Numerical simulation of the water budget interval for unsteady two-dimensional confined flow

Abstract

Objective Groundwater numerical models often have uncertainties due to the complexity of the hydrogeological conditions and the economic and time constraints in collecting a sufficiently large dataset as inputs for conducting modelling exercises. In the past 50 years, stochastic methods have been one of the main methods of uncertainty analysis. The interval uncertainty is different from the stochastic uncertainty, and it considers the hydrogeological parameters as the intervals (ranges) without considering their stochastic properties. Methods From the perspective of interval uncertainty, a numerical simulation method based on first-order perturbation expansion was proposed for simulating unsteady two-dimensional confined flow with known hydrogeological parameters as intervals in this paper.The proposed method is implemented based on GFModel, a three-dimensional (3D) numerical simulation platform for groundwater flow and pollutant migration. Results The analysis shows that the relative error can be controlled within 10% when the parameter change rate is less than 0.1. The computational efficiency of the proposed method is obviously higher than that of the continuous sampling method with equal spacing. Conclusion This method allows the interval of the head or water budget to be calculated without the requirement for detailed statistical information (which is usually unavailable in advance) if the intervals of hydrogeological parameters are known.It provides a theoretical basis for decisions on the use and protection of groundwater resources.

Keywords

• groundwater numerical simulation
• water balance
• interval
• gfmodel
• uncertainty
• unsteady flow