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Abstract

The ecological risk attached to the filling of Quito’s ravines, together with the subsequent loss of a memory about their existence, are the focus of this paper which aims to provide a base for both comprehension and action. Ravines are part of the geomorphology of the city’s basin and play a vital role in the hydrogeological system of Quito’s water cycle. They have been filled over time, disappearing from urban maps. This disrupts ravines’ original course and natural drainage system generating risks. An integral multi-scale perspective that considers geomorphological and hydrogeological modifications is missing. Three problematics can be observed. Technical-infrastructural, Urban-spatial and Architectural-cultural. The conjugation of all the phenomena described above, constitutes a call to consciously establish the risk level to which this territory is exposed. The damage goes beyond material or human loss. It affects history, living memory, identity, and knowledge. All these aspects have contributed to the consideration of HCQ (Historical Centre of Quito) as World Heritage Site. These are valuable legacies that need to be preserved. Therefore, it is necessary to undertake a detailed inventory of: i) the technical constructive state of patrimonial buildings made using raw earth; ii) the modifications and current state of DMQ’s (Metropolitan District of Quito) ravines; iii) the existing interstitial spaces associated to the ravines’ path within the HCQ. The paradigm under consideration for the future is not conservation but integral protection. Rescuing Memory in relation to HCQ’s ravines as an active operator for transformative provisions associated to social, environmental, urban and architectonic dimensions becomes fundamental for future development.
URBAN AND HYDROGEOLOGICAL ALERT ON THE MORPHOCLIMATIC RISK
AFFECTING QUITO’S WORLD HERITAGE
P. Bracchi 1, *, F.J Torrijo 2, A. Boix 1, M. Cruz Cabrera 1, D. Giordanelli 1
1 Facultad de Arquitectura y Urbanismo, Universidad UTE de Quito - (paola.bracchi, alberto.boix, marianela.cruz, dario.giordanelli)
@ute.edu.ec
2 Departamento de Ingeniería del Terreno, Universitat Politècnica de València - fratorec@trr.upv.es
Commission II - WG II/8
KEY WORDS: Natural Risk, Ravines, Quito, Heritage, Memory
ABSTRACT:
The ecological risk attached to the filling of Quito’s ravines, together with the subsequent loss of a memory about their existence,
are the focus of this paper which aims to provide a base for both comprehension and action. Ravines are part of the
geomorphology of the city’s basin and play a vital role in the hydrogeological system of Quito’s water cycle. They have been
filled over time, disappearing from urban maps. This disrupts ravines’ original course and natural drainage system generati ng
risks. An integral multi-scale perspective that considers geomorphological and hydrogeological modifications is missing. Three
problematics can be observed. Technical-infrastructural, Urban-spatial and Architectural-cultural. The conjugation of all the
phenomena described above, constitutes a call to consciously establish the risk level to which this territory is exposed. The
damage goes beyond material or human loss. It affects history, living memory, identity, and knowledge. All these aspects have
contributed to the consideration of HCQ (Historical Centre of Quito) as World Heritage Site. These are valuable legacies that
need to be preserved. Therefore, it is necessary to undertake a detailed inventory of: i) the technical constructive state of
patrimonial buildings made using raw earth; ii) the modifications and current state of DMQ’s (Metropolitan District of Quito)
ravines; iii) the existing interstitial spaces associated to the ravines’ path within the HCQ. The paradigm under considerati on for
the future is not conservation but integral protection. Rescuing Memory in relation to HCQ’s ravines as an active operator for
transformative provisions associated to social, environmental, urban and architectonic dimensions becomes fundamental for
future development.
* Corresponding author
1. INTRODUCTION
The ecological risk attached to the filling of Quito’s ravines,
together with the subsequent loss of a memory about their
existence, are the focus of this paper which aims at providing
a base for both comprehension and action. Ravines structure
the functioning and environmental balance of the city. They
are part of a reality which exposes issues produced by the
response to technical-infrastructural matters, reflected in
urban-spatial and architectural-cultural aspects. If these issues
are not urgently taken into consideration, the greatest risk
observed in this study is the loss of the built heritage of Quito
(UNESCO World Heritage Site since 1978).
