Flood Discharge Calculator - Empirical Methods in India

Flood Discharge Calculator for Empirical Methods Used in India

This calculator implements empirical formulas for estimating peak flood discharge (Q in m³/s) based on catchment area (A in km²) used in India. It also calculates coefficients for Dickens, Ryves, and Nawab Jung Bahadur formulas to match the average discharge of Inglis and Myers formulas.

Input Parameters

Catchment Area (A in km²): Dickens C (typically 11.4-25): Ryves C (typically 6.75-30): Nawab Jung Bahadur C (typically 48-60):

Comparative Chart of Empirical Methods

Method	Equation (Q in m³/s, A in km²)	Typical C Values	Applicable Locations/Regions	Conditions/Remarks
Dickens Formula	Q = C × A^(3/4)	11.4 (annual rainfall 60-120 cm), 14-19.5 (MP, Maharashtra), 22 (Northern India with heavy rainfall)	North and Central India (e.g., Madhya Pradesh, Uttar Pradesh, Bihar)	Applicable for moderate to large catchments with higher rainfall intensity. Empirical; reverse calculation can adjust C to match Inglis-Myers average for site-specific calibration.
Ryves Formula	Q = C × A^(2/3)	6.75 (within 80 km from east coast), 8.45 (80-160 km from coast), 10.1 (limited hilly areas), up to 30 for heavy rainfall zones	Southern India (e.g., Tamil Nadu, Karnataka, Andhra Pradesh)	Suitable for moderate rainfall intensity areas in peninsular India. Reverse-calculated C can align with Inglis-Myers for regional tuning.
Inglis Formula	Q = (124 × A) / √(A + 10.4)	N/A (fixed constants)	Western India (Maharashtra, Gujarat, parts of Karnataka; Western Ghats)	Developed for fan-shaped catchments in Western Ghats. Used as a baseline for reverse calculations due to its regional specificity.
Nawab Jung Bahadur Formula	Q = C × A^(0.993 - (1/14) × log10(A))	48-60 (Southern parts), up to 83.5-118 for other areas	Deccan Plateau (Telangana, Andhra Pradesh, Maharashtra)	Adjusts exponent for area size. Reverse calculation provides C to match Inglis-Myers average, useful for semi-arid regions.
Fuller's Formula	Q = C × A^0.8 × (1 + 0.8 × log10(T)) × (1 + 2.67 / A^0.3)	C ≈ 0.18-0.4	Various parts of India, less region-specific	Includes return period (T). Not used in reverse calculation due to additional variables but included for completeness.
Myers Formula	Q ≈ 123 × √A	N/A (fixed for max flood)	General use in India for max flood estimation	Conservative estimate for worst-case scenarios. Used with Inglis for averaging in reverse calculations.

Note: Coefficients are empirical and should be validated with local hydrological data or Indian Standards (IS codes). Reverse calculations help calibrate Dickens, Ryves, and Nawab Jung Bahadur formulas to match the average of Inglis and Myers discharges for specific catchments.