Donald and Martha Harleman Professor
Margaret MacVicar Fellow
Fellow, American Geophysical Union
ASCE, Hunter Rouse Hydraulic Engineering Award
Chi Epsilon Honor Member
Distinguished Engineering Alumni Award – Bucknell University
18th Harold Jan Schoemaker Award
NSF Career Award
School of Engineering Bose Award for Excellence in Teaching
Samual M. Seegal Prize, MIT – for inspiring student in pursuing excellence
Earll Murman Award for Excellence in Undergraduate Advising
In natural streams, vegetation may grow in spatially heterogeneous patterns of individual patches. Different flow regimes develop near the vegetation, depending on the evolution of wake structure between the patches. The flow regime affects the ecological, biological, morphological processes in aquatic system. My current research focuses on the growth of turbulent flow structures in the gap between patches and on how the wakes interact to develop flow structure over a wide range of scales. Specifically, I am conducting a series of laboratory experiments with submerged flexible vegetation (Rotala indica), in which I will vary the gap between patches. The experiments will identify the patch spatial density (gap spacing) for which there is a transition from heterogeneous near-bed flow, moving around individual patches, to flow structure defined by a vertical shear layer, with uniformly low velocity near the bed. The result of this study will provide a model to predict real-world fluvial processes such as morphodynamic evolution, flow resistance, and habitat in channels with submerged flexible vegetation patches.
I am examining sediment transport. In my undergraduate studies, I had field experiences observing suspended cohesive sediment transport on tidal flats. In particular, my trips to coastal saltmarshes in Jiangsu, China, have set me thinking about how marsh plant species like Spartina alterniflora and Spartina anglica will interact with local sediment transport and morphodynamics, and how researchers can integrate vegetation-induced turbulence and drag into sediment transport models. To study these problems, I have started my graduate career in the Nepf Lab in Fall 2018.
Research Affiliate, Nepf Environmental Fluid Mechanics Laboratory, MIT
Senior Research Assistant, Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich
Numerous rivers have been confined and are eco-morphologically impaired, resulting in an increased demand for river restoration projects. Wood placements are a common and inexpensive measure for river restoration. To plan and evaluate river restoration projects including wood accumulations, it is important to understand the interactions between flow, wood, and sediment. Using physical modeling, my project aims to quantify flow and morphological structures associated with different wood accumulation setups. The results will be used to develop design recommendations for wood accumulations.
I grew up on the East Coast and have spent many summers in the Great Lakes region. It’s easy to take for granted the roles that vegetation play in nature, and view plants as ugly weeds to clear instead of species to protect. Seagrasses provide important habitat, carbon sinks, and other ecological functions, but are threatened by overdevelopment, pollution, and climate change. Long meadows of seagrass have been shown to attenuate currents and attenuate wave energy, but the dynamics of wave damping in the presence of currents are not as well understood. In addition, the morphological characteristics of plants vary widely in scope and in their relative contributions to vegetation-induced drag in oscillatory flow. I plan to investigate these areas to improve our understanding of the complex but ubiquitous interactions between flow and vegetation. Improved models of flow interactions with vegetation can help predict how storms and currents will affect vulnerable meadows, and help design infrastructure and living shorelines to protect coastal areas.
Coastal environments, such as mangrove forests, provide an unparalleled amount of ecosystem services, from water purification and flood prevention to the mitigation of climate change. In the Nepf Lab, I will investigate the critical conditions for erosion and deposition within black mangrove’s pneumatophores, which are also known as pencil roots because of their vertical and pencil-like shape. Pencil roots have an influence on sediment transport. They can both generate turbulence that can promote erosion and slow the currents near the bed that can promote deposition. If we know these critical conditions, then we can better understand the sediment fate and transport as well as how much carbon is stored in mangrove forests.
To determine these critical conditions, I am combining field work conducted in Port Fourchon, LA with laboratory methods. I will then use my observational field data and laboratory results to construct sub-grid scale models for erosion and deposition, which will be incorporated into a coastal-scale model to explore the role of channels in optimizing sediment retention within mangrove forests.
Coastal marshes serve as a natural source of coastal protection. To determine the makeup and size of coastal marshes, drones with RGB and NIR capability will be used to both quantify (biomass distribution + vegetation height) and qualify (species) coastal marshes. My goal is to determine the effectiveness of coastal marshes as a source of coastal protection by calculating, and identifying trends linking vegetation makeup and size to effectiveness, the wave attenuation given various marsh sizes.
When water with excess sediment flows through gravel streams it can clog the small spaces in between the gravel, known as interstitial spaces. These interstitial spaces are important for young fish, such as trout and salmon. I will work on a project modeling how sediment clogs up gravel streams, and investigate how adding obstacles (like logs, rocks, etc.) to these streams affects clogging. The turbulence created by adding these obstructions create can alleviate clogging, so this project aims to quantify if and how much clogging is prevented.
Visiting Graduate Student from Dalian University of Technology
My research focuses on sediment transport in a submerged flexible meadow influenced by waves and current. Previous studies have shown that the near bed turbulence is the main trigger for sediment resuspension. In my study, I will measure vertical profiles of velocity and sediment concentration under different hydrodynamics conditions and uses these measurement to predict the threshold level of turbulence for sediment resuspension and deposition. Moreover, I will also consider how submerged flexible vegetation influences the formation of ripples in wave and current flow.
Nature has evolved to know best how to stay resilient against natural forces. My research examines the science of how marshes can be placed in front of seawalls to attenuate wave amplitude and wave energy to reduce over topping and erosion. This is studied using wave dissipation models based on the physics of wave-vegetation hydrodynamic interactions. Hybrid coastal defence strategies not only offers important ecosystem services to combat climate change challenges, but also potentially deliver the same level of coastal protection more economically. Therefore, I will also conduct cost-benefit analysis on combined marshes and seawall infrastructures to examine whether societies would benefit economically from implementing nature based coastal protection and live more harmoniously with the natural environment.
My research is concerned with the design and implementation of nature-based coastal adaptation in urban settings. Despite increased interest in the incorporation of natural ecosystems in coastal engineering projects, there are still many gaps in our understanding of how these ecosystems perform hydrodynamically under extreme weather conditions and future climate scenarios. Using a combination of physical and numerical experiments, I will investigate wave attenuation and resilience of hybrid coastal defense strategies under various flow conditions, particularly the ability of oyster beds to reduce wave-driven flooding and overtopping during storms. I will then use a coastal-scale hydrodynamic model to explore implementation in an urban study area, with the goal of providing coastal communities with the tools to design physically and ecologically resilient waterfronts.
For profiles of lab alumni, visit the alumni page.