A strategic intervention for the recovery of Jaboque wetland in - Wetlands on the edge

A strategic intervention for the recovery of Jaboque wetland in Bogotá - Colombia

POLITECNICO DI MILANO

Scuola di Architettura e società Master of science in Urban Planning and Policy Design Academic year 2011 - 2012

JUANA MARCELA LEAL SIMBAQUEBA Matricola: 766713

THESIS SUPERVISOR: EUGENIO MORELLO “If you want to build a ship, do not call people togheter to provide the pieces of wood, to command and to do the work, but call them on the desire to the spacious and endless sea”

Antoine de Saint-Euxpéry Abstract

The global awareness of urban wetlands as areas where crucial issues as urban growth and policies against climate change overlap, must be addressed with critical urgency on developing countries with rapid rates of transformation. The late consciousness about the environmental value of Bogota wetlands have created a rich field of discussion regarding the role of these places in the city, but specially and what constitutes the main purpose of this investigation, the deve- lopment of a vision which could lead to new kinds of physical interventions bet- ween the protected areas and the existing urban settlements. This work aims at recognizing and providing basic principles to guarantee that these physical reali- ties are compatible with the needs of the main natural elements which constitute these ecosystems; for instance, the urban wetlands are intended as places which cannot be separated from human action and presence, and the other way around, human settlements are influenced by the physical proximity of wetlands. Refe- rring to urban ecology principles, wetlands and human settlements are intended as part of the same ecosystem and their reciprocal relations from an urban design perspective is the object of this investigation.

There is a visible polarization among environmental actors which have been wor- king for the recognition of wetlands as protected areas,and public institutions in charge of the management and regulation of these areas as public space.Both perspectives influence and determine the way in which the inclusion of these areas in the city is planned,most of the time with solutions that could be seen as banal as the design or location of a bike path or a simple fence. Furthermore,this situation puts in evidence stereotypical ideas which influence the sort of interven- tions and are responsible for the physical layout of the place.

The urgency of this kind of reflections could be illustrated on the urban transfor- mation of the wetlands.In fact, we can recognize a relation among the dramatic consumption and devastation of soil during the second half of the 20th century and the profile of the settlements which invaded these areas.Degradation and po- verty determined the image of the western border of the city for a long time. Now, that the city has started to intervene and recover these areas and the image of the border has gradually been changing, new urban patterns along the wetlands are emerging. For instance, the appearance of gated communities and twenty storey buildings urge to ask if these could be interpreted as some sort of succession pro- cesses and how these dynamics affect the perception of the wetlands as public space. .A trivialization of the wetlands would mean the loss of an enormous opportunity to create a new border for the city based on new paradigms able to recover values from the existing situation. So far, wetlands have been interpreted in a very simple way; either to get rid of waste, the cause of flooding and disease, and in the best of the cases as potential golf fields or parks, always imposing over them physical transformations according to human needs, forgetting that they already have a vi- tal mission in balancing the ecosystem (drainage, biodiversity and environmental quality in general).

The Jaboque wetland, for its size and location, offers interesting conditions to ca- rry on the morphological investigation in order to define series of principles which explore this new physical dimension, and in particular, the construction of con- cept-plan and master-plan guidelines, aiming at overcoming typical limitations of general and not site-related policies, and finally which could influence actions on other wetlands with similar characteristics. Aknowledgements

I would like to take this opportunity to thank the following people for their contribution to the successful completion of this thesis:

• Politecnico di Milano and Colfuturo, for their support with the continuation of my studies to become an urban planner and a better architect.

• My parents, Consuelo and Javier, for always been here, for their love, inconditio- nal support and trust during this two years.

• My supervisor, Eugenio Morello, for his time and continuity which were funda- mental to achieve the objectives of this thesis in the proposed schedule, for his curiosity with the subject, the respect and trust.

• Natalia and Felipe, thanks for the interoceanic bibliographic support!

• The Humedales Bogotá team, first of all thanks for your commitment and love for Bogotá and its wetlands, but also for letting me be part of your group.

• Claudia Manconi, for being such a good friend since I put a foot in this country, for her generosity, for Chiara and Davide and our Sardegna road trip, for taking a break of your super fancy londonese life and been here to support me once again,

• Juli, for this two years of hard work, all the coffee, tarallini,and library that we have shared. Thanks for been always available and your infectious love for this profession.

• Cata, specially thanks for been here today and for your understanding and pa- tience during this last week, it meant a lot to me.

• Juanito, thanks for your unconditional help, these two years would not be as half as fun without our controversial discussions and the continuous dose of drama .

• Isabel, for your sincere interest, bright remarks and interesting conversation.

• Thanks to all my classmates, from whom I have learnt so much, not just about urban planning, but about the delightful places around the world where all come from. • Thanks to Mariachiara and Mariangela for being such a beautiful human beings and sharing with me this last year.

• Thanks to my friends back home, that are waiting for me with arms wide open and for whom the distance has not ever been an obstacle.

• For all the people who have sincerely been interested in the subject of my thesis and that have shared their opinions, knowledge and advice. Contents

Introduction _ 1

GREEN INFRASTRUCTURE AND URBAN FORM_5

Wetlands _ 7 Urban wetlands. Atributes, problems and values _ 10 Landscape ecology and green infrastructure _ 17 Sustainable urban form _ 22 Resilience _27

THINK GLOBAL ACT LOCAL_ 31

Bogotá’s growth and its urban form _ 33 From ecological structure to green infrastructure? _ 41 Flooding and other environmental issues _ 44 Bogotá’s wetlands _ 48 Engativa and the Jaboque wetland _ 67

INTERVENTIONS ON THE EDGE_85

Expanding the wetland _ 87 Concept plan_ 91 Master plan _ 95 Catalogue of actions_99 Ambits of intervention _108

