_GRADUATION WORK_ by Dirk Harden and Jeroen Castricum
In the 21st century, the ongoing process of urbanization will result in many new challenges in the field of landscape architecture. Strong urbanization forces many metropolises around the world to explore their boundaries for growth. When urban growth is informal, uncontrollable due to a strong influence of the economic market or reinforcement of legislation is insufficient, the growing metropolises will consume their surrounding landscape. This landscape provides many resources and services for the inhabitants of a city, and was initially the main reason for founding the city at its specific location. Jeroen Castricum and Dirk Harden researched how landscape architects can contribute to the issue of preventing growing cities from reducing its living standards by urbanizing their surroundings.
All images © Dirk Harden and Jeroen Castricum
In this project the rapidly growing metropole of Istanbul is studied. The aim is to develop new design strategies for protecting resource landscapes in the vicinity of unplanned, rapid growing metropolises like Istanbul. To illustrate how landscape architecture can be used, a new neighbourhood will be designed following these strategies. The largest challenge was to get a grip on the rapidly changing landscape of the Istanbul province. The project was inspired by the vision of H+N+S Landscape Architects for the Sazlıdere basin in Istanbul. This vision shows that landscape architecture is able to provide strategies for the protection of the landscape’s water resource, while urban growth is able to continue (H+N+S, 2011).
In Istanbul, pollution caused by chaotic and unplanned urbanization threatens the water quality in the city’s surrounding water basins (dammed watersheds with lake reservoirs) that provide clean fresh water for the city. In fact, two problems meet at the same time. First, the already limited amount of fresh water is expected to be insufficient for the growing city. Second, pollution caused by new developments in the basins will reduce the usability of the city’s water resources (Çdur et al., 2007). Therefore, the growing city is cutting its own lifelines.
The vision for the Sazlıdere basin shows us a possible solution to protect the fresh water resource, while urban growth is allowed (H+N+S, 2011). The landscape of the Sazlıdere basin is characterized by extensive agriculture. In contrast, many other basins around Istanbul are characterized by large forests. Together, these forests form the forest belt of Istanbul, which provides many services and resources to the city: i.a. recreation, climate control, and the provision of many different materials. Above all, the forests purify rainwater, which is collected in the reservoirs of the basins. From the perspective of the fresh water resource, forests are very important to preserve.
In this project, the focus is on the forested Alibey basin, which is situated east of the Sazlıdere basin. Like in the Sazlıdere basin, water quality is threatened by unplanned development in the municipality of Arnavutköy. This municipality is strongly influenced by development of the Istanbul metropole. Arnavutköy is situated on the ridge of the two basins.
Considering the city as a complex adaptive system, dependent on resources provided by the landscape, the Istanbul province is studied. It appears that ‘magnets’, which are often part of the city itself, can describe the behaviour of the growing, unplanned city. The defined magnets are spatial elements that guide and organize urban growth. In this project we consider i.a. facilities, highway exits, waterways, bridges, scenic landscapes, but also disrupted or empty landscapes without a visible function, which can attract urban growth.
Scientific literature did not only confirm the attracting effect of certain spatial elements. Literature also reveals a repelling side of magnets: spatial elements that repel urban development from a landscape. These can be spatial elements that educate people about the importance or the function of a certain landscape. Likewise, multifunctional and accessible landscapes can create support for protection by involving larger groups of people. By making clear borders, people are more likely to accept nature.
This project investigates how attracting and repelling magnets can be used in design to steer unplanned development, in order to secure a city’s fresh water resource. Urban growth is considered here a development that has to be included in water resource protection: interventions for improving water quality, together with the involvement of urban development to create support for landscape protection, will protect the water resource while urban growth is allowed.
Attracted urban development
Cosidering magnets, it is interesting to know what kinds of development are attracted in the forested Alibey basin. A study on the connection between the kind of urban development and the presence of certain magnets revealed that gated communities are most likely to develop in the forested areas of the Alibey basin. In the Istanbul province, this kind of isolated high-class development is attracted by scenic landscapes, earthquake safe areas, and is located near highway exits. In comparison to other kinds of urban development, gated communities appear more frequently on acquired state property, which contains the majority of the water purifying forests. Given that these developments do not provide solutions for fresh water protection, gated communities are a substantial threat for water quality in the basin.
