灌溉排水系统工程

Slope Effects on the Pressure Head Profile Patterns of Sprinkler Irrigation Laterals, II. Evaluation Based on Simulation

Abstract

Zerihun D, Sanchez CA and Bautista E

Theoretical analysis of slope effects on the spatial patterns of the pressure head profiles of an irrigation lateral is presented in the companion paper. Results of the analysis are evaluated here based on simulations. Simulations were conducted for data sets covering a wide range of lateral parameters. The results show that the pressure profile patterns of a lateral, and possibly the locations of the pressure extrema along the lateral, can be determined by comparing the negative lateral slope with the friction slope at the inlet and/or distal ends, confirming an important inference of the analysis. The simulation study also shows that the full range of variation of lateral pressure profile patterns can be differentiated into the three distinct categories defined based on theory. While results of the analysis developed in the companion paper are generally true, they nonetheless produce only particular solutions (i.e., solutions specific to a given lateral slope). The simulation results, however, provide additional insights, into the relationships between slopes and pressure profile patterns, which would enhance the practical significance of the theoretical analysis. For each data set, considered, simulation outputs reveal that there exists a unique pair of threshold slopes that delimits the feasible range of variation of the lateral slope into three subintervals, each with a specific lateral pressure head profile pattern. Furthermore, the spatial pattern of the simulated lateral pressure profiles, within each of these slope subintervals, corresponds to one of the three categories defined in the companion paper. Hence, the full range of variation of the lateral pressure profile patterns can be completely characterized based on a pair of threshold slopes that are unique to the lateral, which is an advantage. Results of the simulation study are, nonetheless, empirical. Thus, more comprehensive studies are needed to conclusively establish the broader significance of these results.