Downstream ecological effects of dams: a geomorphic perspective

Vol. 45(3) 183-192

The goal of this article is to illustrate a geomorphically based approach to understanding and reducing some of the cataclysmic effects of dams on downstream riverine ecosystems. Additionally, we hope to provoke debate on the merits of different approaches to river conservation. We suggest that geomorphic studies directed at ecologically significant features of river morphology and hydraulics may sometimes be more valuable in short-term evaluations associated with the environmental assessment of new dams or the relicensing of existing dams. We believe that more often than has been realized, geomorphological changes are the key to understanding the long-term ecological consequences of dams and other stream disturbances. We also have some reservations about the efficacyof biological research in short-term studies to lead to successful management plans. The biological research necessary to develop a management plans is substantial--often a multiyear undertaking--and may not lead to a clear understanding of improtant features affecting the ecosystem.


Ligon , F.K. , Dietrich , W.E., Trush , W.J.