A quantitative approach to spring hydrograph decomposition

A combined analytical–numerical study for the characterization of spring hydrographs is presented. Two-dimensional analytical solutions for diffusive flux from rectangular blocks of arbitrary shape facilitate a quantitative characterization of exponential hydrograph components. Together with analytical solutions for block discharge, a systematic analysis of numerically simulated spring hydrographs of synthetic karst systems provides an insight into karst hydrodynamics. Different hydrograph components do not represent different classes of rock permeability. Hydrographs of individual homogeneous blocks can be decomposed into several exponential components. Discharge hydrographs of symmetric rectangular blocks can be reconstructed by the sum of only three exponential components. Increasing block asymmetry results in an increasing number of exponential components contributing significantly to total discharge. Spring hydrographs represent a sum of individual block discharges originating from diffuse infiltration and conduit discharge originating from concentrated recharge. Beyond the inflection of the recession limb, a spring hydrograph can be decomposed in a similar manner to that of individual homogeneous blocks. The presented hydrograph analytical method facilitates the estimation of hydraulic and geometric parameters of karst hydrogeological systems.