1998-present: AMAX Distinguished Chair of Environmental Sciences and Engineering; Director, Center for Experimental Study of Subsurface Environmental Processes (CESEP).
2007-2008: Program Director, Hydrological Sciences, National Science Foundation, Washington DC
1990-1998: Professor, Department of Civil Environmental and Architectural Engineering, University of Colorado, Boulder.
1986-1989: Associate Professor, Department of Civil Environmental and Architectural Engineering, University of Colorado, Boulder.
1983-1986: Assistant Professor - Department of Civil Engineering, Louisiana State University.
1978-1983: Research Assistant Professor- Civil Engineering Department, Colorado State University.
1974: Research Associate, Division of Water Resources Engineering, Asian Institute of Technology, Bangkok, Thailand.
1972-1974: Assistant Lecturer on leave, Faculty of Engineering, University of Ceylon, Peradeniya, Sri Lanka
1971-1972: Instructor in Civil Engineering, Faculty of Engineering, University of Ceylon, Peradeniya, Sri Lanka.
I have taught graduate and undergraduate courses in fluid mechanics, hydraulics, surface hydrology, groundwater hydrology, physical hydrology, groundwater modeling, numerical modeling, hydrologic and hydraulic modeling, porous media flow and transport and operations research. I have supervised 45 MS thesis, 36 PhD students and 17 post-doctoral research associates. These students are employed in academia, federal agencies, national laboratories and industry in the US and abroad.
Groundwater hydrology, conjunctive use, integrated modeling; arid and semi-arid zone hydrology; Mathematical modeling, computational methods and numerical analysis; finite elements, finite difference; Applied mathematics, systems analysis, mathematical optimization, operations research; Environmental fluid mechanics; contaminant transport and hazardous waste management; multiphase flow, aquifer remediation, pesticides, radioactive waste; Non Aqueous Phase Liquids (NAPLs)- refinery waste products (LANPLs) & solvents (DNAPLs); Experimental investigation of surface-subsurface flow processes and multiphase flow and transport; Dam safety analyses; flow in cracks and rock joints; centrifuge modeling of flow and transport in porous and fractured media; Global hydrology; Ice wastage and water flow in snow, arctic hydrology; Western Water Rights; Wireless Sensor Networking for Environmental Applications; Natural disasters and tsunamis/ contamination of coastal aquifers; Energy extraction from coal and oil shale; Nano technologies for subsurface contaminant treatment; Remote detection of land mines and buried objects; Carbon sequestration and leakage
I have international research collaborations in England, Denmark, Germany, Egypt, Korea, Japan, Sweden, Czech Republic and Spain. Students and faculty from foreign institutions in these countries have visited Colorado to work in my laboratory to conduct collaborative research.