Ravines are part of the geomorphology of the city’s basin and
play a vital role in the hydrogeological system of Quito’s
water cycle. They have been filled over time, disappearing
from urban maps. This disrupts the ravines’ original course
and natural drainage system generating risks. Quito is
particularly exposed to a wide variety of natural risks given its
location and its spatial development, including seismic,
volcanic (Pichincha, Cotopaxi) and morphoclimatic risks,
such as landslides, sliding, avalanches, mudflows and flooding
(Sierra, 1997). Following the objectives of this paper we
concentrate in the existing relationship between
morphoclimatic risk affecting Quito’s built heritage and the
filling of ravines.
From a general depiction of the city and the Historic Centre of
Quito (HCQ) as World Heritage Site, the paper analysis the
issues brought about by the filling of ravines in the HCQ. We
consider two related problematics (hydrogeological and urban)
which are seen as the base for the architectural-cultural
problematic. HCQ is an admirable context of architectural quality.
The colonial buildings were made according to the Hispanic
model of a patio house, adapted through local construction
modalities, such as the use of raw earth techniques. Among these,
adobe-based methods, the use of rammed earth for walls and
wood for the structural system were frequent. Many monumental
buildings also present large adobe walls supported by continuous
stone foundations. Nowadays we can see that more than 50% of
central buildings continue to have a raw earth structure. Quito’s
built heritage has always been looked after from an architectural
perspective. Nevertheless, the current morphoclimatic risk, which
incorporates hydrogeological and urban issues on a territorial
scale, implies a much larger threat.
As Corboz (1983) points out: land is not a piece of information,
but rather the result of several processes. Therefore, it is
possible to state that this local amnesia on ravines is a land of
oblivion, which does not follow pre-existing geological systems
but rather develops against them. The sad fate of this titanic and
impossible struggle is the wait for the breaking point. This risk
condition determines a fragile city which seems to remain in a
brutal, announced fatalism.
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825
2. THE SITE. QUITO AND THE RAVINES
2.1 General profile
San Francisco de Quito is one of the oldest cities in Latin
America. It is the capital and the political, cultural and financial
centre of the Republic of Ecuador. It is located at an average
height of 2850 m.a.s.l. in the Andes range, more accurately
within the Guayllabamba valley, in the Inter-Andean Alley
plateau which separates the eastern and western sides of the
Andean range. The city’s western end is defined by the eastern
slopes of the active Pichincha volcano, which dominates the
urban extension in such way that its hillsides are visible from
any angle, shaping the city’s sectors. This geographical
condition gives the city its peculiar elongated pattern, with 50
km in length and averaging 3 to 7 km in width, traversed by
more than 100 ravines from east to west. The city, located about
25 km north of Quito’s old town, is crossed by the equator,
which produces significant landscape diversity.
Enclosed within colonial borders until the 20th century, Quito
experiences an important population explosion fairly fast. While
in 1902 the city took up 200 hectares of land, this number
increased to 1300 hectares in 1950 and currently the whole
Distrito Metropolitano (which includes the city and its
surroundings) has an area of 290746 hectares. Urbanised land
has an area of 43116 hectares. From the second half of the 20th
century until now the size of Quito has grown tenfold, with a
significant acceleration in the last decade. Its urban population
reached 1.98 million people according to the latest census.
Figure 1. Quito urban growth. Credits: Paola Bracchi.
The colonial town was founded above the pre-Columbian city
on 6th December 1534 by Sebastián de Benalcázar and it
became the country’s capital in 1830. Within its urban area, the
Historic Centre stands out, declared World Heritage Site by
Unesco in 1978. The monumental appearance of its great
buildings, but especially the multiple cultural aspects contained
at the architectural, artistic and landscape levels, ratified the
exceptional universal value of this location.
