Soluciones basadas en la naturaleza en la quebrada Caupicho

Nature-based solutions for urban resilience

Implementation in the Caupicho stream, Quito (Ecuador)

The World Food Programme (WFP) in Ecuador implemented the PRORED Project "Strengthening the Capacity of Local Governments in Disaster Risk Reduction and Preparedness with a Focus on Food Security and Gender in Densely Populated Urban Centres", with the objective of defining and implementing priority measures in seven municipalities in the country, including the Metropolitan District of Quito (DMQ).

In Quito, the intervention site is the Caupicho stream, in a still open stretch located in the south of the city, at the edge of the municipal park of the same name. The Caupicho stream connects to the Machángara river at this site where there are several city-scale water management infrastructures. The stream suffered from a lack of maintenance and had a very low drainage capacity, which made the area swampy and prone to flooding, as well as being invaded by grass, which impeded the passage or any use of the area. There were multiple contaminations, either by solid waste or wastewater discharges. Access to the park was informal and dangerous, and the stream was perceived as a barrier between the park and the city. These problems generated a rejection of the stream by the community.

 

 

 

CONTEXT

 

The aim is to restore the stream and enhance its value with nature-based solutions to raise community awareness of the importance of its existence and proper functioning within this sector. It is also to show the need to recover these natural components in the face of climate change as solutions to improve the resilience of the city.

 

The process of defining intervention strategies and designing solutions for the limited time of the project was carried out through an agile process. Working with the direct neighbours of the area and with the technical implementation teams, this allowed the proposals to be adjusted effectively during the implementation phase.

 

Eight types of devices were implemented, with the aim to establish experimental bases with nature-based solutions (NBS) that could be replicated on a larger scale. These techniques are all low-cost, robust, constructible with locally available materials, based on or inspired by nature to manage water, introduce vegetation and facilitate access.

 

The devices are arranged as a connected system on a 1:1 scale that seeks to demonstrate how nature works as a team and that each solution needs the other to function properly. The interventions propose local solutions, however it is necessary to complete them with a larger scale work in the whole stream so that the impact would be higher, especially in terms of water quality.

 

The system starts at the access to Caupicho Park along the street parallel to the stream.  The whole area was resettled, clearing was carried out along the creek, the creek was cleaned along the entire stretch of intervention, water sources were identified and routes of this underground water to the stream were formalised. Areas were defined which, due to their vegetation value, should not be intervened, considering these areas as islands of biodiversity. In this intervention it was also established as an objective not to generate waste and to reuse everything on site.

 

The devices are connected by a pedestrian route through the entire intervention area, generating a promenade that can raise awareness among users, neighbours and visitors to the sector.

 

1. Drainage ditches

Ditches were implemented at the entrances to the site from the park and from the side streets to capture and organise the flow of runoff. Two ditches were implemented in areas where runoff generated flooding problems in neighbouring houses.

 

 

2. Flow dissipaters

The stream was clogged with sediment and vegetation along its entire open stretch, preventing proper drainage of runoff water (and discharges) and causing local flooding that affected neighbouring houses. It was then necessary to channel the canal to ensure a controlled flow of water. This also led to an acceleration of the water flow in the channel, so it was necessary to implement barriers that slow down the flow and also pond the water thanks to small dammed areas.

The dissipators are microstructures implanted in the bed of the stream drainage channel that slow down the flow, allowing a gradual flow of water during rainfall peaks, and allowing part of the water to infiltrate and evaporate.

 

 

3. Lombrifilters

Lombrifiltration (or vermifiltration) is a wastewater treatment technique using earthworms. It is a robust, simple and proven technique (and already experimented in Quito, cf. the INNOQUA project) which allows treated water to be discharged into the stream, in compliance with Ecuadorian standards. Two lombrifilters were implemented to treat water from two houses adjacent to the stream for which connection to the sewerage system was not possible. These devices were intended to represent two cases that can occur in streams: houses that cannot connect to the sewer because they are lower than the level of the sewer or houses that do not have a sewer to which they can connect.

