Abstract
Sustainable Development Goal indicator 6.4.1 is defined as the change in water use efficiency over time and measured as the change in the ratio of gross economic value added by irrigated agriculture, industry and the services sector to the volume of water withdrawn over time. The rationale behind this indicator is to decouple a country's economic growth from its water use. Yet, this unwittingly results in an economic distortion of the water balance, favouring increased water withdrawal in service of higher water-use efficiency, at the expense of environmental sustainability. This paper discusses three methodological flaws. First, aggregation of only economic values across all sectors ignores social and environmental values and is very sensitive to changes in the relative water use by agriculture versus industry and services. Second, the economic value derived from agriculture and from imports cannot in fact be decoupled from agricultural water use. Third, the indicator completely ignores the effects of diminished return flows to the environment due to increased re-use of water. A novel alternative, disaggregated WUE approach is therefore proposed, which links water consumption to the water balance. It is defined as the economic value of irrigated and rainfed agriculture combined with water consumption (ETa) by rainfed and irrigated agriculture per area based on earth observation data. It is measured as the change in the ratio of gross economic value added by irrigated and rainfed agriculture to the volume of water consumed by rainfed and irrigated agriculture over time. This approach is more consistent and objective, while being methodologically, hydrologically and environmentally sound. It acknowledges the coupling of economic growth and water depletion, and the need to strike a balance between opportunities for economic growth and environmental sustainability. This better serves the full breadth of the water and sanitation goal as defined in SDG 6.
Highlights
In September 2015, the United Nations General Assembly adopted the 2030 Agenda for Sustainable Development consisting of 17 Sustainable Development Goals (SDGs) with 169 targets under the various goals (UN, 2015; UN, 2017; UN-Water, 2018a)
Despite criticisms that many of the suggested indicators lack comprehensive, cross-country data and even lack agreed statistical definitions (Schmidt-Traub et al, 2017), the United Nations Statistical Commission (UNSC) adopted a set of 232 indicators proposed by IAEG-SDG in March 2016 as a starting point for progress monitoring (Allen et al, 2017)
The water balance-based water-use efficiency (WUE) becomes $70/85 m3 = 0.82 $/m3, while the return flows to the environment diminish from 35 to 15 m3 and only 115 m3 of water instead of 135 m3 remains available at the resource, affecting the sustainability of water withdrawal
Summary
In September 2015, the United Nations General Assembly adopted the 2030 Agenda for Sustainable Development consisting of 17 Sustainable Development Goals (SDGs) with 169 targets under the various goals (UN, 2015; UN, 2017; UN-Water, 2018a). Indicator 6.4.1 was designed to address the economic component of SDG target 6.4 by assessing the relationship between economic growth and water use It measures the change in the ratio of gross economic value added by irrigated agriculture, industry and the services sector in US dollars to the volume of water withdrawn in cubic metres over time (Rossi et al, 2019). This SDG definition of WUE is inconsistent with the WUE definition applied by the AQUASTAT database, which is the FAO global information system on water resources and agricultural water management. It is important to be cautious in supporting abandonment of crops with a relatively low WUE (such as wheat) in favour of crops with a relatively high WUE (such as flowers)
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