FINAL CONSIDERATIONS_125

Bibliography_ 129

List of pictures _137 List of figures _139 List of maps _141 Introduction

The geological past of Bogotá reveals that during the Quaternary period, most of its current surface was covered by a gigantic lake (Tunha/Humboldt), which gradually changed its contained condition when a series of climatic chan- ges during the Pleistocene, and some other morphological transformations like the deepening of the “Salto del ” cascade, ended up with the drai- nage of a vast quantity of water. (Calvachi, Guarnizo V2, 31) This transformation is recalled on the oral tradition of the prehispanic population who settled down in the area. The myth tells that people was suffering because downpours and flooding were ruining their crops, all of them sent as a punishment from Chiminigagua, later, thanks to the intervention of god , who using his ma- gic powers, let the water flow through the Tequendama cascade(EEAB, CI Colom- bia, 2000 V1, 157) From ancient times, recognition of water and wetlands on the determined the relation of people with its environment, from their conception of the universe to the solution for basic needs for surviving, there are still traces which let us see the impressive agricultural system that they used to cultivate; “an infinity of canals and elevated fields with patterns of reticular distri- bution doing zigzags in parallel or fish spine shaped patterns, along both sides of the river” (EEAB, CI Colombia, 2000 V1, 159). Beyond that, it shows the high level of anthropization of wetlands since early stages.

The Spanish colonization without any doubt marked a big transformation in the landscape. The foundational center of the city was located on the foot of the eastern Bogotá hills, near the water springs and far from the wetlands, only a few indigenous settlements would remain near them. This first situation would create the first rupture between the city and the wetlands, the lack of a sewage system implied that waste would be throw down the river and disappear in the wetlands, however, at this point damage for the ecosystem was very low, and it was able to recover because the waste was not over passing its charge capacity.

Although the original extension of wetlands before the Conquest has not been calculated, it has been estimated that the remnant surface is situated under a 5% of what it used to be. By the middle of the past century the coverage area could have reached around 50.000 Hectares in the Bogotá’s Savanna, recently it has been estimated that the surface coverage has been reduced to 500 Hectares. (EEAB, CI Colombia, 2000)

1 beneficiario colfuturo 2010 The big transformation occurred during the 70’s, the big masses of immi- grant population who arrived from the countryside, pushed by the internal vio- lence conflicts and looking for a better future, arrived to the city in poverty con- ditions, the first wave would settle down on the city centre, but as this keeps on being a current reality, poor people would locate on the peripheral areas of the city, specially the south and the south west, taking advantage of the low value of land and the urban developments which took place on these areas, many illegal settlements found the occasion also, on the western part, near the river and the wetlands and on the inaccessible hills. The expansion of the city would radically change the relation between the human settlements and its surrounding environ- ment.

Urban wetlands have served to people in different ways, from food reser- voir, irrigation for agriculture, cattle fields after and during the colony, and most recently have been surrounded by industrial developments and flower corps which found there cheap soil to develop their activities and get rid of waste, a deposit for debris in the construction of the rest of the city, that at the same time would help to fill and expand urban soil to supply the housing needs of people arriving to Bogota.

It is difficulto t identify which activity produced more damage to the wet- lands, but there are some facts which let us know the intensity. Extinction of spe- cies for instance, is an indicator of degradation of the ecosystem, per example, among others, it has been documented the disappearance of the “pez graso del lago de Tota” (fish) , the “ Zambullidor andino” (bird), and currently, there are many others under risk of extinction as the “Tingua moteada”(bird) (EEAB, CI Colombia, 2000).

Perhaps, one of the most important signs of the degradation is the image that people has of wetlands, during the first part of the 19th century, people used to have a healthier relation with them, and even if they were not perceived as part of the city, people used to go there to contemplate and carry on activities like fishing, boating, even, there were culinary traditions related with this sites, as the crab soup that takes advantage of this specie which is still present in some wet- lands.

The second half of the century, marked a big rupture and change of image,

2 as they start receiving amounts of waste overloading its capacity of regeneration, bad smells, plagues and diseases start to influence how people gave its back to the area, segregation of people with low income generate a barrier between rich and poor with clear physical boundaries, lack of knowledge about the environmental value and role of the wetlands, uncertainty about the property of regulation of the land. The urban wetlands policy was released on 2006 heavily influenced by the

adhesion of Colombia to the Ramsar convention1.

Although it is not a novelty, during the last decade the damages caused by flooding in areas near the wetlands have made people review the vision of the problem, living in a risk area may be not a good idea, but what about the measu- res taken to mitigate the disaster, how effective have been the canalizations so far. The last two decades have triggered a sort of recognition of these areas and the establishment of duties and regulations on the public sector, but at the same time a wider conscience by the community, however is still very narrow and limited to what constitute the wetland, from the border were the wetland starts and what it is inside, but there is a lack of reflection on what happens on the border and on the strip beyond the border, and this discussion is very important considering that the city will keep on growing and is very uncertain where and how.

To address these issues this thesis has been structured in three main sec- tions; Green infrastructure and urban form is an effort to identify and link those concepts that intermingle around the idea of and urban wetland, furthermore, how these overlaps can provide insights for solutions in order to achieve a coexis- tence, or better and hybridization of two contrasting habitats as are the wetlands and the city. From Global to local is the analysis of those concepts deffined on the first chapter on the particular case of Bogotá, more exactly on Jaboque wetland. Final chapter, Interventions on the edge is the transition from theory of previous two chapters into a series of strategic principles and actions on the physical reality of Jaboque wetland, that can be deconstructed and adapted in other wetlands under similar circumstances.

