Use of indirect methodologies for determining the flow rate in water pumping systems.

Water flow rate measurements are important for monitoring the irrigation practice. It is essential to find the real value of this variable using alternative low-cost methods which are easy to use or readily available. This study aimed to perform a comparative analysis among different methodologies for determining the flow rate in water pumping systems. Seven methodologies were analyzed, with 13 tests each. Three tests were done for adjustment and ten to test the equations. The correlation between the observed value and the values obtained by the methodologies was performed for the adjustment. The equations were subsequently used to obtain the estimated flow rate for comparison with the observed values. The comparative analysis was performed through the following statistical indicators: Precision Index, Agreement Index, Performance index, Root mean square deviation and Nash-Sutcliffe efficiency. The methodology which showed the best adjustment in the flow estimation was the U-tube vacuometer. The pressure showed the best general performance among the tested parameters with the Tensiometer, Bourdon vacuum gauge and U-tube vacuum gauge instruments. [ABSTRACT FROM AUTHOR]