Yiwei Cheng

Phd Candidate
Environmental Fluid Mechanics & Water Resources
School of Civil and Environmental Engineering
Georgia Institute of Technology

RM 102 DEEL
e-mail: gtg985z@mail.gatech.edu (Send Mail)
Main Thesis Advisor: Dr Marc Stieglitz
Advisor: Dr Greg Turk

Education

Georgia Institute of Technology, B.S. Civil and Environmental Engineering, 2007
Areas of Concentration: Environmental Engineering

Georgia Institute of Technology, M.S. Civil and Environmental Engineering, 2009
Areas of Concentration: Environmental Water Resource and Fluid Dynamics, Ecohydrology, Climate Change, Ecosystem Modeling and Management

Georgia Institute of Technology, M.S. Computer Science and Engineering, 2012 (Expected)
Areas of Concentration: High Performance Computing (CUDA by NVIDIA), Algorithm Optimization

Georgia Institute of Technology, Ph.D. Civil and Environmental Engineering, 2012 (Expected)
Areas of Concentration: Environmental Water Resource and Fluid Dynamics, Ecohydrology, Climte Change, Ecosystem Modeling and Management
Minor: City Planning

Honors and Awards

Everglades Foundation Fellowship 2010

Keith Runcorn Award from European Geosciences Union 2011

Research

Climate change poses a real threat to the various ecosystems around the world. However, the positive and negative feedbacks as well as the disparities of scales that they operate over are too numerous for simple analysis. Further, most current multi-decadal impact studies have omitted small-scale ecosystem processes, reducing the realism of the model and the accuracy of their predictions. My research interests focus on understanding and predicting terrestrial ecosystem processes through an integration of modeling and field experimentation. Key topics include: interactions of nutrient and hydrological cycles, and environmental controls on vegetation. In addition to field experiments, I am also interested in making use of recent advances in computer techniques and technologies and develop multipurpose software libraries that are computationally fast and will allow scientists who work in a typical desktop environment to simulate dynamics at scale. Visualization and interactivity are also part and parcel of the simulations to allow rapid communication of underlying scientific concepts and ideas. My current research sites are:

• Arctic
• Everglades

Arctic

Objective: Integrating physical models and field experiments to investigate the potential effects of changes in seasonal snow regime on Arctic terrestrial ecosystem

Vegetation composition across much of the Arctic tundra biome is shifting from graminoid to shrub dominance. The balance between winter and summer processes, which control the evolution of ground temperatures, may be altered as tundra converts to shrubs. This shift has the potential to alter regional energy and water balance, and the rates of carbon (C) and nitrogen (N) cycling between the atmosphere, soil, and vegetation.Because >30% of the world's soil carbon is stored in arctic and boreal regions, changes in the carbon budget of the Arctic may also feedback strongly to global climate. The goal of my research is to develop a mechanistic understanding of how snow and shrubs independently and interactively affect physical and biological controls over soil N dynamics and decomposition in arctic tundra, and how these in turn affect vegetation composition and productivity. I seek to understand the interactions among vegetation, snow, and biogeochemical cycles through an integration of modeling and field experimentation.

Snow Manipulation Experiment	Snow Model

Everglades

Objective: Integrating physical models and experimental data to investigate the potential effects of changes in hydrologic regime on Ridge and Slough habitat in the Everglades ecosystem

The ridge and slough habitat in the Everglades ecosystem has undergone dramatic changes with the construction of C&SF project. Prior to the advent of the C&SF project, this habitat is a system of linear, slightly elevated sawgrass ridges separated by deeper water sloughs which are oriented parallel to the prevailing flow direction. Since the inception of the C&SF project, these parallel formations have degraded in areas where hydroperiods and flow fields no longer match the natural flow condition. Spatial pattern formation in ecosystems reveal dominant ecological processes and may indicate catastrophic shifts between ecosystem states. I seek to understand the interactions among vegetation, water and nutrient flows through physical models driven by field experimental data.

Simulated Maze Pattern	Simulated Perpendicular Stripe Pattern	Simulated Parallel Stripe Pattern

1. Cheng, Y., Stieglitz, M., Pan, F. The Biological Response of a Small Catchment to Clear-Cutting, American Geophysical Union Conference, San Francisco, USA, Dec 2006.

2. Cheng, Y., Stieglitz, M., Pan, F. Simple Method to Evolve Daily Ground Temperatures From Surface Air Temperatures in Snow Dominated Regions, American Geophysical Union Conference, San Francisco, USA, Dec 2008.

3. Cheng, Y., Stieglitz, M., Turk, G., Engel, V. Parallel Vegetation Stripe Formation Through Hydrologic Interactions, American Geophysical Union Conference, San Francisco, USA, Dec 2009.

4. Cheng, Y., Stieglitz, M., Turk, G., Engel, V. Flow Field and Nutrient Dynamics Governing the Formation of Parallel Vegetation Patterns in the Florida Everglades, American Geophysical Union Conference, San Francisco, USA, Dec 2009.

5. Cheng, Y., Stieglitz, M., Turk, G., Engel, V. Parallel Vegetation Stripe Formation Through Hydrologic Interactions, European Geophysical Union Conference, Vienna, Austria, May 2010.

6. Cheng, Y., Stieglitz, M. Simulating Watershed Scale Hydrologic Characteristics From Fine Scale Processes, Arctic LTER Meeting, Woods Hole, MA, USA, Feb 2010.

7. Stieglitz, M., Cheng, Y., Engel, V., Turk, G. Scale Dependent Nutrient Feedback as a General Mechanism for Vegetation Patterning and Tree Island Formation in Wetland Ecosystems. Greater Everglades Ecosystem Restoration, Naples, Florida, USA, July 2010.

8. Cheng, Y., Stieglitz, M., Turk, G., Engel, V. The Ubiquitous Nature of Nutrient Depletion and the Consequences for Ecosystem Structure, European Geophysical Union Conference, Vienna, Austria, April 2011.

9. Cheng, Y., Stieglitz, M., Turk, G., Engel, V. Demonstrating the Power of GPU Simulations for an Advection-Reaction-Diffusion Model, European Geophysical Union Conference, Vienna, Austria, April 2011.

10. Stieglitz, M., Cheng, Y., Engel, V., Turk, G., Chen, J., Ross, J. GPU Acceleration of an Advection-Diffusion-Reaction Model to Better Understand the Ubiquitous Nature of Nutrient Depletion and the Consequences for Ecosystem Structure. Florida International University, Miami, Florida, USA, Sept 2011.