The purpose of this study was to evaluate probability distribution models applied to annual minimum daily discharge and mean minimum discharge at seven days duration time in order to adjust regional hydrologic models for these variables working with seven bases located at upstream side of Camargos Hydroelectric Power Plant Reservoir in Alto Rio Grande region, considering topography and weather characteristics of basin as independent variables. Preliminary irrigation water availability was estimated based on Q7,10 and Q90% discharges. Log-normal 3 parameters, Weibull and Gumbel probability distribution models were tested to hydrological long term discharges series. Regional hydrologic models were adjusted by least square methodology and significant variables were selected by "backward" statistical procedure. Annual daily minimum discharge and mean minimum discharge at seven days duration time frequencies of occurrence were better represented by Log-normal 3 parameters probability distribution model, according to qui-square statistical test the regional hydrologic models have good statistical adjusting. This results indicated further necessity of detailed study for fixing water right concession criteria.
probability distribution models; regional hydrologic models; water availability