1. The Ramsar Convention, is an intergovernmental treaty that provides the framework for national action and international cooperation for the conservation and wise use of wetlands and their resources, its mission is “the conservation and wise use of all wetlands through local and national actions and international cooperation, as a contribution towards achieving sustainable development throughout the world”. Colombia adhered to the convention in 1997. Recently, the Ministry of Environment, Housing and Territorial Developmentl, applied the provisions of the Act, based on paragraph 24 of Article 5 of Law 99 of 1993 and by Resolution 157 of February 12, 2004, regulating the sustainable use, conservation and management of wetlands and develop aspects of the implementation of the Ramsar Convention (EEAB, CI Colombia, 2000)

3 beneficiario colfuturo 2010 1. GREEN INFRASTRUCTURE AND URBAN FORM

Wetlands are perhaps one of the most misunderstood and threatened ecosystems in the history of humanity, often related with disease and unproduc- tiveness. Drainage of wetlands was seen most of the times as a step forward in civilization, supported in logics that range from improvements on health and sa- nitation, as happened in ancient Rome during the reign of Emperor Claudio, until economical and political driven reasons, with more recent as the Common Agri- cultural Policies CAP, implemented by the European Union. But probably, one of the most important causes of the destruction of wetlands is the lack of knowledge about the complexity, variety and richness of these ecosystems. This section offers an insight on such complexity, that becomes even more intricate when overlaps with urban realities.

5 beneficiario colfuturo 2010 1.1 Wetlands

First thing to know about wetlands is that “they are found from the tundra to the tropics and on every continent except Antarctica” (EPA,2012). Therefore, it is logic that they are very different one from the other as their circumstances can be so radically different. However there are certain characteristics which all of them have in common: (Marsh, 1991,p 280)

1.The presence of water on the surface, usually relatively shallow water, all or part of the year. 2.The presence of distinctive soils, often with high organic contents, which are clearly different from upland soils. 3.The presence of vegetation composed of species adapted to wet soils, surface water, and/or flooding.

Another definition of wetland, this time, by Watson, provides a vivid description what a wetland might look like and the importance of its attributes:

“Wetlands are a broad category of ecosystems that are supported by water for all part of the year. They include vernal pools, swamps, and fresh-and saltwater marshes. Water can be freshwater, salt water, or brackish. Brackish waters typically characterize a shoreline where there is a saline gradient resulting from location between land and sea, where freshwater seeps and rivers refresh estuaries and coastal waters. Wetlands are a natural habitat for plant and natural life that in turn support the healthy functio- ning and renewal of the wetland systems. Wetlands are essential ecosystems for the control of flooding.

Permanent wetlands are saturated year-round with a stable vegetation community and often a stable water level. Seasonal wetlands fluctuate and may dry out periodi- cally. All wetlands are inundated frequently enough that the root systems of vegeta- tion experience anaerobic (non-oxygen) conditions”.(Watson, 2011, p 38).

From both definitions it is possible to highlight two outstanding characteristics of these ecosystems, which may be severally affected when modified or affected by urbanization processes. The first one is the hydrologic function; “each wet- land can be described as a hydrologic system with inflows and outflows of water” (Marsh,1991,p.281), and as mentioned before its uniqueness; if “the morphology (shape and form) and its position within the landscape greatly influences its char acteristics”(Reinelt,Taylor,Horner, 1997), under anthropization processes they may

17 beneficiario colfuturo 2010 P1.Liminganlahti Bay Area Ramsar site near Oulu, Finland (photo Tobias Salathé, Ramsar). Dec. 2008.

P2. Busanga Swamps, Zambia (Photo: Zambia wildlife Authority)

P3. Narew River National Park, Poland ( Ramsar website)

P4. Gediz Delta, Turkey (photos by Tobias Salathé, Ramsar)

P5. Gosaikunda, Nepal (Ramsar website)

8 become even more particular and at a certain extent unpredictable, reactions expected from a wetland under a certain tension might not be the same as those from another one, vegetation may vary, fauna may vary, water sources may vary and as a logical consequence their pollution thresholds will vary.

The definition adopted by the Policy of wetlands for the Bogotá’s District, recogni- zes such characteristics, especially when recognizes that “this ecosystems are as- sociated with streams and overflow plains, being the reason why biota, nutrients, matter and energy fluxes are adapted to the fluctuations and performances of its associated water systems” and introduces an important element, which was not mentioned in previous definitions, and it is the relevance of human interaction with this ecosystems in a variety of dimensions (historical, social, cultural, econo- mical and political) in order to define its current dynamic and situation (DAMA, 2006). Relevant aspects which differentiate wetlands are taken into account when doing a classification, usually, according to its vegetative cover, hydrologic regime, or physiographic factors , the classification of Bogotá’s wetlands was done with the last one, dividing them in two major types, those situated on the moun- tain and those on the plane, the latter, which are the only type present on urban areas, are subdivided in another two categories, according to its origin they might be fluvial-lacustrine or constructed, however they are subdivided in a parallel ca- tegory, regarding its use they might have a passive or an active recreation use.

The latter category makes apparent one of the most interesting discussion subjects among urban planners and scientists, regarding the kind of use and the value given to these ecosystems. There is a lot of disagreement, specially, since the last decades when studies started to make evident the important services they provide, and the lack of knowledge about their fragility and constant evolution. Next chapter will explore the particular situation of urban wetlands, which at a certain extent are a recent element on contemporary cities, and are the perfect scenario to make evident different visions and perspectives about the future.

9 beneficiario colfuturo 2010 1.2 Urban wetlands. Attributes, problems and values

As mentioned before, the relationship between humans and wetlands has existed since ancient times; men have found in wetlands an important source of goods and services, thus, the category of urban wetlands would not be something new, especially when they have supported the existence of cities, such as Calcutta in India and San Francisco in the United States just to mention some. However, for this study, the urban wetland is understood as a remnant area which has been su- rrounded or invaded by human settlements during urbanization planned and/or sporadic processes, as a consequence of the growth of the city. This differentiation is important because the conception of urban wetlands may be different in the European and American realities, where urban growth has been given under diffe- rent perspectives compared to the Latin American and more particular Bogotá’s case. Even if wetlands are so different, they share similar attributes which are very important to understand the kind of services they provide for the city, among others:

Wetlands “usually hold a large reserve of storage water in the form of soil moistu- re and groundwater. Organic soils, which form the substratum of most wetlands, have a high moisture-holding capacity. At full saturation, organic matter such as muck and peat can hold more than 6 inches of water for each foot of soil” (Marsh, 1991, 281). This means, that on events of heavy rain, wetlands act as a sponge, storing water during the water cycle, when wetlands are urbanized, drainage con- ditions are lost.

