where c and d are recession constants depending on the catchment physical characteristics. In the storage-discharge relationship, d = 1 indicates a linear reservoir; otherwise, the reservoir is nonlinear when d ≠1. They can also be expressed in the form of the baseflow coefficients ae andbe (c = 1/[ae (2-be )], d= 2-be ).
Combining equations (2) and (3), the relationship between the streamflow and flow variation affected by environmental changes can be derived as follows: