Méthodologie de gestion durable des ressources du sous-sol urbain

The world is becoming more and more urban. During the last fifty years, the population in Swiss cities has grown from 45% to 70% of the total population. This change is characterised by urban sprawl and by an increase in the consumption of resources, particularly those coming from rural areas. This evolution is not compatible with the principles of sustainable development. To solve this problem, new urban policies are being developed. They favour development within the urbanised areas and reduced use of exogenous resources. The urban underground contains resources – space, geomaterials, groundwater and geothermal energy – which can efficiently support such policies. This project analyses how these resources have been exploited until now and how they could be used with sustainability in mind. The use of underground resources was analysed in five cities : Mexico, Paris, Helsinki, Tokyo and Montreal. It appears that, although resources participate in the urban metabolism, there is an important lack of planning and coordination in their use. Developments follow a sectional approach where the resources are considered independently, and only at the scale of a given construction project. As a consequence, conflicts occur between uses and resources are wasted. An understanding of the urban underground as a system was developed with the aim of preventing conflicts and promoting synergies. To this effect, the way in which resources interact was considered attentively. Situations in which interactions occur were described and analysed and compatibility conditions were suggested. A methodology was elaborated to evaluate the resource potential of an urban underground. It aims at considering the resources and the interactions between their uses from the beginning of the process of urban planning. The methodology is based on the use of Geographical Information Systems and 3-D modelling of geological and hydrogeological conditions. It aims at reversing the current paradigm, that proceeds from the needs to the resources, into an approach based on resources to satisfy the needs. Spatial information was exploited to determine indicators and maps of potentiality and of restrictions. The derived results will help support decision making by planners and policy makers who seek to better exploit the resources from the urban underground. The methodology was tested and applied on a case study : Geneva. The developed approach allows more efficiency in the use of urban underground resources, it can help prevent conflicts between uses and develop synergies. When integrated in the urban planning process, it highlights new opportunities and helps to develop projects that take into account the physical conditions of the underground.

Métropolisation, habitat précaire et relogement forcé: entre phénomènes d'exclusion et tactiques populaires d'intégration

