Numerical Study on Temporal Domain Discretizing for Hydrogeological Modeling Practices

One of the key operations in the construction of hydrogeological models is the transformation of continuous physical systems into discrete models while conserving the aimed model performance level and optimizing the available resources. Such operation is called discretization, and it has to be applied to both spatial and temporal domains in hydrogeology. The present paper deals with the temporal domain discretization. A literature review is given first, and then a parametric study (using 1D flow modeling) is conducted to assess the effects induced by boundary conditions (specified head or specified recharge rate), data temporal resolution and model simulation time step on hydrogeological flow model performances. It was found that the effect induced by the dynamic comportment of a recharge rate boundary condition type is more important than that due to a specified head. For the recharge rate, the time step must be smaller or equal to the data resolution when using Modflow. As for a specified head boundary condition type, it was recommended to take a time step satisfying Δt∞1/(K × Δh).