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.

Not for the flood that matters. A learned model interpolates within the range of events it was trained on, and the events that drive flood infrastructure decisions, the 100-year design flood and the dam break, sit by definition outside that range. HEC-RAS solves the flow equations, so it remains valid for an event nobody has ever recorded. Machine learning is genuinely useful at the edges of the same workflow: correcting the known bias in a forecast rainfall product before it enters the model, filling gaps in the gauge record the model is calibrated against, and, where an operational warning has to be issued in minutes but a full two-dimensional run takes hours, a fast approximation trained on that model's own outputs can stand in for it. Note that even then the physics defines the answer, because the physical model generated everything the approximation learned from.

Often the free tool is also the right tool, so start there. HEC-RAS is free software from the US Army Corps of Engineers, and with HEC-HMS from the same centre it covers river hydraulics, flood level calculation, inundation mapping and watershed runoff. HEC-RAS also carries the regulatory acceptance that matters when a flood map has to be defended. Move to a commercial package when something specific forces it, typically coastal or complex 2D and 3D work, integrated urban and river modelling, or a client standard you have to meet. On buying: we resell no surface water software. Our Aquaveo reseller agreement covers groundwater software in India only. MIKE 11 and MIKE 21 come from DHI and Delft3D from Deltares; we model in all of them and sell none of them. Describe the study in front of you and we will tell you which of these you actually need, including when the answer is a free tool.