1.2 Planification de l'assainissement urbain

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En provenance du cours de École Polytechnique Fédérale de Lausanne

Planification et Design de Systèmes et Technologies d’Assainissement

78 notes

École Polytechnique Fédérale de Lausanne

Planification et Design de Systèmes et Technologies d’Assainissement

78 notes

Désirez-vous apprendre à mettre en œuvre des solutions d’assainissement abordables et adaptées à différents contextes ? Voulez-vous connaître les derniers développement dans le domaine de la planification de l’assainissement urbain ? Êtes-vous intéressés par des exemples de systèmes d’assainissement urbain qui fonctionnent dans les pays à faible et moyen revenu ? Si oui, alors ce cours est pour vous ! Le cours débute par une introduction à la planification intégrée de l’assainissement et adresse aussi bien la planification à l’échelle de la ville que la planification dans des contextes spécifiques tels que les quartiers informels. Après un survol des différentes approches de planification de l’assainissement, vous aurez l’occasion de passer en revue les différents systèmes et technologies possibles, la terminologie et concepts clé, et comprendre pourquoi il est crucial de réfléchir en termes de « système intégré » pour la planification de l’assainissement urbain. Le cours couvre toute la chaîne de l’assainissement et fournit de l’information détaillée sur les systèmes d’assainissement adaptés aux contextes à faibles et moyen revenus (par exemple, des systèmes basés sur les fosses sèches, des systèmes décentralisés avec différents réseaux d’égout, le transport des eaux noires). Eawag-Sandec et EPFL offrent ce cours conjointement avec des experts en assainissement de la Banque Mondiale et de l’OMS. SERIE DE MOOC « EAU, ASSAINISSEMENT ET DÉCHETS SOLIDES DANS LES CONTEXTES DU DÉVELOPPEMENT » Ce cours est l’un des quatre cours de la série « Eau, Assainissement et Déchets Solides dans les Contextes du Développement ». VERSION ANGLAISE DE CE COURS Ce cours est offert simultanément en français et en anglais. Le nom du cours en anglais est « Planning & Design of Sanitation Systems and Technologies ».

À partir de la leçon

Introduction à la planification de l’assainissement & à l’approche de systèmes

Le cours commencera par une discussion de pourquoi l’assainissement est important pour la santé publique et la protection de l’environnement, en particulier en milieu urbain. Cette introduction sera suivie d’une présentation sur l’importance des conditions-cadre favorables. Finalement, les approches de planification de l’assainissement actuelles (Sanitation21, CLUES, ATPC/CLTS) utilisées dans le secteur du développement seront passées en revue.

1.1 Aperçu du cours5:23

1.2 Planification de l'assainissement urbain12:04

1.3a Outils de diagnostic et cadres de planification de l’assainissement urbain [1]7:50

1.3b Outils de diagnostic et cadres de planification de l’assainissement urbain [2]11:01

1.4 Planification de l’assainissement au niveau local [1]8:01

1.5 Planification de l’assainissement au niveau local [2]4:20

1.6 Planification de l’assainissement au niveau local [3]10:54

1.7 Résumé de la 1ère Semaine3:22

Rencontrer les enseignants

Christoph Lüthi
Dr.
Sanitation, Water and Solid Waste for Development / Eawag

Hi, my name is Jonathan Parkinson

I'm a civil and environmental engineer

with 20 years of consulting and research experience

working on international development projects

focusing on urban sanitation.

This module focuses on city sanitation planning,

which is a key part to the development process

for city authorities to make strategic decisions

about where their priorities lie,

what approaches are most appropriate for that context,

and how best to ensure that limited resources

are most efficiently utilized.

This module provides an instruction to urban sanitation planning,

which firstly aims to promote an understanding

of the existing sanitation situation in cities in the developing world,

and secondly, to gain an appreciation of the limitations

of conventional approaches towards the design of projects

to improve urban sanitation.

First of all,

I'd like to draw our attention to the existing reality in cities

in the developing world.

As a result of this,

city sanitation planning is not an easy task.

As I'm sure many of you well know from your own experience,

cities in the developing world are both complex and chaotic.

A lot of this is due to the fact that growth of cities

is unplanned in the first place.

How is it possible to plan for improvement

for one specific municipal service such as sanitation,

when the city as a whole is growing in such an unpredictable manner?

And in addition,

there are frequently high levels of poverty and social inequality,

which means that there are many competing demands

for investments and improvements.

These competing demands combined with a lack of resources

means that sanitation frequently is not a high political priority,

even though we know that to improve sanitation

can result in improvements to public health

promoting social development, enhancing the attractiveness of cities,

and all this combined together to strengthen the economy.

In this slide, and the following two slides,

we can see the scale of urbanization.

Here we can see the urban population distribution in 1970.

Over the past half a decade,

as a result of unplanned and uncontrolled growth,

many cities have been characterized by a large proportion of population

living in informal settlements, some of which, are illegal.

Here we see the projection for the urban population in 2025.

Municipal authorities struggle to deal with

the infrastructure and service delivery needs,

and the level of growth makes it very difficult to retrofit,

and urban planning for settlements,

which are already established and developed in such a chaotic manner,

is very challenging.

Official statistics show steady improvements

in sanitation coverage over the past 25 years.

In this slide, we can see the urban sanitation coverage

in the different regions in the world,

focusing particularly on developing countries.

