An analytical solution was developed to evaluate free-draining sloping furrows based on Walker and Skogerboe (1987) volume balance approach. Its application allows the mathematical calculation of a system performance, instead of constructing graphs that define the evaluation parameters. The mathematical solution is based on fitting equations to potential models, calculating the areas under the curves defined by the fitting and on curve intersection, , from which the system performance is obtained. To validate the methodology, we conducted a field experiment at the Experimental Farm of the Federal University of Ceará, in the municipality of Pentecoste, belonging to the Center of Agricultural Sciences, where field data were analyzed by the two methods. The results showed that the analytical methodology can be used to evaluate the free draining sloping furrows irrigation.
volume balance; irrigation evaluation; surface irrigation
