This document provides information on a case study of the Areia Creek basin located in Porto Alegre, Brazil. Porto Alegre is the 10th most populous city in Brazil and the capital of Rio Grande do Sul state. Areia Creek basin is one of the 14 urban drainage catchments in the city, draining 12 neighborhoods. The document discusses the physical, social, economic, and institutional challenges facing water management in the basin, as well as current and alternative strategies to address flood risks considering future urban growth and climate change.

1. Adhitya Wirayasa
Alida Alves Beloqui
Gonzalo Duro
Maria Luisa Salingay
Case study:
Areia Creek ,Porto Alegre

2. o 10th most populous city in Brazil
o State capital of Rio Grande do Sul.
o Lies on the eastern bank of Rio Guaiba, where
five rivers converge to form Lagoa dos Patos.
o Important alluvial port for industry and
commerce.
Porto Alegre
Areia (Sand) Creek Basin
o One of the 14 urban drainage catchments
o 12 neighborhoods

5. The most relevant aspects of water and flood risk management:
Physical Social-Economic Institutional
Macro
 Insufficient drainage system capacity.
 Combined drainage and sewage system in
major areas of the city.
 Solid waste management problems:
frequently clogs sewerage network (mainly
PET bottles and plastic bags).
 Erosion & sedimentation, depending on the
soil type of each catchment.
 30% of the city (at the South) is rural area,
limited by natural hills from the urbanized
area.
 Local financial
weakness to execute
hard structural
measures, operate
and maintain them.
 Inability to impose
stormwater taxes:
lack of public and
administrative
support.
 Rapid population
growth.
 Lack of integrated approach to solve
flood problems: no cooperation between
Water and Sewage Agency and the
Department of Cleaning; no involvement
of the Secretariat of Environment into
the Master Plan (managers of parks
where detention ponds are projected).
 Data deficiency (hydrological, networks).
 Insufficient new technical knowledge
(soft measures).
 Lack of law enforcement.
 Lack of management for adaptation
measures.
Meso
 Catchment with the highest flood risk.
 Combined drainage and sewage system in
almost all the basin.
 Water quality problem: fluoride in
groundwater of 6 mg/lt. In the sewerage
there is an estimated mean BOD of 300mg/lt.
 An estimated 5% of solid waste ends in water
bodies (1.4 ton/day).
 Illegal settlements
 Lack of information
for WASH in informal
settlements.
 Lack of public
participation in the
Master Plan
development.
 Participatory approach by the local
community by means of the participatory
budgets.
Micro
 Most frequent flood events in the catchment
(every 2 years) due to insufficient capacity of
the network conduits.
 High slopes (2% to 30%).
 Disconnected Sewer system in illegal and
informal settlers.
 High impervious areas (66%).
 Highest population
density in the
catchment (185
inhab/ha).

6. Four (4) capacity vulnerability framework:
Flood Safety Water Security Ecosystem Health Status
Threshold  Drainage system
 Levees
 Detention basin
 Impervious areas regulation
 Land use regulation
 Centralized water supply
 Impervious areas
regulation
 Sewerage system
 Waste water treatment (27% )
 Canalization of natural streams.
 Controlled solid waste disposal
(95%).
Coping  Detention basin
 Solid waste management
 Infiltration
 Detention basin
 Solid waste management
 Wetlands
Recovery
Adaptive
Capacity
Additional/Generic:
Environmental education to general public, Administrative actions/ institutional interpretation/ long term
planning/ information to planner/architect and decision maker

7. Four (4) capacity vulnerability framework:
Additional/Generic:
Environmental education to general public, Administrative actions/ institutional interpretation/ long term
planning/ information to planner/architect and decision maker
Combined
systems
Separated
systems

8. Driving forces/pressures that alter the hydrological cycle:
Water Quality Water Quantity
Macro  Climate change.
 Urban growth.
 Climate change.
 Urban growth.
Meso  Untreated waste water.
 Illegal settlement.
 Poor garbage disposal.
 Urban growth.
 Decrement of permeable surfaces.
 Illegal settlements.
 Urban growth.
Micro  Illegal settlement.
 Poor garbage disposal.
 Illegal settlements.

9. Control alternatives considered:
1- Network expansion/enlargement,
for 10 years RP rainfall.
2- Storages construction to decrease
peak of 10 years RP rainfall.
3- Combination of alternatives 1 and
2.

10. Current strategy
Results analysis:
 Peak Flow: Alt.2 < Alt.3 < Alt. 1
 Cost: Alt.3 < Alt.2 < Alt.1
 Alternative 3 has lower
environmental impact.
 Problems for building storages in
steep zones.

