LOWFLOWS ANALYSIS OF BAITARANI RIVER

Abstract

Assessment of lowflows is of utmost importance in the water resources development planning, particularly in hydro-power, irrigation, navigation and pollution abatement projects. The exponentially decaying function, Q Qo e-t.R is generally used for the analysis of lowflows. But it is observed that this equation does not represent the lowflow correctly. A few attempts have been made to make suitable modifications by considering transformed time function etc. In the present study the if low data of river Baitarani have been analysed and an exponential relationship, kt +At +k Q`t+At = exp . [ In Ut . ex_p { - _ .~. = — a . At } 2 has been evolved. The suggested model is based on the assumption that the recession coefficient is not time in-varient. A variable recession coefficient to represent the lowflows has been considered in the model. This assumption is very much valid in field situations, particularly in view of fluctuating watertable, heterogeinity and anisotropy of the aquifers and varying losses through evaporation, evapo-transpiration, leakages etc. A suitable representation for the variation in the volues of recession coefficient with respect to time from a defined cutoff point has also been established.