Baseflow separation based on analytical solutions of the Boussinesq equation

A technique for baseflow separation is presented based on similarity solutions of the Boussinesq equation. The method makes use of the simplifying assumptions that a horizontal impermeable layer underlies a Dupuit aquifer which is drained by a fully penetrating stream. The value of the baseflow maximum as well as the baseflow recession hydrograph can be estimated by fitting the analytical solutions of the Boussinesq equation to the observed discharge values for individual flood events. For the rising limb of the baseflow hydrograph a linear function is assumed for simplicity. The method is first demonstrated on three watersheds for a total of five flood events and extensively applied over a three year period for the Mahantango Creek, Pennsylvania watershed. The proposed method reduces some of the subjective aspects long associated with baseflow separation techniques.