Temperature regulation, precipitations and climatic cycles: Water from wetlands, retains heat with more efficiency than soil, diminishing the impact of ground frost and favors the production of food.

Evapotranspiration of wetlands contributes to moisturize the atmosphere and re- gulate precipitation (EEAB, CI Colombia, 2000 V2, 23)

Provides water, which is necessary for industrial production and which has been particularly taken in advantage on the Bogotá Savanna, among others, by flower growing (EEAB, CI Colombia, 2000 v2, 23)

10 Generation and maintenance of biodiversity, which is one of the most valuable potentialities of the Colombian territory. Wetlands favor the appearance and con- servation of many species, in part because are environments of difficult access, which turn them into proper biological natural refuges. (EEAB, CI Colombia, 2000, 23)

Wetlands act as vast oxidation pools, where a very important part of organic ma- terial is decomposed preventing biggest damages down the stream. (EEAB, CI Co- lombia, 2000, 23)

All these services are affected under urbanization processes, the most visi- ble effects caused by the construction of infrastructure; roads, pipelines, facilities, commercial and residential developments, but also in a no that self-evident way, as might be the impairment of wetland function in remaining urban wetlands. (Boyer, Polasky, 2004). “For example, construction reportedly impacts wetlands by causing direct habitat loss, suspended solids additions, hydrologic changes, and altered water quality. Indirect impacts, including changes in hydrology, eutro- phication, and sedimentation, can alter wetlands more than direct impacts, such as drainage and filling. Urbanization may affect wetlands on the landscape level, through loss of extensive areas, at the wetland complex level, through drainage or modification of some of the units in a group of closely spaced wetlands, and at the level of the individual wetland, through modification or fragmentation” (Azouz, Horner, 1997).

Furthermore, as these ecosystems are intermingled, something that could be seen as an isolated problem, for instance pollution of water , will not remain as an isolated disturbance; on the contrary, it can create a sort of chain reaction, on soil, vegetation and fauna, which may end up with the destruction of the ecosys- tem.

During this research was possible to individuate five typologies of transfor- mation which can occur separatedly or simultaneusly in the same wetland; Clus- terization due to the fragmentation of the ecosystem after the construction of a physical barrier, usually infrastructure as roads; Erosion as a consequence of the invasion of the wetland area and its adaptation for other activities accelerating the terrification process; Pauperization resulting from the loss of natural resources and biodiversity as a consequence of drainage and disturbances on the hydrolo-

11 beneficiario colfuturo 2010 Clusterization Erosion

Pauperization Taming

Isolation

Physical transformations on urban wet- lands (figure 1)

12 gic regime; Taming is the modification of an ecosystem to make it useful for cer- tain activities (golf fields, parks), the loss of wildness generates loss of natural con- ditions to host certain natural processes; and finally Isolation which is the impo- sibility to connect and transit between similar ecosystems in a wider scale due to physical barriers like residential areas.

Unfortunately, all this problematic and conflictive situations which affect wetlands are not considered until the chain reaction gets bigger and its effects reach people, and probably is flooding the most common way in which this is taking place. Last two years were terribly harsh for Colombia, the whole territory was affected by extreme weather conditions, under the so-called “Fenomeno del niño” , with terrible consequences of human and economical losses, under the magnitude of the tragedy, the government had to create a special found to relo- cate victims and towns which were vanished under the alluviums, and at certain stage it was necessary the intervention of the international community to provide aid. As usual, this kind of situations affect people with less resource, which for economical reasons tends to live in risk areas. This “winter wave” apart from the big damage left behind, was important because it created attention over two im- portant subjects which had not received the importance deserved; climate chan- ge and the relation of urbanization patterns and environmental quality. Even if “El fenomeno del niño” is a periodical event, it is evident that the magnitude rea- ched matches with the effects of global warming that many scientists have been warning, especially on the last three decades. Extreme climate events, tend to hit people who live in the most remote and uncivilized locations, but this time was different, people from the city was stricken too, and specially in Bogotá, TV news broadcasted images of people with water until their waist, trying to save electro domestics and furniture from water, all of them, trying to figure out what was ha- ppening and why.

But when seen in depth, these events are a logic consequence of lack of planning and control, and the worst thing, is that they will happen again and probably more frequently, if measures are not taken in order to reestablish a balance among wet- lands and urban areas.

Probably there are many other benefits and problems that were not men- tioned, but just recognizing the most relevant, it would be enough to establish several policies and actions in order to study and protect these ecosystems, howe

13 beneficiario colfuturo 2010 P6.Flooding at Bosa - Bogotá. December 2011. Source El Espectador

P7.Flooding at Bosa - Bogotá. December 2011. Source El Espectador

P8.Flooding at Bosa - Bogotá. December 2011. Source El Espectador

P9. Flooding at Bogotá. December 2011. Source El Espectador

P910 Flooding at Bogotá. December 2011. Source El Espectador

14 ver this is not the case, and there are several deep reasons which make difficult to identify and allocate a value on them. Most of environmental goods, which provide support for human life, are present in the world under situation of scarcit- yand non excludability, this means that in the economical world, it is very difficult to assign a price to all the complex services that they provide, which at a certain degree leads to the over exploitation of them. “Although wetlands provide im- portant services to society, these services typically are not sold nor do they have a market price. Therefore, private landowners do not typically receive a return on preserving wetlands, even though these wetlands may provide valuable services to society” (Boyer,Polasky, 2004). And this becomes ever more difficult, when there is scarcity of land in the urban area for new developments, and land price rises, making difficult to preserve this “vacant” areas.

