Pierre Y. Julien
Professor of Civil Engineering
Dr. Julien received his B.Sc.A. in Civil Engineering from Laval University in 1977. He completed his M.Sc. and Ph.D. at Laval University in 1979 and 1983, and received the coveted NATO Scholarship of the Canadian National Research Council CNRC-CRSNG for post-doctoral studies at Colorado State University from 1983-1985. His academic career started as substitute professor at Laval University in 1979. He joined the faculty at Colorado State University in 1985 and became Full Professor in 1995. He also served as Associate Dean for International Research and Development in 2005-06.
Dr. Julien worked extensively in the field of sedimentation and river engineering. He has more than 35 years of civil and environmental engineering experience. He made significant contributions to computer modeling of upland runoff and erosion processes as well as river morphology, resistance to flow, sediment transport and reservoir sedimentation. He developed watershed models of the analysis of runoff, upland erosion and contaminant transport in mountain watersheds. He carried experiments on bedforms and sediment transport at the Engineering Research Center. He contributed to the analysis of sediment transport in sand-bed rivers with the Modified Einstein Method. He also developed algorithms for the analysis of the downstream hydraulic geometry and lateral migration for meandering channels.
He co-authored more than 500 scientific publications including two textbooks, 25 book chapters and lecture manuals, 185 refereed articles including 105 full papers in scientific journals, 230 professional presentations and conference papers, and 125 technical reports. Under his guidance, 125 engineering students including 39 Ph.D. graduated in Civil and Environmental Engineering. He is currently advising numerous graduate students.
In 2004, he received the H.A. Einstein Award for his research in sedimentation and river mechanics. He made numerous contributions to upland erosion modeling with models CASC-2D, CASC2D-SED and TREX. Dr. Julien delivered 20 Keynote Addresses at numerous International Conferences including the United States, South Korea, Mexico, Malaysia, Argentina, China, Singapore, Thailand, India...
Julien was invited to
speak at the International Conference
on River Restoration
Green Growth in Seoul.
He received an award
from Dr. Myung Pil Shim, Minister
of the Office of River
Restoration in South
In 2015, Dr. Julien presented research developments on climate change in relation to river flows at the World Water Forum in Gyeongju. He also moderated a Plenary Session at the WWF7 in Daegu, South Korea. In May, he delivered the Hunter Rouse Lecture in Hydraulic Engineering at the ASCE/EWRI Congress. The Hunter Rouse Award celebrated his numerous achievements and contributions to the hydraulic engineering profession in the areas of river mechanics and erosion and sedimentation throughout a most distinguished, dedicated research and academic career.
several research projects Dr. Julien and his
international team worked
on over the years.
The site has been prepared
to share technical
with the scientific community.
The user should find a brief description
and a few illustrations,
of the research projects. In many cases,
scientific publications can be downloaded.
In some cases, data
sets, software programs, pptx presentations,
demos and calculation procedures are also made
Power of Collaborative Research - Pune,
India, July 23, 2012
In 2022, Dr. Julien received the Distinguished membership award from ASCE: "For his seminal contributions on hyper-concentrated sediment flows, mudflows and debris flows, physically based modeling of runoff and erosion in watersheds, modeling the transport and fate of contaminants in watersheds, and predicting floods and downstream hydraulic geometry of river systems."
Research on overland flow has started in Canada as my part of Dr. Julien's own M.S. thesis and Ph.D. dissertation More recent research on overland flow has been funded by ARO and ARL since 1986. Some papers below refer to the overland flow characteristics from raindrop impact to sheet flows, roll waves and the applicability of simplified equations of motion.
Surface Runoff Modeling
Surface runoff modeling has been the emphasis of our activities within the Center for Geosciences. This on-going project has been funded by ARO and ARL since 1986. We have developed numerical algorithms for the simulation of rainfall-runoff using GIS terrain data, raingages and/or radar rainfall precipitation. The model CASC2D has been developed at CSU through the involvement of B. Saghafian, F. Ogden, W. Doe, D. Molnar, A. Sharma and J. Jorgeson who completed PhD's.
Papers on the model CASC2D
Papers on spatial and temporal variability
Papers on climate and radars
Early research papers on upland erosion date back to erosion from snowmelt in Canada. More recent research on overland flow has been funded by ARO and ARL since 1986. Some of the papers below refer to the modeling with CASC2D-SED and the transforms for the analysis of flow and sediment duration curves. The model CASC2D-SED was more recently coupled with WASP5, the significant changes in the model framework resulted in the model TREX. TREX is a Two-dimensional Runoff, Erosion and Export of contaminants from watersheds. It has been developed with M. Velleux and J. England with funding from the Center for Geosciences, the Hazardous Substance Research Center and the US Bureau of Reclamation.
