ABSTRACT
Hydraulic engineering projects are capable of changing the hydrological and sediment regimes of a river system by creating artificial storages, by diverting flows from one basin to another, by changing the sediment input into a river, etc. Because many of the responses of a river system to these changes cannot be predicted from theory alone, it is important to document case histories which will aid in the solution of problems as they arise in the future.
This paper documents a few Canadian cases of known changes in fluvial systems which can be attributed to the works of man. These cases include: the downstream effects of a large storage reservoir on a major river; the effects of major interbasin diversions along the diversion routes; the effects of channel straightening; the effects of the closure of a tidal estuary; and the effects of road construction along a northern river in permafrost.
The documentation of changes in natural rivers due to human interference often points to the difficulty of directly transferring the results from analytical or laboratory studies to the field case. The writers believe that the best estimates of the change of a fluvial system due to the works of man must be made by a combination of the qualitative geomorphological approach with the more quantitative approach which is generally established from two dimensional steady uniform flow concepts.
