Jochen A.G. Jaeger - Department of Geography, Planning and Environment, Concordia University Montréal;
Christian Schwick - Die Geographen Schwick+Spichtig;
Alain Jarne and Martin Schuler - CEAT, École Polytechnique Fédérale de Lausanne (EPFL)
Abstract
Transformation of land use in and around European cities is proceeding as fast as never before, and urban sprawl is a reality in Europe. This process is coming along with significant landscape changes that can even lead to the loss of landscape identity. Is it possible to find indications of which regions are prone to urban sprawl in order to curtail undesired future settlement developments in time? To answer this question we used settlement development scenarios for Switzerland, and analysed their spatial implications using a set of four metrics, which allow for comparing the degree of urban sprawl in different regions. Two aspects were explored: (1) by how much settlement development could potentially increase in Switzerland, and (2) the suitability of the metrics as indicators for characterizing and assessing the development of urban sprawl. The results show that overall in Switzerland the urban permeation and dispersion of settlement areas is likely to increase (in all scenar- ios), but to different degrees. However, the results differ very much between the various types of settlement and between the cantons, and even a decrease in urban dispersion is possible. In combination with scenarios of set- tlement growth, the metrics provide useful evidence on regional characteristics such as the overall pressure of settlement development and likely transformations of the respective settlement types that should be taken into account in spatial development concepts. There is a need for calibration of the indicators on a regional level to define specific thresholds to limit urban sprawl.
Introduction
Settlement structures in combination with other landscape elements, e.g., water bodies, vegetation, and types of cultivation, can build unitary and comprehensive contexts with high informational content and stimulating ori- entation patterns contributing to the character of various landscape types (Kim and Pauleit 2007; Nohl 2001). Settlement development changes the view of a landscape significantly (Antrop 2004), and since the 1960s, it has frequently created conditions that are denoted as urban sprawl, i.e., particular types of scattered and fragmented peri-urban areas. Associated with these settlement structures are a number of negative effects, such as: loss of cultivated land and loss of biodiversity, irreversible loss of heritage values, aesthetic degradation, declining recreational quality of the landscape and reduced quality of life (Catalán et al. 2008; Ewing 1997; Frenkel and Ashkenazi 2007; Gagné and Fahrig 2007; Jaeger et al. 2007a, 2010a; Siedentop 2005). Affected landscapes often lose their identity (Nohl 2001).
Urban sprawl has been identified as an undesired trend in many countries. There are some examples of planning and land management systems that have been successful in urban containment and countryside stewardship, e.g. the Dutch system and to a lesser degree, the British system (Alterman 1997). However, most attempts to guide development activities in the direction of more desirable settlement patterns have had little success (Bengston et al. 2004; Kasanko et al. 2006; Ulfarsson and Carruthers 2006). Will urban sprawl become even worse in the future?
One difficulty in answering this question is that the future settlement development is difficult to predict. The combination of many factors may lead to completely different alternatives regarding where and how people decide to live and work, with spatial, economic and political dimensions being interconnected (Ulfarsson and Carruthers 2006). A second problem is that it is often not clear which degree of urban sprawl should be assessed as so harmful that further negative development should be strongly avoided. A common consensus on the evaluation of urban sprawl and what criteria should be applied is still missing (Siedentop 2005), even on a na- tional level.
In this paper, we aim to overcome these difficulties by (1) using a set of alternative future settlement develop- ment scenarios for Switzerland, and by (2) analysing and assessing their characteristics and implications through the application of a set of new urban sprawl metrics. These metrics allow for a quantitative approximation of the description of landscape quality by indicating the anthropogenic pressure on the landscape (Jaeger and Bertiller 2006; Jaeger et al. 2010b). The following research questions were addressed:
• First, we asked by how much settlement will potentially increase in Switzerland by 2030 according to the four scenarios, and where the most substantial changes would be expected under these scenarios.
