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San Luis Basin Sustainability Metrics Project: A Methodology for Evaluating Regional Sustainability (EPA/600/R-10/182) March 2011 | Fisher Information MATLAB Code (ZIP) (500 KB)

Sustainability relates to finding and maintaining conditions that can support social and economic development without adversely altering the environment to too great an extent. Moreover, in order to satisfy the definition of sustainability, the environmental, social, and economic characteristics of the system must effectively meet the needs of current and future generations, indefinitely. Our definition of sustainability depends on the extent to which the environment can be altered and still maintain a high quality of life for people, without jeopardizing the quality of life for future generations. Consequently, to assess sustainability, information is needed to understand the requirements for human well-being and the linkages and demands of human activity (e.g., society, economy, government, industry, etc.) on environmental systems. One way to collect needed information is through metrics that quantify the environmental, social, and economic characteristics of a system. We used a collaborative, interdisciplinary approach to investigate this complex problem. Specifically, we set out to: 1) determine the applicability of using existing datasets to estimate metrics of sustainability at a regional scale, 2) calculate the metrics through time (1980-2005), and 3) compare and contrast the results to determine if a regional system is moving toward or away from sustainability. This information can help decision makers determine if their region is on a sustainable path (i.e., moving toward sustainability).

As a starting point, we identified and tested a set of four metrics that capture some of the most basic properties of an environmental system. The metrics represent: 1) ecological impacts of human activity to produce the resources consumed and to assimilate the wastes generated using Ecological Footprint Analysis; 2) economic well-being or welfare with Green Net Regional Product; 3) flow of available energy through the system using Emergy Analysis; and 4) overall system order with Fisher information (i.e., a well-functioning system is orderly and departure from such a state can lead to decreased function). Each of these metrics is most sensitive at capturing some particular aspect of the system, although there is some overlap or redundancy (e.g., consider a physician using multiple tests to examine a patient’s health). We tested the methodology on the San Luis Basin (SLB) in south-central Colorado. The SLB is a rural, agricultural region with a limited population. This seven county region contains the Upper Rio Grande River Basin, the San Luis Valley, and the Great Sand Dunes National Park and Preserve.

Even though data for some of the variables were not available at the county level, we were able to calculate the metrics through time. From our analyses, Ecological Footprint Analysis indicated the SLB was moving away from sustainability. Green Net Regional Product appears to have an upward trend over the 26-year period providing no indication that the SLB was moving away from sustainability (this one-sided test can only tell if a system is moving away from sustainability). Due to data unavailability, a complete Emergy Analysis was estimated only for an 11-year period (1995-2005). One emergy index (fraction of renewable emergy used) that captures sustainability within the system suggested a gradual movement away from sustainability, but a second index (Emergy Sustainability Index) revealed the region improved its relationship with the larger system, (i.e., other states and US) from 2003 until the end of the period. Finally, the results of the Fisher information assessment revealed that, although the system was relatively stable during the 26 years, there was an indication of slight movement away from sustainability near the end of the study period.

We consider the entire system moving away from sustainability if any one metric reveals movement away from sustainability. Therefore, the weight of the evidence from our results indicate that the broad trend of the SLB was moving away from sustainability over the period examined. Because this was a pilot study, we offer a number of recommendations for future research based on what we learned while developing and using this approach.


Heriberto Cabeza

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