Section 2(10)(iii) in State Water Resources Regulatory Authority (Guidelines on Selection of Water Sources and for, ensuring availability of Water for the Water Supply Irrigation Systems) Regulations, 2018
(iii)Use of River Gauging Data : (a) Wherever river gauging data for at least 8 years is available, the minimum and maximum discharge likely once in a 30 years period may be statistically arrived at and adopted. A 100 years period may be used, if the data available is for a minimum of 25 years.