The aim of this paper is to analyze archaeological sites occurring in alluvial plains so as to define morphoecological units contemporaneous with human settlement (active channels, bars, levees, temporary arms, dead arms, marshes, flood plain). In geomorphology and sedimentology an extension of CM method (of R. Passega) is used; the observation of sedimentary structures and the use of granulometric curves allow a precise analysis of the competency of streams and the modalities of load transport, thereby enabling deductions about the relations between primary geomorphic units and running or standing waters. In zoology and ecology the analysis deals with Cladoceran remains (high density microcrustaceans in quiet or standing freshwater) preserved in unreworked fine sediments. The comparison of faunal spectra, contemporaneous with dated human settlements, with the spectra of present environments, the functioning and ecology of which are known, allows a precise reconstitution of the aquatic and marshy archaeoenvironments. The two components of this method are applied jointly or separately on sites from different times in the Rhône-Alpes region (Lyon, Vienne, St. Romain-en-Gal, and archaeological salvages of the Upper-Rhône valley). -- AATA