Calculating and Communicating Solute Mass Flux Distribution Using GIS

Mass flux is defined as the rate at which mass moves through a cross-sectional area perpendicular to the direction of groundwater flow. It is a commonly used metric in hydrogeology, specifically in the design and monitoring of groundwater remediation systems. While mass flux is generally calculated as a point measurement through a defined cross-section, the mass flux in a given area can also be mapped across an entire flow field.

 Calculating mass flux requires synthesizing information from multiple sources, including: groundwater potentiometric surface elevations; top and bottom elevations of aquifer; the hydraulic conductivities of the aquifer(s); and solute concentrations in groundwater.

 Communicating the resulting calculated mass flux requires presentation of parameters in multiple dimensions (mass flux is calculated through a two-dimensional cross-sectional plane and varies over a two-dimensional plan-view region).

 This paper describes how Geographical Information Systems (GIS) is used as a tool to assist in both the calculation and communication of solute mass flux. In this method, input parameters are interpolated or mapped to a consistent grid and the grids are combined in sequence to arrive at a grid in which a value for mass flux is calculated at every node. This mass flux grid is then color-coded by value to create a mass flux map that can be used to communicate the mass flux, or changes in mass flux, at a given site.