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Case Study

NextGen Flood Early Warning Program Planning & Benefit-Cost Analysis

San Antonio NextGen flood early warning map showing watersheds and 70 monitoring gages for program planning and benefit-cost analysis.

Challenge

Following devastating flood events across Bexar County, Bexar County, City of San Antonio and San Antonio River Authority sought to modernize flood warning infrastructure through the NextGen Flood Warning System. To compete for FEMA Building Resilient Infrastructure and Communities (BRIC) funding, the project required a defensible, FEMA-compliant Benefit-Cost Analysis demonstrating that investments in automated flood warning technology would significantly reduce flood-related fatalities, roadway incidents, property losses, and emergency response costs across the region.

Our Approach

Streamline Engineering evaluated flood risk across Bexar County by integrating Base Level Engineering (BLE), effective and draft DFIRM floodplain mapping, Atlas 14 rainfall data, hydraulic model outputs, roadway inventories, and TxDOT traffic data to identify 70 high-priority low-water crossings. Using FEMA’s Benefit-Cost Analysis Toolkit and the Texas Water Development Board BCA methodology, our team quantified existing flood risk, estimated roadway inundation durations, developed engineering assumptions for traffic disruptions and emergency operations, and calculated long-term economic benefits associated with automated flood warning improvements.

Results & Impact

  • Evaluated 70 critical low-water crossings across six major watersheds
  • Supported a $13.5 million regional flood warning infrastructure program
  • Quantified over $200 million in anticipated flood damage reduction benefits
  • Demonstrated a Benefit-Cost Ratio (BCR) of 7.59, substantially exceeding FEMA’s funding threshold
  • Provided the technical foundation supporting FEMA BRIC grant funding for one of Texas’ most comprehensive next-generation flood warning initiatives
  • Advanced implementation of predictive flood warning infrastructure designed to improve public safety, reduce flood-related losses, and enhance regional emergency response capabilities

Client

City of San Antonio

Location

Bexar County, Texas

Related Services

  • Benefit-Cost Analysis (BCA)
  • FEMA BRIC Grant Support
  • Flood Early Warning Systems
  • GIS & Spatial Analytics
  • Hydrologic & Hydraulic Modeling
  • Flood Risk Assessments
  • Low-Water Crossing Evaluations
  • Capital Planning & Funding Strategy
  • Hazard Mitigation Planning
  • Infrastructure Resilience Planning

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