Discussion of “An Alternative Analytical Approach to Designing Paired Lateral Lines for Microirrigation on Slopes” by João Audifax Cézar de Albuquerque Filho, Ceres Duarte Guedes Cabral de Almeida, Manassés Mesquita da Silva, José Antonio Frizzone, José Amilton dos Santos Júnior, and Alexsandro Oliveira da Silva.

Abstract

The discussers would like to express sincere appreciation to the authors of the original article (OA), for conducting valuable research on paired drip laterals on slopes, with particular emphasis in identifying the best design solution. As part of their design procedure, the authors adopted the assumption  originally proposed by Keller and Bliesner (1990)  that the pressure head at the distal end of the downhill lateral (hd) is equal to that at the uphill end (hu). This assumption is referred to as Case A (Fig. 1). The objective of this discussion is twofold. First, it aims to present an alternative dimensionless approach, in which all key design parameters (uphill and downhill emitters, Nu and Nd, their sum, N, slope, S0, emitter spacing, S, inside lateral diameter, D, and inlet pressure head, hin) are consolidated in two dimensionless groups. The second objective is to compare Case A with that from Baiamonte (2018a), who imposed i) hd equal to the inlet pressure head at the manifold connection, hin, and ii) hu equal to the minimum pressure head, hmin, occurring at a specific section, imin, of the downhill lateral (Fig. 1). For this second case, denoted as Case B, the best submanifold position was found, BSP = Nu / N  0.24, for any paired drip lateral (Baiamonte 2018a), while for Case A, BSP is expressed by Eq. (21) of the OA.