O Tejo, de selvagem a domado

Abstract

The Tagus and its Lezíria were the object of study for around 10 years, by a group of researchers from various university institutions, national and foreign. Based on bibliographical sources (geological, geomorphological, archaeological and historical), ancient cartography, and using surveys and multidisciplinary analysis of the sediments collected (texture, calibre’s, geochemical and heavy metal analysis, palynological analysis, numerous radiocarbon dates and radionuclide markers), one of the aim was to recognize the changes in the mesomorphology of the alluvial plain and the role of human action, in an extended time window (last 10,000 years), which are referred. The research and investigation conducted revealed a Lezíria crossed by multiple channels (anastomosed river), even in historical times, which changed position after major floods and caused extensive damage. Anthropogenic action, since Antiquity to present day, has focused on the attempt to tame the river, through specific works in the effort to improve the general drainage, culminating in the last century with the construction of dams aimed at control floods. Some examples are mentioned.