Evaluation of environmental impacts resulting from river regulation works: A case study from Portugal

Abstract

Modifications observed on the hydraulic regime of river systems caused by engineering works led to growing awareness of the impacts caused by these engineering constructions. The need to harmonize and integrate both the hydraulic and the ecological/environmental components has been growing, namely in Portugal. This paper presents the work of a multidisciplinary team that carried out, from 1998 to 2003, an evaluation of the ecological impacts of realignment and construction works implemented at the lower part of Mondego river, in central Portugal, in the 80’s. The hydraulic and hydrologic alterations in Mondego river, caused by regularization works, have been analyzed and quantified. The main conclusions of the study are that the changes in the Mondego river geometry induced more homogeneous physical and hydraulic conditions and reduced life diversity. However, the construction of a set of transversal groynes, and discontinuities of the bottom elevation, had an opposite effect. Similar conclusions are reported in the literature.