During the operations of purging and disposal of sediments of a reservoir it is necessary to know the values of turbidity in the river downstream in natural condition,in the absence of dams or river training works.The paper shows that under these conditions the ratio of the average values of sediment discharge to the annual maximum value of water discharge is a function of the average annual turbidity.Turbidity can be considered as representative synthetic index of the climatic conditions,the lithological features and the land cover of the basin,and the geometric characteristics of the river network.The proposed relationship of sediment discharge as a function of water discharge were validated on the basis of data collected from different Italian regions that have very different morphological,geo-lithological and rainfall features and that are characterised by a basin area changing between a few dozen and thousands of square kilometres.The results can be considered satisfying. During the operations of purging and disposal of sediments of a reservoir it is necessary to know the values ​​of turbidity in the river downstream in natural conditions, in the absence of dams or river training works. The paper shows that under these conditions the ratio of the average values ​​of sediment discharge to the annual maximum value of water discharge is a function of the average annual turbidity.Turbidity can be considered as representative synthetic index of the climatic conditions, the lithological features and the land cover of the basin, and the geometric characteristics of the river network. the proposed relationship of sediment discharge as a function of water discharge were validated on the basis of data collected from different Italian regions that have very different morphological, geo-lithological and rainfall features and that are characterised by a basin area changing between a few dozen and thousands of square kilometres. The results can be considered satisfying.