Decorrelation is not dissociation: there is no rational solution to the
Brutsaert-Nieber parameter association problem
Abstract
The coefficient (k) of the Brutsaert-Niber equation (-dQ/dt = kQ^α, Q
being discharge at time t) cannot provide information on streamflow
dynamics independently because its unit depends on the exponent α. One
way to address this challenge is to compute k after fixing α at α
median, which may involve large fitting errors. A recent study has
therefore adopted a method to decorrelate k from α by resealing Q and
demonstrated that the decorrelated coefficients hold useful information
on streamflow dynamics. Here, I argue that decorrelation is not
dissociation and propose a framework to evaluate the parameter
estimation methods quantitatively. Analysis of real as well as synthetic
recession curves suggests that under no circumstance the decorrelation
method is superior to the fixed exponent method. To conclude, there
seems to be no rational solution to the Brutsaert-Niber parameter
association problem.