11. Current strategy
ALTERNATIVE 3 WAS SELECTED AS STRUCTURAL
PART OF CURRENT STRATEGY.
Non structural measures:
 Regulation of impervious areas in private properties to
avoid runoff increment.
 Control of sediments and solid waste management in
the catchment.
 Educational programs about urban drainage.

12. Socio-economic and environmental aspects of
current waste water management
 Increment from 27% to 77% in
wastewater treatment.
 Resettlement of 1680 families
living under flood risk in the
banks.
 Employment and income
generation for resettled people.

13.  Protected areas and green zones in banks.
 Environmental and urban management tools to
implement protected areas.
 Environmental management plan with compensation
and mitigation programmes.
Socio-economic and environmental aspects of
current waste water management

14. Scenarios
Urban growth:
 Current condition of urbanization.
 Maximum urbanization in accordance with Master
Plan of Urban Development.
Rainfall:
Return periods of 2, 5, 10, 25 and 50 years were
considered.
As a result, 10 different scenarios were analyzed.
Flood problems from 2 years return period.

15. Scenarios
 Based in results obtained from scenarios study the
accepted flood risk was defined as a balance between
impact of floods and cost of drainage construction
(RP= 10 years).
 Higher influence of strong urbanization was
indentified for low rain events and in the upper part of
the catchment.

16.  CC and urban growth tend to increase
rainfall intensities and runoff quantity
respectively.
 The consequences of urban growth in the
future could be the lack of capacity in
sewerage network and wastewater
treatment.
Influence of Socio-Economic & CC to Urban
Water System

17.  Insufficient drainage capacity and increased rainfall
tend to increase flood risk due to runoff increment.
 Excess sediments from erosion in the upper
catchment area and uncontrolled solid waste disposal
lead to more O & M in the drainage system
 Uncontrolled urban growth leads to insufficient space
for new development area (i.e network, utilities,
housing, detention basin)
 Uncontrolled population growth leads to more solid
waste generation, illegal settlements in public areas,
lack of ‘green’ open spaces.
Consequences of Urban Growth & CC to Physical TP

18.  Hard structural: levees/dike, drainage system,
sewerage system, waste water treatment plant
 Soft structural: detention basin, infiltration,
canalization of natural streams, solid waste
management, wetlands
 Non structural: impervious areas regulation, land use
regulation, solid waste management
Incremental Measures to Postpone TP from
Current Strategy

19.  Community tend to rejected current strategy such as
not allowing build the open storage to dampen the
flood peaks of the drainage system due to odor issue &
hygiene aspects since adopted combine system.
 Above situations will lead the changes from physical
TP to socio-political TP.
Socio-Political TPs

20. Urgency of Alternative Strategy
 Alternative strategy is required to overcome
the current problems as well as to postpone
future ATPs.
 In short term, the existent strategy can be
successful.
 For medium and long term, additional
strategy is needed since increased
uncertainty due to urban dynamics and
climate change in the future.

21. Alternative strategy – Goals
Run-off reduction.
 Drainage system flow
alleviation.
 Investment reduction.
 O&M reduction.
2002 2013
2002 2013 2002 2013

22. PROBLEM ALTERNATIVE SOLUTION
High urbanization with strong
influence in upper part of catchment.
Increment of green areas, runoff
reduction.
Lack of pipes capacity. Reduction of flow in pipe system.
Local financial weakness. Soft-structural measures.
Drainage O&M problems. Solid waste management.
Unplanned urban growth and CC. Flexible solution combining distributed
measures.
Lack of social awareness and
cooperation.
Communication and education
mechanisms. Participation
development.
Institutional coordination and
communication problems.
Institutional cooperation enforcement.
Institutional capacity building.
Alternative strategy – Measures

23. Alternative strategy – Measures
location
Upper part:
Runoff reduction
Public area disconnection
Medium part:
Runoff reduction - Public area disconnection
Streets as conveyance system - Storages
Lower part:
Runoff reduction
Public area disconnection
Storages
Dry-proofing measures

24. Alternative strategy-Structural
measures
Public areas disconnection
and stormwater storage
Storages in
public green space areas/
Pervious pavements Infiltration structures
Green Rooftop
Individual rainwater storages

25. Alternative strategy-Structural
measures in public areas
Estimated runoff reduction of 25%.
Around 30% of total area. First
measures to be implemented.
 Infiltration structures in current green areas in sidewalks
(around 30% of sidewalks).
 Pervious pavements (50% of pavements: secondary roads
an less than 5% slope).
 Disconnection from pipe network.
 Surface storage of stormwater in green areas already
selected.

