Table 2.

Flow model outputs generated by the SPAN algorithm.

flow model outputs	definition	estimation methods
theoretical source, sink, use maps	in situ provision, depletion, or use of a service	values calculated without the SPAN model, not considering service flows
possible source, use, flow maps	service dynamics when accounting for flows but not sinks	values calculated by the SPAN model considering flows but not sinks
actual source, sink, use, flow maps	service dynamics when accounting for sinks and flows	values calculated by the SPAN model considering sinks and flows
inaccessible source, sink, use maps	service flows not delivered due to a lack of flow connections	calculated by subtracting actual from theoretical values
blocked source, use, flow maps	service flows blocked by sinks	calculated by subtracting actual from possible values