Sustainable efficiency (sefficiency) of water use systems amidst environmental impacts

Abstract

Water use systems (WUSs), such as, urban areas and irrigated agriculture, are under increasing pressure due to various uncertain drivers, such as, global warming and population increase. Because of these phenomena, water scarcity and pollution are increasing causing severe economic, environmental and social damages. Consequently, water management and design (WMD) must focus on comprehensive performance of WUSs by integrating three pillars: water quantity, quality and benefits. These are the foundations of a new framework called Sefficiency, which incorporates the three dimensions of sustainability: environmental, economic and social. Sefficiency indicators have three levels Macro, Meso and Micro (3ME, in %), which make the trade-offs between pillars, dimensions and levels transparent. The crucial distinction between water use and water consumption produces both IN / OUT Sefficiency indicators, crucial for comprehensive and systemic analyses. The logical proof of Sefficiency is objective based on the water balance principle for any WUS under analysis. This universal law guarantees the robustness of the results of 3ME by defining nine Water Flow path Types (WFT). The fact that they are fixed and hydrologically unambiguous promotes a powerful and explicit enabler for active and effective involvement of various types of stakeholders. Usefulness Criterion for each WFT and/or Water Flow Paths is the multiplicative impact of both water quality and beneficial weights. Hence, Sefficiency is the ratio of useful outflow to its corresponding total useful flow, which can reveal the complexities and non-linearities in WMD. For this paper, after presenting a summary of Sefficiency, a simple agricultural example is explained, showing some of the possibilities of Sefficiency. For example, the use of technology as a positive change agent may, under some circumstances, prove to be harmful. This is particularly so if the system has more than one objective, such as, food production and groundwater recharge or pollution control.