Prediction of annual maximum daily rainfall of Almora based on probability analysis

摘要

Annual maximum daily rainfall of different return-periods is often required by design engineers, and hydrologists for appropriate planning and design of small and medium hydraulic structures like small dams, bridges, culverts etc. (Agarwal et al. 1988). Though the nature of rainfall remains erratic and varies with time and space, yet it is possible to predict rainfall fairly accurately for certain return period using various probability distributions (Upadhaya and Singh 1998). The probability distribution functions most commonly used to estimate the rainfall frequency are Gumbel, Log Pearson Type III and Log Normal distribution. Kumar (2000) and Singh (2001) concluded that the Log Normal distribution is the best probability model for predicting annual maximum daily rainfall for Ranichauri (Tehri-Garhwal) and Tandong (Sikkim), respectively. Kumar (2000) further suggested that planning a hydrological design of soil conservation and drainage structures at Ranichauri should be based on Log Normal distribution. In recent years, lot of variations in climate have been observed globally and these variations become larger in hills with respect to altitude, time and space. Therefore, in the present study, an attempt has been made to evaluate the most suitable probability distribution for predicting annual maximum daily rainfall at Almora.