Quito’s Historic Centre, located south of the city centre, has an
area of 375 hectares. It can be considered a complex location
where great social, spatial, environmental and cultural diversity
co-exists. It is defined by a consolidated and unique
patrimonial, touristic, socio-administrative and commercial
dimension. QHC has 14 neighbourhoods and is considered
Latin America’s best-preserved historic site and one the most
important in the whole region. It contains around 130
monumental buildings and more than 5000 placements
registered as historic sites (Empresa Pública Metropolitana de
Gestión de Destino Turístico, 2011).
The reticulated urban layout, typical of a colonial town, is based
in the urban reticular structure inspired by the Roman castrum.
The regular checkerboard was adapted to the site’s topography,
where necessary adjustments were made not so much due to
mountain hillsides but mostly because of the presence of
ravines. HQC is the meeting point par excellence due both to its
central location which makes it a city’s focal point and its
sum of time into the past (Empresa Pública Metropolitana de
Gestión de Destino Turístico, 2011) which allows it to acquire a
historical value. Because of a double quality of space
(centrality) on the one hand and temporality (history) on the
other, it is the meeting point of a population that inhabits spaces
which surpass them (trans-territoriality) and it is also the sphere
where different societies from different times and historical
moments (trans-temporality) meet. This condition provides
the Historic Centre with the particular symbiotic quality of
spatial, time and patrimonial plurality (Carrión, 2009).
Figure 2. Quito built-up heritage. Photo by Paola Bracchi.
2.2 Geological Framework
The most important geological trait of the Inter Andean Central
Valley is the Active Quito Fault System. Its morphological
depiction is defined by a group of three hills which, without
being connected, keep a common orientation (N-NNE)
(Villagómez, 2002).
As a consequence of this tectonic system, the Inter Andean
Central Valley is divided in three basins, each of which
manages individually its own sedimentary processes. These
three sub-basins are Quito, San Antonio and Guayllabama. The
one studied in this paper is the Quito sub-basin and is found
between the western Andean range (Complejo Volcánico
Pichincha) and the Batán La Bota fault. The intense rain and
wind erosion modified the existing geomorphological units,
producing canyons and very steep slopes.
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The eastern slope of Pichincha and the block raised by Quito’s
fault (where the city is built) are made of lava, hardened
limestone and volcanic deposits covered almost evenly by a
layer of 10-20 metres thick of slimy volcanic ash. The
lithological formations present the singularity of opposing little
resistance to fluvial erosion, giving way to a network of ravines
that cross through the entire urban location (Peltre, 1989).
2.2.1 Climate: Quito has a high elevation subtropical
climate. Three sectors can be observed within the city. The
southern sector, located at higher altitude and with lower
temperatures. The central sector, on the other hand, is the
warmest. The northern sector presents the mildest climate.
Data from the National Institue of Meteorology and Hydrology
(INAMHI, 2015) shows that between 2000 and 2012, the
average temperature is roughly 15°C. Regarding maximum
temperatures, the average is roughly 22°C, with highs of up to
30°C in dry months (June, July and August). In terms of
minimum temperatures, annual average oscillates between 8°C
and 10°C, reaching night lows of 4°C or 5°C.
Table 1. Average temperature 2000-2012, INAMHI.
2.2.2 Pluviometry: In order to talk about Quito’s
pluviometry, we have to differentiate two well defined seasons.
The dry season, including June, July, August and September.
And the humid season where the remaining months are found,
with peaks in April and November.
According to data from INAMHI, between 2000 and 2012,
March and April were the rainiest months with average values
ranging between 140 mm and 196 mm, and August is the driest
month with average rainfall values that reach a meagre 15 mm.
The differentiation between the south/central region and the
north region of the city should be noted regarding rainfall. As
Peltre (1989) points out, ‘’the Pichinca volcano protects the
north of the city from the incoming humid air masses from
south-west. In addition, the effects of dry and warm winds
flowing down through the Guayllabamba basin, which strongly
diminishes the concentration of atmospheric humidity in the
northern part of the city and in the Perucho, Guayllabamba and
San Antonio sectors. The intensity of rainfalls, despite not very
voluminous in absolute terms, allows fairly strong drippings in
the steep slopes.
