# inglis formula for runoff

To Calculate Runoff for Morbe Dam Project, The INGLIS Method is used. Inglish formula is derived by using the data of rivers of Mahashtra, where it is commonly used. 10 124 A A Q P Contd… Originally developed for the catchments in Western Ghats in Maharashtra At present this is used all over in Maharashtra with a modification in the numerator (the value of 124) Qe= 0.7356 P- 12 Where, Qe= Estimated runoff in cms P= Rainfall in inch The results obtained from the above empirical formula are shown in Appendix: 3, In which it is shown that there is a huge difference between estimated and observed runoff, So INGLIS 5) Khosla’sformula: developed for time period of the month. From rainfall records 2. Inglis and Disooza (1929)  developed regional formula between annual runoff (R) in cm and annual rainfall (P) in cm for different regions of India, given as: 1. 1) Sir Inglis Formula: Ghats fed Catchment (i.e. Khosla’srelationship for runoff estimation is given by Rm = Pm –Lm Lm = 0.48 Tm ( Tm > 4.5OC ) Rm = monthly runoff in cm Pm = monthly rainfall in cm Lm = monthly losses in cm Tm = … Some of the leading empirical formulae for estimating the storm water (or rain water) flow or runoff are given below: Inglis formula was derived by using the data of catchment areas or drainage areas of Maharashtra where it is commonly used. Empirical formulae a) Khosla’s formula R-Annual run-off in mm. 4) Inglis’sformula : developed for western India. T-mean temperature in ˚C. Runoff or streamflow comprises the gravity movement of water in Inglis formula: • Q= 124 A = 124 A ½ √A + 10.4 Where Q= discharge in cumec A= area of catchment in Sq.. Km. For Ghat regions of western India, R = 0.85 P – 30.5 2. best estimates, followed by the Khosla`s formula, the rational method was the last. INGLIS AND DE SOUZA'S, LACEY'S, PARKER'S BRITISH AND USA, AND TAPI BASIN Formula use for corelationship. b) Inglis formula for areas of Maharashtra For ghat region, For plain region, R = 0.88 P – 304.8 R = (P-177.8) x P / 2540 R = P - 4.811 T Run-off over the catchment = rainfall x coefficient 10. the western slopes of western Ghats receiving heavy rain from the south west monsoon winds). Rational Equation: Q=ciA The Rational equation requires the following units: Ali Nawab Jang Bahadur formula: ( 0.993Q= CA - 1/14 log A) Where, Q= Discharge in Cumec A=area of catchment insq .km R= 0.85 P - 30.5 Where in, R= Runoff (in mm) P= Precipitation (in mm) 2) Khosla’s Formula: After studying empirical methods for annual flood flow rate estimation and comparing the It is not as sophisticated as the SCS TR-55 method, but is the most common method used for sizing sewer systems. Inglis formula (1930) Where Q p = maximum flood discharge (m 3 /s) A = catchment area (km 2) 4. Following formulae are used to calculate the rainfall-runoff relationship. The Rational equation is the simplest method to determine peak discharge from drainage basin runoff. P-Annual rainfall in mm. empirical runoff estimation method including Dredge & Burge, Bourges, Inglis, Faning, Hyderabad, Burkli Ziegler, Cramar and Possenti were calculated in Bakhtegan watershed which is located in Fars province.