An ecological approach for estimating turbidity in a river

In purging and disposal of sediments operations of a reservoir it is necessary to know the values of turbidity in the river downstream in natural conditions. The paper shows that under these conditions, in the absence of dams or river training works, 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 regarded 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 from in different regions of Italy, with very different morphological, geo-lithological and rainfall characteristics, and with basin area changing between a few dozen and thousands of square kilometres. The results can be considered satisfying.