Available online at www.sciencedirect.com ScienceDirect Procedia Engineering 165 (2016) 355 – 363 15th International scientific conference “Underground Urbanisation as a Prerequisite for Sustainable Development” Predetermined? – Systems thinking for the urban subsurface Loretta von der Tanna,*, Brian Collinsa, Nicole Metjeb a Department of Civil, Environmental and Geomatic Engineering, University College London, UK b Department of Civil Engineering, School of Engineering, University of Birmingham, UK Abstract In recent years the topic of urban underground projects and infrastructure networks as well as their contribution to sustainability and resilience of cities has been widely addressed Major projects deal with questions of interdependencies, mapping and untangling of the existing underground infrastructure web, which constitutes not only a service but also a major constraint for future projects and planning in the underground space In addition, the use of urban underground space is more and more extended from purely ‘technical’ functions like infrastructure and storage to developing the space itself into, for example, shopping malls, extensions of museums or parking facilities, recreational spaces, archives, or computer centres To capture and plan for these manifold interests in the long-term, a holistic approach to analyse the urban subsurface is needed which goes beyond the analysis of singular projects or networks Masterplans which integrate the subsurface seem to be feasible but ultimately can only be successful if the underlying system properties are sufficiently understood This paper reviews the development of system thinking as well as its applicability for analysis of the urban subsurface as multifunctional, holistic entity Prospects and outstanding issues when adopting a systems perspective to a spatial entity are discussed in order to interpret what they might mean for the urban subsurface In this context, the influence of system boundaries on system properties like flexibility, adaptability and resilience is highlighted, challenging the notion that the potential for further exploitation of the subsurface is predetermined by the local geology, the legacy of human impact and the advancement of technologies © 2016 by Elsevier Ltd This is an open access article under the CC BY-NC-ND license © 2016Published The Authors Published by Elsevier Ltd (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the scientific committee of the 15th International scientific conference “Underground Peer-review under scientific committee of the 15th International scientific conference “Underground Urbanisation as a Urbanisation as aresponsibility PrerequisiteoffortheSustainable Development Prerequisite for Sustainable Development Keywords: systems thinking, urban underground space, sustainability * Corresponding author Tel.: +44-7591-961299 E-mail address: loretta.tann.13@ucl.ac.uk 1877-7058 © 2016 Published by Elsevier Ltd This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/) Peer-review under responsibility of the scientific committee of the 15th International scientific conference “Underground Urbanisation as a Prerequisite for Sustainable Development doi:10.1016/j.proeng.2016.11.710 356 Loretta von der Tann et al / Procedia Engineering 165 (2016) 355 – 363 Introduction How to deal with the urban subsurface given its multiple functions on the one hand and its “congestion” with built structures on the other hand, is a recurrent discussion The importance of this question for urban sustainability has been increasingly addressed in recent years (Bobylev, 2009; de Mulder et al., 2012; Hunt et al., 2015; Magsino et al., 2013; Parker, 2004; Price et al., 2016; Sterling et al., 2012) Authors often refer to the growth of urban areas as an incentive to extend the utilisation of the urban subsurface (e.g Hunt et al.; 2015, Price et al., 2016; Zhao and Cao, 2011) Shortage of surface space in dense cities alongside with acknowledgement of the value of green spaces for liveability (Chiesura, 2004) has led to undergrounding of parking facilities, recreational and shopping facilities (Zhao and Cao, 2011) The conceptual notion of growth and limits to growth as formulated by Meadows et al (1972) are closely related to the systems view However, major cities lack a coherent planning strategy which integrates surface and subsurface assets (Sterling et al., 2012; Price et al., 2016) For example, the spatial development strategy for London, the London Plan, does not include specific policies for spaces in the subsurface, despite regular revisions and a “subterranean building boom” including several large infrastructure projects as well as the construction of mega basements (Reynolds and Reynolds, 2015) To underpin the claim for a more coherent planning strategy and a more holistic view of the urban subsurface, authors frequently borrow systems terminology or concepts: The need for cooperation and mutual understanding amongst different stakeholders and owners of subsurface assets (Magsino et al., 2013), for example, can be seen as an analogy to the basic notion of systems theory that overspecialization impedes seeing the broader context (von