What many authors suggest and ask for is a change on perspective, “from an anthropocentric view to a biocentric or ecocentric view in which the source of value may be other species or ecosystem processes rather than how species or ecosystems satisfy human wants and needs”. (Boyer,Polasky, 2004) This is an idea which goes beyond the pure economical aspect, definitely it open questions about the way in which urban planning should understand this areas and inte- grate them in the city, about the necessity to assign a use, and particularly in the Bogotá example, how accurate and adequate is this classification of wetlands as “recreational” places, either passive or active, in front of the complexity which was just mention before, this categories definitely seem simplistic and basic, especially when recreation is a concept which may have so many connotations and interpre- tations far from the traditional definition, even more when located in a city with a population of around eight million people. The traditional idea of recreation in urbanism, has not yet fully absorbed the richness that the city has to potentiate this dimension (imaginative and critique) from a population which is far from be constrained to the simple activities of basic leisure and fun (EEAB, CI Colombia, 2000, v2, 42).

A discipline where this vision has found a platform to develop, and extend its in- fluence on urban planning is landscape ecology, this connection will be explained in the following section.

15 beneficiario colfuturo 2010 Fig 2. Natural and Human edges. Most natural edges are curvilinear, complex, and soft, whe- reas humans tend to make straight, simple and hard edges. (Dramsdat, Olson, Forman, 1996)

Fig 3 and 4. A better design (left) Continuous vegetated corridor mantained through back- yards of houses; Housing setbacks at minumum distance from road/maximum from corridor; use of native vegetation / minimal threat due to spread of exotic species. (Dramsdat, Olson; Foreman, 1996) Figure 2

Fig 5. Patch selection for conservation based on their contrubution to the overall system and unusual or distinctive characteristics (Dramsdat, Olson, Foreman, 1996)

Fig 6. Administrative and natural ecological boundary, the area in between may act as a bu- ffer zone (Dramsdat, Olson, Foreman, 1996)

Fig 7. In landscapes undergoing suburbaniza- tion and consequent invasion of exotic species, Figure 3 Figure 4 a biodiversity or nature reserve may be protec- ted against damage by invaders using a buffer zone.(Dramsdat, Olson, Foreman, 1996)

Fig 8 Stream corridor and dissolved substances. (Dramsdat, Olson, Foreman, 1996)

Figure 5 Figure 6

Figure 7 Figure 8

16 1.3 Landscape ecology and Green Infrastructure

A direction on this perspective can be found through the landscape eco- logy, because it recognizes the important role of natural ecosystems as wetlands, for instance, beyond the economical dimension it also recognizes the imminent influence of man over them not just as a dangerous external agent but as another element which is part of it. This assumption opens the path to the search of diffe- rent ways in which a determinate landscape finds an ecological balance. Landscape ecology, was first used by the German geographer Carl Troll to “descri- be a new field of knowledge that focused holistically on the spatial arrangement of elements in the landscape (such as fields, woodlots, rivers or towns) and how their distribution affected the distribution and flow of energy and individuals in the environment (Benedict and McMahon, 2006). Since the 90’s it started to gain relevance because it provides important tools to deal with conflictive land use situations in different scales and at different levels of anthropization.

A very useful contribution in this direction is given in the book Landscape Ecology principles in Landscape Architecture and Land Use Planning (Dramstad, Olson and Forman, 1996) with the definition of a set of principles according to four basic elements; patches, edges, corridors and mosaics, and the further expla- nation of what kind of interventions are more convenient in order to maintain or foster ecosystem functions in those elements:

• Patches are those remnant habitats of plants and animals, which increasingly appear scattered on a territory with a certain degree of isolation, for instance a wetland in a city would be an environmental resource, as an oasis in a desert. (Fi- gure 4). • “An edge is the outer portion of a patch where the environment differs signifi- cantly from the interior of the patch. They increasingly become the critical point of interactions between human-made and natural habitats”. (figures 1,5 and 6) • Corridors and connectivity are the linkages created between patches to avoid isolation and improve the conditions for wildlife movement through a territory. (Figures 2,3 and 7)

17 beneficiario colfuturo 2010 • A land mosaic is the main component of a landscape, where particular local ecosystems and land-uses recur. Usually when many corridors are connected, they form networks where flows and movements take place. (Figure 6)

The implementation of these principles should be not seen just convenient for the natural reserves, protected or suburban areas, on the contrary, it could have a positive impact in the urban planning and design of cities, where the scarcity of natural areas becomes every time more critical.The whole landscape is a mosaic, but the local neighborhood is likewise a configuration of patches, corridors, and matrix” (Dramstad, Olson, Forman. 1996).

This necessity has given rise to the development of a relative new concept, but that with the pace of time becomes more consistent and perhaps more adequa- te to address environmental issues within the cities. The green infrastructure in a comprehensive way takes these principles and shapes an adaptable structure with many elements that help to frame a more ambitious vision on the role of nature in cities.

Along all the different definitions and research about the Green Infrastructure, one of the common remarks made is that “the nature of everything is different to the mere sum of the parts” (Capra, 1996), which is a very simple way to ask for a comprehensive vision of the nature on the city, where its elements cannot keep on being seen in an isolated way, constrained to basic functions far from the ecosystemical requirements of cities. Something simple like a neighborhood park, no longer can be seen just as a place for recreation, taking a dog for a walk or having a picnic, it is necessary to understand how all open spaces are potential resources which are framed in bigger scale infrastructures, that have ecological functions which are our natural life-support system.

