Hydrochemical and Ecological Quality Assessment of a Mediterranean River System

In order to explore the complex interrelations among the factors and processes that determine a rivers’
hydrochemical and biological quality, statistical techniques were applied to a variety of hydrochemical,
petrologic, biological, habitat, hydrological and morphologic data from 16 sites of the upper-part of the
Aliakmon river. Catchment morphology and geology control both, aquatic and biological quality, the latter
is mainly governed by substrate composition. The principal processes that control aquatic quality are:
a) baseflow contribution in river flow b) in-stream biological activity and pollution c) weathering of mafic
silicates. Using a Nutrient Pollution Metric (which has been developed), a hydrochemical quality classification
has been performed. Furthermore, a methodology, based on benthic macroinvertebrates and
aquatic quality, for the assessment of the ecological quality of running waters is presented.