Articles | Volume 20, issue 12
Hydrol. Earth Syst. Sci., 20, 4963–4981, 2016
Hydrol. Earth Syst. Sci., 20, 4963–4981, 2016

Research article 16 Dec 2016

Research article | 16 Dec 2016

Estimating catchment-scale groundwater dynamics from recession analysis – enhanced constraining of hydrological models

Thomas Skaugen and Zelalem Mengistu Thomas Skaugen and Zelalem Mengistu
  • Dept. of Hydrology, Norwegian Water Resources and Energy Directorate, Oslo, Norway

Abstract. In this study, we propose a new formulation of subsurface water storage dynamics for use in rainfall–runoff models. Under the assumption of a strong relationship between storage and runoff, the temporal distribution of catchment-scale storage is considered to have the same shape as the distribution of observed recessions (measured as the difference between the log of runoff values). The mean subsurface storage is estimated as the storage at steady state, where moisture input equals the mean annual runoff. An important contribution of the new formulation is that its parameters are derived directly from observed recession data and the mean annual runoff. The parameters are hence estimated prior to model calibration against runoff. The new storage routine is implemented in the parameter parsimonious distance distribution dynamics (DDD) model and has been tested for 73 catchments in Norway of varying size, mean elevation and landscape type. Runoff simulations for the 73 catchments from two model structures (DDD with calibrated subsurface storage and DDD with the new estimated subsurface storage) were compared. Little loss in precision of runoff simulations was found using the new estimated storage routine. For the 73 catchments, an average of the Nash–Sutcliffe efficiency criterion of 0.73 was obtained using the new estimated storage routine compared with 0.75 using calibrated storage routine. The average Kling–Gupta efficiency criterion was 0.80 and 0.81 for the new and old storage routine, respectively. Runoff recessions are more realistically modelled using the new approach since the root mean square error between the mean of observed and simulated recession characteristics was reduced by almost 50 % using the new storage routine. The parameters of the proposed storage routine are found to be significantly correlated to catchment characteristics, which is potentially useful for predictions in ungauged basins.

Short summary
This paper introduces a new formulation of hydrological subsurface dynamics for hydrological models. The frequency distribution of the fluctuations of the catchment-scale subsurface storage is estimated from observed recessions and the mean annual runoff. The new formulation of the subsurface has been tested for 73 Norwegian catchments and is found to perform as well as the previous calibrated subsurface formulation. Recessions are better simulated using the new formulation.