Green space as alternative infrastructure

Look closely at the fabric of any world city and you will find pockets of open space scattered amongst the urban sprawl. These open spaces contribute towards the liveability of a city environment and from the Central Business District to the suburbs act as a hub for human scale activity.

With increasing pressure to densify development within built-up areas open spaces have often been targeted as opportunities for development due to their prime locations and low redevelopment costs.

Figure 1: An example of an urban park in Riyadh.

Instead of losing these open areas to new development Buro Happold believe it is essential and hugely beneficial to safeguard these spaces and to improve them so they can play a key role in the city’s green infrastructure network. Furthermore, cities should aim to connect these green networks with the wider city utility, drainage and transport networks.

Densification and greening of cities can co-exist! All over the world, green spaces in urban areas have been shown to provide significant improvements to the liveability of cities.

With our experience of working in Riyadh we know that the value of urban open space is no different in the Saudi environment than elsewhere. In this environment a great example of a high-profile and high-quality urban open space is Wadi Hanifah, located to the west of the central part of Riyadh city. From our experience with the regeneration of Wadi Hanifah we can break down the key benefits of urban green space in this environment as follows:

•  Improved recreation space for those that have limited choices – large visitor numbers to Wadi Hanifah throughout the week show that good quality recreation space is at a premium in Riyadh.

•  Improved urban biodiversity – the Wadi is home to variety of vegetation species and shows increasing birdlife.

•  Improved management of locally generated stormwater – the Wadi receives stormwater from the city and by conveying stormwater out of the urban area reduces the risk of flooding to other parts of the city.

•  Mitigation of heat island effects – the Wadi environment provides shade and reduced density of heat absorbing surfaces, resulting in a more pleasant environment.

•  Improved citizen perception of cities – the Wadi is popular with residents throughout the city; its value to the city is understood and residents take pride in the quality of the Wadi environment.

•  Improved health and wellbeing – residents use the Wadi for walking, running, cycling and for relaxing in the evenings and weekends. The Wadi provides an opportunity for family events and there is good use of the picnic sites.

•  Improvements to property values – the neighbourhoods adjacent to the Wadi are seeing increases in land values as a result of their proximity to the Wadi and this in turn is contributing to the development of new property along the Wadi corridor.

Figure 2: Al Ilb Dam Park, Wadi Hanifah, Riyadh.

The success of Wadi Hanifah shows that urban green space can not only be successful in an arid environment such as Riyadh, but when delivered to a high-standard becomes a defining character of the city environment. Wadi Hanifah now has its own identity. Buro Happold believe that it is possible to build on this success story and extend the character of Wadi Hanifah into the urban areas of Riyadh through a green infrastructure network so that some of these desperately needed benefits can be delivered at a local neighbourhood scale.

Buro Happold and Barton Willmore have supported the Arriyadh Development Authority in investigating the opportunity for improving the network of green space in Riyadh and adopting a dual or multi-use approach to improve the contribution of these spaces to the management of stormwater within the Wadi Alaysan sub-catchment. The Wadi Alaysan sub-catchment along the eastern bank of Wadi Hanifah covers an area of the city which is expected to experience significant increases in urban land cover over the next 10 years in its upper reaches.

Figure 3: Location of Wadi Alaysan catchment and Junction 8 in relation to Wadi Hanifah and Riyadh City.

The study proposed storage and attenuation of stormwater in new and retrofitted public parklands in the urban environment in an effort to reduce the impact of disruptive upgrades to existing stormwater networks as the city expands and densifies. The strategy showed that an urban network of green space could address existing surface water flooding and address the needs of the catchments into the future, including both densification and the effects of climate change.

Buro Happold has also worked with the Riyadh Municipality to develop green infrastructure solutions for mitigating the flood risk to key road junctions such as Junction 8 between the Eastern Ring Road and the Northern Ring Road. In this case, attenuation and storage in public neighbourhood parks and undevelopable land in the catchment contributing to flooding at the junction was proposed to increase the standard of service of the drainage network from the 1 in 10-year event closer to the desired 1 in 50-year standard. This included the innovative use of otherwise undevelopable land beneath HV power cable corridor.

Figure 4 :Sketch of possible stormwater attenuation area within electrical corridor, Riyadh, from the Wadi Alaysan Stormwater Strategy, Buro Happold and Barton Willmore.

As well as dealing with stormwater management during severe rainfall events, the role that these open spaces can play in contributing to increased recreation space for the city’s residents was a key consideration for the Arriyadh Development Authority and the Riyadh Municipality. It is accepted that Riyadh as a city would benefit from more urban green space and measures are already in place to address this through the development of the Wadi Sulay corridor to the east of the city. A study by Almayouf*1 estimated that Riyadh provides approximately 0.86m2 of green space per city inhabitant, which is significantly less than other GCC cities such as Dubai (2.49m2) and the World Health Organisation recommended standard (9m2).

Figure 5: Green space per inhabitant in the GCC vs WHO Guidance, based on Almayouf[1] .

The long term approach for addressing this shortfall will require changes to urban planning policy and guidance, and will need to become enshrined in planning regulations, including the adoption of a formal designated land use for stormwater management. It is anticipated that these changes are likely to be more medium and longer term, but the use of green open space as a form of infrastructure can provide planners with an effective means of meeting the much needed improvement in green space. By demonstrating the benefit of this approach, we believe that green infrastructure can have an immediate impact in the expansion of the city.

In both of these Riyadh examples, Wadi Alaysan and Junction 8, not only do the individual pieces of green space provide valuable benefits to the open space and recreation network of Riyadh but they also form part of the overall stormwater network required to manage runoff during periods of heavy rain. The Arriyadh Development Authority and Riyadh Municipality understand the value of allocating space to land uses that contribute multiple benefits to the wider city and the potential for city-wide applications.

In the current economic environment where public sector capital expenditure is increasingly constrained, perhaps one of the most compelling benefits to City Government is the significant and proven financial savings that green stormwater infrastructure provides when compared to conventional hard engineered ‘end of pipe’ solutions.

Preliminary costing of the approach for Wadi Alaysan suggested that the strategy would have a similar order of magnitude cost to more conventional drainage solutions proposed to manage the stormwater demand, but with the added benefit of providing open space within the budget. In the case of Junction 8, the relative costs were much more in favour of the green approach.

Perhaps green is the alternative infrastructure we should be investing in.

References:

[1] Almayouf, A., 2013, Preserving the green in hot-arid desert environments: the case of Riyadh, Saudi Arabia, J King Saud University, Vol 25, Arch & Planning, pp 39-49.

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