TITLE:
The Review of Water Use Efficiency and Water Productivity Metrics and Their Role in Sustainable Water Resources Management
AUTHORS:
Dominico B. Kilemo
KEYWORDS:
Water Resources Management, Water Use Efficiency (WUE), Crop Water Productivity (CWP)
JOURNAL NAME:
Open Access Library Journal,
Vol.9 No.1,
January
28,
2022
ABSTRACT: Our planet faces a challenge of producing food to meet the demand of current population which is projected to increase by the year 2050. This implies producing more food from the existing fresh water resources which are already stressed. This is because agriculture accounts for 70% global fresh water consumption; the rest is domestic and industrial use. Yet, water is unevenly distributed globally, causing some countries to be water-rich and others water-poor. Agricultural water management provides opportunities to optimize crop yield from less water. This necessitates a shift from conventional crop production approaches which aimed at maximizing yield per unit area of land to more water conscious methods that seek to maximize crop yield per unit water consumption which is determined by evapotranspiration. Water Use Efficiency (WUE) and Crop Water Productivity (CWP) are water accounting metrics aimed at monitoring the efficiency with which water is supplied to the field and the rate at which the plant converts water into food respectively. This paper reviews these metrics by examining their differences, assessing their contribution to sustainable water management, factors affecting each of them and strategies for increasing both metrics. Findings from literature suggest that WUE and CWP are different terms, but often misused especially WUE which is wrongly applied in the contexts meant for CWP. Factors affecting CWP which must be also considered in devising strategies for increasing it can be grouped into crop specific factors, climate factors and management factors. The paper recommends a number of interventions aiming at increasing WUE and CWP from local to global scale. These include provision of technical and financial support to developing counties to enable reduce water wastage, benefit from rainfall through rain harvesting technologies and low cost irrigation infrastructures that reduce evaporation, runoff and deep percolation losses. Water-poor countries are recommended to grow high value crops and use the proceeds to import food from water-rich countries under virtual water trade agreements.