Sébastien Wust

This work was carried out within the interdisciplinary scientific program named "Sustainable Development, Metropolisation and Pollution of Natural Resources in Ho Chi Minh-City, Vietnam". This program, launched in 1994, is financed by the Swiss National Science Foundation (Priority Program Environment, Module 7 "Environment and development"). The main goal of this thesis is to grasp the social, economic and spatial dimensions at stake of involuntary resettlement of precarious settlements. in the context of developing countries' metropolisation. One of the approach selected fits within a thorough study of southern metropolis evolution dynamics, more precisely that of disadvantaged neighbourhoods. Moreover, we decided to develop a specific approach of involuntary resettlement, which is constructed using mainly two dialectical and interdependent concepts: exclusion and integration. In this way, this work differs from the most frequently used theoretical models, which are based on impoverishment or stress dimensions. In third world metropolis, government forces have an increasing tendency to turn to involuntary resettlement in order to implement or promote urban planning. Every year, approximately 6 million people are forced to move into an urban environment. This concerns mainly the most underprivileged sections of the population corning from precarious settlements. In recent times, this phenomenon has grown to such a point that some international institutions have even talked about the century of involuntary resettlement. The theoretical framework of this thesis refers to three different fields of knowledge, which nevertheless are linked to one another. The first field concerns developing countries metropolisation. Closely associated with the globalisation and polarisation of international trade, this process leads not only to the rise of exclusion but also to the dualisation of economic, social and political spheres and the fragmentation of urban spaces. The second theoretical field of study is based on questions raised by precarious settlements in southern metropolis. We analyse the way vulnerable populations living in disadvantaged neighbourhoods develop urban integration tactics in order to counter metropolitan exclusion forces and to alleviate precariousness. Finally, the third field is part of involuntary resettlement problematic. While it shares a close link to public policy evaluation, this problematic analyses the institutional values, norms, and practices underlying relocation policies of the people living in disadvantaged neighbourhoods. Our goal is also to develop a better understanding of the consequences associated to this kind of urban program and the way they might contribute to strengthening living conditions as well as residential situation precariousness for those who have been forced to move, leading them to develop defence mechanisms in order to guaranty their integration in the metropolis. In this analysis, we will focus on Ho Chi Minh-City and on the relocation program concerning the populations living in Nhieu Loc-Thi Nghe canal's precarious settlements. In the empirical part of this work, we will analyse and measure the consequences of this policy on their living conditions as well as on their behaviour. We will try to analyse to what extent those consequences tend to increase exclusion of underprivileged populations, limit their integration capacity, and enhances their residential mobility towards new precarious settlements that fit more to the aspirations, and above all, to the means of the underprivileged. Given the complexity of the topic covered in this work, we opted for an interdisciplinary approach. It appeals to different fields of social sciences: sociology, economics, geography, political sciences, but also architecture and urban planning. Moreover, we chose a quantitative as well as a qualitative method. Based on a multidimensional analysis of Nhieu Loc-Thi Nghe canal's population living in precarious settlements, we will be able to grasp the discriminating dimension of involuntary resettlement policy set up by metropolitan authorities as well as its severe impact on the population at a residential, social and economical level. Restrictive economic criteria or in some cases insufficient compensations offered by public authorities are such that a number of persons are excluded from the program. But on top of that, part of the families relocated in modern and salubrious apartments suffer from exclusion. As regards housing, the new apartments are characterised by their limited residential functions. This is mainly due to constraints linked to high rise housing, which acts as an economic and social barrier. In terms of social organisation, involuntary resettlement leads to a family nuclearisation process, and traditional sociability tends to turn to a more individualistic way of life, a phenomenon which results in a partial deconstruction of solidarity and protection networks. Finally, at the domestic economy level, resettled populations have to deal with an increase in service charges as well as working conditions deterioration which involve decreasing incomes. Although this modern way of life appeals to resettled families, most of them are brought to develop new integration tactics in order to limit involuntary resettlement exclusion effects. These tactics are to a large extent conservative inasmuch as they tend to reproduce ways of life and space habits characteristic of the former residential areas. To a large extent, they are characterised by palliative measures of space utilisation, professional insertion, income improvement and domestic means reallocation. Despite their willingness, families have a hard time fighting against resettlement exclusion forces. Residential mobility as well as subsidised apartments resale then become the way for some families to minimise precarious living conditions. Nevertheless, the benefits they gain from these illegal practices are often insufficient for them to buy or build an accommodation close to the center of the metropolis. The only possibility left to the reseller is then to rent a dwelling unit in a disadvantaged neighbourhoods or to move on the outskirts. While residential mobility leads to the creation of new precarious settlements in Ho Chi Minh-City, some families living conditions as well as residential situation keep on deteriorating, a decline which might bring some of them to experience a kind of urban nomadism. While the results of our study confirm the hypothesis stated at the beginning of this work, they also point out how hard it is to fulfill the housing aspirations of the most underprivileged considering the precariousness of their living conditions. The inadequacy of precarious settlements relocation policy is even worse when based on a modernist and standardised approach of the housing problem which favours typological and technical dimensions of residential space to the detriment of social, economic and ecological dimensions. What is at stake in involuntary resettlement concerns mainly the multidimensional mechanisms of exclusion and integration of which depends the subsistence of the most underprivileged in Ho Chi Minh-City. Urban authorities need to make political adjustments if they want resettlement impacts to fit the goals of sustainable development. In order to achieve this objective, popular participation and exchange between involved actors is the first condition they need to fulfill for the implementation of any policy in order to fight against exclusion and promote the integration of the most underprivileged as well as for any policy which aims to take into account the capacity of urban ecosystems.