Bertalanffy, 1968) Even if it has been claimed in the systems community that the notion of expertise and the “inability to deal adequately with conflicting values, viewpoints, policy preferences, ideologies & power relations” has already been addressed in the 1960s and 1970s (Richardson and Midgley, 2007), on the city planning level this has not yet been resolved (Orr, 2014) Apart from looking separately at the various systems embedded in the subsurface (infrastructure systems, groundwater system, natural resources) or shaping the subsurface (geological system), some authors categorize the functions of the subsurface as resources or ecosystem services (Bobylev, 2009; Price et al., 2016), directly referring to systems terminology and the subsurface as part of the earth’s ecosystem Ideas have been proposed on how to deal with future challenges regarding the urban subsurface; Masterplans for the subsurface analogue to surface plans and stating the city of Helsinki as well as recent initiatives in Singapore as examples are postulated as the way forward (Bobylev, 2009; Hunt et al., 2015) However, the urban subsurface as a spatially bounded entity has not been discussed from the perspective of systems thinking in more detail This paper gives a short overview of systems thinking and in particular land systems theory Different ways of classification of subsurface functions are described as classification influences system models as well as the perception of the questions asked and solutions sought The paper introduces the discussion about opportunities and limitations of systems theories in this context to subsurface professionals in the hope to trigger a discussion about problem contexts and boundaries when dealing with the urban subsurface Systems Thinking A system is an entity assembling a number of components which form a coherent whole and act together for a common purpose The concept of systems as a new way of scientific thinking or paradigm as opposed to the traditional mechanical paradigm or engineering attitude is attributed to the biologist Ludwig von Bertalanffy In his book “General Systems Theory” (von Bertalanffy, 1968) he emphasized two main limitations of the so far dominant mechanistic idea of isolable causal chains: First, the analysis of system elements as independent entities neglects interactions between the elements Second, the assumption that a system can be explained through understanding and adding up of its parts only holds if linear behaviour of the elements is assumed (von Bertalanffy, 1968) Von Bertalanffy criticised that systems thinking how it had evolved to that date was running the risk of just developing into yet another mechanistic discipline Loretta von der Tann et al / Procedia Engineering 165 (2016) 355 – 363 2.1 General Systems Theory General Systems Theory (GST) focused on the behaviour of system parts in mutual interaction emphasizing that this can differ as to how these parts would behave in isolation Von Bertalanffy (1968) specified a set of principles which can be applied to a wide range of systems Some of the core ideas are summarized in the next paragraphs The holism principle says that a system is “more than the sum of its parts” (Meadows and Wright, 2008) - in fact, it is “characterized by the interactions of its components and the nonlinearity of those interactions” (Walonick, 1993) It is accepted that the behaviour of a system cannot exhaustively be explained by description of the systems components In other words, the whole is always different from its parts (Richardson, 2004) A system is an entity assembling a number of components which form a coherent whole and act together for a common purpose According to the principle of hierarchy or hierarchic order, systems are organized in a hierarchal manner Each particular component must devote its functionality to the purpose of the higher order system they belong to while at the same time they rely on the functionality of their subsystems (Meadows and Wright, 2008) Open systems as opposed to closed systems are systems which exchange material and energy with their environment They need this exchange of matter for survival The second law of thermodynamics states that entropy in closed systems always increases Thus, decrease in entropy and increase in order which goes along with an increase in complexity is only possible in open systems (von Bertalanffy, 1968) A system transforms input into higher order output and waste As long as the increase in order through the transformation of input into output exceeds the decrease in order through the transformation of input into waste, entropy inside the system decreases and the system grows (Goldsmith, 1971) System growth is generated by reinforcing feedback loops - the system output influences the system in a way that more of the same output is produced It is important to note that the different processes reinforce each other and thus their analysis as unidirectional causal chains is not suitable (Meadows and Wright, 2008) System growth is constrained by balancing feedback loops which arise because the environment is finite (Meadows and Wright, 2008) The system seeks an equilibrium or steady state between