Dual-Benefit Digital Twins: Modeling Water Retention and Urban Heat Mitigation in Arid Cities

Rapid urbanisation in Oman’s extreme climate is intensifying water stress and expanding Urban Heat Islands (UHI), which directly threaten population health, economic productivity, and municipal budgets. Urban planners must optimise resource allocation and capital investments while maintaining urban livability. This study presents a Digital Twin (DT) framework, grounded in the Astra Terra architecture, to model the dual benefits of Nature-based Solutions (NbS) for UHI mitigation and hydrological resilience. In contrast to traditional models that focus exclusively on vegetation, this approach incorporates "wetness" as a primary variable in regulating the urban microclimate.

The methodology integrates a federated data ecosystem, utilising the Copernicus Climate Data Store (CDS) for baseline indicators and Landsat 8 thermal imagery for hotspot identification. A Data Fusion Core merges satellite Earth Observation data with three-dimensional urban morphology. The framework follows FAIR data principles and high-performance computing (HPC) standards, ensuring scalability and policy-driven simulation capabilities compatible with the Destination Earth (DestinE) platform.

As a proof-of-concept demonstrator, this framework explores the theoretical ability to simulate urban responses to varying 'wetness' levels. This initial iteration focuses on modeling 'wet infrastructure' to establish the basic principles of hydro-thermal feedback in arid environments. By mapping existing wadis and topographical depressions, the framework simulates Blue-Green Infiltration Basins and water-retention zones. These scenarios are used to evaluate two critical environmental and economic responses:

• Hydrological Resilience and Financial Optimisation: Zones are modeled as Managed Aquifer Recharge (MAR) sites. The Digital Twin simulates how infiltration rates stabilize local aquifers, thereby reducing the long-term costs associated with water scarcity management. Incorporating native species such as Acacia and Date palm, the model demonstrates ecological balance with minimal maintenance requirements.
• Thermal Cooling and Public Health: The framework quantifies the thermal response to increased soil moisture. Simulations indicate that higher thermal inertia and latent heat dissipation can reduce surface temperatures by 3–5°C near critical infrastructure. This temperature reduction is directly associated with improved population mobility and reduced heat-related health risks, both of which are essential for sustaining economic activity and resident well-being.
• Eco-Hydrological Feedback: "Greenness" serves as a biological indicator of subsurface water availability. The Digital Twin models the feedback loop in which urban vegetation protects water resources from evaporation, thereby supporting the longevity of urban investments.

Impact and Decision Support: Through advanced analytics, the Digital Twin provides actionable insights to help planners prioritise multifunctional spaces. By demonstrating that interventions are both thermally effective and economically viable, this approach offers a practical roadmap for reducing complexity in urban planning and enhancing the climate resilience of heat-stressed arid cities.