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Water Insights Seminar Series 2020: The Multi-layer Network Structure of Virtual Water Flows in the United States

Date/Time: 
Tuesday, January 21, 2020 - 12:00pm
Venue: 
312 Ag. Engineering building

 Alfonso Mejia, Associate Professor Civil and Environmental Engineering Penn State University will be presenting on: The Multi-layer Network Structure of Virtual Water Flows in the United States

ZOOM Link: https://psu.zoom.us/j/904363125 Or by phone only: +1 646 876 9923 (US Toll) Meeting ID: 904 363 125

Abstract: Engineered water-related networks (e.g., potable water distribution and wastewater collection systems) involve real or physical transfers of water and, therefore, tend to cover local to regional spatial scales. However, through virtual or embodied water transfers, human-water interactions span beyond local and regional spatial scales. Virtual water is the water required for the production of a product or service along its supply chain. To understand human-water interactions over broad spatial scales, virtual water flows have been analyzed using network science approaches. These approaches have relied on single-layer (monolayer) network representations. Such monolayer networks are built by aggregating the virtual water flows associated with different traded products (e.g., cereal grains, milled grains, meat, etc.). The structure of virtual water flows, however, is more complex than that because of sectoral interdependencies. Ignoring these interdependencies results in substantial loss of information. Here, using an environmental multiregional input-output model, I build and analyze for the first time the multilayer network structure of virtual water flows in the United States. Using this new multilayer network, I will show that 1) ignoring sectoral interdependencies can result in large truncation errors, particularly for network nodes representing cities, and 2) that modeling virtual water flows as a multilayer network is an effective approach to avoid such truncation errors. In addition, I will highlight other advantages from using a multilayer network to study environmental and economic flows.

Hosted by: Environment and Natural Resources Institute College of Agricultural Sciences