the various forces acting upon it Even if no real closed systems exists except of the Universe (Richardson, 2004), in this stable state a system can temporarily behave like a closed system The equifinality principle refers to the statement that there is always more than one way from one system state to another An open system which seeks a steady state will reach the same steady state independently of its initial conditions (Richardson, 2005) Equifinality implies a certain degree of predictability and thus is the basis for regulability of non-mechanic systems To analyse a system in its own right, a definition of the system boundaries is essential (von Bertalanffy, 1968) The boundary of a system allows to distinguish between internal and external elements as well as describing and quantifying input and output between the system and its environment In other words, boundaries enable systems to regulate the in- and outflow of matter Where a boundary is drawn depends on the problem looked at and there is no exclusive way to so (Meadows and Wright, 2008) 2.2 Changeability of systems Systems thinking changed the focus of researchers from subject matter to processes (Simutis et al., 1973) and thus to understanding not only how a system works but also how it behaves when it undergoes change Today it seems evident that processes have to be analysed and understood in the long-term and planning for sustainability and resilience requires the recognition of time and thinking in various time scales as a determining factor for decision making However, the extended time scale of the human impact implicating complexity and uncertainties was only recognized recently (Moffat and Kohler, 2008) The effect of time results in a constant change of a system itself as well as of its environment (Ross et al., 2008) Systems have to accommodate this change for the span of their lifetime The capability to so is determined by system properties like flexibility, adaptability, or resilience Ross et al (2008) define flexibility as the capability of a system to be changed by an external agent This is to distinguish from adaptability which implies an actual self- 357 358 Loretta von der Tann et al / Procedia Engineering 165 (2016) 355 – 363 acting change of the system as a reaction to external factors or threats as well as to rigidity which implies that no change can occur If no change occurs despite external shocks, a system is called robust (Ross et al., 2008) In contrast, a resilient system can undergo considerable change It bounces back to a stable state which can be different to the state the system was in before the occurrence (Meadows and Wright, 2008) Thus, resilience in the time scale looked at might embrace failure of the same system’s robustness at a shorter time scale (Bankes, 2010) 2.3 Critical systems thinking Systems approaches are methods or frameworks “for identifying and describing complex patterns of interdependencies.” (Simutis et al., 1973) A range of systems theories and approaches were developed preceding as well as subsequent to GST and ranging from methods like systems engineering to descriptions of viable systems, smart systems or living systems The different methods coexisted despite differences in epistemological position potentially conflicting elements (Mele et al., 2010) This complementarism formed a starting point for the development of Critical Systems Thinking (CST) and the process of Total Systems Intervention (Flood and Jackson, 1991), which extended the commitment to complementarism from the methodological level to the theoretical level or underlying rationalities The question of incommensurability between the different theories or how the various approaches can be compared when applied complementary has been discussed by the authors of CST (Jackson, 1991) but remains unresolved (Bowers, 2014) In this context the importance of critical awareness about methodologies and theories as well as assumptions and values for system design or interventions was emphasized (Jackson, 1991) Another feature of CST was to bring the human factor of systems into focus Jackson (1991) stated that users of systems methodologies should not only be aware of consequences of their interventions as well as influences acting upon them, but also commit to the idea of human emancipation and the global objective to maximise individual development Consequently, besides the option to choose a methodology depending on the problem context, methodological and theoretical complementarism or pluralism also allows the researcher to change perspective using different methods and theories and thus to embrace the fact that the different actors in a system are self-conscious (Richardson and Midgley, 2007) and the conceptualization of a system regarding space and time always refers to the actor’s specific point of view (Mele et al., 2010) Systems thinking for urban areas and the build environment The recognition of different worldviews or different mental models is fundamental when approaching urban planning from a systems perspective (Perdicoúlis, 2010) Yet, on the city level, the debate about the division of the dealing with and thinking about systems into sub-tasks