The permanent measurement of discharge even in normal conditions is difficult and very expensive and
the related problem is increased when floods take place. Towards solving the problem, it is tried to develop
discharge-stage relationship through reading the stage and measuring the associated discharge in particular
conditions. In this study, the stage-discharge relationship was developed and then analyzed for different
time scales of rising and falling limbs of hydrographs, daily, monthly and seasonal by using bivariate
regression and classic discharge rating models. The study was conducted in Kojour Forest Educational
Watershed with an area of some 50000 ha in Mazandaran Province, Iran. The results showed that the developed
relationships, for each time scale, are specific, so that they cannot be applied for the other scales with
reliable accuracy. The linear and power regression models with the minimum correlation coefficient of
58%, the maximum respective calibration and verification relative errors of 70 and 75%, lower RMSE and
the minimum efficiency coefficient of 35% were also found superior to and more accurate than classics
models for all study time scales.