Dr. Onishi was born in Osaka, Japan. He obtained BS and MS in mechanical engineering at University of Osaka Prefecture. He obtained his Ph.D. in hydraulics at University of Iowa in the United States.

He is one of U.S. pioneers to conduct environmental and risk assessment, and works extensively on American, Japanese, the Western European, former Soviet Union’s, and international environmental issues.

He is an independent consultant and adjunct full professor of Washington State University (WSU). He has worked as a Chief Scientist at the U.S. Department of Energy (DOE)’s 3,500-staff, Pacific Northwest National Laboratory (PNNL) operated by Battelle Memorial Institute through 2005. Prior to working at PNNL, he was a Research Engineer at the renowned Iowa Institute of Hydraulic Research, University of Iowa. He teaches WSU environmental engineering graduate classes. Dr. Onishi has served as an advisor and thesis examiner of two dozen WSU and University of Minnesota graduate students.

His principal discipline is hydraulics, chemically-active fluid dynamics, and environmental exposure and risk assessment. His work on sediment-contaminant transport modeling is internationally recognized. He was a committee chairman of the American Society of Civil Engineers. He is listed in the “Who’s Who in America”.

Dr. Onishi was a member of the U.S. National Academy of Sciences’ committee, and is an adjunct member of the U.S. National Council of Radiation Protection and Measurements. He was the U.S. Government Coordinator of Chernobyl nuclear accident’s aquatic environmental program of “U.S./U.S.S.R. Joint Coordinating Committee on Civilian Nuclear Reactor Safety”. Recently, he conceptually designed and evaluated benefits of the “New Safe Confinement” being constructed over the Chernobyl sarcophagus. He has been an environmental advisor to the International Atomic Energy Agency (IAEA) of the United Nations (U.N.), and helped the Philippine Government to develop a marine radiological assessment capability, as requested by IAEA. He was the Chief Scientist of a $200-million, radioactive waste retrieval operation at DOE’s Hanford Site. He was a member of an international “Slurry Transfer Expert Panel” for DOE.

As a PNNL manager, he developed and supervised dozens of Japanese environmental studies, including those on the low level radioactive waste disposal at Rokkasho Mura, Japan from disposal system conceptual development to successfully obtaining its site operational license, and on the high level radioactive waste disposal.

His several sediment-contaminant transport models have been the world most advanced contaminant (radionuclide and toxic chemical) transport codes for rivers, estuaries, coastal waters, and lakes for over two decades. His modeling approach has been adapted by researchers in many countries. His pioneering, toxic chemical transport/risk assessment methodology opened a stochastic risk assessment modeling approach to hazardous materials, pesticides, and heavy metals in U.S. His simple but robust models are official IAEA surface water radiological assessment models. Dr. Onishi also developed the most advanced computer code to simulate interacting flows and chemical reactions. Dr. Onishi assessed removal, liquidation, and deep ocean disposal of CO2 gas generated by a power plant for possible mitigation of global climate change.

Dr. Onishi has published over 200 papers and reports, and co-authored 16 books, e.g., a 2007 Chernobyl book as a senior editor. He gave a workshop at a 2007 U.N. conference on climate change impacts. Dr. Onishi was featured in the U.S. high school textbook, Earth Science. He and his work were also featured in the popular scientific TV program, “NOVA” of the U.S. Public Broadcasting Service.