Don was born in 1929 and raised in the small town of Princeton in the Okanagan Valley of British Columbia, at that time recognised for mining, logging, farming, brewing and skiing. What information is available from his youth anticipates an interest, perhaps not entirely academic, in water and snow, through trout fishing, hunting and starring in an early British Columbia downhill ski team for which he won the western junior championship in downhill and slalom. His skill in applied aerodynamics gained him the offer of a lucrative baseball career via the Yankee’s farm team, which he turned down for the more intellectual pursuit of engineering. This interest in athletics and the outdoors, most notoriously a very competitive style of handball and more lately swimming, has been a feature since that time, however. He first went to the west coast to study engineering and found a way to combine that with his interest in agriculture, graduating from the UBC College of Agriculture with a BSA in Agricultural Mechanics in 1952. His interests migrated east with a MSA in Agricultural Engineering from the University of Toronto, Ontario Agricultural College, Guelph (now University of Guelph) in 1955 where he specialised in agricultural mechanics and soil physics under the supervision of Hugh Ayers. At this time he also worked as a research assistant in soil science. As upper-level graduate training in hydrology was non-existent in Canada at the time, Don went to Iowa State University for training in soil physics under Howard Johnson and received a Ph.D. in Agricultural Engineering in 1960 for the thesis “Derivation of hydrographs for small watersheds from measurable physical characteristics”.   He worked for a time in Iowa as a research scientist and assistant professor in Agricultural and Civil Engineering and Soil Physics in Iowa from 1955 to 1961 and was fortunate enough to meet Beverly Knudson at that time.

Don returned to the cold regions of Canada with his wife Bev and a young family for a position as an assistant professor in the Department of Agricultural Engineering, University of Saskatchewan in 1961. The prairies were a long way from home for a BC boy, but he rapidly comprehended the challenges and problems of the semi-arid, cold environment and prospered at the University. He assumed the Chairmanship of the Division of Hydrology in 1965 and was a tenured full Professor at the early age of 37 (1968). Don quickly transformed the Division of Hydrology into the international leader in the study of prairie, northern and snow hydrology and the national focus for the relatively new field of hydrology. His success with the Division was partly due to his ability to attract and encourage high calibre faculty members such as David Male, Jack Wigham, Don Norum, Jim Murray and others to contribute to the Division and to work with external scientists such as Gord McKay, Eugene Peck, Lars Bengtsson, Michel Slivitsky, Howard Ferguson, Kersi Davar, Barry Goodison, Jim Bruce, Fred Durrant and Bob Swanson, among many others.

After “retirement” in 1995, Don continued to teach his graduate level class in Cold Regions Hydrology, chair the Division of Hydrology, train a healthy number of graduate students, and prepare a substantial update in a new ‘Handbook of Hydrology’. The Division of Hydrology closed in 2001 but Don continued to publish papers and train students and advise former students. He took particular pride in presenting the D.M. Gray Award for Best CGU Student Paper in Hydrology at the Annual CGU Meeting. Don received the J Tuzo Wilson Award from the Canadian Geophysical Union in May, 2000 at Banff. In his acceptance speech he stressed the importance of developing hydrology as a geoscience in Canada, and that he felt his achievements were the result of the support and assistance he had received from family, co-workers, colleagues and friends over the years. Don arranged for the reprinting of the 1981 Handbook of Snow for January, 2005; demand for the book remained high over the decades and the few used copies still available had recently been selling on eBay for $1200. With Bev and family, he very much enjoyed their five grandchildren and his dog, Muffin.

Hydrological Achievements

One of Don’s first publications in the Journal of Geophysical Research (1960) used dimensional analysis to show that the then popular technique of ‘basin morphometry’, which used watershed characteristics stream length and basin perimeter to predict streamflow, was invalid because the “independent” variables were, in fact, related. This anticipated the development in current research on fractal river basin morphometry.

In organizing and presenting the Familiarization Seminars on the Principles of Hydrology on behalf of NRC from 1967 to 1974, Don emphasised rigorous scientific practise and so acted as the catalyst for the rapid development of hydrology as a geophysical science at university and government centres across the country. At this time Don also played a major role in organizing the Canadian effort for the International Hydrological Decade (IHD) and the organisation of experimental and representative basins across the country, of which the Division of Hydrology’s Bad Lake was one of the most successful and productive in terms of research. The Familiarization Seminars were transformed into the first and only Canadian hydrology textbook, the Handbook on the Principles of Hydrology (Water Information Centre, 1970) in both English and French versions, with Don as Editor-in-Chief and primary contributor. By the end of the 1960’s Don and Bev also had developed a thriving family with three daughters Kathryn, Lynn and Sharon. 

Comprehensive hydrology research, some very competitive handball matches and a substantial increase in Don’s research and administrative activities as his IHD research grew, marked the 1970’s. During this decade Don helped to set the stage for the present science of hydrology in Canada by:

• Ensuring that the hydrology research arms of the Inland Waters Directorate and Atmospheric Environment Service of Environment Canada would move from Ottawa and Toronto to Saskatoon (later forming the National Hydrology Research Centre). 
  
