Modelling tasks

Using results from two sectoral models and a behavioral model, the session translated complex modeling outputs into practical insights for regional decision-making. For Granollers/Besos Tordera Basin the following domains were modelled and conclusions introduced.

• Floods 
• Heat wave 
  • Vulnerability, risk, and impact maps for both hazards
• Others: behaviour

Flooding

Spain’s Royal Decree 903/2010 (transposing EU Directive 2007/60/EC) mandates ARPSI definition and Flood Risk Management Plans, initially focusing on fluvial flooding only. Due to growing pluvial flood risks, the Catalan Water Agency (ACA) now requires its inclusion in the third assessment cycle, with permanent integration expected in future cycles.

The objectives of the flooding modelling task comprise:

• Develop a comprehensive hydrological and hydrodynamic model (1D+2D) of Granollers, covering the drainage network, surface runoff, and the Congost River (both pluvial and fluvial).
• Model current and future scenarios, incorporating climate change adaptation measures and the evolution of land uses in the Congost basin and Granollers throughout the 21st century.
• Serve as a living decision-making tool for the city to minimize flood risks and damage, anticipate future requirements, and integrate into a global dynamic model to quantify the impact of mitigation and adaptation actions on CO₂ reduction.

Potential applications feature:

• Design and validate future measures in the sewer system (PDC and PIGSS).
• Support urban planning development.
• Design and validate actions along the Congost River.
• Calculate and monitor flood risk indicators.
• Identify high-risk areas in the city for people and potential tangible/intangible damage.
• Update municipal planning and emergency plans (DUPROCIM).

The results of the simulations were exported and integrated into a GIS-based risk assessment framework, composed of three analytical layers: 

Hazard maps classify flood intensity (low, medium, high) based on water depth and flow velocity. Exposure and vulnerability layers use spatial data (population, critical facilities, land use). Risk maps combine both via weighted overlay, yielding quantitative indicators (m² per risk class) to compare scenarios and assess the effectiveness of interventions in reducing urban flood risk.

Heat Wave

The  model (PALM-4U) assessed urban greening interventions to mitigate heat in Granollers and the Congost river basin, where heatwaves are a critical climate hazard alongside flooding. The 12 km × 12 km domain (10 m resolution) used meteorological data from July 21, 2013, with key outputs including 2-meter air temperature and the Universal Thermal Climate Index (UTCI).

Three interventions were modeled:

• B2 (Renaturalization of Parc del Congost): Replaced impermeable surfaces with permeable pavements, vegetation, and 450 trees/15,800 m² shrubs/meadows.
• B3 (Superblocks in Barrio 1er de Maig): Converted parking spots into green spaces and planted trees to reduce through traffic.
• B4 (Green Connector): Added isolated vegetation, planters, and trees along narrow streets (Calle Tres Torres, Calle Emili Botey).

Behaviour

The AIT behavior model was presented as an innovative approach to estimate citizens' behavioral responses (acceptance, rejection, etc.) to Granollers’ mitigation and adaptation measures. In a 15-minute presentation, the conceptual model and Spain-specific results for urban areas were shared. The model classifies citizens' reactions—ranging from "Active antagonists" to "Fierce forerunners"—and estimates the effectiveness of measures by predicting behavioral responses: desired changes, unachieved potential (rebound effects), and undesired side effects (boomerang effects).

Observations and conclusions

1. Flooding

In the base scenario (Sc1), even moderate events (T10–T100) cause significant flooding in Granollers’ lowest urban areas, particularly near the river.

The Conecta Congost Natura 2025 project (Sc2) slightly improves infiltration and delays runoff peaks locally but does not significantly reduce flooded areas or risk, as its measures focus on renaturalization rather than hydraulic needs.

In Sc3 (with SUDS), improvements are limited for low-probability scenarios:

• Long-lasting rains (10 h) exceed SUDS’ (Sustainable Urban Drainage System) infiltration capacity.
• SUDS placement followed available space, not hydraulic need—problematic points must be identified.
• Ordinary scenarios still need testing.

Hybrid measures (green/blue + grey) and upstream actions are required to effectively address flooding, especially river flooding.

2. Heat Wave

The proposed interventions (B2, B3, B4) transformed paved areas into natural spaces. Intervention B2 (removing a road and parking lot to revegetate Congost Park) achieved the most significant cooling impact, reducing temperatures by up to -3.8 °C during the day and -1.2 °C at night where trees and vegetation were added. B3 (creating two natural spaces) also reduced temperatures by up to -1.2 °C during the day and -3.1 °C at night, while B4 (naturalizing an urban connector) showed cooling effects as well. These results highlight the potential of urban green infrastructure to protect populations from increasingly frequent and prolonged heatwaves.

3. Behaviour

The behavior model estimates the distribution of behavioral responses and the overall effectiveness of interventions, aiding the development of supportive measures and communication strategies.

Two scenarios were modeled:

• Current scenario: Based on Granollers’ observed distribution of Coping Types.
• 2050 scenario: Assumes fewer Active Antagonists and a shift toward Emphatic Engagers.

The model provides initial insights into climate crisis response types, refines trajectory modeling by evaluating effectiveness and side effects of measures and specific interventions, and indicates that delaying measures for future acceptance does not work. It suggests avoiding rebound and counterproductive responses through regulation and communication and helps plan targeted information campaigns and accompanying measures to guide desired outcomes.

