Chapter 20 



SEDIMENTATION IN RESERVOIRS 



Albert S. Fry 



Chief, Hydraulic Data Branch 

 Tennessee Valley Authority 



This chapter outlines generally the problems of reservoir sedimenta- 

 tion and their significance and considers remedial measures in a broad 

 manner. Covered in some detail are the methods used in measuring 

 sediment deposition in reservoirs. The extent to which the discussion 

 is unbalanced with regard to the various phases of the subject that 

 might be discussed is due to the treatment elsewhere in this symposium 

 of material applicable to reservoir sedimentation, duplication of which 

 is undesirable. 



THE PROBLEM AND ITS IMPORTANCE 



Sedimentation in reservoirs has become increasingly important be- 

 cause of the ever-increasing number of dams and reservoirs built 

 and continuing to be built during the era beginning in the early 1930's. 

 Particularly is this true for large reservoirs, many of which are for 

 multiple purposes. Such reservoirs may be so affected by sedimenta- 

 tion that one or more of their major purposes, such as flood control, 

 navigation, irrigation, water supply, hydroelectric-power production, 

 may be seriously curtailed or even cancelled. Minor uses such as 

 recreation are also affected by reservoir sedimentation. Sedimentation 

 in the many relatively small reservoirs scattered throughout the 

 country which furnish water supply for cities and towns may seriously 

 affect the available carry-over water supply and necessitate abandon- 

 ment and new construction at considerable cost. 



For reservoirs proposed for future construction, sedimentation is 

 particularly important in those areas where streams carry heavy sedi- 

 ment loads. In such areas, rates of reservoir sedimentation must be 

 estimated accurately in order that the useful reservoir life may be de- 



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