for multiple institutions and disciplines, is still present Orr (2014) describes ongoing institutional fragmentation: “Despite the inherent logic of systems thinking, governments, corporations, foundations, universities, and non-profit organizations still work mostly by breaking issues and problems into their separate parts and dealing with each in isolation.” Temporal and spatial fragmentation concerning the build environment in general are observed by Moffat and Kohler (2008): “In conventional practice, the built environment is most commonly surveyed or analysed either as a piece of private property (the parcel), or as a collection of properties with their associated buildings, infrastructure and constructed open spaces Spatially, the analysis of energy or mass flows is limited to what crosses the property limits Temporally, the analysis is limited to the time period beginning with project initiation and ending with commissioning, or to a typical day or year of occupation and management.” Nonetheless, system theories and analogies did influence the conceptualization of the city early on; cities have been analyzed as ecosystems, social systems, and management problems (Simutis et al., 1973) Rittel and Webber (1973) criticised that systems thinking to that point had been focused on the system outcome rather than purpose and thus was not applicable to urban planning, which deals with “wicked” problems They stated that the outcome of planning activities will always be uncertain and thus a focus on the purpose of actions or interferences is needed In Loretta von der Tann et al / Procedia Engineering 165 (2016) 355 – 363 359 addition, Simutis et al (1973) claimed that systems approaches had failed to provide a synthesis of traditional “atomic” disciplines in urban studies Today, due to the perceived inability of systems theory to tackle untraceable and indeterminate problems, the attempt to apply systems thinking to planning may seem outdated (Banerjee, 2012) However, urban theorists moved from looking at first order processes or the assumption that all processes can be represented by algorithms, to second order processes, namely emergence and autopoiesis (Boyer, 2010) and the general task of urban planning shifts from creating places to creating collaborative approaches which generate ongoing “place-making activities” (Healey, 1998) In addition, recent system frameworks like land system science address questions of urbanisation from a systems perspective 3.1 Land systems and urban ecosystem services Land systems are described as the terrestrial component of the complete ecosystem of our planet which arises from human interaction with the natural environment (Verburg et al., 2013) Changes of land systems directly result from human decisions at multiple scales and decisions at an apparently minor scale can impact the whole ecosystem and feed back into human well-being and decision making (Crossman et al., 2013) One of the land changes considered most problematic is urbanisation or “conversion of land to built-up […] due to its perceived irreversibility and severe consequences for climate, biodiversity, ecosystem quality and ecosystem services, which are difficult to mitigate and manage” (Elmqvist et al., 2013) As part of the earth’s ecosystem, land systems provide ecosystem services which the Millennium Ecosystem Assessment (2005) links to components of human well-being and categorizes into: x x x x resources or provisioning services like fuel, fibres, or food; supporting services such as nutrient cycling or soil formation; regulating services like water purification or flood mitigation and cultural services which include aesthetic, spiritual and recreational functions Ecosystem services are materials and functions provided by nature which are essential for the survival of humanity The capacity of nature to accommodate these services is influenced by human land-use (Verburg et al., 2013) In other words, “ecosystem services are co-produced by human-environment interactions, and not exist if there are no beneficiaries” (Wolff et al., 2015, cited by Verburg et al., 2015) Nowadays, particular in urban areas, the place of service use and service provision are decoupled: most of the ecosystem services consumed in cities are generated by outside of the city itself (Gómez-Baggethun et al., 2013) The mutual influence of systems which can be distant from each other and the potential mismatch of governance systems and physical systems was emphasized in the concept of telecoupling (Verburg et al., 2015) However, to achieve sustainable land use we have to move “beyond the vision of cities as centres of consumption that externalise land use impacts on rural hinterlands, and acknowledge that cities and urban lifestyles and institutions can also contribute to solutions” (Verburg et al., 2015, referencing Seto and Reenberg, 2014) Gómez-Baggethun et al (2013) discuss classification and values of ecosystem services specific for urban areas as well as how their assessment may inform urban planning and governance They list noise reduction, urban temperature regulation, moderation of climate extremes, outdoor recreation, cognitive development, and