Summary Overland Flow Alluvial Channels Sedimentation  

Dream Team  Surface Runoff  
Resistance to Flow  
Upland Erosion Local Scour

     Research Projects

     Pierre Y. Julien

    Emeritus Professor
    Department of Civil and             Environmental Engineering

    Engineering Research Center     B-205
    Colorado State University
    Fort Collins, CO 80523


  Tel: (970)-491-8450

  Research Summary 

Dr. Julien received his B.ScHAE.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.

Pierre Julien retired as a faculty member in 2023 after 40 years of service to CSU. 

Dr. Julienriog 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 sedimentaRiverMechtion. 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 44 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... MPS

In 2011, Dr. Julien was invited to speak at the International Conference on River Restoration for Green Growth in Seoul.  He received an award from Dr. Myung Pil Shim, Minister of the Office of River RestGreenoration in South Korea.

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. Rouse

This web site describes several research projects Dr. Julien and his international team worked on over the years.  The site has been prepared to share technical information with the scientific community.  The user should find a brief description and a few illustrations, whenever possible, 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 available. 

The Power of Collaborative Research - Pune, India, July 23, 2012
Keynote at the ICCE Congress in New Orleans, December 2014
World Water Forum 7 Climate Change, Daegu, Korea, April 2015
Hunter Rouse Lecture - Austin, May 20, 2015 ASCE article
Congratulatory Note: Journal of Disaster Research, August 2015

Distinguished Julien

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."


  Overland Flow  met

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  dec

    • Paper describing the model CASC2D, with B. Saghafian and F. Ogden - Color Figures
    • Brochure with synopsis of CASC2D
    • Papers on spatial and temporal variability  

    • Results with the earlier 1-D finite element model CASC, with G. Moglen
    • Suitability of simplified overland flow equations, with J. Richardson
    • Runoff plane and small basin scale, with F. Ogden
    • Stationary rainstorms, with B. Saghafian and F. Ogden
    • Moving rainstorms, with J. Richardson and F. Ogden
    • Timeto equilibrium, with B. Saghafian
    • Rainstorms - Eulerian and Lagrangian, with D. May 
    • Land-use impact, with B. Doe
    • Flashflood forecasting, with D. Molnar, B. Johnson and P. Combs
    • Grid-size effects, with D. Molnar
    • Flood Control Report Muda River, Malaysia (21MB)
    • ASCE Paper Muda River
    • Rainfall precipitation for monsoon climates, with Shazwani and Dr. Salas
    • Flood Control and Modeling at Kota Tinggi in JFRM, with Jazuri, Shazwani, Junaidah and Atikah

  Upland Erosion   haiti

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.    

CASC2D-SED Model on Sediment Transport at a Watershed Scale

cascThe 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  

  • Model CASC2D-SED with B. Johnson and D. Molnar  

  • Paper on the model CASC2D-SED with R. Rojas
  • Power Point Presentation using CASC2D-SED and radars with R. Rojas
  • The model was later developed and converted into CASC2D-SED.  
  • CASC2D-SED Movie
  • Rosalia's CASC2D-SED model download
  • Posters #1 , #2 
  • Recent paper with application to the Arkansas River basin with J. England
  • Simulation of runoff on the Arkansas River by J. England
  • California Gulch 3-D Animation
  • Grid-size paper in ASCE-JHoE with R. Rojas, M. Velleux and B. Johnson
  • Upland Erosion Modeling at BMGR, with Woochul Kang
  • Sediment Yield from Ungauged Watersheds in South Korea, with Woochul Kang, C.Y. Yang and J.H. Lee
  • Geospatial Analysis of soil erosion in South Korea, with Woochul Kang, E.K. Jang, and C.Y. Yang
   TREX Model on Fate and Transport of Contaminants
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.ark

  Alluvial Channels and Stream Restoration Waimakariri

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 

ripples 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.


  Local Scour

bridgeResearch 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.  sac04



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.Cochiti Dam

  Mudflows and Debris Flows     ven1

    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. ven2

    • Quadratic formulation for hyperconcentrations, ASCE conf. in Utah, 1985, with J. O'Brien   
    • Mudflow properties, with J. O'Brien
    • Shear stress in hyperconcentrations with H. Woo
    • Suspensions of large concentrations of sands, with H. Woo et al.
    • Rheology of Hyperconcentrations, with Y. Lan
    • Mudflow Model FLO2D, with J. O'Brien and W. Fullerton
    • Kagoshima conference, with J. O'Brien
    • Mudballs from Arroyo Hondo, California
    • Sediment Flushing on the Nakdong River in Korean
    • Report on the Johoor Floods in Malaysia, from A. Shafie
    • Sediment flocculation at Arroyo Pasajero, with A. Mendelsberg


   Dream Team - "Rising Stars

At the present time, several visiting professors and about 20 graduate students currently work with Dr. Julien. 

Visiting professors and post-docs hosted by Dr. Julien: 

    Prof. M. Gonzalez del Tanago, University Politecnidad de Madrid, Spain.
    Prof. Shinji Egashira, Ritsumeikan University, Japan.
    Prof. Shigeru Kawai, Maizuru College of Technology, Japan.
    Prof. Jose Luis Lopez, Universidad Central de Venezuela, Venezuela.
    Prof. Sang Kil Park, Pusan National University, South Korea.
    Prof. Hyun Suk Shin, Pusan National University, South Korea.
    Prof. Suk Hwan Jang, Daejin University, South Korea.
    Vice-Pres. Prof. Chao Liu, Yangzhou Univ., China.  
    Prof. Sang Ho Kim, Sangji University, South Korea.
    Prof. Charlie Schlinger, Northern Arizona University, AZ.
    Prof. Kyewon Jun, Kangwon University, South Korea.
    Prof. Hojin Lee, National Chungbuk University, South Korea.
    Prof. Jong Seok Lee, Hanbat University, South Korea.
    Dr. Jai Hong Lee, Hanyang University, South Korea.
    Prof. Jose Batista Anderson, State University of Campinas, Brazil.
    Dr. Seongjoon Byeon, Incheon University, South Korea.
    Prof. Joonhak Lee, Korean Military Academy, South Korea.
    Dr. Lingyun Li, Tsinghua University, China.

    Prof. Xudong Chen, Zhengzhou University, China.
    Dr. Eunkyung Jang, KICT, South Korea


  Software and Miscellaneous

Einstein Integrals: Technical 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 and MatLab.

Software Program in FORTRAN  and DATA to determine the type of bed material of a sample based on d50 and d84 - Note: the user must download both the executable and the data file.

Transfer pptx

Transfer  pdf

Transfer  video

Transfer xls

The end of a long working day for the College; J. Gessler and P. Julien, April 2006

Skryabin op 8 no 10

Refreshing video on the future of hydraulics in the heat of the debate on global warming.

History of CSU:  paper at the 2003 World Water Congress and slides.