Integrated Mitigation Pathway 

The workshop focused on future climate scenarios, particularly flooding and heatwaves, to improve the prediction and understanding of climate risks in Granollers and similar municipalities. Participants explored how current models and methodologies could be adapted to other vulnerable areas, extending the project’s impact.

A collaborative approach was emphasized to define use cases and develop comprehensive roadmaps with implementation strategies, timelines, and resource requirements. The event also connected municipalities and stakeholders, fostering networking and knowledge exchange to strengthen collective resilience and coordinated climate adaptation.

Relevance for Local Climate Programs

The modelled scenarios coherently align with a wide range of strategic local and supra-local programmes and planning instruments, including:

• PAESC, PDC, PIGGS (especially for CBR system calculations),
• PDAR (Master Plan for Reclaimed Water), and
• PACÍFICA (CERTEI) for water management and territorial resilience. They also connect with the new TARU, reinforcing coherence between modelling and public policies on climate adaptation and urban sustainability.

At the local level, the scenarios integrate with:

• Sewerage Master Plan, PIGGS (focusing on CSOs in river environments),
• Urbanisation projects, public works, SuDS construction programmes,
• Sustainable Urban Mobility Plan, infrastructure planning, Urban Green Master Plan, and municipal heat plans, enabling the identification and prioritisation of action areas.

Together, these scenarios strengthen territorial response capacity to climate and urban challenges.

Stakeholder Perspective: Model Use Cases, Value, Risks & Opportunities

Value and Practical Applications

The models deliver significant value in territorial understanding, risk assessment, and future scenario prediction, with practical applications enhancing flood management, urban planning, green infrastructure, and heat action plans. In sanitation, the PIGGS model optimizes layouts and identifies priority zones at basin and river levels, while the heatwave model anticipates impacts and guides mitigation measures.

Risks and Opportunities

Despite their benefits, risks include potential economic devaluation of at-risk areas, social vulnerability without equity considerations, limited public acceptance, and comprehension challenges among municipal staff. However, the opportunities are substantial: improved planning and prioritization of actions, dynamic models incorporating social behavior, measurable results via indicators, and scalability to other regions. Together, these elements strengthen climate and urban resilience.

A Diverse Stakeholder Network Ensures Effective Implementation

A multi-actor collaboration drives the practical application of models, with each group playing a distinct role:
Citizens act as end users and potential contributors, while political leaders provide institutional direction. Local and supra-municipal administrations handle territorial management, and coordinators—supported by technical advisers—oversee processes and ensure expert interpretation. Research centers develop and study the tools, and the economic sector supplies technological solutions. Service and infrastructure operators manage critical systems (electricity, water, transport), urban services apply models directly to infrastructures, and legislators enable implementation through subsidies, guidelines, and standardization.

This balanced network integrates technical expertise, political leadership, citizen engagement, and sectoral innovation to ensure models are applied effectively.

Usefulness

1. Roadmap Utility and Feasibility

The roadmap for Granollers and the Congost river basin is deemed useful and realistic, effectively supporting decision-making at both local and supra-local levels. It excels in addressing water-related objectives, such as drinking water and reclaimed water network management. However, its impact could be amplified by incorporating electricity infrastructure, mobility, and other essential services, alongside interpretative indicators to simplify result interpretation. There is also a need to integrate wastewater treatment plants (EDARs) and mobility considerations (e.g., cycling and driving) in sensitive areas, including flood-prone zones.

2. Key Recommendations for Implementation

The roadmap holds particular value for experts and decision-makers, with a recommendation to present core models to contractors. The behavioural model is critical for defining measures, while the basin’s agricultural model can help anticipate flood impacts. To enhance scalability, extending model results to the entire basin would guide investment and risk prevention. Working with time horizons (2030, 2040, 2050) is advised to calculate investment levels and impacts. Additionally, flood risk model results could inform Flood Control Plan reviews and urban planning, including impermeability assessments.

3. Enhancing Model Precision

To improve accuracy, the heatwave model should incorporate additional data, such as roof types (VNS), and adaptation solutions, like creating spaces that facilitate water runoff.

Agreed Actions & Milestones

1. Ensuring Continuity Beyond the KNOWING Project

To sustain the use cases after the KNOWING project, a comprehensive implementation timetable is essential. This should include applied research to consolidate models, securing funding for economic viability, integrated territorial planning, identification of critical points and priority areas, influence on legislators for regulatory support, and updating the PIGGS investment list with a basin-wide perspective.

2. Alignment with the PIGSS Implementation Plan

The continuity of these use cases is tied to the PIGSS implementation plan, expected by May 2026. This plan outlines a three-year period for urgent measures and a ten-year horizon for remaining actions, ensuring detailed planning and budget allocation. By integrating these elements, the PIGSS will guarantee the continuity and real-world impact of the proposed actions.

Summary of Granollers´exploitation plans following the Climate Mitigation Pathway development

In the aftermath of the Pathway seminar, opportunities for local implementation of the pathway and exploitation were established in the Granollers local hub.

Key Takeaways

• Granollers focuses on localizing and adopting KNOWING tools and services
• Integrated Climate Risk Assessment and Analytics
• Decision Support System Utilization in Granollers
• Knowledge Base Utilization in Granollers
• Climate Coping Typology in Granollers

All exploitation projects aim to bridge the gap between modeling results and practical implementation, ensuring scalability for regions with similar challenges.