MANAGING DOMESTIC WATER IN THE METROPOLITAN REGION OF BARCELONA: A PARTICIPATORY, AGENT-BASED APPROACH David Saurí Adolfo López Mercè Capellades Mònica Rivera José Manuel Galán Universidad de Valladolid

THE SITUATION OF THE DOMESTIC WATER SECTOR IN THE METROPOLITAN REGION OF BARCELONA

The three most important issues at stake: 1)Water supply: current and projected demand threatens current supplies 2)Population change: migration from the compact to the diffuse city 3)Supply versus demand management

The Metropolitan region of Barcelona

PRESSURESSTATEIMPACTSRESPONSES NATURAL SYSTEM  Climate change  Increasing uncertainty in water supplies  Increase in the frequency of drought periods  Increase water supply (external sources)  Decrease water demand  or a combination of both TECHNICAL SYSTEM  Increase in system efficiency (general level+household level)  Insufficient regional and municipal water supply networks  General non- availability of domestic water saving technology  Leakages  Higher domestic consumption  Increase and improve surface water networks  Slow installation of water saving technology in new households (not required by law) SOCIO- ECONOMIC SYSTEM  Population structure  Migration  Change in land use  Increase in welfare  Increase in domestic water demand in the diffuse city  Stabilization or decrease of water demand in the compact city  Chances of water restrictions  Decrease in water quality  Large-scale water transfer (Ebro, Rhône)  Behavioural change (campaigns for water conservation)  Prices and taxes (block tariffs) The model: Pressures, States, Impacts, Responses

Water stored in the Llobregat reservoirs Capacity: 139 Hm 3

Water stored in the Ter reservoirs

Population change in the Metropolitan Region of Barcelona 1950 – 2001 Source: Institut d’Estadística de Catalunya

Source: A. Serratosa Urban land use in the MRB New housing units by type, (in %) Source: Department of Land Use Policy and Public Works. Generalitat de Catalunya.

Evolution of the domestic water consumption (liters/inhab/day) Delivery system losses (%) 1999 Source: ATLL

THE PARTICIPATORY PROCESS

AIMS AND SCOPE  The most important objective is the discussion of water management alternatives through stakeholder participation.  Creation of a stakeholder platform that incorporate a wide number of views on the domestic water sector. Selection of the participatory methods most suited to extract stakeholders goals, preferences and attitudes.  The method of participation used is based on the development of a number of scenarios for water demand according to the opinions given by stakeholders in interwiews and group meetings.

public organizations private companies civil society Composition of the Stakeholder platform:

Scenario-building exercise: Several meetings with the stakeholder platform Elaboration of three scenarios regarding the future of the domestic water sector in the study area. Scenarios were used as the basic input for the elaboration of the agent-based model. All scenarios have three basic components: 1) Climate 2) Changes in population and type of housing 3) Demand management alternatives

Three scenarios for simulation a)Scenario “A”: Residential mobility from the “compact” to the “diffuse” city continues and water conservation measures are introduced. The scenario has two variants:”normal” climate conditions and “extreme” climate conditions. This scenario was considered as the “more plausible” by the stakeholders platform. b)Scenario “B”: Residential mobility from the “compact” to the “diffuse” city continues without water conservation measures. The two variants (“normal” and “extreme” climate) also considered. c) Scenario “C”: Residential mobility from the compact to the diffuse city stops, and no water conservation measures are introduced. The two variants (“normal” and “extreme” climate) also considered.

THE AGENT-BASED MODEL

Market Module Government Module Emergency Infrastructure Module Supply Module Social Module Demand Module Territorial Module Stakeholders Module Climate Module Model description

Escenario A: perfil climático 1

Escenario A: perfil climático 2

Escenario A: perfil climático 3

Escenario B: resultados.

Escenario C: resultados

Main results of the simulation: Scenario “A” continuation in the trend of residential mobility from the compact to the diffuse city and introduction water conservation measures. In this scenario, water supply is insufficient to absorb demand despite conservation. In normal climatic situations, emergency levels are not reached. However, they are reached in extreme climate conditions. Scenario “B” continuation in the trend of residential mobility without water conservation measures. Rapid rise of emergency situations that can only be solved through a substatial increase in water supply such a large scale transfer from the Ebro or Rhône rivers. Scenario “C” changes in residential mobility (migratory fluxes towards the diffuse city diminish) without water conservation measures. Emergency situation are not reached even under conditions of climatic stress.

CONCLUSIONS -Relevance of the urban form for water planning and management (need of integration of water planning with spatial planning). -Participatory process allowed for the consideration of stakeholders’ concerns into problem definition (elaboration of scenarios) and ways to approach this problem (elaboration of the agent-based model). To our knowledge, first participatory exercise of this kind in the area. -Agent-based modelling provided an alternative way to think about water issues in the Barcelona region by integrating a number of natural, technical and socioeconomic factors (richer view, in our opinion, than that given by traditional forecasting techniques).

ALL DRESSED UP AND NOWHERE TO GO? (Possible future avenues for research) -Advance in the understanding of water consumption behaviour at the household level (vey important for improving the ABM model) -Advance in the understanding of the effects of water policy (privatization of municipal supplies, impact of prices and taxes, etc.). -Consolidate the stakeholder platform for future assessment of water policy alternatives, and improve the presence of some of its members (only about two thirds of the platform has participated actively in the process). -Enhance simulation to other parts of the hydrological cycle (especially water quality)