According to the statistics from UNICEF and WHO in 2011,

the average access to improve sanitation throughout developing countries is 74%.

In Latin America, the statistics are as high as 87%,

and South-East Asia, 81%.

In Southern Asia, the value is a lot lower, 64%,

and in Sub-Saharan Africa, only 42%.

But we need to consider that the overall population in Southern Asia

is much higher, and therefore, in absolute terms,

the number of people without access to improved sanitation

in Southern Asia is greatest.

We can also see the level of sharing of sanitation facilities,

which has great implications on the quality of sanitation in these cities.

So in Sub-Saharan Africa, 30% of people are using shared toilets,

compared with the average of 17 throughout the developing world.

But these statistics don't necessarily provide an adequate reflection

of the reality in many cities, because they only focus on coverage.

The poor quality of sanitation facilities combined with the lack of servicing

means that a significant proportion of the population

are likely not to have achieved the status of improved,

even though these statistics may indicate that they do.

And the lack of these systems has major environmental health implications,

affecting public health, productivity, and socio-economic development.

These statistics that we see previously, say very little about the arrangements

for waste water and fecal sludge management,

and many investments tend to focus more on construction

and rehabilitation of sewerage and waste water treatment,

which overlooks the actual problem.

In this slide, showing the fecal waste flows

from Maputo in Mozambique,

we can see that,

in fact, only 24% of the waste is related to toilets discharging into sewerage,

whereas, a much greater proportion is in fact related

to onsite sanitation facilities.

And here, we're talking about pit latrines and septic tanks.

Only recently has the extent of the problem started to be recognized,

and projects been designed to respond to this situation.

In the next few slides, we see examples of urban sanitation

that are common in cities in the developing world.

In this photograph, we see a basic pit latrine

where hygienic conditions are compromised by poor quality design and construction,

overuse by too much sharing, and a lack of handwashing facilities.

Although this latrine provides a better sanitation than open defecation,

facilities like this are not considered to provide adequate sanitation.

Thinking more widely in the public domain,

flows of untreated black water from pits and tanks

flow into open channels or drains,

and this is often mixed with solid waste and urban runoff.

This cocktail of waste results in heightened disease transmission

in low income communities.

And then looking more widely in the city,

although more affluent households are likely to be able to afford

to pay for a system or service to collect waste water or fecal sludge,

and they can pay a private company to take this waste away,

this waste is often discharged, untreated into the environment,

due to lack of facilities.

In the previous slides, we saw that status of urban sanitation,

and there have been responses to deal with this problem,

but often that we see too much focus on construction of sewerage

and waste water treatment systems, whereas the needs and requirements

of people living in low-income communities are overlooked.

Conventional responses to the problem also tend to overlook the important role

played by the informal sector,

who are involved with various forms of sanitation service delivery,

and also, the importance of operation and maintenance.

The imbalance of supply and demand for improved services

combined with the inability of urban authorities

to provide sanitation services has resulted in a sanitation crisis

in many towns and cities,

particularly unplanned, informal, and low-income settlements.

In the next part of this module,

I will be talking about common elements for good sanitation planning,

focusing on delivery of sanitation services.

In the previous part of the presentation,

we saw how traditional responses to urban sanitation challenges

have tended to focus more upon solving urban sanitation problems

by the insulation of large-scale,

downstream infrastructure and sewerage systems,

and the need for more focus on onsite sanitation.

More recently, a new generation of sanitation planning has emerged,

with examples from Indonesia, India, and Brazil,

where three national sanitation programs have been initiated,

to develop city sanitation plans linked to funding and investment,

standardized planning processes, and capacity building,

and technical support.

Based upon these experiences,

a set of common elements for good sanitation planning have emerged,

one of these being responding to expectations

for sanitation service improvement, otherwise known as demand.

Another one being, planning for inclusion and equitable sanitation services,

focusing on the needs of vulnerable groups and the urban poor.

A third one being, ensuring that services are affordable and financially viable.

There's no point making investments in urban infrastructure

if these systems cannot be maintained financially.

The fourth common element for good sanitation planning

is focusing on behavioral change.

This includes behavior at all levels,

from the household up to the city authorities.

Change management down to hygiene behavior,

are all key elements of good sanitation planning.

And the final one, a key one, is engaging with stakeholders.

It's clear, therefore, that technology is only a means

to deliver services, and meet customer needs.

It's about people, and not pipes.

In the urban sanitation planning process,

there is a need to take onboard the interests

from a range of different stakeholders.

From the household domain,

to the community, and their interests,

up to the local authority or municipality,

with their interests at city level.

And above that, there will be ministries,

perhaps the ministry of the environment,

with their main interest on protecting and preserving

the quality of the environment.

What's clear is the need to focus on delivering sanitation services

to customers that are acceptable, appropriate, and affordable.

Technology is a means to an end,

but it is not the way in which customers judge services.

What the technology does is more important.

For sustainability, service delivery must be customer orientated,

and services developed in line

with customer affordability and willingness to pay.

City sanitation plans must focus on supply meeting demand, i.e., the market.

Both suppliers and customers may need access to credit

to be able to make investments for improved sanitation.

Urban sanitation plans provide a set of service delivery models

for different parts of the city,

including elements of infrastructure development,

finance and cost recovery, management and regulation.

In the next presentation,

we will see how a systematic approach towards planning

can support the development of a comprehensive and equitable

city sanitation plan.

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