Table 2. Average rainfall 2000-2012, INAMHI.
The geological and hydrometeorological traits mentioned
above corroborate the fragile ground condition of Quito’s
basin. The HCQ is specifically affected by anthropization.
Within this research, close attention is paid to the closure of
ravines, the layout of the drainage system and the urban
boomb which influence the oversaturation of the ground at
various levels. All these factors increase the fragility and risk
to which Heritage is exposed.
2.3 Ravines of Quito
From the slopes of the Pichincha volcano and other
mountainous formations along the western end an intense web
of ravines passes through the entire urban site (Peltre, 1989). It
is a system of intermittently-formed rivers that rhythmically go
through the city’s plain from east to west. These ravines can
reach 15-20 metres of depth with steep edge and strong slopes
(20-30 degrees). They constitute an important natural drainage
network which has been modified over time to favour the city’s
growth. According to current urban development there are more
than 120 ravines, many of which have been filled up.
Figure 3. Quito’s ravine in relation with the ancient urban fabric
of the historical city centre. Credits: Paola Bracchi.
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As previously stated, initially the urban fabric of HQC before
the fillings was adapted to the presence of ravines which
made their way down from the eastern slope of the Pichincha
volcano down to the Machángara river. The historical maps
provide evidence for the existence of four main ravines. The
first one, the Jerusalén ravine, defined the southern rim of the
city and it coincides with current 24 de Mayo Street. The
second one, Tejar or Manosalvas ravine/s, crossed the central
part of HQC which is completely covered by the urban fabric
today. The third one, the Ichimbía or Pilishuaico ravine,
crossed through the northern end of the historic centre. It also
runs below the urban fabric and borders the current theatre
square. The fourth one, the Marín ravine, is a ravine of smaller
size which marks the eastern end between the historical centre
and the Itchimbía hill.
It is important to point out that none of these ravines is currently
visible within the HQC perimeter. The process of urban growth
and the need to answer technical and infrastructural questions of
fabric continuation, fulfilment of direct connections and water
channelling, determined the gradual filling of the ravines.
Figure 4. Quito’s ravine in relation with the contemporary urban
fabric of the historical city centre. Credits: Paola Bracchi.
From the 18th century onwards, the ravines began to be closed
in a fragmented and discontinuous manner according to
particular interests. This phenomenon became symptomatic and
recurrent when the city began to grow consistently outside the
limits of the colonial model, that is, from the 20th century
onwards.
3. PROBLEMATIC OF THE HCQ
3.1 General problematic
In 2011, UNESCO’s Recommendation on the Historic Urban
Landscape was adopted, which established that this kind of
landscape includes the site's morphology, geomorphology,
hydrology and natural features; its built environment, whether
historic or contemporary; its infrastructures both above and
below ground; its “open spaces” and gardens, its “land use
patterns” and “spatial organization”; perceptions and visual
relationships; and all other elements of “urban structure”. It
includes social, cultural and economic practices and values,
and immaterial dimensions of heritage, diversity and identity
(UNESCO, 2011). Geography (uneven topography and
presence of great ravines) in the context of HCQ plays a
significant role in its spatial configuration and also in its
transformation and conservation over time.
HCQ has been the object of multiple interventions1 over more
than 20 years, including several aims such as: conservation and
rehabilitation of HCQ’s heritage, improvement of living
conditions, revitalisation of commercial activity and traditional
services, land use heterogeneity and residential development.
More recently, touristic management and development has been
given a major role as a key engine for the area’s future
development (Cruz Cabrera, 2017). Despite concerns about
built heritage and its preservation, and prioritisation of touristic
activity, the landscape associated with its peculiar geography
has not been addressed enough. Recovering the values of urban
historic landscapes translates into better habitats and living
conditions for people.
Figure 5. Closer point of Jerusalén ravine.
