An order of magnitude: How a detailed, real-data-based return flow analysis identified large discrepancies in modeled water consumption volumes for Finland. (March 2020) - Weckström, Markus M.
Graphical abstract: Highlights: Specific waste water volumes and water consumption rates provided for 195 industries. Differences up to an order of magnitude revealed in figures produced by global models. 'Water use' suggested to be preferred to 'water consumption' as a general indicator. Novel contributions to transparency and data quality assessment of water accounts. Abstract: Sustainable exploitation of water resources is an essential global challenge and several approaches have been applied for studying water flows through economies. However, the applicability, accuracy, and reliability of all approaches is generally constrained by the lack of real data, especially when analyzing the return water flows from the economy back into the environment and when estimating the volume of consumptive water use. Sector-specific water consumption volumes reported in the literature are mainly based on modeled figures of unknown uncertainty. In this paper we demonstrate how a reliable and disaggregated national return water flow accountancy, including industry-specific consumption rates, can be compiled, and how the quality of the produced data can be assessed and documented. The introduced protocol for data quality assessment in return flow analysis is a transparent system that classifies industry-specific data representativeness into quality categories and hence allows the estimation of data reliability and the identification of important development areas. Furthermore, we compare the results of the real-data-based accountancy to modeled figures in the existing literature and widely applied modeling tools, and show that the differences are extremely large. We also analyze the potential reasons behind these differences. This study clearly illustrates the need for real data in water accountings and in various water footprint studies. We propose that water use rates based on real data should be used as an indicator of pressures exerted on water resources by national economies. We furthermore suggest that water consumption rates could be considered as an additional indicator in small-scale regional studies, where case-specific, reliable data on return flows and water resources are available.