social cohesion as the ecosystem services most important for urban areas Valuation of these services is challenging as service value and risks of losing urban ecosystem service capacity can be perceived differently by different groups or stakeholders (Martín-López et al., 2014) In addition, trade-offs can arise between ecosystem services which depend on alternative land uses (Verburg et al., 2015) The urban subsurface – a system? This brief summary of systems thinking leads to the following interpretations concerning the urban subsurface: 360 Loretta von der Tann et al / Procedia Engineering 165 (2016) 355 – 363 x Understanding of urban growth as a systemic reinforcing feedback loop poses the challenge to think not only about how urban growth generates subsurface use but also about how the development of space generates growth (see Meadows and Wright, 2008) x Adopting the definition of changeability by Ross et al (2008) and interpreting the human influence on it as external agent, the urban subsurface can be conceptualized as system or spatial entity which: (a) adapts constantly to internal factors (b) has rigid features like the geology and legacy of the build environment (c) Needs to be kept flexible to enable adaption to future needs This list directly leads to the importance of boundary definitions If humans are influencing the system as external agents, some general phenomena like plate tectonics will easily be accepted as being internal to the system Other phenomena like climate change or changes in groundwater flow or quality, which are influenced by human activity, could be internal or external depending on the time scale and period looked at Boundaries can be defined in multiple ways The definition of the system boundaries has to react to the needs of every particular project and the same matter can be “element, system or component of the environment depending on the chosen frame of reference” (Skyttner, 1996) Regarding the subsurface, thus the definition of problem boundaries will determine if the subsurface is looked at as a system in itself or rather as stock, providing resources or services to a larger system Not only is the definition of external boundaries crucial for understanding and analysing of a specific entity Boundaries are also drawn between the various internal elements in a system, for example through categorization The terminology used to describe a system and its parts will “change apperception, i.e., which features of experienced reality are focused and emphasized, and which are underplayed.” (von Bertanaffly, 1968), and it is essential to specify the functions of the subsurface as well as the societal benefits of using the ground beneath our cities (Price et al., 2016) 4.1 Categorization of the subsurface The functions of the urban subsurface for humans have been categorized in different ways Parriaux (2007), distinguishes four groups of resources: space, geothermal energy, groundwater and geomaterials This classification is resumed amongst others by Sterling et al (2012) and Hunt et al (2015) Bobylev (2009) also described urban underground space as a resource, but lists more specific services provided by the urban subsurface, which analogue to resources he classified as renewable (drinking water supply, groundwater supply to surface vegetation, surface water reserves supplied by groundwater and geothermal energy) and non-renewable (physical space, space continuum that has certain soil strength properties, excavated materials, and cultural heritage) While de Mulder et al (2012) specify seven groups of subsurface functions differentiating between utilisations of physical space, Price et al (2016) adopt the notion of the subsurface delivering ecosystem services as well as the four classes of ecosystem services defined in the Millennium Ecosystem Assessment (2005) (see section 3.1) They extend this list by a fifth class, “platform” which was proposed by Rawlins et al (2015) and acknowledges “carrying” functions, in particular bearing capacity and electrical earthing potential Another approach to the categorization of the subsurface is focusing on ownership and administrative boundaries instead of functions Distinction by depth can be found in ownership models of countries like Japan or Greece (de Mulder et al., 2012) as well as to set administrative boundaries like in the municipality of Rotterdam (van Campenhout and de Vette, 2016) Even if these depths are derived taking functional points into consideration, the resulting regulation seems to be independent of the local geological conditions, as in the end the depth, for example, of private ownership is fixed in metre This does not reflect the rules and regulations about natural hazards like earthquake or flooding which of course are determined locally Loretta von der Tann et al / Procedia Engineering 165 (2016) 355 – 363 Discussion Systems thinking has evolved over the last decades from a new way of modelling organizational, technological, and social situations to a world view which recognizes the interrelation of matter and action as well as continuous change This recognition of global interconnectedness is today more important than ever when sufficient