Surface Water & Flood Modeling

Flood modeling typically requires topographic data (LiDAR or surveyed cross-sections), hydrologic data (rainfall records, streamflow measurements), land use information, and details of hydraulic structures like bridges and culverts. We can work with available data and recommend cost-effective surveys to fill any gaps.

When properly calibrated with observed flood data, HEC-RAS models typically achieve accuracy within 10-15 cm for water levels. Accuracy depends on data quality, model calibration, and the complexity of the river system. We always validate our models against historical flood events when data is available.

1D modeling simulates flow along a river channel and is faster and suitable for most river studies. 2D modeling simulates flow across floodplains in two dimensions and is better for complex urban areas, wide floodplains, or where flow paths are uncertain. We recommend the appropriate approach based on your project needs and budget.

A basic flood study for a small river reach takes 4-6 weeks. Comprehensive studies with detailed floodplain mapping for larger areas typically take 3-6 months. Dam break analyses and complex urban flood studies may require 6-12 months depending on scope and data availability.

A dam break analysis simulates the catastrophic failure of a dam to predict downstream flooding, warning times, and potential impacts. It's required for dam safety permits, emergency action plans, and downstream hazard classification. We use HEC-RAS to model breach formation and route the flood wave downstream.

The 100-year flood has a 1% chance of occurring in any given year. We determine it through statistical analysis of historical flood records or rainfall-runoff modeling when streamflow data is limited. The 100-year discharge is then routed through the hydraulic model to calculate corresponding water levels.

Yes, we incorporate climate change by adjusting rainfall intensities and sea levels based on climate projections. This allows assessment of future flood risks under different climate scenarios. Many jurisdictions now require climate change considerations in flood studies for infrastructure planning.

Both are industry-standard tools. HEC-RAS is free and widely accepted in North America, while MIKE (by DHI) is commercial software popular in Europe and Asia. MIKE offers more integrated modules for coastal and urban flooding. We're proficient in both and recommend based on project requirements and client preferences.

Flood maps delineate areas at risk of flooding for different return periods (10-year, 100-year, etc.). Planners use these to restrict development in high-risk zones, set building floor levels, design drainage infrastructure, and inform emergency response plans. Accurate flood mapping is essential for sustainable urban development.