How to Build a Rainfall-Runoff Model | SCS Unit Hydrograph Tutorial
In this video, we build a complete rainfall–runoff model from scratch using the SCS Curve Number (CN) method and the Unit Hydrograph (UH) approach—implemented step by step in Excel.
This tutorial takes you through the full modelling workflow:
• Understanding the theory behind SCS and Unit Hydrograph methods
• Converting rainfall into effective rainfall using the SCS CN method
• Transforming effective rainfall into a runoff hydrograph using the Unit Hydrograph
• Running a numerical example in Excel
• Comparing simulated and observed hydrographs
• Evaluating model performance
• Calibrating and adjusting model parameters for improved results
This approach reflects the core workflow used in many industry tools like HEC-HMS, but implemented in a transparent and easy-to-follow way.
This video is ideal for hydrologists, water engineers, students, and researchers who want to understand how rainfall–runoff models work behind the scenes.
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⏱️ Timestamps
00:00 – Introduction: From Rainfall to Runoff
00:23 – SCS Curve Number Method (Concept & Assumptions)
02:29 – Unit Hydrograph Theory and Convolution
04:18 – Model Development Methodology
05:08 – Excel Example: Model Setup & Simulation
14:22 – Comparing Simulated vs Observed Runoff
14:58 – Sensitivity Analysis on Model Parameters
17:09 – Optimising Model Parameters
23:40 – Key Takeaways
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Keywords
#civilengineering #hydrologytutorial #hydrologicalmodelling #rainfallrunoffmodel #scscurvenumber #unithydrograph #modelperformance #modelcalibration #optimization #hec-hms #exceltutorial