It is important to point out that towards the end of 2018 Quito’s
Council, together with the UNESCO office in Quito and the
Metropolitan Institute of Heritage presented the ‘’Disaster Risk
Management Plan for the Historic Centre of Quito’’ (MDMQ.,
UNESCO., 2018). The document has the objective of
proposing strategies to reduce the risks to which patrimonial
goods are exposed in the face of natural disasters (seismic risk,
volcanic eruptions, earthquakes, flooding and fires). Although
the document provided a detailed analysis about monumental
buildings in the centre of HCQ, some doubts remain regarding
the level of focus sought. The document measures the risk of
each building within the perimeter of the city centre, and does
not operate based on relationship between territorial-urban risk
on all of the HCQ, but rather focuses on specific cases. Even if
it encourages an integral vision between risk typologies, it
leaves out an integral multi-scale perspective that would
consider geomorphological and hydrogeological modifications
that the city has had over time, and which can be considered
the pillar of morphoclimatic risk.
This premise, in relation with the closure of HCQ’s ravines
allows the identification of three emerging and co-related
problematics which provide a base for this paper’s objective
3.2 First Problematic. Technical/Infrastructural
The first drainage system in Quito began construction in 1905,
with the water discharge network placed in the ravines. The
first sewer pipe built was located in the Jerusalén ravine,
followed by those of Sucre and Manasalvas (found in the Tejar
and the Manosalvas ravines). The Tejar sewer pipe was built
along the Tejar ravine and connects with the Itchimbía ravine.
1 Plan Maestro de Rehabilitación Integral para las Zonas Históricas de
Quito (1991); ii) Plan de Rehabilitación del Centro Histórico-BID
1ra fase (1994); iii) Plan Especial del Centro Histórico (2003): iv)
Plan Q (2003); v) Plan de Rehabilitación del Centro Histórico-BID
2da fase (2004); v) Plan Q 2012.
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In the beginning of the 20th century, the widespread
conception of ravines was that they served only as evacuation
systems for used wastewater, rainwater and trash.
Environmental issues, such as the reduction of natural drainage
these actions entail (Hazen & Sawyer, 2011), were not
reflected upon then. Hazen and Sawyer’s report on EPMAPS,
together with other relevant documents, confirm that the
sewage system, even if partially fixed, continues to be the same
than in 1900 and still works as initially conceived: through a
combined form. That means, both rainwater and wastewater
(disposal water from human activity) run through the same
pipes (Hazen & Sawyer, 2011).
The state of the sewage system reveals important issues:
1. Sewer pipe combined usage and capacity. The diameter
of pipes used in the early 20th century does not respond
to the increase of fluid volume generated by larger
population and higher torrential rain intensity due to
climate change. Moreover, bottle neck conditions in
joints create pressure flows. This phenomenon worsens
during rainfall season as the combined system overloads
and leads to flooding.
Within the HCQ sewer pipe system improvements have
taken place, although the latest catastrophic events (HQC
March 2019 flooding) show that the issue is on-going.
2. Obsolescence. Many pipes remain the same than in the
beginning of the 20th century. The old sewer pipes have
varied forms, made through composite construction
(stone, brick and concrete) and present holes and
infiltrations. There are quick obsolescence processes in
more recent pipes due to lack of maintenance, sediment
accumulation and construction defects.
3. Underground dripping. The joining of sewer pipes is
often done in forced angles and at great speed, leading to
hydraulic singularities which damage the sewer pipes
(Hazen & Sawyer, 2011). This is observed at the contact
point between the slopes and the plain, exhibiting
underground dripping parallel to the sewer pipes (Peltre,
1998). Unstable filled soil can reveal underground
erosion which can lead to street sinking, as it happened
with the sinking of Vial del Trebol in 2008 and the recent
street sinking between the Amazonas and Naciones
Unidas avenues (21 January 2020).
4. Torrential lava/mud flows. At times of intense torrential
rain, the generated flows above the ravines can bring up
soil and mud which block the pipes. These flows seek
other routes towards the lower plain and along the streets,
knocking down what they find in the way (mud flow in
Barrio del Pinar Alto, March 2019).
