Flood Routing

A method used for routing floods through the Tennessee River is described in this paper. First, a method for routing floods in the natural condition from Knoxville, Tenn., to the mouth of the Tennessee River was developed, and then the procedure was adapted to routing through the reservoirs of authorized and proposed projects. To analyze flood reduction, the complet e river system was considered as a unit for various floods.

Routing was accomplished by dividing the river length into seven reaches and applying the storage equation to each reach. Total inflow into each reach was determined day by day from the routed outflow of the adjacent up-streamr each, published discharges of metered streams flowing into the reach, and an inflow estimated from rainfall on the unmeasured areas draining into the reach. Total flood volume at each dam site was assumed to be known. The storage in the reach for various flows was determined from topographic maps a nd crosssections of the river valley in conjunction with flow profiles determined from back-water curves. The outflow was then derived from the relation of storage and discharge for the reach.

The general procedure for all reaches is described, and a detailed example for the Watts Bar-Chickamauga Reach is included. Finally, results are given for the effect of the proposed system of dams on the 1926-1927 flood and on a flood 50 larger.