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Service 04

Hydrological Studies
Rainfall-runoff. Peak discharge.

Rigorous rainfall-runoff analysis and peak discharge estimation — the foundational data on which all flood modelling, drainage design, infrastructure sizing and flood risk assessment is built.

HEC-HMSSCS Curve NumberNOAA/IMD dataPeak dischargeRP2–RP5007–14 days
At a glance
7–14 days
Standard delivery
RP500
Max return period
NOAA
Primary data source
Every study includes
  • Rainfall frequency analysis using NOAA, GSMaP or ERA5 data
  • Peak discharge estimation — RP2 to RP500
  • IDF curve development & design storm generation
  • Hydrograph generation as hydraulic model input
  • Named engineer · Post-delivery support
HEC-HMS
Primary tool
RP2–500
Return periods
NOAA Atlas 14
US data
GSMaP
GCC data
What it is

Hydrological Studies — what HYDRisk delivers.

Hydrological analysis is the first step in any flood-related study. Before we can model how water flows across a site, we need to know how much water arrives — and how fast. That requires a rigorous analysis of rainfall patterns, catchment characteristics, and the rainfall-to-runoff conversion process.

HYDRisk hydrological studies use site-specific data calibrated to the local climate. For the United States we use NOAA Atlas 14 precipitation frequency estimates with USGS discharge records. For the Middle East we use GSMaP satellite rainfall and regional IDF curves calibrated to GCC conditions. For international projects we use ERA5 reanalysis data supplemented by local gauge records.

The hydrological model output — peak discharge estimates and flood hydrographs — feeds directly into hydraulic models, drainage designs and flood risk assessments. The quality of the hydrological analysis determines the quality of every downstream study.

All HYDRisk hydrological studies are delivered with a full methodology report documenting data sources, model parameters, calibration results and uncertainty analysis — so the client engineer or lender's technical advisor can verify every step.

Why hydrology quality matters
“Garbage in, garbage out. Get the hydrology wrong and every downstream study is wrong.”
Site-specific data — not generic regional estimates
Full methodology documentation for verification
Direct hydraulic model input format
Uncertainty analysis included as standard
Why it matters

Four reasons this service is critical to your project.

Understanding what this study delivers — and what happens without it — is the fastest way to evaluate whether your project needs it.

Undersized drainage is caused by underestimated peak discharge
If peak discharge is underestimated — due to poor data or inappropriate methodology — drainage infrastructure is undersized. Consequences range from regular flooding to structural failure.
Lenders require analysis to be traceable and verifiable
A lender's technical advisor reviews the hydrological analysis first. Unsupported assumptions or unverified rainfall data are the most common reason FRAs fail lender review.
Climate change is making historical data inadequate
Designing to historical rainfall frequencies assumes the future looks like the past. A hydrological study that ignores CMIP6 trends underdesigns infrastructure from day one.
Every downstream model depends on hydrological accuracy
Hydraulic models, drainage designs and dam safety assessments all take discharge estimates as an input — an error here propagates through every subsequent study.
What we deliver

Specific deliverables — not vague promises.

Every HYDRisk study produces a defined set of technical outputs — here is exactly what you receive.

Technical analysis outputs
  • Rainfall frequency analysis — IDF curves for RP2 to RP500
  • Design storm generation — duration and temporal distribution
  • Catchment delineation & watershed characterisation from DEM
  • Rainfall-runoff modelling — HEC-HMS with SCS Curve Number
  • Peak discharge estimation — all required return periods
  • Flood hydrograph generation — timing, shape and volume
Report & data deliverables
  • Hydrological study report — data, methodology, results, calibration
  • IDF curves — graphical and tabular format, all return periods
  • Peak discharge table — all return periods and sub-catchments
  • Flood hydrographs — suitable for direct hydraulic model input
  • Catchment GIS data — boundary, stream network, sub-catchments
  • Model files — HEC-HMS project files delivered with results
Data formats: Results in PDF report. IDF curves and discharge data in Excel. GIS catchment data in Shapefile and GeoTIFF. HEC-HMS model files delivered with all runs.
Request a scope →
Tools & methodology

Industry-standard tools. Region-specific data.

Every tool we use is the same software trusted by government agencies, major engineering firms and regulatory bodies worldwide.

HEC-HMS
US Army Corps of Engineers
Industry-standard hydrological modelling for rainfall-runoff simulation, peak discharge estimation and hydrograph generation.
Rainfall-runoffMulti-basin
NOAA & GSMaP
NOAA / JAXA
Primary rainfall data for US and Middle East catchments. NOAA Atlas 14 for US, GSMaP satellite rainfall for arid regions.
Frequency analysisCalibration
QGIS / ArcGIS
Open Source / Esri
Catchment delineation, GIS deliverable production, and spatial analysis for all hydrological studies.
Catchment mapsGeoTIFF

Step-by-step methodology

Step 01
Data collection
Rainfall records, river discharge, DEM terrain, land use, soil maps. Regional frequency database for ungauged sites.
Step 02
Catchment delineation
DEM-based watershed delineation. Sub-catchment boundaries, stream network, slope and drainage area calculation.
Step 03
Rainfall frequency analysis
Regional frequency analysis using available gauge data. IDF curve development. Design storm generation.
Step 04
Rainfall-runoff modelling
HEC-HMS model build — SCS Curve Number or rational method. Peak discharge and hydrograph simulation.
Step 05
Calibration & validation
Model calibrated against observed flood events where records exist. Sensitivity analysis on key parameters.
Step 06
Report & deliverables
Full report, IDF curves, peak discharge table, hydrographs for hydraulic model input, GIS catchment data.
Regional applicability

Calibrated for your region and regulatory framework.

Methodology, data sources and regulatory requirements differ between geographies. HYDRisk delivers the right approach for every region.

United States — Primary market
NOAA-based methodology
NOAA Atlas 14, USGS discharge, FEMA and state-level compliance.
Regulatory frameworks
FEMA NFIPUSACE
  • NOAA Atlas 14 rainfall frequency data
  • USGS gauge records for calibration
  • FEMA compliance reporting
Middle East & GCC
GCC-specific methodology
GSMaP rainfall, arid-region hydrology, wadi flash flood methods.
Regulatory frameworks
UAE MunicipalityAshghal (Qatar)
  • GSMaP satellite rainfall for arid catchments
  • Wadi flash flood methodology — desert soils
  • Bankable studies for GCC lenders
International
IFC & global methodology
ERA5 reanalysis, CMIP6 projections, IFC Performance Standards compliance.
Regulatory frameworks
IFC PS1 & PS4Equator Principles
  • IFC Performance Standards compliance
  • ERA5 for data-sparse regions
  • Remote delivery — any geography covered
Related services

Services often commissioned alongside this study.

Service 01
Flood Risk Assessment
Hydrological peak discharge is the primary input to the flood risk assessment — often commissioned as a combined package.
View service →
Service 03
Hydraulic Modelling
Flood hydrographs generated here are the boundary conditions that drive the hydraulic simulation.
View service →
Service 07
Watershed Analysis
Extended catchment analysis including land use, soil characterisation, and drainage network mapping.
View service →

Ready to commission a hydrological study?

Tell us your catchment, data availability, and study purpose. We will recommend the right approach and scope the work within 24 hours.

Get a free consultation →
Proposal within 24hFixed-fee pricingNo obligation