The development of the combined evacuation network of
ravine waters has contributed to the disappearance of the site’s
natural drainage. The filling of ravines generates flooding,
underground dripping, sinking, mud flow and torrential lava.
These are catastrophic phenomena which threaten the city in
general and the heritage of HCQ in particular.
Figure 6. Pichincha slope water system facing with the valley.
Surface runoff and Groundwater flow.
3.3 Second Problematic. Urban/Spatial
Urban-spatial issues contribute to the disappearance of the city’s
natural drainage. Modifications to the squared block model used
originally in the colonial city were made with the objective of
allowing the passing of water streams. The conquerors did not
respect the presence of ravines for their environmental role, but
because the fluvial pathways were used as dumping sites, which
could get rid of urban trash using water power. The
environmental role of water drainage is not considered during
rainy periods.
The need to respond to such phenomenon of accelerated and
invasive growth through the north-south spectrum, but also
along the valley’s slopes, has led to decisions being made on the
basis of urgency rather than on structured and integrated
thinking of the city. A radical change in the relationship with
the natural context took place: the ravines, seen as elements
which prevent fast growth, instead of being interpreted as
systems of environmental framing for urban development, were
literally erased from maps. The geographical memory of a
millenary past was voluntarily removed from the decision-
making processes on the city’s urban development.
In the specific case of HCQ the relationship between ravines and
urban growth was revealed through two recognisable tendencies
found in maps, endorsed by the political powers of the time.
1. The ravines have been filled for the production of road
axes. The first public construction work efforts by the
Cabildo de Quito in the late 16th century consist of a
system of beam bridges which crossed over the ravines, so
as to give streets continuity at some points of the original
checkerboard. As the city centre expanded and external
relations intensified, the bridge system was not enough. In
early 20th century the Jerusalén ravine was closed along
its east-west spectrum (within the limits of HCQ) to
provide a road axis which marks the south end of HCQ
and the beginning of Panecillo hill. In 1922 the 24 de
Mayo Boulevard is opened. This road, based on
Haussmann’s work in Paris, was considered the widest
and most modern in the city (Ortiz Crespo, 2004).
The city’s first regulatory plan came about in 1944,
inspired by maps of European origin which foresaw great
axes for wheeled transport. It is in these dates that the
avenue Pichincha is realized, that it breaks carelessly in
the historical centre and it extends on the filled ravines of
Itchimbía and La Marín. Sucre street expanded towards
the south above the filled Manosalvas ravine. These two
streets, which follow the original ravine’s paths, flow into
a major transport intersection in HCQ, the Marín bus
station.
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829
Figure 7. 24 de Mayo Boulevard realized above the Jerusalén
ravine. Photo by Marianela Cruz.
In the early 70’s the latest transformations of the historic
path took place, which also modified the relationship with
the ravines’ natural system, creating significant problems
in built-up spaces. At HCQs eastern rim the San Juan
tunnels were built. The great displacements needed to
create these underground road systems, caused structural
damage to La Merced church and several other buildings
in San Diego’s neighbourhood. Furthermore, this
underground system also breaks up the natural
relationship with the ravines and is subject to great
flooding during rainy season.
2. The ravines have been filled as a consequence of the
increasing price of land. Towards the end of the 16th
century, Quito experiences a population rise. This rise
determines the expansion of the original colonial town. It
also defines the willingness of central land-owners to sell
their land at good prices. These reasons explain why the
Historic Centre’s ravines have been filled in a fragmented
manner and with no planning. This is obvious at the
Tejar/Manosalvas ravine, where various owners had the
chance to engage in fillings around the Plaza Mayor with
their own money. This became the norm over time, and
anyone with enough funds could fill up the part of the
ravine within its property area in order to increase
buildable space. This is exactly what was found with the
Jesuits. Under the Compañía de Jesús church the
Tejar/Manosalvas ravine flows. Some excavations
undertaken for maintenance have revealed the system of
cementation used with an ancient Roman technique
known as sostruzione.