In the first case the lombrifilter was implemented in a space that can fit within the area of a sidewalk, collecting water from a typical family.  In the second case it was implemented in a natural space at the exit of the house in a place that can simulate a rural area.

 

4. Pedestrian footbridges

Three footbridges were implemented to facilitate access to the park. It is particularly important that the stream is not seen as a barrier in the urban environment, to avoid the need for it to be filled in by neighbours. For this reason, these formal accesses were implemented at each street mouth, ensuring safe, formal and dry accesses. A metal structure and vacuum-pressure treated local pine wood were used for exterior use. In the process of implementing the footbridges, the neighbours requested that no handrails be placed, as cows, goats, motorbikes with loads or bicycles pass through here.

 

 

5. Tiny forest

In order to participate in the protection of local urban biodiversity and to create space for insects and small birds, we experimented with the implementation of a  tiny forest using the Miyawaki technique, which rapidly achieves higher levels of tree growth, CO2 storage and habitat generation for biodiversity. This technique is based on good soil preparation and dense planting of diversified trees. In the case of Caupicho, mainly native trees are used. These tiny forests also limit access to private areas and were planted as vegetation barriers in areas where the route required them at the request of neighbours.

 

 

6. Rain gardens

The eastern entrance to the park suffers from recurrent flooding, preventing pedestrian passage as the way becomes a stream. One of the causes lies in the significant flow of runoff water from the entrance road that discharges at the bottom of the walkway into the park. While the walkway implemented seeks to ensure a dry passageway, rain gardens were also implemented to contain this runoff water. The three implemented gardens are formed as landscape elements integrated into the park. They are fed by drainage ditches implemented transversally along the downstream path intercepting the runoff flow. The gardens are planted with decorative vegetation resistant to temporary flooding, which with their roots ensure good permeability of the substrate. These devices allow in fine the retention, infiltration and evaporation of runoff water, reducing and time-delaying the discharge of water into the river downstream.

 

 

7. Hugelkultur Bed

With the aim of reusing the sludge and earth extracted during the cleaning of the canals (and thus avoiding its discharge as waste), mounds were configured as landscape elements inspired by permaculture beds (Hugelkultur beds). The base of these mounds is made of tree branches (in this case from fallen trees in the Caupicho park that could be recovered) and is completed, in addition to the sludge, by soil and vegetation. The proposed form has a landscaping objective, to animate the lower part of the park at the eastern entrance and to avoid approaching the existing unsafe infrastructures. These mounds are located in an area of recurrent flooding and allow rainwater to be retained for temporary infiltration while the large infrastructures are being discharged.

 

 

8. Slope trees

Trees were planted on the edge of slopes that present a risk of landslides along the ravine. The trees provide a natural physical support for the slope, thus reducing the risk of landslides.

 

 

 

 

 

 

 

 

 

 

 

The implementation took place from August to October 2022 and was inaugurated with the community shortly after with a process of sensitisation to the protection of the stream and the use of natural techniques to manage water for municipal technicians and neighbours. A monitoring process of the solutions is underway in order to evaluate the contributions of each technique and the evolution of the site, both in its environmental and social aspects.

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Caupicho stream prior to intervention(YES Innovation, 2022)

Drainage ditch implemented at the entrance of the site to discharge into the stream channel (YES Innovation, 2022)

Water flow dissipators before, during and after a rain event in Caupicho (YES Innovation, 2022)

Lombrifilter implanted at the entrance of the intervention area.(YES Innovation, 2022)

Pedestrian footbridges implemented to facilitate access to the park (YES Innovation, 2022)

Rain gardens fed by drainage ditches transversal to the road (YES Innovation, 2022)

Hugelkultur beds implemented to recycle onsite the sludge extracted from the canal (YES Innovation, 2022)