A spatial analysis of emergy of an internationally shared drainage basin and the implications for policy decisions

In order to make policy decisions for an internationally shared basin, there needs to be an understanding of the larger systems that may influence the basin and the spatial relationship between resources and development. Ecological and economic components of a basin can be compared using emergy, which sums on the same basis all the energy inputs required. An emergy evaluation and spatial analysis of the Catatumbo River drainage basin, located between Colombia and Venezuela, were conducted to consider alternate management policies.; The Catatumbo, basin was divided into watersheds using GIS (geographic information system). The watersheds more categorized by the order of their main stream. The basin had a maximum stream-order of five. Empower density (sej/m2/yr) was used to evaluate renewable resources and development. Storages were evaluated using emergy density (sej/m2). Emergy per volume of river water (sej/m3) was analyzed to address water-quality problems.; The Colombian emdollar (8E12 sej/{dollar}) is higher than that for Venezuela (6E12 sej/{dollar}). Colombia loses emergy when exchanging goods and services with Venezuela or other countries with a lower ratio. The states containing the basin also have a trade deficit. This practice reduces environmental resources of each system and could affect those of the Catatumbo basin.; Total renewable empower density increases with stream-order watershed (1E12--9E13 sej/m2/yr). Development increases upstream (1E12--1E16 sej/m2/yr), but is at a maximum in second-order watersheds (5E17 sej/m2/yr).; Storages of emergy increase inversely to stream-order watershed (1E12--2E14 sej/m2). This pattern is due to potential mining materials. Biomass and soils increase downstream.; Emergy per volume of river water increases with stream-order watershed (7E11--6E15 sej/m3). River sediments influence this pattern. Total nitrogen and phosphorus are within a narrow range (1E9--5E9 sej/m 3). Oil spills in the third and fourth-order watersheds elevate the total emergy in those areas. Unique biogeophysical characteristics influence the differences in emergy in the Catatumbo basin. Development should be restrained in the Venezuelan watersheds as the renewable energies and large storage of wetlands help buffer pollutants. Growth in Colombia should be guided so fewer raw materials are traded and better agricultural practices enforced to improve water quality.