Mixed Distributions in Low-Flow Frequency Analysis

Abstract

LOW-FLOW CHARACTERISTICS ARE REQUIRED TO SOLVE SEVERAL WATER-ENGINEERING PROBLEMS. IN THIS PAPER, THE MIXED GUMBEL AND THE TWO COMPONENT EXTREME VALUE DISTRIBUTIONS ARE PRESENTED TOWARD THEIR APPLICATIONS IN LOW-FLOW FREQUENCY ANALYSIS. A REGION IN SOUTHERN MÉXICO, WITH 39 GAUGING STATIONS WAS SELECTED TO ANALYZE THE LOWEST 1 DAY FLOWS. ADDITIONALLY, IN ORDER TO CALCULATE THE STREAM DESIGN FLOW (7Q10) FOR WATER QUALITY STANDARDS DOWN STREAM OF THE HYDROELECTRIC PROJECT LA PAROTA, THE LOWEST 7 DAY AVERAGE FLOWS WERE USED. RESULTS PRODUCED BY FITTING THE MIXED DISTRIBUTION WERE COMPARED WITH THOSE OBTAINED BY THE WEIBULL-3, GUMBEL, LOGNORMAL-3 AND GENERAL EXTREME VALUE DISTRIBUTIONS. RESULTS SUGGEST THAT MIXED DISTRIBUTIONS ARE A SUITABLE OPTION TO BE CONSIDERED WHEN ANALYZING MINIMUM FLOWS.