In the Rio Grande do Sul state, the irrigation systems for growing use contributes to make the water reserves through barrages more important. In this case, it is essential to determine the volume of water available in these structures for the appropriate projection of the irrigated systems and concessions for water usage.Currently, the determination of the volume is not much frequent because the direct method (bathymetry) is characterizes as onerous and besides demands specialized workforce and available time. Thus, this research had the objective to evaluate a mathematical model to determine the volume of water stored in irrigation reservoirs The mathematical model chose was represented by Schoklisch formula, where the volume of water of a reservoir is given by the product of the area and the maximum depth in normal level and the Schoklisch parameter (η). The analysis of the parameter η was based on the data provided by 210 reservoirs destined to irrigation, located in the Campanha of Rio Grande do Sul state. Through the results it is possible to notice that the Schoklisch (η) coefficient value varied between 0.47 and 0.53, presenting a average value of 0.50 and standard deviation of 0.05 considering the localities altogether. It was also observed, that all localities studied fitted in the class of optimum performance. The coefficients of determination found for the studied regions were superior to 0.99. The relation between the expected volume and the observed volume in reservoirs demonstrates the high degree of correlation between the tested values and allows the recommendation of the Schoklisch model for the determination of the volume of water stored in irrigation reservoirs in the localities studied.
volumetry; hydrometry; bathymetry
