FLASHBACK: "Re-Inventing Urban Hydrology – Going Back to Basics to Develop New Tools"



Note to Reader:

The post below is extracted from an article published in February 2003 by FreshOutlook Magazine. Co-authored by Kim A Stephens and Dr. Thomas Debo, the article provided historical context in connecting the dots to the legacy of Professor Ray Linsley (1917-1990).

Ray Linsley served on the Stanford University faculty for twenty five years, from 1950 to 1975. Prior to that, he was with the United States Weather Bureau. At the time he arrived at Stanford, he already had published twelve outstanding papers and one textbook.

While at the Weather Bureau, Ray (as senior author) and two colleagues burned the midnight oil and spent their weekends writing the classic textbook, Applied Hydrology, published by McGraw-Hill in 1949. This book was unique because existing books on hydrology were largely descriptive and qualitative, whereas Applied Hydrology presented quantitative approaches to various hydrologic phenomena. Many of these approaches were developed by Ray himself. To learn more, click on A Memorial Tribute.

Kim Stephens is the Executive Director of the Partnership for Water Sustainability in British Columbia. Thomas Debo is co-author of the best-selling textbook Municipal Stormwater Management; and is a Professor Emeritus at the Georgia Institute of Technology. He was a former colleague and friend of Dr. Linsley.

To download a copy of their article, click on Re-Inventing Urban Hydrology: Going Back to Basics to Develop New Tools.

Looking At Rainfall Differently in British Columbia

“British Columbia is leading the way in North Americain developing and implementing innovative approaches, criteria and tools for reducing stormwater runoff volumes at the source, where rain falls. Through Stormwater Planning: A Guidebook for British Columbia, science-based performance targets have been established for designing individual sites and entire neighbourhoods to function hydrologically as though they are still naturally forested. Getting to this point has involved the re-thinking of traditional approaches to urban hydrology and computer modelling.”

“Drainage engineers have traditionally thought in terms of flow rates, not volumes. In dealing with urban hydrology, we need to focus on how much rainfall volume has fallen, how we are going to capture it, and what we are going to do with it.”

Volume-Based Approach

“The volume-based approach that is being implemented in British Columbia picks up the baton that Dr. Ray Linsley started more than a generation ago. As a professor of Civil Engineering at StanfordUniversity, and later as a consulting engineer, Linsley pioneered the development of continuous hydrologic simulation as the foundation for water balance management. He has received world-wide recognition for his vision and his contributions to the field of hydrology and continuous hydrologic simulation modelling.”

“In the 1960s, Linsley championed the paradigm-shift from empirical relationships to computer simulation of hydrologic processes. He had little or no use for ‘simple hydrology’ and the many simple equations that were used to represent the hydrologic cycle.”

“Linsley fought a difficult war to replace the established procedures that had been used for many years, and that continue to be used in most urban hydrologic analyses throughout North America and in other locations around the world. He believed that continuous simulation was the only hydrology that should be used for most design and analysis applications.”

The Missing Link

“The missing link in urban hydrology has been a tool that quantifies the benefits, in terms of reducing stormwater runoff volume at the site level, of installing source controls under a variety of circumstances. The water balance modeling approach was developed to demonstrate how to meet performance targets for water balance management at the site, neighbourhood, drainage catchment, and watershed scales. The Water Balance Model™   assists local governments to integrate land use planning with volume-based analysis of stormwater management strategies.”

The Legacy of Ray Linsley

“For water resource practitioners of my generation, Ray Linsley is one of the gods of engineering. For those of us with aspirations in applied hydrology, his textbook was the bible,” recalls Kim Stephens. “Hence, meeting and collaborating with Tom Debo a decade ago was special to me because Tom represented my living link to Ray Linsley. As a young engineer, Tom had worked for Ray Linsley and said he had been inspired by the experience. He shared his insights in the article that we subsequently co-authored.”

“When British Columbia started down the water balance path more than a decade ago, I delivered presentations at venues both in BC and beyond our boundaries. On a number of occasions when I was in the United States, I was approached with enthusiasm by individuals who told me they were peers or contemporaries of Ray Linsley.”

“Typically they had PhDs behind their names. This made me initially apprehensive because I thought they were going to be critical. Not so! Their message was always the same: ‘Kim, you have picked up where Ray Linsley left off’, they would say.”

“This is why it was so personally significant to spend time with Tom Debo and learn the story behind the legend and legacy of Ray Linsley. It was reassuring to make the water balance connection. This is the reason why Tom suggested using the baton analogy in our article.”

To Learn More:

To read the complete article by Kim  Stephens and Tom Debo, click on Re-Inventing Urban Hydrology: Going Back to Basics to Develop New Tools.