Objective of WG2 : Elaboration of a White Paper, focus on why to use irrigation on the green areas

Third EIA Working Group 2 (Urban Landscape) meeting was held end on July 2nd.

The participants were:

  • Xavier Botrel from RainBird
  • Damir Cizmek from Inaqua
  • Rafael Diaz from Riegoturf
  • Lorenzo Arcangeli from Hunter
  • Ramunas Rederis from Sodo

The absences were:

  • Joao Florido from Norma
  • Paul Van Breda from VBS
  • Vojtech Malina from Clever fram
  • Rob Hoogeveen from Certified design

 

After present the content of the slides was agreed to not focus on water scarcity as it maybe a negative message despite we may not skip it.

It was also agreed that each one will think and send some key points that we should develop. After have reviewed them, The WG leader, Santiago Casanella will choose the main points and assign to each participant one of these topics to be developed and see if in WG2 next meeting in September we may have some draft to keep progressing in a kind of white paper.

End of the month, The WG leader will decide which points to be developed more deeply and assign them to the participants. About mid-September, before EIA Board Meeting, Santi will try to set up another WG meeting and see what has been developed.

 

You will find below the various points raised were the following :

An accurate irrigation system is certainly the first and fundamental step for the conservation and maintenance of green areas.

 

The challenges of water management in green space maintenance

https://www.paysalia.com/en/blog/environment/water-management-green-space-maintenance

Water makes plants breathe, brings them oxygen and allows them to absorb CO₂ better - up to 4 times more than in a green space where water is scarce. It also permeabilizes the soil, reduces run-off and prolongs flowering periods which has a direct impact on biodiversity. Limiting watering can seem to be sensible but in fact does more harm than good. Sprinkling green spaces also reduces the ambient temperature by 3 to 4 degrees - a good solution to fight heat pockets in urban environments accentuated by global warming which disturb the wellbeing of the inhabitants. Plus, some public authorities prefer to save water and let their plants die, replacing them the following year. However, these new plants also need water to grow! This is neither environmentally-friendly nor economically sensible.

 

What are the Benefits of an Irrigation System?

https://www.e-landscapellc.com/what-are-the-benefits-of-an-irrigation-system/

  • Increased sequestration of carbon
  • Dust control
  • Noise reduction
  • A reduction in heat and water retention benefits
  •  

 

The importance of irrigated urban green space: health and recreational benefits perspectives

http://www.goyderinstitute.org/_r115/media/system/attrib/file/106/U.2.2%20Task%206%20-%20Greenspace%20Report_Final.pdf

Water is an essential component of green space. When it can be seen, water is pleasing to the human eye; people often prefer landscapes that contain bodies of water, or water features (Lothian et al., 2010). Just as importantly, even when water cannot be seen, it is enjoyed. Water is what keeps vegetation alive, and water is what enables vegetation to cool the environment through transpiration (Ely & Pitman, 2012). Some researchers believe that the human preference for lush, green landscapes is the result of evolution, and stems from the fact that these environments appear fertile and The importance of irrigated urban green space | Page iii potentially survival-enhancing to people (Orians&Heerwagen, 1992;

 

Associations between physical activity and irrigation

In terms of irrigation, irrigated parks were significantly associated with a range of physical activities, such as sports and low intensity activities (e.g. slow-paced walking). Most trail-based activities, such as cycling, walking and running were significantly associated with non-irrigated parks, however, this is likely due to the high percentage of these activities that take place along the Torrens River Linear Park, which is largely unwatered. Future studies will need to control for variations in park type in order to determine the influence of irrigation on physical activity and benefits.

From the pilot study, irrigated parks have the strongest association with social benefits such as spending time with friends, connecting with family, and being around good people. This is an interesting finding, however, again it may be a reflection of park type, as it can be expected that the more popular, attractive parks within the Council area are those that receive irrigation. Without ceasing irrigation in a park that has a known level of use, and examining the effects of this on recreation, it cannot be concluded that irrigation is the source of the association between social benefits and certain areas of green space. Non-irrigated parks demonstrated a strong association with environmental benefits such as enjoying nature, which may be due to the high level of use along the largely non-irrigated Linear Park. Interestingly, two of the key parks within the Council area for facilitating environmental benefits and mental health benefits were Torrens Linear Park and Thorndon Park. Whilst these two parks are of differing park type: linear park and community park; and whilst one is largely non-irrigated and one is largely irrigated; they do share one defining feature, and that is the presence of a body of water. Future studies should explore the importance of these features to park-based physical activity and benefit attainment in South Australia. The state’s warm, dry weather could mean that rivers and reservoirs, such as those contained in these two parks, are of increased importance to the community

