Identification of groundwater flow patterns and barriers in aquifers

Abstract

The use of inverse methods has been increasing in hydrology. Numerical methods can help identify groundwater barriers and flow patterns in an aquifer, which can reduce errors when comparing the exact and estimated solutions. This thesis uses the method of characteristics (MOC) to identify transmissivity T in an area of abnormal region. From Darcy’s law for steady-state groundwater flow, we start with a one-dimensional case, which helps us consider what may and may not be in the two-dimensional case. Then we use the 2D case to calculate the stream function and find that the gradient of the stream function is orthogonal to the gradient of the head, and we use this when calculating the stream function everywhere. We use MODFLOW to generate head data for the known distribution T and to estimate T under different inflow examples. MOC gives a stable solution and can help identify the area of low T without requiring smoothness of the T distribution.