Figure 8. Contemporary condition: constructions above the
Itchimbía ravine. San Juan slope. Photo by Marianela Cruz.
3.4 Third problematic. Architectural-cultural
A building is the visible element on which the aforementioned
issues, described with an obvious intensity, take form. We need
to consider that this object also provides the tangible value
required for the territory to be considered World Heritage Site.
It seems important to state that neither the technical-
infrastructural nor the urban-spatial problematics manifest in a
direct manner, but rather generate effects to the surrounding
context, which in HCQ's case are seen in built spaces.
It seems necessary to identify the issues that characterize HCQ's
buildings, as previous research suggests that 50% of them are
built on raw earth adobe and rammed earth or taipa. Research
also suggests that these buildings are affected by capillary
moisture, which originates in the ground conditions on which
they are constructed.
We can identify the actions of four particular phenomena which
impact these buildings:
1. Time. From the 16th century, buildings have been
constructed according to local techniques, that is, with
raw earth adobe and taipa. Over time, this construction
technique endured and with the gradual appearance of
new materials some exceptional work begins to make use
of concrete and steel. Some buildings made with
traditional materials were supported with steel and
concrete structures, which given their resistance and
behaviour, rather than being of help actually caused
damage instead.
2. Ground conditions. The ground is subject to tensions due
to the geological configuration and water saturation
caused by the filling of ravines, drainage inefficiency and
network obsolescence.
3. Human action. Human activity was often undertaken in an
improvised manner and without adequate techniques.
Intervention on built spaces lacked control. At HCQ high
commercial activity has significantly changed the built-up
fabric. The facades of many buildings were kept, but
behind many modifications were done in an uncontrolled
manner.
4. Hydrometeorological events. The territory is under
constant threats of seisms, volcanic eruptions, torrential
rains, flooding and sinking. Furthermore, seismic risk,
despite not having its epicentre inside the studied area, is
considered a relevant threat as it can significantly damage
buildings whose structures and stability are already
affected due to humidity. Finally, it must be pointed out
that morphoclimatic risk is the main danger affecting built
heritage. Recurring pathologies are detected in buildings,
such as capillary moisture, which make buildings
vulnerable to structural damage and differential
settlement. These gradually affect the entire building and
threat their stability and permanence. It must be stressed
out that these pathologies are discovered as a consequence
of the filling of ravines.
The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLIV-M-1-2020, 2020
HERITAGE2020 (3DPast | RISK-Terra) International Conference, 9–12 September 2020, Valencia, Spain
This contribution has been peer-reviewed.
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830
Figure 9. Relation between Ravines filling and built-up heritage.
Credits: Dario Giordanelli.
The conjugation of all the phenomena described above,
worsened by the frequent threat of hydrometeorological activity,
constitutes a warning to consciously establish the risk level to
which this valuable territory is exposed. The damage goes
beyond material or human loss. It reaches the history, living
memory, identity, knowledge (of technical and construction
processes). These are valuable legacies that need to be
preserved.
Figure 10. Relation between the loss of memory and risk.
Credits: Dario Giordanelli.
4. CONCLUSIONS
This paper reveals the high level of risk to which HCQ is
exposed. The permanence and preservation of this valuable area
of Quito are of paramount importance. The filling of its ravines
has led to the worsening of several issues over time. At an
environmental level, its natural course, water cycle, vegetation
and urban fauna are affected. Regarding infrastructure, the
functioning of its drainage and sewage systems is also exposed.
On the architectural front, buildings their walls, foundations
are affected by humidity conditions which endanger their
durability.
Two different dynamics related to memory are also exemplified:
(i) A lost memory of the hydrogeological system of ravines and
(ii) a memory at risk of being lost, that of raw earth buildings
inside the HCQ. Both involve material and immaterial
components related to urban and architectural issues.