Natural England provides a comprehensive definition of a green infrastructure un- der this perspective: “Green Infrastructure (GI) is a strategically planned and delive- red network of high quality green spaces and other environmental features. It should be designed and managed as a multifunctional resource capable of delivering a wide range of environmental and quality of life benefits for local communities. Green in- frastructure includes parks, open spaces, playing fields, woodlands, allotments and private gardens”. (Natural England, 2012)

18 The elements of a green network have been individuated by many authors, and all of them keep relation with those first described for landscape ecology, for ins- tance Carlo Peraboni in his book “Reti ecologiche e infrastrutture Verdi” (2010), individuates the following :

• Nodes: Areas that have a high ecological value in relation with its context, which have been identified as key elements to protect and potentiate as part of a strate- gy to consolidate and develop natural values. • Ecological corridors and connections: It can be considered as a strip of the territory different to the matrix in which is contained, and operates in a way that prevents habitat isolation, which is the main cause of the extinction of species. • Stepping stones: Is a category conceptually attached to the ecological corri- dors, and consist of habitat patches which act as rest and refugee areas for deter- minate species. At the same time those patches constitute support areas for the transference of organisms along big natural basins under the lack of continuous corridors. • Besides, the author identifies an additional element, the barriers, which inte- rrupt the ecological networks, some of them, which are very important for the subject of this thesis:

•Urban areas: The absence of inadequate habitat, the high proportion of paved surfaces, the strong human presence, the traffic disturbance and the high densities, make of the populated centers hostile barriers for the transit of species •Areas of intensive agriculture: Intensive agriculture in vast areas of terri- tory, where there has not left behind space for native trees, hedges or other places where animals can refugee makes difficult its transit and survival. •Roads and railroads: road infrastructure may become insurmountable ba- rriers, specially for amphibious, reptiles and small mammals. •Paved canals: Artificial courses of water, with smooth banks can constitu- te barriers and death traps for many animals. •Electric lines: aerial cables can cause death on birds, either for collision or for electrocution.

Especially the last element puts in evidence the clash between the green networ- ks and the green infrastructures, and gives weight to the necessity of a green in- frastructure, able to integrate all the elements of a green network and create a sort

19 beneficiario colfuturo 2010 of dialogue and negotiation with the city, and particularly its grey infrastructu- res. (Figure 9) This negotiation is the big opportunity and the big challenge, some authors as Benedict and McMahon warn that green infrastructures need to be planned before any development, which would be the ideal situation, because it is better to prevent damages rather than solve them. However, reality of many cities is quite different, and on the implementation of green infrastructures could appear as a stimulating opportunity for research and experimentation. From this necessity to integrate both infrastructures, Carlo Peraboni individuates a set of principles which can guide a project of a green infrastructure:

1.Green infrastructure has to be a scheme of reference for the conservation of na- tural elements, and at the same time a vision to show the exit of the transforma- tions. This aspect emphasizes the necessity of an strategy in which specific pro- jects can be frame and not the other way around, in this way it would be easier to control and know what to expect about changes not just on the green but also in the grey infrastructure.

2.To plan and design the green infrastructure before transformations.

3.Connection is the key concept, but multifunctionality is the objective. This point argues for a concept of connection which explores more than the basic naturalis- tic function, especially when this goal is not achievable, creative solutions may be required, and muntifunctionality is an important condition to integrate different functions that take place in the same territory.

4.Green infrastructure crosses different administrative areas and at different sca- les, therefore it has to be one, but different. It means that GI has to be diverse in contexts, rich in habitats and dense in connections, able to provide a wide variety of services to the city and the ecosystem. The GI to carry on its efficacy has to be integrated with the margins and the connections of the urban system, recogni- zing the nature and the composition of the places of hybridization.

5.GI is a relevant public investment, therefore it is necessary to arrange a preventi- ve balance of costs in order to promote the benefits.

6.GI implicates many subjects. It is necessary to select and involve those key actors and public entities.

20 The importance of the implementation of a green infrastructure, is not just an opportunity to recover wetlands, but is an opportunity for cities to become better places for people and for nature, however going from the theory to the practice may become a difficult step, in all aspects, especially in what concerns high anthropized areas as urban wetlands. For that reason it is necessary to have a look through the looking glass and understand better what constitutes the so called gray infrastructure, but focusing on the aspects which could represent op- portunities to hybridize both.

GRA Y INFRastruCTURE TYPOLOGIES GREEN INFRASTRUCTURE TYPOLOGIES

Transport Infrastructure: Parks and public gardens Motorways General amenity space Roads Outdoor sports facilities Car parks School playing fields Railways Woodland Ports/Freight terminals Watercourses and waterways Airports Waterbodies Commercial Infrastructure: Grassland and Heathland Factories & Industrial Coastal habitat Offices Moorland Retail Agricultural land Mines and quarries Allotments, community gardens and urban farms Utilities and distribution of services: Cemeteries, churchyards and burial grounds Sewers Derilict land Cables (Underground and overhead) Private gardens Water and gas pipelines Street trees Waste management and landfill Sewage treatment Energy generation Social Infrastructure: Schools, Universities and Colleges Hospitals, Clinics and Healthcare facilities Gymnasia, swimming and sports buildings Housing Coastal defenses and flood control MOD and govt establishments

Figure 9. Elements which compose the green and gray infrastructures (Peraboni, 2010)

21 beneficiario colfuturo 2010 1.4 Sustainable Urban Form

Cities are responsible of the greatest damages on environment and re- sources consumption, this is a reality that has been comprehended no so long time ago, and unfortunately has not been fully understood by the vast majority of world’s population. However, disciplines as urban planning, architecture and ur- ban design, in front of such image which shows its worst face with the form of an environmental disaster, have been studying and understanding many dimensions and layers that compose the complexity of cities, in order to find ways in which the city can reduce its negative impacts on environment, and luckily to provide new benefits. These studies have shown that there are cities with certain characteris- tics where resources are used in a more efficient way than some other cities, and many of these characteristics are related with this form.

