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Hydrology Survey Report: Runoff, Peak Discharge, and Design Rainfall

A hydrology survey report quantifies surface water behaviour at a site — design rainfall, runoff volume, peak discharge, and time of concentration — for stormwater sizing, culvert design, and rainwater-harvesting overflow structures. Rain GEO SAT's Expert workspace assembles this report using satellite rainfall, DEM-derived catchment, and CN-based runoff estimation.

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Report contents

Every hydrology report includes design rainfall (typically 1-in-10-year, 1-hour intensity from IMD IDF curves), catchment area from DEM delineation, runoff volume via SCS Curve Number, time of concentration via Kirpich, and peak discharge via the Rational Method.

  • Design storm — 1-in-2, 1-in-5, 1-in-10, 1-in-25, 1-in-100-year events
  • Catchment area — from Copernicus DEM (30 m) or Bhuvan Cartosat (30 m)
  • Curve Number — from SoilGrids texture × land-use (Sentinel-2 NDVI)
  • Time of concentration — Kirpich or SCS Lag equation
  • Peak discharge — Rational Method (Q = 0.278 × C × I × A)
  • Provenance table — data source, retrieval date, and formula version

When it is required

Municipal building permits for plots >2000 m². State PCB stormwater discharge NOC. IGBC/LEED SS credits for rainwater management. World Bank ESF hydrology annexes. CSR watershed-development baseline reports.

Frequently asked questions

How is this different from a hydrogeological survey report?
Hydrology focuses on surface water — rainfall, runoff, peak discharge. Hydrogeology focuses on subsurface water — aquifer, water table, borewell yield. Rain GEO SAT generates both from the same project.
Which return period should I design for?
1-in-10-year is standard for urban stormwater drains. 1-in-25-year for major culverts. 1-in-100-year for critical infrastructure and dam spillways.

Ready to apply this on your site?

Rain GEO SAT calculators use IMD, NASA POWER, Open-Meteo, and CGWB data to deliver engineer-grade rainwater harvesting and groundwater recharge designs.

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