particular case and how disparate knowledge systems can be brought to bear on a complex
THE ANATOMY OF A MODEL
The IDAM is based on the work of the World Commission on Environment and Devel-
opment, which recommended that sustainable-development projects balance the needs of
biophysical, socioeconomic, and geopolitical systems. Using this idea as a foundation, our
research team designed the IDAM to evaluate the outcomes of dam construction on three
• Biophysical Impacts : How does a given dam project affect the environmental aspects of a river ecosystem?
• Socioeconomic Impacts : How does a given dam project affect human communities, economies, and cultures?
• Geopolitical Impacts : How does a given dam project affect natural-resource decision making, governance, and in-
The model works by analyzing twenty-one different impacts, seven from each of the
mensions: magnitude , which is the objective measure of the severity of that impact on a
0-3 scale; and salience , which is the subjective importance or significance assigned to the
impact, also on a 0-3 scale, by whatever group of stakeholders is using the model. Com-
puter scientists on the team constructed a graphical user interface that allows users to input
data for a given scenario and to compare different projects based on size, location, or other
Reservoir may change cycling of nutrients and carbon, decrease turbidity and dissolved oxy-
gen, or change temperature.
BP1: Water Quality
Habitat classification of affected areas, species occurrence, changes to hydraulic habitat.
BP3: Impact Area
Measurement of surface area of the reservoir and length of river impounded.
Reservoir may disrupt natural-sediment movement; downstream channel may degrade; depos-
itional features and channel morphology may change.