Form of the cities is the result of several transformations influenced by so- cial, economical, environmental, cultural and many more aspects, if there is no a wetland same to another one, exactly the same happens with a city, therefore, the argument is far from finding in the shape of an idealized city a “one size fits all” approach or solution, on the contrary, the idea is to recognize some urban principles, which according to an specific context, could be relevant in the quest of intersections and interactions in the design and penetration of a physical green infrastructure into the existing city. “Sustainability integrates natural systems with human patterns and celebrates continuity, uniqueness, and place making” (Jenks,Dempsey 2005)

Three principles which are relevant for the further understanding of the study area were identified; accessibility and connectivity, density and mixed uses.

ACCESIBILITY AND CONNECTIVITY

Most of the consumption of energy and one of the biggest sources of CO2 emissions is caused by travel, especially in cities with big extensions and without a consolidated and efficient public transport system as Bogotá. Alternatives to sol- ve this problem are proposed through compact city models where the access to different public services is facilitated by the polycentric schemes, reducing the ne- cessity of doing long trips within the city, stimulating the use of alternative means of transport, as cycling and walking, and encouraging multimodality.

22 connectivity refers to the capacity “to get to places easily and be integrated phy- sically and visually with their surroundings” (Homes and Communities Agency, 2008,12). The improvements of these features require specific actions, supported in bigger infrastructures and framed on wider strategies, otherwise could remain as isolated actions with low impact.

From the urban compendium we can extract some important improvements that can be done in the urban fabric in order to achieve a “successful urban framework”:

Design for ease walking: Local facilities bring residents together, reinforce com- munity and discourage car use. So the first component of a movement framework should be the walking distances from facilities. The quality of the routes is impor- tant, especially where there are obstructions such as busy roads or railway lines. To give walking priority means putting the everyday experience of the street first on the agenda.

People should be able to walk in 2-3 minutes (250 metres) to the post box or telephone box: the newsagent’s should be within 5 minutes (400 metres). The- re should be local shops, the bus stop, the health centre and perhaps a primary school within a walking distance of (say) 10 minutes (800 metres).

Connect with the existing network: Direct, attractive connections between key facilities, avoiding dead ends, help to create more convenient and comfortable places. An assessment of how best the site can plug into the wider movement net- works should aim to provide the maximum number of direct connections to main streets carrying through traffic. The more direct the links between main streets, the greater the potential for mixed use (the links do not have to be vehicular). Decide which links are most important to extend into the scheme, to provide the basis for the internal movement structure.

Make or break boundaries: The linear elements that define the boundaries of a place - the edges – may be used to define the limits of a development site or re- generation area. Rivers, canals, parklands, busy roads or viaducts, may provide the definition that contributes to a sense of place. But sometimes punching through or spanning these edges will create an enhanced spatial dynamic, by forging links with surrounding areas and reducing severance.

23 beneficiario colfuturo 2010 DENSITY

Scarcity of urban land and the imminent growth of urban population re- quire new space to allocate new citizens. The risk of expanding to rural land and the devastation of natural resources is not an option in the current situation; it is not a sustainable solution from an economical neither from an environmental perspective. A more sensible solution would be the maximization of existing land through densification, which at the same time can foster certain desirable situa- tions: “density is an essential element of community urbanity and civility. Without reaching a reasonable density in any urban area, it is difficult to justify the efficient utilization of urban resources and services”. (Jenks and Dempsey, 2005, 236)

However, many people feel threaten by the narrow line that differentiates high density and overcrowding, once again, it depends on the context, cultural and physical aspects which make certain conditions more acceptable for some people than for others; thresholds of high density surely vary in cities as Singapo- re, Bogotá and London; in fact “Density is only a measure. It is a product of design, not a determinant of it”.

Authors like Jenks and Dempsey suggest that “perhaps, if the claimed be- nefits of higher densities are to be achieved, the key is less the density standard but more the style and image that such densities might portray – and the level of acceptability of such densities and styles in the wider cultural context”. A symilar perspective is shared on the Urban Design Compendium Issued by the Homes and Communities Agency of the UK government; “The aim should therefore be not to achieve a given residential density, but to generate a critical mass of people able to support urban services such as public transport, local shops and schools” (Homes and Communities Agency, 2008)

In that order of ideas, density should not be as an objective but as a mean to achieve certain benefits, but for sure what is required is an evaluation of the characteristics of the place where an intervention would take place, to define if a densification process is necessary, what improvements or problems can create, and which kind of interventions are required to succeed; bringing more people to live in a limited space creates more pressure over public space, facilities, public transport, and on environment.

24 Strategies may include the variation of net densities, choosing strategic spaces where the mass can have a strategic function, for instance, near public transport hubs, centers and parks; provision of quality spaces, it means that buil- dings and streets should have a human scale, use quality landscaping to soften perceptions of a place; cater for a range of lifestyles, this requires a wider offer of residential typologies in order to attract different income and age groups and to ensure that high-density proposals use adequate floor plate standards and thus avoid cramped living conditions. ((Homes and Communities Agency, 2008,47)

MIXED USES

Zoning and isolation of functions across the city has proved to be a major issue to deal with in the search for sustainability, it has contribute to the appearan- ce of phenomena like sprawl, dormitory neighborhoods, segregated neighborho- ods among others, that at the same time have increased the necessity to make long and frequent journeys in order to do basic activities as working, shopping or recreating, besides, this has caused many expenses in order to extend the infras- tructures to connect those activities, that apart from the economical cost, repre- sent a big cost on the environment.