26. Alternative strategy-Structural
measures in private areas
Estimated runoff reduction of 20%.
40% of flow reduction into pipe
network.
 Green area in front of parcels (20% of private areas).
 Roofs are around 50% of private area.
If can disconnect roofs: individual storages or infiltration
ponds.
If cannot disconnect roofs: green roofs.

27. Alternative strategy-Non-structural
measures.
 Institutional capacity building: O&M and control.
 Coordination & cooperation between institutions
 Public education through communication campaigns.
 Public participation in decision making processes.
 Regulation, control and incentives.
 Solid waste management plan.
 Parks development in green public
areas to avoid new settlements.

28. Alternative strategy-ATPs delay.
 Alternative strategy is more flexible and require less
financing because it avoids big structures construction.
 Investment can be done in different stages over time.
 Public participation & awareness will support the
sustainability of the strategy.
 Separations of public-private drainage system (run-off)
reducing the pressure over the pipe network.
 The alternative is efficient specially for low return
periods events, which currently causes floods.
 Reduction of polluted water in the surface.

29. Alternative strategy-Additional
benefits and multiple value.
 Enhanced ecosystem services with multiple benefits:
improving water quality (regulation services);
aesthetic and recreational improvements are added
with the concept of green city (cultural services).
 Increasing efficiency of economic investment.
 Improving city liveability.
 Decreasing water quantity in the sewerage system &
decreases the overflows frequency improving water
quality in the receptor.

30. Major Stakeholders

31. Stakeholders Sector Responsibilities Interest/Ambitions Added Value
Representatives
Districts/Sectoral
Community Properly represent the district/sector in
strategic deliberation/planning.
To be heard. Influence
Co-planners & co-managers
City Councilors Public Create, approved or amend laws. Effective and efficient
legislation.
Influence and regulation
support
Academe, Researchers,
Scientists & Tech Support
Private/
Public
Educate, inform and share knowledge. Recognition/Credit Contribute with expertise in
an impartial way.
Business Community Private Give services or goods. Create jobs
and improve economy
Gain profit/income. Financial support, technical
knowledge.
Citizens of Porto Alegre Community Actively participate and be informed. Make the government aware
of their concerns and issues.
Public support, concensus
Lake Guiba Conservation
Program
NGO Have prompt information
dissemination and actively participate
on issues of concern.
Non-profit agency assisting in
integrating issues and
policies.
Integrity
Forum of Environmental
Issues
Public Exercise duties and responsibilities as
representatives of the different
government agencies.
Coordinated plans to have
effective implementation of
environmental policies.
Support, environmental
awareness. Teamwork
Mun.Environmental Sec Public Protect and maintain a sound
environment.
Implement environmental
laws and policies.
Support, influence and co-
planning
Mun.Water & Sewerage Public Supply quality water and treat
wastewater.
Customers' satisfaction/
Public health
Support and co-planning
Municipal Cleansing Dept Public Integration of Solid Waste
Management.
Strict implementation SWM. Support and co-planning
Department of Drainage Public Planning, operation and maintenance
of drainage system.
Functional and effective
drainage system.
Support and co-planning
Mun. Planning Secretariat Public Distribution of resources and
coordination of different private and
public sectors.
Harmonious administration.
Concerted effort in term of
extreme stress.
Integrity. Planning
coordination. Commitment
Stakeholders Analysis

32. Learning and Action Alliances (LAA)

33. Motivation, opportunity and capacity
Major stakeholders
Stakeholders Motivation Opportunity Capacity
Representatives
Districts/Sectoral
Sense of responsibility To be heard. Co-decision.
Co-management.
City Councilors Effective legislation Create, approved or amend
laws.
Decision makers.
Academe, Researchers,
Scientists & Tech Support
Educate, inform and share
knowledge.
Share expertise in a noble
way.
Information/education
dissemination.
Business
Community/Investors
Incentive Influence, provide
employment and gain profit
Relevance for economic
growth.
Citizens of Porto Alegre Participate and be
informed
Co-design Co-decision
Co-management
Lake Guiba Conservation
Program
Active participation on
issues of concern
Co-design Co-decision
Co-management
Forum of Environmental
Issues
Concerted effort on issues
at hand.
Shared responsibility in terms
of execution of policies.
Executive branch of the
government.
Strict implementation of
policies.
Mun.Environmental Sec
Mun.Water & Sewerage
Municipal Cleansing Dept
Department of Drainage
Mun. Planning Secretariat
Duties and responsibility Provide influence Execute policies/laws.

34. Thank you for listening!
Adhitya
Maria
Alida
Gonzalo