Assessment of probability distributions and minimum storage draft-rate analysis in the equatorial region

Abstract

Abstract. Streamflow information is critical to the management and development of water resources strategies. The reliability of water supply from rivers depends on their low flow characteristics. Low flow frequency analysis was derived using the Weibull plotting position and four specific distributions. Maximum likelihood was used to parameterise, while Kolmogorov–Smirnov tests are used to evaluate their fit to the dataset. The best probability distribution is then selected based on individual probabilistic analysis and the flow duration curve for the study threshold level (Q90 percentiles) with the pooling procedure derived to quantify the drought characteristics. The mass curve is used to quantify the minimum storage draft-rate required to maintain the 50 % mean annual flow for a recurrence interval of 10 years. The results indicated the hydrological droughts have generally become more frequent and critical in the availability of rivers to sustain water demand during low flows.