cumulative impacts

Development of small versus large hydropower in Norway comparison of environmental impacts

Science Direct

This study has compared the accumulated environmental impacts from 27 small-scale hydropower plants with 3 large hydropower projects. The results show a slight tendency that large hydropower has a lower degree of impacts than many small-scale projects, but lack of precision in the data and weak methodological foundation introduces uncertainty in the results. Taking into account other benefits such as the provision of regulated power, it is reasonable to assume that a few large hydropower projects will produce electricity to a lower environmental cost compared to many small projects, which should be considered when realizing renewable energy policy objectives.



 Tor Haakon Bakken, Håkon Sundt, Audun Ruud & Atle Harby

Panel Recommends Studying Downstream Impacts in Merced River Relicensing

A panel formed to investigate the study related disputes in the relicensing of Merced River projects has found that FERC erred in limiting the geographic area which needed to be studied for impacts from the project.

The three-person panel was formed after the US Fish and Wildlife Service (FWS), National Marine Fisheries Service (NMFS) and the California State Water Resources Control Board did not agree with FERC’s previous determination and asked for a formal dispute resolution.


Impact interaction potential: a basin-wide algorithm for assessing cumulative impacts from hydropower projects

Vol. 23( ) 341-360

The US Federal Energy Regulatory Commission (FERC) has proposed a "Cluster Impact Assessment Procedure" (CIAP) for analyzing cumulative impacts from hydropower projects on the resources of a river basin. While the CIAP is based on analyses of perceived magnitudes of impacts, it avoids any interpretation of the potential for basin-wide interaction among the projects leading to an accumulation of their effects in the resources. A measure of an "impact interaction potential" (IIP) is suggested here to describe the functional side of cumulative impacts. This tendency of a project cluster to cause cumulative impacts, or its "cumulativity", is examined through subbasin disaggregations of projects and resources. A dispersion of the project's impacts across subbasins I evaluated using linear algebra and principles of information theory. The formalized algorithm is programmed in BASIC and proposed as an IIP Assessment Loop in the CIAP. The IIP loop attaches to the Multiple Projects Assessment Phase as a causal interpretation of cumulative impacts, complementary to the effects analyzed via the CIAP's use of weighted summations. Use of the algorithm is demonstrated with a hypothetical project cluster in the Salmon River Basin (Idaho).


Emery, R.M.