EPFL2001

Vers un assainissement urbain durable en Afrique subsaharienne

Halidou Koanda

Justification In Sub-Saharan Africa, excreta and wastewater disposal is characterised primarily by on-site sanitation systems. This sanitation option is more likely to increase as governments, municipalities, communities, private operators and donor agencies strive to reach the Millennium Development Goals aimed at reducing by half the proportion of people without access to basic sanitation facilities. Due to increased urban population growth in Sub-Saharan Africa, the faecal sludge volumes will increase to alarming quantities in the coming decades. An evaluation of faecal sludge management practices reveals that the main shortcomings relate to the widespread lack of involvement and foresight by the municipalities, the paucity of effective legal provisions and organization, and the absence of stakeholder coordination. Stakeholder involvement for planning and implementing faecal sludge management is virtually inexistent or excluded from urban sanitation planning processes. In the majority of situations, faecal sludge management is financially not viable. This is a major cause of the indiscriminate dumping of faecal sludge in urban areas or its untreated use in urban agriculture. These practices not only pose permanent and serious health risks but also contaminate both scarce ground and surface water. Objective and general approach On the basis of these facts, which present a real challenge to sector specialists, the overall objective of our research is to develop an innovative strategic planning approach for sustainable faecal sludge management in urban areas which allows minimising public health and environmental risks. Focus is placed on developing a reproducible methodology for stakeholder involvement, on enhancing population awareness for improved faecal sludge disposal and attributing a leading role to the dynamic private faecal sludge emptying and transport operators. These aspects form the three pillars of our search for a comprehensive methodological approach. The municipality of Ouahigouya in Burkina Faso with a population of about 65'000 inhabitants was used as pilot site to launch, implement and scientifically validate the approach. Analysis and stakeholder involvement The stakeholder-based planning approach developed in Ouahigouya relies on a combination of stakeholder identification and analysis, and participatory planning techniques (focus groups, workshops, informal meetings, all-stakeholder workshops). A quantitative survey among households allowed collecting stakeholders' proposals and evaluating suggestions for improvement of faecal sludge management and neighbourhood hygiene proposed by the population. The main steps in the stakeholder involvement approach include: Jointly clarifying the objectives of the planning process together with the stakeholders; Identifying stakeholders and their interests; Classifying stakeholders according to their importance and influence based on defined criteria and confirmed by the stakeholders themselves; Identifying the interactions between the stakeholders; Verifying the results of the stakeholder analysis by the stakeholders themselves; Choosing stakeholder involvement techniques; Implementing the chosen method of stakeholder involvement: development of faecal sludge management scenarios, acceptance of the scenarios by the stakeholders in focus groups, choice and acceptance of a basic scenario for development of the future strategy in an all-stakeholder workshop; Evaluating the chosen involvement process by the stakeholders. The experience gained with the planning methods developed and implemented in Ouahigouya reveals that the "Stakeholder analysis" method is efficient and provides answers to questions such as: Who are the important and influential stakeholders? Who should participate in the planning process and in which manner? This experience also revealed the need for capacity building of certain stakeholder categories (emptying operators, women's associations, etc.) to increase their degree of involvement in the planning process. Improvement in stakeholder involvement was achieved thanks to a combination of workshops, focus groups and other informal meetings allowing less influential stakeholders (associations of local women, horticulturists, emptiers) to share information and to freely express their opinions and concern and to defend their interests. Thus, providing an excellent example of local democracy appreciated by all stakeholders of Ouahigouya. The approach developed provides tools for policy-makers and planners to ensure an effective stakeholder involvement in the process of developing a common vision and implementation of improved urban sanitation measures. The conditions for replicating the approach developed and tested in Ouahigouya are due to participatory democracy, great commitment of the local authorities and the high motivation of the stakeholders involved. Levers for the willingness-to-improve faecal sludge management and neighbourhood hygiene The evaluation method of the willingness to improve faecal sludge management by the population was based on a combination of the planned behavior model of Ajzen and the contingent valuation method, financial analysis of the pit emptying and faecal sludge enterprise, and on focus groups of stakeholders. By focusing on local practices, perceptions and individual behavior, this method revealed that financial viability – often reduced to willingness-to-pay – is not the only factor to consider when planning improvement of sanitation practices. Willingness-to-improve is highly dependant on psycho-sociological factors such as attitude towards and beliefs in an improved neighbourhood environment, social pressure on the households by the neighbourhood as well as the subjective costs and benefits expected from improved faecal sludge management. These factors therefore present levers allowing planners and decision-makers to encourage, increase and develop the demand for improved latrine emptying services, e.g. though social marketing. Promoting private entrepreneurs According to market analysis of emptying services and stakeholders involved, small private and mainly informal enterprises play a leading role in faecal sludge management in most cities of Sub-Saharan Africa. These operators, dynamic but fragile, require an appropriate institutional, jurisdictional and economic environment based on a balanced partnership between the municipality (public) and the private sector. Our study reveals that for a company truck to be profitable, about 1'000 trips per year (at 6'000 FCFA per trip) are required or the equivalent of a city of 56'000 inhabitants. In the case of Ouahigouya, profitability is increased if the emptying operators apply the latest management and professional tools and techniques, and manage to provide emptying services in neighbouring towns. Decision support tools The research led to developing decision support tools for professionals and policy-makers. These tools facilitate the development of a tariff-oriented policy to avoid uncontrolled faecal sludge discharge into the environment, to render investments by private operators profitable, and still make emptying services accessible to low-income households. This involves: Analysis of the cost structure of 3 pit emptying companies has revealed that fuel, maintenance/repair and personnel costs make up 45%, 20% and 30%, respectively, of an enterprise's operating expenses. An Excel programme was developed to allow municipalities and private operators to determine the operating costs of emptying services. This allowed to establish a sustainable money flux between the different stakeholders involved and to define the tariffs. To prevent faecal sludge discharges in the immediate residential environment or on unauthorised sites, it might under specific circumstances prove necessary and feasible to reimburse rather than charge entrepreneurs for delivering faecal sludge to the treatment sites, hence, create a strong incentive for good emptying and haulage practice. Evaluation methods of the sludge quantities to be disposed of have been developed to allow faecal sludge planning by the municipal authorities, assessment of the potential market and return on investment by the private operators. Advantages of the approach for the population of Ouahigouya Based on the results of our study, it was possible to formulate practical recommendations for the organisation of the urban sanitation sector for the municipality of Ouahigouya – now in possession of a sustainable faecal sludge management strategy. Our study has also contributed to promoting local consultation and raising the awareness of the role and contribution of each stakeholder group, in particular the previously neglected manual emptiers in their daily efforts to improve the living conditions of the urban inhabitants. The "Strategic Excreta and Wastewater Sanitation Plan", that was developed and supported by the "Office National de l'Eau et de l'Assainissement - National Water and Sanitation Agency", provides an excellent framework for the implementation of the elaborated faecal sludge management model (as part of the this strategic plan).

