Design of multiquality irrigation water supply systems using the Q–C feasibility domain concept: II. QCFD model and applications

Abstract

The world shortage in water sources for irrigation indicates a need to exploit poor water quality sources. Traditional design methods of irrigation systems consider primarily the hydraulic aspects. Inclusion of water quality aspects requires new tailored design methods. The method suggested herein is part of a continuous effort taken in that direction. Earlier works paved the way for the presently suggested design model which computes the feasibility domain of water discharge and quality of supply networks. Steady-state conditions, conservative water quality parameters, instantaneous and complete mixing of water from diverse water quality sources were assumed. The Q-C (chemical transport sub-problem) was dealt with and the QC feasibility domains of sources for the inner nodes and outlets were computed for every feasible flow pattern in a given network. Feasibility of supply was evaluated by comparing demand (water discharge and quality) values with the supply values computed by the QCFD. Real water supply in a rural community in the Arava desert, Israel, was designed using the QCFD model. Feasibility of various irrigation schedules was tested and a guideline for operation derived. The method, however, needs further improvement. Copyright # 2008 John Wiley & Sons, Ltd.key words: irrigation; irrigation systems; irrigation water supply systems; poor quality water; water quality; feasibility domain RÉ SUMÉLa rareté de l'eau dans le monde rend nécessaire l'exploitation des eaux de mauvaise qualité. Les méthodes de conception traditionnelles des systèmes d'irrigation considèrent principalement les aspects hydrauliques. L'inclusion des aspects de qualité de l'eau exige de nouvelles méthodes de conception. La méthode suggérée ici s'inscrit dans un effort continu dans cette direction. Les premiers travaux ont préparé le terrain pour le modèle ici suggéré qui calcule le domaine de faisabilité du débit et de la qualité dans les réseaux. On suppose des conditions de stabilité, de conservation des paramètres de qualité, de mélange instantané et complet des eaux de qualité différentes. Le Q-C (sous-problème de transport des sels) a été traité et les domaines de faisabilité des sources, des noeuds intérieurs et des sorties ont été calculés pour chaque série de débits dans un réseau donné. La faisabilité de la fourniture d'eau a été évaluée en comparant des valeurs de demande (débit et qualité) aux valeurs de fourniture calculées par le QCFD. La fourniture réelle pour une communauté rurale dans le désert d'Arava, Israel, a été conçue en utilisant ce modèle de QCFD. La faisabilité de divers programmes de pilotage de l'irrigation a été examinée et IRRIGATION AND DRAINAGE Irrig. and Drain. 58: 61-71 (2009)

Design of irrigation water supply systems using the Q–C feasibility domain concept: I. Introduction and theory

“…A model (QCFD) was developed, which computed all the supply QCFD of the networks nodes for a given flow pattern (FP). This QCFD model is presented in the follow-up paper (Sinai and Dalins, 2008). Evaluation of all the QCFDs for every feasible FP (FFP) enabled a complete analysis of all feasible water discharges and solute concentrations of the examined supply systems.…”

“…The design model therefore computed a truncated QCFD for every pipe/link which was the unbounded QCFD, minus the domain of Q > Q max of the inlet and outlet pipes of the junction considered. The Q max bounded QCFDs are demonstrated in the example in the next paper of this series (Sinai and Dalins, 2008).…”

“…Here the design methods suited for multiquality networks are suggested. In a follow-up paper (Sinai and Dalins, 2008), the effect of network layout and a design of a real case are demonstrated.…”