Aquifer heterogeneity is a research area that focuses on the variability of physical and chemical properties within groundwater reservoirs, known as aquifers. This variability can affect the movement and distribution of groundwater, as well as the behavior of contaminants within the aquifer. Researchers study factors such as grain size distribution, porosity, permeability, and connectivity of aquifer materials to understand how heterogeneity influences groundwater flow and quality. By characterizing and modeling aquifer heterogeneity, scientists can improve the accuracy of groundwater flow models and better predict the transport of contaminants in groundwater systems.