  
• Undertaking with David Male the editing, writing and assembly of a “Book on Snow” on behalf of the National Research Council which became the 776 page “handbook” Handbook of Snow: Principles, Processes, Management and Use (Pergamon Press,1981; Blackburn Press: 2005).
  
  
• Insisting on a rigorous physical basis for all hydrological investigations under his purview, something that was not common at the time and an attitude that eventually permitted hydrology to take its place as a geophysical science in Canada.
  
  
• Recognising that electronic data acquisition and advanced instrumentation were the key to the advance of hydrology and investing heavily in such through the employment of research engineers and the operation of an instrumentation development laboratory in the Division of Hydrology. This resulted in improved measurements of rainfall, snowfall, snow accumulation, blowing snow, snowmelt, radiation, stream discharge, and frozen soil ice content that continue to set the standard of measurement accuracy and reliability in hydrology.

The Division of Hydrology became a focus of a comprehensive study of the semi-arid Prairie environment that included about 15 projects and 20-25 faculty and research personnel with training in agricultural, chemical, civil, electrical and mechanical engineering, forestry, meteorology, physics and aquatic biology. Don’s recruitment and retention of several long serving members of the Division of Hydrology, Mrs. Elaine Wigham (secretary), Mr. Tom Brown (research engineer) and Mr. Dell Bayne (research technician) from the 1970’s to the 1990’s provided remarkable expertise and continuity to the Division and the science. Don also took on the duties of Assistant Dean for Research in the College of Engineering, helping to insure that the Space Engineering Division became SED Systems Ltd. with the ability to design and build satellites (now a major Saskatoon laboratory of a multinational aerospace firm) and instigating the research park that became Innovation Place, the largest on-campus research park in Canada.

In the 1980’s Don’s research matured with the analysis and publishing of results from the extensive datasets gathered in the 1970’s and major field investigations of prairie snow hydrology, specifically snowmelt infiltration into frozen soils, blowing snow redistribution and snowmelt energetics. The results of many experiments were incorporated into hydrological models both in Canada and abroad. Don played a major role in guiding the formulation of Swedish funding mechanisms for hydrology and aiding the establishment of a Water Resources Engineering school near the Arctic Circle at the University of Luleå, Sweden. Don’s research activity increased again later in the decade as he began to collaborate with new neighbours at the National Hydrology Research Centre in Saskatoon and in doing so provided important guidance to the developing research programmes of Environment Canada. It is no coincidence that many scientists at NHRC and the Meteorological Service of Canada were initially trained by Don and remained quite happy to continue collaborating with him. 

In the 1990’s hydrology in Canada faced a great crisis with the demise of the National Research Council “Associate Committee on Hydrology” and concurrent decline in funding for hydrological training and research in both governments and universities. Don proposed the creation of a ‘Society for Hydrological Science’, insisting that Hydrology retain and enhance its status as a geophysical science. The proposal led to the establishment of the CGU Hydrology Section, for which he drafted the initial terms of reference and served as the first secretary/treasurer in 1993.  

Don later negotiated that CGU-HS would host the Canadian National Committee for the International Association of Hydrological Sciences and take on the responsibility to the International Council of Scientific Unions for selection of National Delegates to IAHS and its constituents. He served on the Canadian Global Energy and Water Cycling Experiment (GEWEX) Science Committee and headed up one of the major hydrology components of this NSERC/Government study, which contributes to the World Climate Research Programme.  

Don Gray’s career was more than the sum of his research intake of $4.1 million (much of it when a dollar was worth far more than now), 68 graduate students or many books and publications. His career is indexed far better by the:

1) standard of excellence in problem identification, experimentation, analysis and writing that he set for Canadian hydrology,

2) extraordinary loyalty he inspired among colleagues and co-workers and

3) the great excitement he generated by suggesting that Canada could have a confident, scientific assessment of its water resources and that Canada could show the way for the world in doing so.

There is no doubt that Don Gray was the first and foremost Canadian hydrologist of the 20^th Century.  He is memorialized in Canadian hydrology through the Don Gray Scholarship of the Canadian Geophysical Union for doctoral candidates in Canadian hydrology http://cgu-ugc.ca/awards/dongray/ and by the D.M. Gray Award for Best Student Paper in Hydrology of the Hydrology Section of the Canadian Geophysical Union http://cgu-ugc.ca/cguwp/docs/hs/StudentAward_DMGray.pdf.

Bibliography

Books

Gray, D.M., 1970. Handbook on the Principles of Hydrology, Water Information Center. Inc., New York.

Gray, D.M. and Male, D.H. eds., 1981. Handbook of Snow: Principles, Processes, Management & Use. Pergamon Press.

Pomeroy, J.W., Gray, D.M., 1995. Snowcover: Accumulation, Relocation and Management. National Hydrology Research Institute Science Report No. 7. Environment Canada Saskatoon, Canada.

