The basic equations used in flood routing are developed from the law of continuity. In each method the assumptions are discussed to enable the user to select an appropriate technique.
In the stage-storage method the storage is related to the mean gage height in the reach under consideration. In the discharge-storage method the storage is determined, from weighted values of inflow and outflow discharge. In the reservoir-storage method the storage is considered as a function of outflow discharge alone.
A detailed example is given for each method to illustrate that particular technique.