In Quito, the restoration process for historical buildings is based
on an architectural perspective, without taking into account the
high hydrogeological risk that threatens the Historic Centre. The
urban and architectonic scales need to be considered
simultaneously. Otherwise the risk of memory loss
understood as the disappearance of the ancestral relationship
between the territory and the ravine system can provoke
irreversible damage in buildings. Morphoclimatic risk, in the
form of flooding or landslides, becomes a real threat in the
context of a clogged-up system that lacks adequate draining in
filled ravines. Conservative interventions at the architectural
level alone cannot reduce the level of risk affecting heritage at
an urban scale. An intervention is considered necessary to
recover the memory of the hydrogeological system’s
functioning, which has vanished from the general knowledge
pool of Quito’s citizenship.
This recovery process will not be conservative in the traditional
sense of a recovery of ravines as they existed in the past.
Similarly, it will not be a superficial, architectural cover up
through a frivolous level of vegetation. The proposal suggests
recovering the transformative aspect of memory through
operations that not only work on an architectural scale, but also
propose urban-scale transformations to increase filled ground’s
permeability at patrimonial locations.
All this defines a transformative, active memory, that foresees
the inclusion of future operations that define a manual of good
practices for protection-based rather than conservation-based
development.
HCQ is a high-risk location, from a social, environmental, urban
and architectural perspective. Therefore, it is necessary and
essential to undertake:
1. Detailed inventories of the technical constructive state of
those patrimonial buildings made with raw earth which
could be affected by capillary moisture. Those buildings
located in the influence area of filled ravines within the
perimeter of the World Heritage Site area should be
prioritised.
2. Detailed inventories about modifications and current state
of DMQ’s ravines, with special attention to the
functioning state and deterioration of the sewage system.
A detailed analysis of HCQ’s situation will also take
place, given the undeniable importance of the state of raw
earth edifications with high patrimonial value within the
World Heritage Site area.
3. An inventory of existing interstitial spaces associated to
the ravines’ path within the World Heritage Site area.
They are considered possible areas of intervention that
lead to a transformation of the future city from a passive
memory towards an active memory.
4. A rescue of Memory in relation to the ravines within HCQ
as an active operator for future transformative provisions
associated to the social, environmental, urban and
architectural dimensions.
5. Considering a ‘’Manual of Good Practice’’ for the future
planning of HCQ. This document would assume active
memory as an operator of innovation and stimulation of
current and future transformations of a territory with
internationally recognised patrimonial value.
6. Visibilize the consequences of the closure of HCQ’s
ravines at an urban level.
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The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLIV-M-1-2020, 2020
HERITAGE2020 (3DPast | RISK-Terra) International Conference, 9–12 September 2020, Valencia, Spain
This contribution has been peer-reviewed.
https://doi.org/10.5194/isprs-archives-XLIV-M-1-2020-825-2020 | © Authors 2020. CC BY 4.0 License.
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The International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Volume XLIV-M-1-2020, 2020
HERITAGE2020 (3DPast | RISK-Terra) International Conference, 9–12 September 2020, Valencia, Spain
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La construcción tradicional y su vulnerabilidad sísmica "el caso de Quito y sus construcciones con valor patrimonial
  • L Calderón
Calderón, L., 2015. La construcción tradicional y su vulnerabilidad sísmica "el caso de Quito y sus construcciones con valor patrimonial. Congreso CONPAT, Lisboa, Portugal
Patología de la construcción en tierra cruda en el área andina ecuatoriana. AUC revista de arquitectura
  • L Calderón
Calderón, L., 2017. Patología de la construcción en tierra cruda en el área andina ecuatoriana. AUC revista de arquitectura, 38, p.31-41,http://editorial.ucsg.edu.ec/ojs-auc/index.php/aucucsg/article/view/69
Regeneración y revitalización urbana en las Américas: Hacia un estado estable
  • F Carrión
Carrión, F., 2009. El centro histórico como objeto de deseo. In F. Carrión y L. Hanley (ed.). Regeneración y revitalización urbana en las Américas: Hacia un estado estable, p. 35-57. FLACSO-E / USAID, Quito.