توابع تجربي براي تخمين شاخص هاي طراحي آبياري جويچه اي در رژيم كاهش جريان

Empirical Functions for a Determination of Furrow Irrigation Dependent Variables in Cutback Regime

Water scarcity along with its high demand in agriculture sector have arisen the attentions of many to manage and optimize irrigation systems. Among surface irrigation systems, furrow irrigation with cutback regime is a common system because of higher efficiency, lower costs, and lower demand of technical labor as well as more adoption to farmerʹs culture. This system is affected by management and design parameters, and hence different management scenarios should be evaluated before being applied in practice. To this end, empirical functions of evaluation performance indices become useful. This paper employs sensitivity, dimensional and regression analysis to develop empirical functions of application efficiency (Ea), deep percolation (Dr), runoff (Rr) and uniformity distribution (Du) by furrow bed slope and flow cross sectional area and through the design and management of such variables as; inlet flow rate, furrow length and cutoff time. The proposed functions were evaluated by a numerical zero-inertia model Determination coefficients of Ea, Dr, Rr and Du were calculated to be 0.90, 0.91, 0.90 and 0.84, respectively. These values indicate that the proposed functions enable one to satisfactorily estimate evaluation indices. The results of developed dimensionless functions showed a very good agreement with the outputs of a zero-inertia model as well as with field recorded data.