Surface Water Prize


yang_pcture Dr. Chih Ted Yang of Colorado State University (USA).

Topic: Sedimentation Control in Surface Water Systems

Dr. Yang has made significant contributions to the understanding of sediment transport and river hydraulics, particularly through the development of the Unit Stream Power Equation. The equation provides accurate predictions of total sediment discharge in natural rivers under diversified flow and sediment conditions. It also has proven utility for engineering concerns where sediment transport is an issue.

In his association with the US Department of the Interior, he has provided leadership in developing standard computational procedures for handling sediment transport in alluvial rivers. He has developed the well-known GSTARS Program for sediment computations.

GSTARS is a series of Generalized Stream Tube computer models for Alluvial River Simulation developed by Dr. Yang and his colleagues for the U.S. Bureau of Reclamation.

The first version of GSTARS was developed by Molinas and Yang back in 1985 for mainframe computers to simulate the flow conditions in a semi-two-dimensional manner and the change of channel geometry in a semi-three-dimensional manner based on the stream tube concept.

In 1988, GSTARS 2.0 was developed to significantly expand the program’s capabilities and adapt it for PC applications.

With a new graphical interface, GSTARS 2.1 replaced GSTARS 2.0 in the year 2000 for cohesive and non-cohesive sediment transport in rivers.

GSTARS 3, developed in 2002, further expanded the capabilities of GSTARS 2.1.

Winner Profile

  • Professor Chih Ted Yang is the Borland Professor of Water Resources and Director of the Hydrosciences and Training Center for the Department of Civil and Engineering at Colorado State University.
  • He received his PhD in Civil Engineering from Colorado State University in 1968.
  • In 2001, he graduated from the Senior Executive Fellow Program, Harvard University.
  • In 2002, he graduated from the Interior Senior Executive Service (SES) Candidate Development Program and is certified by the Office of Personnel Management as a qualified SES for all Federal agencies.
  • From 1994 to 2003, he was the manager of the Sedimentation and River Hydraulics Group, Technical Service Center, U.S. Bureau of Reclamation.

Acceptance Speech

yangspeechYour Royal Highness Crown Prince Sultan Bin Abdulaziz, Honorable guests, and distinguished scientists and engineers:

Chih Ted Yang, Borland Professor of Water Resources and Director of Hydroscience and Training Center, Colorado State University, Fort Collins, Colorado 80528, USA

 I am deeply honored to receive the prestigious international Prince Sultan Bin Abdulaziz for Water – First Branch: Surface Water Award. The topic of the prize is for Sedimentation Control in Surface Water Systems. On behalf of scientists and engineers working on sedimentation related subjects, we appreciate this recognition of the importance of sedimentation on sustainable development, use, and operation of surface water systems. Due to the international importance of sedimentation on surface water systems, I would like to share some of my observations based on those projects I have worked on in the United States and in other countries.

Erosion and sedimentation have been the subjects of extensive studies by geologists, geomorphologists, and hydraulic engineers for centuries due to their importance to our understanding of the formation and evolution of river systems and the need to develop and operate water resources projects.

The emphasis of the studies has gradually expanded from basic engineering applications to focus more on the impacts of erosion and sedimentation processes on watershed environments and the ecosystem, water quality, fish and wildlife, the total maximum daily load of sediment, and the sustainable development and operation of surface water systems.

Sediment transport and sedimentation studies were mainly done by hydraulic engineers based on Newton’s law of motion in the past. This vectorial approach requires the determination of the direction and magnitude of the force acting on sediment particles and moving water in a river with changing direction and magnitude with respect to time and location. More recently, the use of an energy or power approach has gained increasing acceptance in the development of sediment transport formulas. For example, among the four most accurate sediment transport formulas ranked by the American Society of Civil Engineers Task Committee on Sedimentation (1982), three out of the four most accurate formulas are based directly or indirectly on the stream power or unit stream power approach. One major deficiency of our conventional approaches in fluvial hydraulic studies is the lack of rational theory or equations for the determination of channel width and cross-sectional shape adjustment. I have been working on the development and application of the theory of minimum energy dissipation rate since 1971. With this relatively new theory or its simplified minimum stream power or minimum unit stream power theory, we can change the indeterminate river system to a determinate system so we can solve it analytically.

Winning Works

  1. Sediment Transport: Theory and Practice
  2. Erosion and Sedimentation Manual
  3. GSTARS2.1 Computer Model User's Manual
  4. GSTARS3 Computer Model User's Manual

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