Prof. Craig performs research into numerical and analytical methods for modeling groundwater flow, subsurface contaminant transport, surface water, and the surface water / groundwater interface. He has dabbled in parameter estimation, uncertainty analysis, and the integration of GIS and environmental models.

Current research addresses fundamental and computational improvements to series solution methods and the analytic element method (AEM), novel applications of analytical solution approaches to complex local and regional problems in unsaturated and saturated flow systems, and the development and assessment of robust numerical surface and subsurface simulation software.