DESIGN OF IRRIGATION WATER SUPPLY SYSTEMS USING THE Q-C FEASIBILITY DOMAIN CONCEPT: I. INTRODUCTION AND THEORY

The Q-C Feasibility Domain (QCFD) was defined and proposed as a tool for design of multiquality irrigation water supply systems. It determines all feasible combinations of water discharge and water quality, and can be represented by a point, a line, or an area in a diagram of water discharge versus solute flow rate (a Q-J diagram). The shape of the QCFD is the result of dilution of two or more flows from sources of different water quality. (assuming conservative substances) Several types of QCFDs were analyzed at sources, inner nodes of a network, and of consumer outlets. The effect of water discharge constraints (due to flow limitations in the network) on the QCFDs was formulated and analyzed. Computation of QCFDs of dilution junctions by vector addition of their inflows was described. The method was extended numerically to nonlinear mixing due to dependence of water salinity. Use of this method enables computation of QCFDs for inner nodes in networks, including dilution junctions. The effect of network topology and flow direction was discussed. Application and demonstration will follow in the next paper in this series. Copyright (C) 2008 John Wiley & Sons, Ltd.