TR-43 : Forecasting of monsoon runoff using data from specific basins

Abstract

The water resources planning and operation activities are dependent mainly on the monsoon behaviour that being a crucial period contributing 80-90% of annual rainfall and runoff. The forecasting of monsoon runoff based upon the available runoff data upto the end of June, July, August and September coule he an important aspect for drought management and in planning and operation of surface water reservoirs. The correct and timely assessment of water resources before the beginning of their utilization period say before Rabi is a must.

For forecasting of monsoon rainfall and runoff, a methodology based on simple regression relationships was earlier developed and was applied to the data of Mahanadi river basin at Hirakud. The methodology gave very encouraging results in forecasting the monsoon rainfall and runoff and in identifying whether the current year is going to be below normal or above normal. In order to examine the applicability of the technique for other reservoirs and rivers located b in different agro climatic regions of the country, the methodology has been applied to the runoff data of following reservoirs/river sites in the present study; (i ) Bhima at Dhond, (ii) Bhima at Wodakabal, (iii) Bhima at Narsingpur,(iv)Bhima at Takali, (v) Bhima at Yadgir, (vi) Tungbhadra at Haralahalli (vii) Tungbhadra at T Ramapuram, (viii) Koyna reservoir, (ix) Gandhisagar reservoir, (x) Mahanadi at Hirakud (xi) Chaliyar river, (xii) Kanhirpuzha river, (xiii ) Koodathai river, (xiv) Punnarpuzha river, (xv) Gobindsagar at Bhakra, (xvi) Sabarmati at Dharoi, (xvii) Fong reservoir, (xviii) Malaprabha, and (xix) Jayakwadi reservoir. The catchment areas very from 71.77 Km² to 83400 Km² and the length of data vary from 10 years to 41 years.

The report gives the efficiency in percentage in estimation and forecasting of monsoon runoff on the basis of total runoff upto the end of (i ) June, (ii) July, (iii ) August, and (iv) September. The report also gives the results of these relationships in identifying whether the current year is going to be below normal or above normal from runoff point of view.