Current Members

Postdoctoral Fellow

hpark418@mit.edu

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.

Research Affiliate, Nepf Environmental Fluid Mechanics Laboratory, MIT

Senior Research Assistant, Laboratory of Hydraulics, Hydrology and Glaciology (VAW), ETH Zurich

ischalko (at) mit.edu

Personal Website

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.

Graduate Student

autumnd (at) mit.edu

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. 

Undergraduate Student

slassar (at) mit.edu

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.

Graduate Student

inhim838@mit.edu

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.