Streamflow recession in basins with multiple water storages

Abstract

A streamflow recession formula for natural basins is derived by linear hydrologic routing of the sum of inflows from discrete, independent water storages through a channel storage. Water storages include depression, detention, snow and ice, channel bank, aquifer and cavern. Evapotranspiration is incorporated in the recession formula, but seasonal effects and basin wetness and storage conditions before storms are not considered. Data from seven basins involving 156 precipitation-free recessions are used to test the performance of two- and three-parameter approximations to the theoretical recession formula. Recessions are defined to last at least 2 weeks and to begin 2 days after the peak of a basin outflow hydrograph, or at a point on the falling limb 2 days after any precipitation occurs. Recessions end when precipitation recommences, or when daily flow data stop decreasing. An inverse square formula explains most variance in the two-parameter case, in contrast to the simple exponential formula usually recommended for recession modelling. With three parameters, equally good performance is shown by formulae involving a constant plus an inverse square, or inverse cubic, or simple exponential term. These theoretically based formulae should be useful at basin scale for interpolating or extrapolating recession data, particularly in basins where little is known about water storage behaviour.