Water Productivity: A new concept for Improving Irrigation Water Use Efficiency

Abstract

Improved water use efficiencies in irrigated agriculture are necessary to assist in coping with the accelerating demand and economic competition for the worlds fresh water supply and increasing ecological concerns. This will likely rely in part on optimum irrigation, which implies water productivity (net monitory return per unit of water). Efficiency is defined as the ratio of output over input. If we look at irrigation water use efficiency from the economical perspective, the outputs will be the net revenue and the input is a unit of water, which yield the definition of water productivity in this paper. While conventional irrigation management is intended to maximize crop yield, optimum irrigation takes an economic approach, focusing on irrigation plans that maximize total benefits. Optimum irrigation management is inherently more complex than conventional irrigation management, requiring advanced analytical tools for identifying the best irrigation design and management strategies. The aim of this paper is to present a model with the general objective to maximize water productivity (monitory units per cubic meter of water) grown in a certain project and/or country, since, this is the ultimate goal of the end-user (farmer), and grow the crops having the highest water productivity, and the optimal cropping pattern to be followed. This model will be subjected to crop price, water requirement per unit weight of crops, crop yield per unit area, and maximum quantity of a certain crop to be produced in order to sustain crop rotation. The results will yield the least water volume of water needed for irrigation to generate the highest revenue, thus maximizing water use efficiency as defined before and sustaining irrigation of crops, as well as conserving water. This model will be applied to case studies in Lebanon.