• The second question focussed on the evaluation of urban sprawl by asking if the metrics provide useful evidence for characterizing and assessing the nature of settlement dispersion.
The overall goal of this article is to assess the informative value of the new urban sprawl metrics in order to provide planners and decision makers with indications on settlement areas that are particularly exposed to urban sprawl, using Switzerland as an example.
Case Study Location and Research Framework
Four Alternative Scenarios: “Switzerland 2030”
- Qualitative Scenarios
- Quantitative Model of Settlement Growth
- Calculating Maps of the Future Settlement Distribution
Methods
- Calculating Metrics of Urban Sprawl: Urban Dispersion, Total Sprawl, Urban Permeation, and Sprawl Per Capita
- Interpreting the Metrics with the Use of Qualitative Scenario Information
Results
- Differences in the Increase of Urban Permeation Between the Scenarios
- Influence of the Scenarios on the Dispersion of the Settlement Areas
- Differences in sprawl per capita
Discussion
- Most Substantial Changes in Settlement Development Under the Four Scenarios
- Indications for Regions Inclined to Urban Sprawl
Conclusions
Our results show that Switzerland has strong tendencies of continued urban sprawl, but these trends are not equally severe in all parts of Switzerland. The metrics help gain insights about the impacts of the scenarios on the spatial pattern of the settlement areas and compare them to the situation of today. Obviously, there is no single one settlement development scenario among our four scenarios that could support the lowest increases, or even decrease, of the metrics in all settlement types with the same effectiveness. Thus, the various settlement types need different strategies for managing their future growth of settlement area.
However, the results do not yet reveal what quantitative limits (based on the metrics) should be set in order to ensure a sustainable settlement development. Focussing on particular cantons, it has become obvious that the landscape structure, the related socio-historically evolved settlement forms, and the locations of the designated building zones have great influence on the values of the metrics, and that limits or thresholds based on the met- rics need a region-specific calibration. It will depend on an evaluation and appreciation of the resulting land- scapes if detected processes should be permitted, changed, or stopped.
The scenarios are not suitable for directly deriving policy recommendations from the simulation results because of the large number of scenario-related assumptions and generalizations. However, due to their inner consis- tency, the scenarios demonstrate potential spatial developments that provide thought-provoking impulses. In scenario C, the population remains more or less where it is today and the consumption of resources is stabilized. Thus, a lowered demand in further build-up area is a very reasonable option for the future. However, scenario D describes a cohesive development (with a strong economy) which is often equated with decentralized settlement growth and urban sprawl. In contrast, metropolitan growth as in scenario B is often equated with densification and thus reduced urban sprawl. Our scenarios show that this equation is not correct in such general terms. They support the hypothesis that cohesive regional development is not accompanied by high rates of land consump- tion but demands relatively little new build-up areas. This result is supported by Alterman’s (1997) findings: Containment of urban growth strongly depends on a nation’s shared norms and values for land development.
As the metrics provide for rather abstract (quantitative) information, the resulting landscape conditions should be studied through 3D landscape visualisations as a next step to aid understanding and communication on all planning levels from the outset on. By integrating visual and non-visual landscape information, these instru- ments show high potential for assisting in the analysis of landscape change and evaluating the character of pos- sible future landscapes (Higgs et al. 2008; Wissen et al. 2008).
The new urban sprawl metrics are suitable to highlight anthropogenic pressures on the landscape. However, human action is one important aspect among others (e.g., physical forms and societal values) which in their combination shape a landscape (Stephenson 2008). In order to further increase the understanding of landscape change, the metrics should be combined with additional indicators, e.g., for the assessment of the view and the ecological impairment of potential future landscapes and for testing the effects of alternative patterns based on societal values (Grêt-Regamey 2007; Nassauer and Corry 2004; Walz et al. 2007).
Acknowledgements
References
The final publication is available at: www.springerlink.com
Link para o artigo completo:
http://www.blogger.com/blogger.g?blogID=1724632761341353698#editor/target=post;postID=7704700052054632863
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