The most recent version of the model is CASC2D-SED which simulates soil erosion from overland flow and routes sediment by size fractions to the outlet of a watershed. The model was developed by B. Johnson, and R. Rojas during the course of their PhD studies at CSU. This web site contains papers and descriptions of the models developed at CSU. The CASC2D-SED web site shows some tremendous results of the model.
Click on the blinking image to the left
The model is CASC2D-SED has been expanded to simulate the fate and transport of metals by M. Velleux and J. England for their PhD's at CSU. The new web site below contains lots of information on their dissertations and a user's guide and source code to the TREX model. The standard computation time required for TREX has been for a California Gulch simulation (hydrology + six solids types + three chemical types on a domain with 34,000 elements and 24 hours of simulated time). Back in 2005, Mark Velleux' simulation took 40 hour to run. In 2011 it took about 18.5 hours. Now, that same run takes just over 3.5h. If the code is compiled with the Intel C compiler (rather than GCC) the run finishes in just under 3 hours. That performance is fast enough that, in an age where a server could have 24 or more cores, Monte Carlo simulations can be realistically performed.
Alluvial Channels and Stream Restoration
We have developed a method for the determination of the downstream hydraulic geometry of alluvial channels. The research has been carried out in collaboration with J. Wargadalam, C. Leon, T. Bauer and G. Richard, who received graduate degrees at CSU. This web site contains numerous papers and a spreadsheet for the calculation of the hydraulic geometry from the Julien-Wargadalam algorithm, also called the J-W equation. Several articles relate to the changes in downstream hydraulic geometry downstream of dams on the Rio Grande and below Hapcheon Dam in South Korea. The book on River Mechanics supports graduate teaching.
Resistance to Flow and Bedforms
The analysis of resistance to flow and bedforms has been the subject of research in collaboration with Delft Hydraulics and the USBR. The analysis of bedform geometry and resistance to flow has been the author's research topic during his two sabbaticals in 1991 and 2000. Research on the Rhine River has been in collaboration with Gerrit Klaassen at Delft Hydraulics. Additional research at CSU has been carried out by Y. Raslan during the course of his Ph.D degree at CSU. This web site contains a few papers and data sets from recent investigations on the Rhine River.
Research on local scour has been sustained with interest from USDA for the analysis of rill erosion and interest from FHWA for the analysis of pier scour and scour below drop structures. The investigations have been performed in collaboration with N. Bormann, O. Stein, and C. Santoro, who received degrees from CSU. This web site contains numerous papers and descriptions of the models developed at CSU.
Dr. Julien's interest in sediment transport dates back to 1977. First studies relate to sediment transport in canadian rivers in collaboration with Marcel Frenette. Recent investigations refer to the mechanics of sediment transport. The research results available here refer to the studies in collaboration with H. Woo, J. Guo, O. Stein and many graduates who received degrees from CSU. This web page contains numerous papers, technical notes and reports on published results. The analysis of hyperconcentration, mudflows and debris flows is available in a separate item below.
Mudflows and Debris Flows
Research on hyperconcentrations, mudflows and debris flows in mountain streams has been on-going since 1983. Research has been carried out in collaboration with J. O'Brien, H. Woo, Y. Lan and J. Guo who not only manifested great interest in the topic, but also earned Ph.D. degrees at CSU. The photos of the recent devastating flows in Venezuela were prepared in collaboration with Claudia Leon and Rosalia Rojas, both Ph.D. graduates from CSU. This web site contains papers and photos of the 1999 debris flows disasters in Venezuela. More recent articles focus on the disasters of Typhoon Maemi and Hurricane Katrina, as well as the increase value of waterfront urban development.
Dream Team - "Rising Stars"
present time, several visiting professors and about 20
graduate students currently work with Dr.
Visiting professors and post-docs hosted by Dr. Julien:
Prof. M. Gonzalez del Tanago, University
Politecnidad de Madrid, Spain.
Software and Miscellaneous
Note by Julien and Guo (2004); and Excel Spreadsheet;
Fortran code of
Roland et al. ; The spreadsheet files of Srivastava
, Abad and
Garcia , and the Fortran code of Roland
are also available; The revised algorithm in the closure
by Julien and Guo (2005) provides the algorithm for Eq. (22)
in Fortran and
MatLab, as well
as the example on the Missouri River in Fortran
The end of a long working day for the College; J. Gessler and P. Julien, April 2006Refreshing video on the future of hydraulics in the heat of the debate on global warming.
Faculty position in Hydraulics
Faculty position in Hydrology