DIMSUB, a computer program for designing microirrigation subunits. Tool definition and case studies

ABSTRACT: DIMSUB is a computer program to complement a decision support tool (DST) to effectively study different hydraulic design alternatives in microirrigation systems. We developed environments in Visual Basic for applications for Microsoft Excel® that allow specific step-by-step functions to be created for the design of irrigation subunits. Different alternatives can be considered, such as types of emitter, lateral and submain pipe sizes, different feeding points, irregular subunit shapes and topography slopes. Furthermore, specific uniformity criteria need to be considered to achieve efficient water applications and proper design systems. Lengths of run lateral and submain pipes, position of the hydrant connection, pressure head and head loss in pipes or pressure-compensating emitters can be assigned to evaluate the results and choose the best design alternative. This user-friendly tool to study hydraulic variables is expected to be a valuable aid for the decision-making process in designing irrigation systems. Some examples of practical cases under specific crop conditions to design drip irrigation subunits are given using DIMSUB.摘要：DIMSUB是一款用于辅助决策支持工具（DST）的计算机程序，可高效开展微灌系统各类水力设计方案的研究工作。我们基于Microsoft Excel®的Visual Basic for Applications（VBA）开发了专属环境，能够搭建灌溉子单元设计所需的分步功能模块。该工具可涵盖多种设计变量，例如滴头类型、毛管与支管管径、不同的供水点位置、不规则的子单元形状以及地形坡度等。此外，为实现高效节水灌溉与合理的系统设计，需遵循特定的均匀性设计标准。用户可自定义毛管与支管的铺设长度、消防栓接口位置、管内压头与水头损失，或是压力补偿式滴头的相关参数，以此评估不同设计方案的结果并选出最优解。这款操作便捷的水力变量研究工具，有望为灌溉系统设计过程中的决策环节提供重要支撑。本文还通过DIMSUB工具，给出了若干针对特定作物种植条件的滴灌子单元设计实用案例。