The literature review and empirical investigation provide some insights into the benefits of urban greenspace. While only associations between irrigation and physical activity levels at this scale of research project, it provides a basis for recommending further research into the influence of irrigation on physical and mental health, controlling for differences in other attributes, such as park type, park size, and the presence of water bodies. In particular it is suggested that the experimental protocol in future research specifically control for different park types and irrigation levels, using paired park types across an LGA. This would necessarily require agreement from the Council to irrigate areas according to a carefully negotiated protocol to examine the changes in physical activity and overall park usage. This would allow the researchers to isolate the effect of irrigation on the population in terms of physical activity levels, benefit attainment, community satisfaction, etc. Non-irrigated green space could be re-irrigated to examine the importance of irrigation to park use.

 

Water Smart Cities Increase Irrigation to Provide Cool Refuge in a Climate Crisis

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1029/2020EF001806

 

Irrigation to Support at Risk Urban Fauna. Irrigation to Support at Risk Vegetation

The targeted use of water in the urban environment is a viable management strategy to actively mitigate heat waves and general summer heat for the benefit of urban animals, vegetation and humans. Irrigation as a heat mitigation strategy is relevant to all towns and cities, including those in low rainfall, arid environments, if alternative water sources can be secured to replace potable water.

Few studies have tested the efficacy of irrigation for the benefit of fauna in urban greenspaces. However, there is ample evidence that relatively small increases in air temperature during a heatwave can negatively impact faunal physiology, behavior, and lead to mortality. Therefore, if targeted irrigation of urban greenspace habitats can decrease air temperatures by 1°C–2°C, this can reduce thermal stress and mortality of vulnerable urban fauna. Irrigation to provide “cool refuge” can be targeted to the habitats of vulnerable fauna so that the intervention is logistically feasible and cost effective.

Making use of stormwater or recycled water to irrigate remnant or valued urban vegetation should increase their resilience to drought and heat. However, the occurrence of plant water stress should not be assumed, but instead tested before investment in irrigation interventions, as there are many reports of mature urban trees that are not directly water stressed even in summer heatwaves and extended droughts. Where water stress does limit urban vegetation survival and growth, irrigation with non potable water sources is a viable mechanism to mitigate extreme climate events.

 

Irrigation to Support Residential Communities

Norton et al. (2015) suggested irrigating urban greenspace to enhance atmospheric cooling effects in Australian cities if evapotranspiration is limited by soil moisture and vegetation experiences water stress

 

Evapotranspiration from Green Infrastructure : Benefit, Measurement, and Simulation

https://www.intechopen.com/books/advanced-evapotranspiration-methods-and-applications/evapotranspiration-from-green-infrastructure-benefit-measurement-and-simulation

The cooling effect of the green roof highly depends on its roof coverage and the substrate moisture content. Irrigation can improve the cooling performance of green roofs by enhancing ET [39]. Under well-watered conditions, the nighttime air above green roof can be even colder than the cool roof, though the reverse may be found during the daytime [42, 44]. With unrestricted irrigation, green roof has a comparable cooling potential as the white roof, but green roof becomes less effective when only sustainable irrigation (harvested roof runoff) or no irrigation is available [45].

 

Barcelona green infrastructure and biodiversity plan 2020

https://ajuntament.barcelona.cat/ecologiaurbana/sites/default/files/Barcelona%20green%20infrastructure%20and%20biodiversity%20plan%202020.pdf

There is sufficient non-domestic water to be allocated to irrigating parks and gardens: 12% of green spaces are irrigated using groundwater; 52% of all irrigation is automated.

 

Positive environmental (and landsaping) impacts as a result of responsible irrigation

 

https://blog.urbanscape-architecture.com/positive-environmental-and-landscaping-impacts-as-a-result-of-responsible-irrigation

When we analyzed all the massive data, and included all the knowledge in to new landscaping designs, the positive results were expected but we all were surprised. Nobody has expected that implementing new findings can bring even up to 50% irrigation water saving in the top summer months where temperatures were superseding 50°C (120F) not to mention positive visual effects that could be seen when same irrigation protocols were used and we have only differ the landscaping design itself.

 

Meeting the water needs of urban green spaces in a sustainable way

https://www.igb-berlin.de/en/news/meeting-water-needs-urban-green-spaces-sustainable-way

Urban green is important – for recreation, micro-climate and biodiversity in cities. But there is no green without blue: water is essential. Urban green spaces are increasingly suffering from persistently warm and dry periods. Even in temperate latitudes such as Germany, precipitation amounts are decreasing while evaporation rates remain high, increasing irrigation needs. An IGB team has therefore analysed the water consumption of common urban vegetation in Berlin.