EPFL2006

Development and application of a numerical simulation system to evaluate the impact of anthropogenic heat fluxes on urban boundary layer climate

Andrea Krpo

Increasing economic development, and growing population, generated during the last decades a very important growth of cities. Urban regions include nowadays more than half of the global population and, by 2030, this proportion is forecasted to increase to three quarters. A consequent more and more extensive use of natural resources, together with increasing anthropogenic activities such as emissions from traffic and factories, or heating from air-conditioning facilities, modify local climate in many different ways, leading to a progressive degradation of life quality in urban areas. Taking these facts into account, there is nowadays a real need for efficient urban planning guidelines and sustainability policies in order to improve life quality in urban areas. Different points should be considered including urban warming, air pollution, human health, economic, and cooling energy needs. The present work goes in this direction, aiming at developing a simulation system for the study of the complex interactions between buildings and the atmosphere. The system of equations describing atmospheric flows is highly non linear and it is common to employ numerical techniques in order to solve them. Moreover, the representation of urban canopy climate, and related air pollution problems, requiree taking the interaction between urban scale (tens of kilometers), and mesoscale (hundreds of kilometers) processes into account. At first, starting from previous studies, a mesoscale meteorological model has been developed as part of this work. Urban induced processes have been considered by implementing inside the model a detailed urban parameterization scheme developed in a previous work. The scheme is able to capture different urban processes, and reproduces the effects of cities in a more accurate way than traditional methods usually used in mesoscale models. However, the heat generated in buildings, and the way this heat is exchanged with the exterior, was not explicitly resolved. In particular, recent studies indicated that anthropogenic heat from air-conditioning facilities can play an important role and should be taken into account for more complete urban climate studies. To this purpose, a Building Energy Model (BEM) has been developed, and coupled to the Urban Canopy Parameterisation (UCP). This building model takes into account the diffusion of heat through walls, roofs, and floors, the natural ventilation, the generation of heat from occupants and equipments, and the consumption of energy through air conditioning systems. Comparisons with other programs indicate that BEM is able to accurately simulate the basic heat transfer phenomena, and to reproduce the heat fluxes exchanged between buildings and the atmosphere. In a second part of the work, the simulation system composed by the Mesoscale Model (MM), UCP, and BEM is tested with respect to one, and two-dimensional configurations. In particular, the impact of BEM on the meteorological variables is analyzed, as well as the efficiency of different urban warming countermeasures, and cooling energy demands control strategies. Two-dimensional results are then utilized as guidance for the application of MM-UCP-BEM over the realistic configuration including the city of Basel and the surrounding areas. At first, comparisons of urban and rural simulated temperatures with measures provided by the BUBBLE project (Basel Urban Boundary Layer Experiment), have shown that the model could reasonably well reproduce the variations in outdoor air temperature. In a second time, the simulations considered for the two-dimensional configuration are applied to the case of Basel. Numerical results confirm that anthropogenic fluxes from air-conditioning facilities can have a non negligent impact on the urban meteorology. Typically, they modify the outdoor temperature and increase the Urban Heat Island (UHI) phenomenon. In the last part of the study, the applicability of the model in performing urban warming countermeasures, and cooling energy demands control strategies, is evaluated. In this purpose in mind, a sensitivity analysis is carried out indicating that appropriate physical properties of built materials, efficient air-conditioning systems, and the application of simple energy saving policies, can lead to very important cooling energy savings. In general, the application of BEM inside the UCP allows computing the heat released into the atmosphere by air-conditioning facilities, as well as the corresponding feedbacks produced on the different meteorological variables. It also increases the capability of the urban parameterisation to provide more detailed studies of urban warming countermeasures, and cooling energy demands in real cities.

EPFL2009