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Adhitya WirayasaAlida Alves BeloquiGonzalo DuroMaria Luisa SalingayCase study: Areia Creek ,Porto Alegre

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

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The most relevant aspects of water and flood risk management:PhysicalSocial-EconomicInstitutionalMacroInsufficient 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.MesoCatchment 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 settlementsLack 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.MicroMost 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).

Four (4) capacity vulnerability framework:Flood SafetyWater SecurityEcosystem Health StatusThresholdDrainage systemLeveesDetention basinImpervious areas regulationLand use regulationCentralized water supplyImpervious areas regulationSewerage systemWaste water treatment (27% )Canalization of natural streams.Controlled solid waste disposal (95%).CopingDetention basinSolid waste managementInfiltrationDetention basin Solid waste management WetlandsRecoveryAdaptive Capacity

Additional/Generic: Environmental education to general public, Administrative actions/ institutional interpretation/ long term planning/ information to planner/architect and decision maker

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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 systemsSeparated systems

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Driving forces/pressures that alter the hydrological cycle:Water QualityWater QuantityMacroClimate change.Urban growth.Climate change.Urban growth.MesoUntreated waste water.Illegal settlement.Poor garbage disposal.Urban growth.Decrement of permeable surfaces.Illegal settlements.Urban growth.MicroIllegal settlement.Poor garbage disposal.Illegal settlements.

Current strategyControl 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.

Current strategyResults 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.

Current strategyALTERNATIVE 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.

Socio-economic and environmental aspects of current waste water managementIncrement 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.

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

ScenariosUrban 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.

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.

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

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 systemUncontrolled 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

Hard structural: levees/dike, drainage system, sewerage system, waste water treatment plantSoft structural: detention basin, infiltration, canalization of natural streams, solid waste management, wetlandsNon structural: impervious areas regulation, land use regulation, solid waste management

Incremental Measures to Postpone TP from Current Strategy

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

Urgency of Alternative StrategyAlternative 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.

Alternative strategy GoalsRun-off reduction.

Drainage system flow alleviation.Investment reduction. O&M reduction.

200220132002201320022013

PROBLEMALTERNATIVE SOLUTIONHigh 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

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

Other objective to separate stormwater. Difficult of measures implementation un upper part because problems are in the lower part.23

Alternative strategy-Structural measures Public areas disconnection and stormwater storageStorages inpublic green space areas/Pervious pavements

Infiltration structures

Green Rooftop

Individual rainwater storages

Alternative strategy-Structural measures in public areasEstimated 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.

50% of pavements: secondary roads an less than 5% slope.25

Alternative strategy-Structural measures in private areasEstimated 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.

80% of green fronts, 50% of green roofs26

Alternative strategy-Non-structural measures. Institutional capacity building: O&M and control.Coordination & cooperation between institutionsPublic 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.

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.

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.

Major Stakeholders

StakeholdersSectorResponsibilitiesInterest/AmbitionsAdded ValueRepresentatives Districts/SectoralCommunityProperly represent the district/sector in strategic deliberation/planning.To be heard.InfluenceCo-planners & co-managersCity CouncilorsPublicCreate, approved or amend laws.Effective and efficient legislation.Influence and regulation supportAcademe, Researchers,Scientists & Tech SupportPrivate/PublicEducate, inform and share knowledge.Recognition/CreditContribute with expertise in an impartial way.Business CommunityPrivateGive services or goods. Create jobs and improve economyGain profit/income.Financial support, technical knowledge.Citizens of Porto AlegreCommunityActively participate and be informed.Make the government aware of their concerns and issues.Public support, concensusLake Guiba Conservation ProgramNGOHave prompt information dissemination and actively participate on issues of concern.Non-profit agency assisting in integrating issues and policies.IntegrityForum of Environmental IssuesPublicExercise duties and responsibilities as representatives of the different government agencies.Coordinated plans to have effective implementation of environmental policies.Support, environmental awareness. TeamworkMun.Environmental SecPublicProtect and maintain a sound environment.Implement environmental laws and policies.Support, influence and co-planningMun.Water & SeweragePublicSupply quality water and treat wastewater.Customers' satisfaction/ Public healthSupport and co-planningMunicipal Cleansing DeptPublicIntegration of Solid Waste Management.Strict implementation SWM.Support and co-planningDepartment of DrainagePublicPlanning, operation and maintenance of drainage system.Functional and effective drainage system.Support and co-planningMun. Planning SecretariatPublicDistribution 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

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Learning and Action Alliances (LAA)

Motivation, opportunity and capacityMajor stakeholdersStakeholdersMotivationOpportunityCapacityRepresentatives Districts/SectoralSense of responsibilityTo be heard.Co-decision.Co-management.City CouncilorsEffective legislationCreate, approved or amend laws.Decision makers.Academe, Researchers,Scientists & Tech SupportEducate, inform and share knowledge.Share expertise in a noble way.Information/education dissemination.Business Community/InvestorsIncentiveInfluence, provide employment and gain profitRelevance for economic growth.Citizens of Porto AlegreParticipate and be informedCo-designCo-decisionCo-managementLake Guiba Conservation ProgramActive participation on issues of concernCo-designCo-decisionCo-managementForum of Environmental IssuesConcerted effort on issues at hand.Shared responsibility in terms of execution of policies.Executive branch of the government.Strict implementation of policies.Mun.Environmental SecMun.Water & SewerageMunicipal Cleansing DeptDepartment of DrainageMun. Planning SecretariatDuties and responsibilityProvide influence Execute policies/laws.

Thank you for listening! AdhityaMariaAlidaGonzalo