Modeling Urban Hydrology and Green Infrastructure Using the AGWA Urban Tool and the KINEROS2 Model

Area of Science:

• Urban Hydrology
• Geospatial Analysis
• Green Infrastructure Modeling

Background:

• Urban environments face challenges in managing stormwater runoff and infiltration.
• Green infrastructure (GI) offers a sustainable approach to mitigate urban hydrological issues.
• Physically based models are crucial for understanding complex urban water processes.

Purpose of the Study:

• To validate the Automated Geospatial Watershed Assessment (AGWA) Urban tool for urban hydrology modeling.
• To assess the effectiveness of various green infrastructure (GI) practices on runoff and peak flow reduction.
• To evaluate the potential of roof runoff capture for water availability in urban areas.

Main Methods:

• Utilized the AGWA Urban tool integrated with the Kinematic Runoff and Erosion (KINEROS2) model.
• Employed a Geographic Information System (GIS) framework for parameter preparation, model execution, and results visualization.
• Validated the model using observed runoff data from a residential subdivision in Arizona over 47 rainfall events.
• Simulated five GI scenarios (retention basins, permeable driveways, rainwater harvesting, and combinations) to assess their impact on runoff and peak flows.

Main Results:

• Model validation showed strong agreement between simulated and observed runoff volumes (R²=0.80) and peak flow rates (R²=0.83).
• Roof runoff capture simulations indicated a 15% capture of average monthly rainfall, potentially meeting up to 70% of domestic water needs.
• Retention basins (S2) demonstrated the highest runoff volume reduction (30%) and peak flow reduction compared to permeable driveways (S3) and rainwater harvesting cisterns (S4).
• Permeable driveways (S3) were more effective at reducing smaller peak flows than rainwater harvesting (S4).

Conclusions:

• The AGWA Urban tool, coupled with KINEROS2, provides a validated and effective framework for modeling urban hydrology and GI.
• GI implementation, particularly retention basins, significantly reduces runoff volume and peak flows in urban watersheds.
• Roof runoff capture presents a viable strategy for augmenting local water supply in arid and semi-arid urban regions.
• Parcel-level GI interventions can collectively contribute to improved watershed-scale hydrological management.