Land‐Grading Design by Using Nonlinear Programming

Abstract

Land grading is an important and necessary operation for successful and efficient surface irrigation. Currently, most lands are graded or reshaped to form a plane surface with uniform slopes in one or two directions. In this research, a new technique has been developed to perform land‐grading designs by selecting a best‐fit curved or plane surface. The profiles of such surfaces along either of the two major directions are assumed to be represented by a general power function. The main goal of this technique is to minimize the volumes of earth work required while obtaining a desirable smooth surface. Furthermore, the fitted surface can be subjected to a series of constraints: Limiting the slope at any point; choosing the desired surface shape, i.e., concave, convex, or plane; and limiting the elevation of the graded surface to allow gravity irrigation from a water source. Nonlinear programming has been used to perform the fitting procedure. The results obtained from the developed procedure have been compared with those obtained from previously developed methods. The new procedure proved efficient and very flexible in selecting a suitable graded surface for a given land.