Optimal Design of Furrow Length of Surface Irrigation

The furrow length design of an irrigation system can be optimized by analyzing overall irrigation system cost when the infiltration intensity function of soils, advance function of inflow stream inside the furrow, and other pertinent information are known. Computer programs were coded for obtaining optimal solution. The curves of cost functions usually have gentle slope close to optimum furrow length when stream size is fixed (advance function known). Therefore, the designer does have limited freedom of choosing a suitable furrow length without incurring extremely high cost. The length of furrow which falls in the interval where cost vary less or equal to 5% of the optimal or the minimum cost is defined arbitrarily as adequate length. Results showed that the irrigation application efficiency is a function of furrow length. Comparison of ordinary system and a cutback system was also conducted. The developed optimization technique can also be used to determine the length of the border.