Scaling Analysis of Energy in Great Lakes Water Supplies.

Resource-scale quantification of energy in water supplies is important for local-scale sustainability and for regional-, national-, and global-scale assessments of the water-energy nexus. Water supply systems within a resource region are characterized by a homogeneity in system type but a heterogeneity in system size. Size heterogeneity has traditionally imposed large challenges to energy quantification because of nonlinearities. Recently, an analytical approach for quantifying nonlinear size effects in water supplies was developed based on the complex system phenomena of skewed size abundance (decreasing abundance with increasing size in a population of systems) and allometric energy scaling (decreasing energy intensity with increasing size in an individual system). Here, building on this advance and using new, resource-scope data on Great Lakes water supplies, we explore the interaction between energy allometry and size abundance and demonstrate the application of scaling for making energy predictions in water supplies. We show that communities are driven by the allometric effect to form "large get larger" supply systems, but ultimately spatial distances impose limits on the effect, resulting in delegation of tasks to local systems to preserve energy optimality. This cross-scale, interaction perspective of scaling and the application of scaling for energy prediction together may lead to a more functional understanding of supply size abundance and more integrative quantification of supply energy and environmental impacts at the water resource scale.