access to basic needs for a growing world population has to be provided while at the same time dealing with global problems like climate change Evidently human action creates legacy which cannot be undone retrospectively Different to the built environment above the surface there is no ‘try and error’ below the ground surface - the result of human action gets internalized in the system acted upon This impossibility of repetition and error correction might help to explain the lack of long term studies of impacts and trade-offs of underground investments mentioned by Magsino et al (2013) The notion of services, functions or resources, implies that the subsurface is not looked at as a system in itself but as part of a bigger system, as stock or in- and outflow for the city as a whole Some of the services provided will not be renewable However, there is a difference to natural, non-renewable resources The latter get extracted first and only the consecutive process converts them into the product or function they are finally used for whereas the final function of subsurface space is typically decided before according action is being taken or the resource is being exploited Thus there are very different cause-effect chains and decision making processes to be considered Looking at ecosystem services as defined by Verburg et al (2015), one has to ask, which of the services listed are essential for the survival of humanity For functions like bearing capacity and groundwater agreement will be found easily, whereas for others like space for transport or private development this will prove more difficult It is an important discussion as regulation will evolve around what society and decision makers perceive as essential or necessary It is interesting to note that none of the categorization schemes explicitly distinguish between man-made and natural systems, which underpins the above statement that in the urban subsurface the man made legacy gets internalized – it becomes something “to deal with” or to manage rather than something to design Also, none of the reviewed categorisation schemes is without conflict between the different categories However, trade-offs between the different categories as described between alternative land uses in land system science have not been studied comprehensively For example, if the subsurface is divided into layers by depth, it has to be acknowledged that deeper layers cannot be accessed without drilling or digging through shallower layers The definition and management of boundaries seems essential to the discussion Setting boundaries also determines system properties like flexibility or adaptability If sustainable management of the subsurface is the objective, the spatial and temporal boundaries of analyses have to be set in a way that allows flexibility and creative thinking, instead of managing legacy with new one-off solutions Purely spatial boundaries such as the zones fixed in master plans were one option but proved insufficient at city level, where many of the goods and services needed are produced outside of the city boundaries They ignore interdependencies with more distant processes and seem to disregard the described focus of system thinking to look at processes instead of places or subject matter The concept of theoretical and methodological pluralism could help not only to foster mutual understanding between stakeholders but also to find a way how to integrate different timescales Conclusions The paper provided a brief overview of how systems thinking and methodologies evolved and how these evolutions and terminologies can be linked with current literature about management of the urban subsurface With the awareness of systems thinking, analyses should change: Instead of studying interdependencies between spatially bounded entities the focus should shift to essential processes and how these are connected through place, time and institutions To be able to be resilient and react flexibly to future challenges, we have to understand how the temporal and spatial scales of our analyses influence the flexibility of the system looked at and thus which is the best scale for intervention Trade-offs between alternative uses have to be studied in detail and the significance of potential uses of the subsurface for society as a whole have to be defined if a sustainable perspective is sought 361 362 Loretta von der Tann et al / Procedia Engineering 165 (2016) 355 – 363 It seems crucial to find the right way of classification and terminology for subsurface functions, as they define boundaries which in turn will shape future decisions and management Current classification schemes treat the subsurface as a resource or service and thus as an input into the larger urban system rather than as a system or bounded entity in itself and hint to the conclusion that the subsurface should be integrated into analyses of cities and urban areas in general Finding the right terminology and managing of internal and external boundaries is crucial to take responsible and foresighted decisions The concept of theoretical and methodological pluralism might help to understand 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