Heuristic Continuous Base Flow Separation

Abstract

A digital filtering algorithm for continuous base flow separation is compared to physically based simulations of base flow. It is shown that the digital filter gives comparable results to model simulations in terms of the multiyear base flow index when a filter coefficient is used that replicates the watershed-specific time delay of model simulations. This way, the application of the heuristic digital filter for practical continuous base flow separation can be justified when auxiliary hydrometeorological data (such as precipitation and air temperature) typically required for physically based base flow separation techniques are not available or not representative of the watershed. The filter coefficient can then be optimized upon an empirical estimate of the watershed-specific time delay, requiring only the drainage area of the watershed.