An important aspect of the statistical assessment of the correlation between precipitations – water and sediments is the way these parameters are assessed by means of statistical correlations of the type Q=f(Pp), R=f(Q) or R=f(Pp). Following the analysis of the three types of correlations the conclusion that water and sediment flows depend much on the quantity of water that falls may be reached. The accumulations however introduce some modifications of the water run-offs depending on the intended use. In order to carry out detailed analyses of some processes related to the evolution of channel bed or reservoirs silting, the equations may be extrapolated to the entire river basin.