest area along the bottom of the slope and collects, slows and filters all the water in the catchment before it enters the Manukau Harbour. This provides assurance that any elements from this catchment will not be contributing to the current deterioration of this important natural resource. The data suggests that the wetland is of a size and capacity that should protect against a 2yr storm event.
This will require a collection of strong resilient native rushes (Ficinia nodosa, Apodasmia similis, Empodisma minus, Sporodanthus ferrugineus), sedges (Gahnia, Cyperus, Carex species, Uncinia, Oreobolus pectinatus, Eleocharis) and trees/herbs/grasses (Cordyline australis, Cortaderia splendens, Coprosma repens and Phormium tenax). These will stay sturdy during wet weather, filter the water in the wetland, release it slowly into the coast and contribute to rare indigenous biodiversity by attracting the declining local insects such as native dragonflies, damsonflies, flax loopers, wirerush loopers and cabbage tree moths.
Coastal area: The coastal area will provide a streamlined recreational sand strip for water to infiltrate before entering the harbour. This creates a final filtration line and recreational place for residents to enjoy. Native coastal saline species will be used to increase indigenous biodiversity including Sarcocornia quinqueflora -glasswort, Juncus kraussii -sea rush, Selliera radicans -remuremu, Plagianthus divaricatus -saltmarsh ribbonwood and Stipa tenuissima -stipa. Artificial shell banks will be constructed and integrated into the area to provide important roosting sites for waders at high tide including the threatened endemic wrybill and New Zealand dotterel.
Figure 4. Cross Section of the treatment train
Figure 5. 3D diagram of the rainwater system
Figure 6. 3D Diagram of the water treatment train
Summary Summary
References
This water treatment scheme creates a strong, sustainable and resilient subdivision that uses practical, environmental, aesthetically pleasing LIUDD devices to treat all water within the catchment.
Land Care Research. (2009). If we adopt LIUDD, what will we meausure to tell us how well it worked? Retrieved 06 2013, from Land Care Research: http://www.landcareresearch.co.nz/publications/ researchpubs/Feeney_2009_adopt_LIUDD.pdf World Wildlife Federation. (2012, 03 01). Auckland Low Impact Urban Design and Development. Retrieved 06 2013, from World Wildlife Federation (WWF) Global: http://wwf.panda.org/?204377/ Auckland CBRE Group. (2012, 04 20). CBRE. Retrieved 05 2013, from NZ office worker space ‘average’, says CBRE: http://www.cbre.co.nz/aboutus/mediacentre/ mediaarchives/Pages/042012.aspx Knowles, M. H. (2012). Conservation Subdivision: Design Phase – Patch Size and Shape of Conserved Open Spaces. Retrieved 05 2013, from EDIS: https:// edis.ifas.ufl.edu/uw320 Landmatters Property Services Pty Ltd. (2012). The Ecovillage at Currumbin An international award winning sustainable community. Retrieved 05 2013, from The Ecovillage: http://theecovillage.com.au/ Maria Ignatieva, C. M. (2012). How to Put Nature into Our Neighbourhoods. Retrieved 05 2013, from Moodle: http://moodle.unitec.ac.nz/mod/resource/
This report demonstrates the application of LIUDD principles and technical solutions for an integrated sustainable stormwater, greywater and biodiversity system in a conservation development context. The subdivision has a minimal impact on the surrounding urban systems by using self sustainable ecological principles to provide its own water treatment, sewage, power and major food sources. The LIUDD devices bind the new urban realm with the existing ecological, geological and hydrological layers, threading them together to create a tightly woven biofabric for the site. For more information on this Karaka subdivision, please visit: http://issuu.com/andreareid
view.php?id=29161 Marshall, G. (2013). Intoductory lecture. Unitec. QV Property Information. (2013). Average house size by area . Retrieved 05 2013, from QV Property Information: http://www.qv.co. nz/propertyinformation/KnowledgeCentre/ Averagehousesizebyarea12042011.htm Steve Allen, M.S. candidate, North Carolina State University. (2010). Conservation subdivision handbook . Retrieved 05 2013, from http://www.ces. ncsu.edu/forestry/pdf/ag/ag742.pdf The Permaculture Research Institute. (2013, 04 21). Letters from New Zealand – a Permaculture Food Forest in the Far South. Retrieved 05 2013, from The Permaculture Research Institute: http://www. permaculturenews.org/2013/4/21/letters-from-newzealand-a-permaculture-food-forest-in-the-farsouth/ Van Bergen Kolpa Architects. (2010, 02 24). Park Supermarket, a spatial development model for urban agriculture in the Metropolitain Parks of the Randstad. Retrieved 05 2013, from Youtube: http://www.youtube.com/watch?feature=player_ embedded&v=shrWmQpb9Hk
Figure 7. Plan of filtering system
Figure 8. 3D sketch/diagram of central filtrational zone
Figure 9. Cross Section showing how the greywater and rainwater systems integrate