Key Papers 

Gray, D.M., 1961. Interrelationships of watershed characteristics. Journal of Geophysical Research, 66(4), pp.1215-1223.

Norum, D.I. and Gray, D.M., 1970. Infiltration equations from rate-of-advance data. Journal of the Irrigation and Drainage Division, 96(2), pp.111-119.

Gray, D.M., Landine, P.G. and Granger, R.J., 1985. Simulating infiltration into frozen prairie soils in streamflow models. Canadian Journal of Earth Sciences, 22(3), pp.464-472.

Gray, D.M., Granger, R.J. and Dyck, G.E., 1985. Overwinter soil moisture changes. Transactions of the ASAE, 28(2), pp.442-0447.

Gray, D.M. and Granger, R.J., 1986. In situ measurements of moisture and salt movement in freezing soils. Canadian Journal of Earth Sciences, 23(5), pp.696-704.

Gray, D.M. and Landine, P.G., 1988. An energy-budget snowmelt model for the Canadian Prairies. Canadian Journal of Earth Sciences, 25(8), pp.1292-1303.

Granger, R.J. and Gray, D.M., 1989. Evaporation from natural nonsaturated surfaces. Journal of Hydrology, 111(1-4), pp.21-29.

Granger, R.J. and Gray, D.M., 1990. Examination of Morton's CRAE model for estimating daily evaporation from field-sized areas. Journal of Hydrology, 120(1-4), pp.309-325.

Granger, R.J. and Gray, D.M., 1990. A Net Radiation Model for Calculating Daily Snowmelt in Open Environments. Paper presented at the 8th Northern Res. Basins Symposium/Workshop (Abisko, Sweden-March 1990). Hydrology Research, 21(4-5), pp.217-234.

Pomeroy, J.W. and Gray, D.M., 1990. Saltation of snow. Water Resources Research, 26(7), pp.1583-1594.

Pomeroy, J.W., Gray, D.M. and Landine, P.G., 1993. The prairie blowing snow model: characteristics, validation, operation. Journal of Hydrology, 144(1-4), pp.165-192.

Gray, D.M. and Prowse, T.D., 1993. Snow and floating ice, in Handbook of Hydrology (DR Maidment, ed.). (Vol. 7, pp. 7-1). McGraw-Hill: New York.

Shook, K., Gray, D.M. and Pomeroy, J.W., 1993. Temporal Variation in Snowcover Area During Melt in Prairie and Alpine Environments, Hydrology Research, 24(2-3), pp.183-198.

Shook, K. and Gray, D.M., 1996. Small‐scale spatial structure of shallow snowcovers. Hydrological Processes, 10(10), pp.1283-1292.

Pomeroy, J.W., Marsh, P. and Gray, D.M., 1997. Application of a distributed blowing snow model to the Arctic. Hydrological processes, 11(11), pp.1451-1464.

Shook, K. and Gray, D.M., 1997. Synthesizing shallow seasonal snow covers. Water Resources Research, 33(3), pp.419-426.

Shook, K. and Gray, D.M., 1997. Snowmelt resulting from advection. Hydrological Processes, 11(13), pp.1725-1736.

Zhao L. and Gray D.M. 1997. A Parametric Expression for Estimating Infiltration into Frozen Soils Hydrological Processes, 11(13), pp. 1761-1775.

Pomeroy, J.W., Gray, D.M., Shook, K.R., Toth, B., Essery, R.L.H., Pietroniro, A. and Hedstrom, N., 1998. An evaluation of snow accumulation and ablation processes for land surface modelling. Hydrological Processes, 12(15), pp.2339-2367.

Pomeroy, J.W., Parviainen, J., Hedstrom, N. and Gray, D.M., 1998. Coupled modelling of forest snow interception and sublimation. Hydrological processes, 12(15), pp.2317-2337.

Gray, D.M., Toth, B., Zhao, L., Pomeroy, J.W. and Granger, R.J., 2001. Estimating areal snowmelt infiltration into frozen soils. Hydrological Processes, 15(16), pp.3095-3111.

Pomeroy, J.W., Gray, D.M., Hedstrom, N.R. and Janowicz, J.R., 2002. Prediction of seasonal snow accumulation in cold climate forests. Hydrological Processes, 16(18), pp.3543-3558.

Pomeroy J.W., Gray D.M., Brown T., Hedstrom N.R., Quinton W.L., Granger R.J. and Carey S.K. (2007) The cold regions hydrological model: a platform for basing process representation and model structure on physical evidence. Hydrological Processes, 21(19), pp. 2650-2667

Pomeroy J.W., Gray D.M. and Marsh P. (2008). Studies on snow redistribution by wind and forest, snow-covered area depletion and frozen soil infiltration. In Cold Region Atmospheric and Hydrologic Studies, the Mackenzie GEWEX Experience, Vol. 2: Hydrologic Processes (ed. M-K Woo): 2, pp. 81-96. Springer-Verlag, Berlin, Germany