Significance evaluation of factors controlling river water composition

In the present paper the factors controlling river water chemistry are described and their significance is evaluated, including: climate, petrography, soils/sediments, geomorphology of the catchment area, hydrography, pollution, biological activity of rivers, and rainwater composition. The results of this study indicate that the dominant factors influencing riverwater chemistry are the climate and the petrography of the catchment area. In the case of heavily polluted rivers, pollution appears to be the dominant factor.The approach followed is based on the watershed information, e.g., climatic, geomorphological, petrographical (percentage distribution of geochemical important petrographic units), soil/sediment composition, rainwater composition, as well as the hydrographic and the hydrochemical data of the rivers.In order to achieve a better understanding of the nature of the factors influencing river water composition as well as to specify them quantitatively, multivariate statistical analyses (factor and cluster analyses) were performed on the rain-corrected hydrochemical and petrographic information of the watersheds.