THREE RIVER SEQUENCES
SCOTLAND - FRANCE - ITALY - SPAIN
ARQUITECTA Y ARQUITECTA DEL PAISAJE
ARQUITECTA Y ARQUITECTA DEL PAISAJE
LANDSCAPE ARCHITECTURE COLLECTIVE,
01_BASIN SCALE STRATEGY
The landscape of the Andalién River Basin presents itself to a contemporary viewer as having been fundamentally altered by anthropogenic change. This accelerated degradation combined with challenging climatic factors and socio-ecological conditions has led to issues manifesting themselves throughout the basin: erosion, flooding, drought, forest fires, pollution, poverty and loss of biodiversity.
72% of the basin consists of four key problematic landscape typologies which contribute to these issues: monoculture on eroded slopes, monoculture on non-eroded slopes, Burned native/non- native forests on eroded slopes and burned native/non-native forests on non-eroded slopes. A fire management regime of low intensity, high frequency controlled burning should be tailored and implemented for each of these four problematics to restore fire as an accepted element of the ecosystem. A fifth key problematic, or to put it more accurately, an underutilized resource was identified, the River Andalién, its tributaries and its associated native scrubland. These five problematics broadly encompass the three objectives of the basin scale strategy: to address fire, water and socio-economic issues.
The holistic view of the basin strategy is to provide viable alternatives to the plantation industry which currently dominates the land use of the basin area; a distinct strategy was formed for each problematic. Intertwined with new sustainable industries, such as agro-forestry and agricultural terracing, is the re-stabilization of eroded slopes (or anticipated eroded slopes of burned Eucalyptus) through bio-engineering techniques such as contour bunding and live fascines of deep-rooted native species. The proposed thinning out of moisture-monopolizing Pinus radiata and Eucalyptus sp. would be replaced with humid, native tree species to restore healthier habitats for local fauna and the installation of retention trenches would store water in the soil for the drought-affected uplands.
The flood management of the River Andalién would see the introduction of a dense riparian buffer which strategically routed tributary streams to the main river, allowing the stream to create its own meanders and leave dead wood from the forest to restrain the flow upstream. This new riparian structure provides the basis for river parks with recreation trails for hiking and cycling promoting activity and tourism, particularly amongst the extended Nonguén native scrubland.
The proposed solutions consist of both physical interventions and changes in land management techniques to conduct the basin and its inhabitants, human and non-human, towards a better equilibrium.
The scale of the hydrological, urban and arboreal issues facing Conception allows us to go further than just treating technical problems but also gives us the opportunity to re-compose a landscape, creating new spaces, connections and relationships. The primary objective for this scale of intervention is to transform the relationship the city has with water. Due to the hydrological work done on the basin scale, the flood risk for Conception is dramatically reduced, allowing for a resilient floodable park that borders the city.
By creating this large continuous park system, three previously divided zones of conception are linked. The Andalién river is given space to overflow, bend and meander forging a diverse undulating landscape running from the zone of new urban expansion in the east to the Delta landscape by the sea.
The river is the key actor within this rich sequential waterscape, re-associating the existing urban frame of conception to the river, morphing a new district and enhancing the remarkable and now heavily protected Delta landscape.
The new riparian edge of the Andalién works as a flood buffer whilst also ensuring an ecological and arboreal continuity between the river and the urban zones. This vegetal network works symbiotically with hydrology and bleeding out from the Andalién binding existing green spaces and anchoring the new district in a large landscape frame. Accessibility to this large park is provided to the citizens of Conception in all seasons and across all flood scenarios via a system of paths, elevated boardwalks and pedestrian bridges which span the entire park. These walkways afford new views of across the landscape, providing opportunities not just for accessibility but also for education.
Composition of Geometries Constructing with and by water
The construction of 2000 new homes by 2033 as part of the expansion of Conception is the occasion to re-think the relationship between the city and the river.
The expansion anchors itself in its wider urban context by borrowing from the city’s existing grid layout and by similarly aligning itself with the river. This grid is however re-interpreted and abstracted by its superposition with the primary geometry, the re-enforced natural meander of the Andalién. This superposition creates pockets of wetland, bordered by agricultural plots and sports fields which are floodable in severe conditions, in turn protecting the city. This three- tier system allows the river a freedom to flood whilst also ensuring inhabitants a safe livable environment, one which is in harmony with water.
03_SITE SPECIFIC CHALLENGE
The Collao-Las Ulloas area is one of the main areas with the highest expectations of urban development, even with the obvious flood risks it currently presents. We approached the challenge of housing 2,000 homes in the area, from the starting point of recovering the water courses that in previous times had populated the area and in turn increasing the water capacity of the courses associated with the Andalién River.
This strategy allows us to position all housing units in a safe position without the need to fill alluvial terraces or wetlands. On the contrary, we try to emphasize the existing wetlands connected to the recovered watercourses, and turn them into micro flooding units. Regarding the Andalién river itself, an expansion and softening of the margins of the river is proposed through bio-engineering techniques such as coir logs and fascines.
We propose 3 zones defined basically by watercourses. The first, more related to the river, will be the most prone to flooding and will offer opportunities for enjoyment in contact with the riverbank nature. The second, also flooding in cases of extreme flood of the river, will house recreational activities of both urban and sports agriculture. To finish, the urban plot is available in a non-flood zone, following the orthogonal grid that comes from the historic center, although distorted by existing elements and water courses. With the intention of reducing the area occupied by urban development, an average height of 3-storey buildings is proposed, with differentiated compositions to accommodate different types of families, and flexible structures for future alterations promoted by the inhabitants. The multi-family buildings are positioned in such a way that they generate courtyard spaces with the intention of promoting community life and green spaces. Services such as schools, markets and other services are distributed to be able to serve the majority of houses equally, always linked to the main streets and most emblematic points.