Encouraging the appearance of diverse activities in a certain area propo- sed as a way to foster several features that enrich the life of cities, and reduce its environmental impact; for instance, providing residential solutions near work areas and vice versa, might be a good occasion for people to move near their jobs, finding advantages as the possibility to walk or bike to their workplaces, avoiding commuting and saving time that can be invested in other activities. Having local shops and facilities in a neighborhood can help with the creation of a sense of community, stimulate the appearance of different kind of activities at different times of the day, 24/7, which at the same time can improve security conditions and attract people with different lifestyles and a therefore diverse tastes and con- sumption patterns. From all points of view it seems like a good option, however the mixture of activities has to be a selective process in which pre existences are considered and respected, and especially in the case of environmental attractions the overexploitation is avoided. From the compendium of urbanism is it possible to extract some principles that can guide this kind of intervention:

25 beneficiario colfuturo 2010 Create a patchwork of different activities, taking advantage of existent character areas, or if not, trying to reinforce the sort of activities which would help to create or reinforce an identity.

Evaluate the kind of uses which are compatible and that can enter to reinforce identity, avoiding conflictive situations between neighborhoods. It is important to understand that all activities have different special and temporal needs, that if not consider can become future problems.

Combining the primary activities of living and working supports a greater variety of secondary facilities (whether commercial, entertainment, leisure or communi- ty-based). Grouping the main elements of the palette of uses to be accommoda- ted will help to make a place.

Distributing different housing types and tenures as a way to promote social diver- sity and avoid the formation of clustered exclusive enclaves.

Identify main transport hubs to consolidate centers where different activities can take place, and identify the connections among centers to strength its identity. •Injecting housing into the mix wherever possible enables activity to be stretched beyond daytime office and shopping hours.

Providing local public services and amenities, like nurseries, libraries, community centers, police stations, etc, that works as focal elements of the urban structure to reinforce the sense of community and emphasize the civic.

Reintroducing the “big boxes” (out-of-town development, often mono-functional in nature, such as industrial, office and retail parks) into the city, this can be achie- ved wrapping the perimeter on the street faces with smaller units, building other uses on the air space above the box, incorporating a well designed upper façade for roof top parking, externalizing more active uses (such as cafés and boutiques) and increasing their ‘transparency’ to the street.

Improving the natural conditions of transition zones which make of them proper places for mixture and can be used to buffer homes and other noise-sensitive uses from activity sources. However, night-time uses (pubs, clubs and restaurants) can also work well here. If positioned away from predominantly residential areas they can also feed off one another when they are clustered. 26 1.5 Resilience

Resilience is a concept which has been used in many disciplines, and in the last years have been gaining favor in its appliance to cities, and is basically described as the capacity of a system to recover from disturbance, going back to its original state, of course this interpretation may vary according to the discipline that uses it, in what respect to cities, it is becoming a powerful concept which can open a lot of possibilities in relation with the causes and consequences of climate change, and its relation with urban form and sustainability. (Vale, taken from Haas, p 22) Perhaps, are catastrophic events as earthquakes, hurricanes or terrorist attacks the scenarios where resilience is most evocated, however, the increasing frequency of other types of catastrophes, perhaps not of such a magnitude, and that have proved to be related with climate change and the neglect with which humans have managed environmental resources, like flooding, drought among others, have open space for the discussion of the kind of reaction that should be taken. In this case, resilience cannot be seen just as the capacity to go back to the place or the state as things were before disruption, in the case of wetlands for instance, this would not be even natural having into account that those are ecosystems which keep on evolving, furthermore, there are physical, social and economical constrains which make of it an unthinkable and naïve pretention, be- sides, what kind of past would be better?, it is a hard choice and not all the times preexistence was necessarily better. For all these reasons, resilience has to be seen as the possibility to recover from disaster, but grounded on the necessity to adapt and adopt new and sustainable ways to relate with its space, in a sort of ecosyste- mical fashion. This is a valuable perspective in order to offer solutions as problems like flooding in urban areas, especially because as mentioned before, people affec- ted by these events usually do not have another possibility to settle down and abandon risk areas, most of the time, necessity makes them remain there even if they are conscious of the recurrent problems they will have, and as these are not isolated events, resources of public institutions are not enough to offer solutions for relocation of these settlements far from risk areas. A more viable solution would be to understand the causes of these events in order to create parallel actions, in one side, there are studies which have proved that physical conditions of cities, as the lack of permeable surfaces may increment the run-off effect, which is strongly related with flash-flooding, modifications in

27 beneficiario colfuturo 2010 Figure 10. Groundwater levels on natural condi- tions (Watson, 2010,p 85)

NATURAL LANDSCAPE DENSE RESIDENTIAL URBAN

Figure 11. Water balance and watershed resilience to flooding can be correlated to the percent of porous versus impervious cover (Watson, 2010,p 85)

Figure 12. Impervious surfaces, such as pave- ments, roofs and lawns, transform nearly all precipitation into runoff (Watson, 2010,p 75)

28 urban form would be a feasible way to mitigate these effects, on the other side, when flooding happens, because is the natural thing to happen, especially in rainy seasons, physical form of settlements could be adapted to find a better relation and reaction, it would require creative solutions to conciliate nature with artificial infrastructures, like housing, streets, lighting and drainage systems, etc.

Understanding of nature cycles is important in order to propose adequate solutions and transformations. The book “Designing for flooding”, explains how the alterations of water balance are altered on the city: “as land uses change as they are developed, the natural hydrologic cycle and water balance are altered. Rainfall continues, but where impervious surfaces have replaced woodland, vir- tually all rainfall is converted to rainwater runoff. Because more water in the cycle is diverted to runoff, the annual volumes of runoff increases dramatically while the annual volume of groundwater recharge and Evapotranspiration decreases”. “When infrequent larger precipitation events exceed the capacity of natural sys- tems to absorb water, a second tier of natural components such as floodplains and wetlands, combine to slow, hold and buffer the runoff”. (Watson, 2011 p 74)

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