Vision for the Alibey basin
To protect the water resource, the existing forest has to be protected. This means that high-class developments have to be repelled from the forests. Instead, this kind of development has to be promoted in non-forest areas that also contain the appropriate magnets, but where development can be used to increase water quality. Here, the former mining areas come to light, which are very common in the North of the Istanbul province. These disrupted areas are very close to the scenic forests, and are often a scenic landscape in itself. These lands are characterized by their empty appearance and strong erosion due to slow vegetation development. On top of pollution by unplanned urban development in the basins, erosion is an additional threat for water quality. High-class development can be used as a motor to stimulate revitalization of disrupted landscapes in order to improve water quality. In order to do this, high-class developments have to be designed in a new way. By adding new magnets to the former mining areas the landscape can become more attractive for high-class development, water quality can be improved, and the existing waterpurifying forests be preserved.
A disrupted project area
A project location is chosen in order to investigate how magnets can be used to combine the protection (and improvement) of the water resource with urban growth. It is the former mining area in the north of Arnavutköy. This area is surrounded with magnets that make the area very attractive for high-class development: nearby facilities of Arnavutköy, a near highway connection to Istanbul’s business centers, scenic forests, more planned highway connections, and a planned airport. Besides this, the area is a unique scenic landscape in itself: the man-made landscape is characterized by many lakes with steep cliffs on the forest edge. However, the scenic landscape is endangered by constructi on waste from the city, which is dumped into the lakes. Between the lakes and the city of Arnavutköy a dump truck landscape can be found: a hilly landscape with small ponds, created by dump trucks that used to dump leftover material from the mines. The area is characterised by a centripetal water system: the lakes collect the run-off water from the surrounding landscape. From the lake there is one out flowing stream to the main stream towards Alibey reservoir.
A revitalized water landscape protected by urban growth
By using a model of one of the centripetal lakes, the design steps are explained above. These steps have been applied to the former mining landscape, resulting in the plan map. Magnets like infrastructure, facilities, prepared plots, and public spaces that will attract development are located in potential urban areas, more close to the urban area of Arnavutköy municipality. In this way, first developments can be close to the facilities of Arnavutköy, as well as have a view on the scenic landscape. By placing the first magnets here, the development will start to grow from the ridge of the different centripetal lakes. This gives the option to keep an eye on the water quality when development continues down the slope.
For one of the centripetal lakes, a detailed design is constructed. The form and location of the different water retention and water purification elements is based on the underlying dump truck landscape. The steep slopes in the underlying landscape are also used as a guide for a large retention wall that creates a readable border of the potential urban area. Vegetated earth-banked terraces are used to promote vegetation development and soil development, which will purify the water. New high-class urban development can profit from the near recreation area, and the scenic landscape with lakes and cliffs can be maintained. At the same time, the water resource provided by this landscape is better protected by support of the new neighbourhood. Spatial elements that attract urban development, like public squares with reserved space for facilities, have been designed on a smaller scale. This illustrates the possibilities of the constructed water landscape for creating an attractive neighbourhood with a lot of green public space, where ecological understanding can arise. Here, stone retention walls and drains can be clear borders, which can be designed in order to define the public spaces. Water flows are visible in the drains, while retention ponds create wetter places. At those wetter places trees are able to grow, to create shade, and to improve the quality and permeability of the soil.
Landscape architecture for guiding urban growth
By investigating existing magnets for development in an area, future developments can be predicted. This project shows that by adjusting and adding magnets that repel and attract development, and by adding readable borders, urban developments can be steered to give room for a valuable water resource. Landscape architecture can provide the unplanned growing city with site-specific solutions for revitalizing landscapes, while allowing urban growth. By landscape design, people can be involved in the protection of the water resource. Innovations in architecture and urban design can further increase the possibilities for living in a recovering water resource landscape. In Istanbul, it is crucial to promote the collaboration between water authorities and project developers to realize neighbourhoods that protect their fresh water resources.
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