Soils under trees are particularly dry, which is mainly due to the high water demand of urban trees. In addition, there are interception losses from the canopy. To counteract future water stress as a result of several consecutive drought years, sustainable irrigation management will be required. While grasslands show high evaporation rates in the upper soil layers, they also promote rainwater infiltration, which can provide moisture to the soil and contribute to groundwater recharge.

 

Irrigation of Urban Green Spaces : a review of the Environmental, Social and Economic benefits

https://www.researchgate.net/publication/237387268_Irrigation_of_Urban_Green_Spaces_a_review_of_the_Environmental_Social_and_Economic_benefits

Urban green space impacts significantly on the micro-climate of a region by modifying extremes of climate, improving the hydrological cycle and improving plant health and biodiversity and adding to soil stability. Most of these advantages are dependant on the vegetation being maintained by irrigation during drought.

Urban parks and golf course can be important ’hotspots’ of biodiversity in cities. During drought, irrigation of these areas can provide an important refuge for fauna.

The lack of irrigation has caused the condition of sports grounds to decline significantly to  the  point  where  some  are  not  able  to  be  used  due  to  the  injury  risk  to  players. Contrary  to  the  implied  value  of  ‘saving  water’  that  dominates  popular  thinking, maintaining  urban  green  areas  such  as  public  parks,  private  gardens  and  sporting ovals  in  the  face  of  water  restrictions  and  rapid  urbanisation  is  necessary  for  the physical, psychological, emotional and spiritual needs of a healthy community.

Maintaining  grassed  areas,  through  irrigation,  around  buildings  can  provide  a  higher albedo surface than many low albedo surfaces, such as bitumen.

Trees also modify the way water moves throughout the urban catchment. Increases in the canopy cover of vegetation can reduce urban run-off. In Ohio, a 22% increase in canopy  cover  resulted  in  a  decrease  in  run  off  by  7%  (Shepherd  2006).    Irrigation during  prolong  droughts  is  required  to  maintain  such  canopy  cover  and  slow  run-off during eventual periods of heavy rain.

Without  urban  green  space,  the  urban  environment  may  encounter  very  large  soil stability  problems  such  as  dust  and  sediment  loss.  By  maintaining  green  space, stability in the soil is retained. In some cases it may be necessary to use irrigation to maintain this green space resource to prevent soil stability problems.

The contribution of irrigated green space to society can be gauged by examining the golf  industry  in  Australia.  According  to  a  report  titled  The  PGA  Report  prepared  by Ernst & Young, in August 2006, the value of the Australian golf economy was estimated at $2.71 billion. It also estimates that 1.25 million people play golf and 23,000 people are  directly  employed  within  the  golf  industry.  Water  is  a  critical  input  to  golf.  The employment rate, a key social indicator, derived from golf is significant at approximately 200 employees per gigalitre of irrigation water used

The value of irrigation in golf courses can be quantified, in water consumption terms, if the irrigation is deemed essential for revenue. A semi private club with an income of AU$800,000 and a water consumption of 100ML, can be quantified as a gross return of AU$8,000 per ML (Connellan 2007).

This research paper has revealed that water restrictions and reduced urban irrigation  has contributed to a decline in urban green space and may have a significant impact  not only on the environment but also the public health of Australian society.

Urban irrigation may also have a significant role to play in maintaining a sense of social  equity  in  Australia  as  the  divide  between  ‘rich  and  poor’  widens.  There  has  been  evidence  presented  in  the  above  paper  that  suggests  that  the  provision  of  green  irrigated  spaces  in  low  income  areas  has  a  positive  impact  on  the  rate  of  domestic  violence, juvenile delinquency and crime. Green space therefore not only provides an  aesthetically  pleasing  environment  for  residents  where  they  can  exercise,  ‘relax’  and  maintain a sense of community but also reduces the costs associated with delinquent behaviour and property damage.

 

White roofs and more green areas would mitigate the effects of heat waves in cities

https://www.uab.cat/web/sala-de-premsa-icta-uab/detall-noticia/white-roofs-and-more-green-areas-would-mitigate-the-effects-of-heat-waves-in-cities-1345819915004.html?detid=1345843400536

Despite the reduction in temperature in all the scenarios studied, the thermal regulation resulting from the combination of the two strategies (white roofs and green areas) is the one with the greatest impact. “It combines the benefits of reducing the temperature at nighttime due to more urban green areas, with the reduction of daytime heat due to the increased albedo and irrigation, thereby abating the heat wave effects throughout a 24-hours period”, explains Sergi Ventura, co-author of the study. He adds that white rooftops lower the temperatures in the central and denser urban areas, while parks help to reduce the heat in the areas closest to them.