technical note: reducing the spin-up time of integrated surface water–groundwater models
;H. Ajami;J. P. Evans;M. F. McCabe;S. Stisen
materials research bulletin2014Vol. 18pp. 5169-5179
59
ajami2014hydrologytechnical
Abstract
One of the main challenges in the application of coupled or integrated
hydrologic models is specifying a catchment's initial conditions in terms of
soil moisture and depth-to-water table (DTWT) distributions. One approach to
reducing uncertainty in model initialization is to run the model recursively
using either a single year or multiple years of forcing data until the system
equilibrates with respect to state and diagnostic variables. However, such
"spin-up" approaches often require many years of simulations, making them
computationally intensive. In this study, a new hybrid approach was developed
to reduce the computational burden of the spin-up procedure by using a
combination of model simulations and an empirical DTWT function. The
methodology is examined across two distinct catchments located in a temperate
region of Denmark and a semi-arid region of Australia. Our results illustrate
that the hybrid approach reduced the spin-up period required for an
integrated groundwater–surface water–land surface model (ParFlow.CLM) by up
to 50%. To generalize results to different climate and catchment
conditions, we outline a methodology that is applicable to other coupled or
integrated modeling frameworks when initialization from an equilibrium state
is required.