| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | July 10, 2019 |
| Latest Amendment Date: | July 6, 2021 |
| Award Number: | 1925850 |
| Award Instrument: | Continuing Grant |
| Program Manager: |
Richard Yuretich
ryuretic@nsf.gov (703)292-4744 EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | July 15, 2019 |
| End Date: | June 30, 2024 (Estimated) |
| Total Intended Award Amount: | $84,986.00 |
| Total Awarded Amount to Date: | $84,986.00 |
| Funds Obligated to Date: |
FY 2021 = $23,010.00 |
| History of Investigator: |
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| Recipient Sponsored Research Office: |
3100 MARINE ST Boulder CO US 80309-0001 (303)492-6221 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
3100 Marine Street, Room 481 Boulder CO US 80303-1058 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): | FRES-Frontier Rsrch Earth Sci |
| Primary Program Source: |
01001920DB NSF RESEARCH & RELATED ACTIVIT |
| Program Reference Code(s): |
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| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
The growth of large coastal cities is putting increasing demand on supplies of potable water as traditional sources are depleted. Increased withdrawal of local groundwater has led to more widespread occurrences of salt-water intrusion and new surface-water supplies are becoming politically and economically difficult to access. As sea level rose and fell over the past million years, the shoreline moved landward and seaward, shifting the boundary between fresh water and salt water with the result that reservoirs of freshwater can often be found offshore. This water could provide a significant reserve for coastal areas if other sources are unavailable. This project will identify the extent of freshwater buried in marine sediments in the continental shelf of New Jersey and in the offshore delta region of Bangladesh. The research will use data from geophysical surveys, sediment deposition, groundwater flow, and solute transport, to develop mathematical models that simulate the accumulation of freshwater in these submarine deposits as sea level rose. The project will also construct simulations of groundwater production from these areas to assess the feasibility of accessing the offshore reservoirs within the next few decades.
The project will assess how sequestration of onshore saltwater and offshore freshwater in coastal environments is influenced by interactions between geomorphic, sedimentological, geodynamic, and hydrologic processes over geologic time scales of one million years or more. The research will develop a new model using the Earth-science community code, Landlab, and apply the code at two field sites with vastly different local sea-level, climate, tectonic and sediment transport regimes: New Jersey and Bangladesh. Calculated sediment type and salinity patterns from these models will be compared to new and existing images from seismic and electromagnetic (EM) data, as well as to available well samples measuring salinity and age of the water. An EM survey will be carried out in Bangladesh to determine the distribution of deep onshore saltwater and freshwater in this active deltaic environment. Along with recently collected EM images from offshore New Jersey, these data will be used to test the Landlab model to elucidate the factors controlling the emplacement of fresh and saline groundwater in coastal regions.
This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.
PROJECT OUTCOMES REPORT
Disclaimer
This Project Outcomes Report for the General Public is displayed verbatim as submitted by the Principal Investigator (PI) for this award. Any opinions, findings, and conclusions or recommendations expressed in this Report are those of the PI and do not necessarily reflect the views of the National Science Foundation; NSF has not approved or endorsed its content.
Understanding How Sediment Builds Up on Continental Margins
Over thousands to millions of years, layers of sediment accumulate along continental margins, shaping the underwater landscape. This process depends on two key factors: how much space is available for sediment to settle (called accommodation space) and how much sediment is supplied to fill that space.
Accommodation space is influenced by sea level changes and the shifting of the Earth's surface due to tectonic forces, such as uplift and subsidence (sinking). At the same time, the shape of the seafloor is constantly evolving as sediment is transported, deposited, and eroded by ocean currents, storms, and river outflows. These processes are interconnected---sediment builds up in layers, which in turn reshape the seafloor and influence where future sediment will settle.
What is Sequence?
To better understand and predict how these sediment layers form, this project developed Sequence, a computer model designed to simulate the movement and deposition of sediment over long periods of time. Written in Python and built using the Landlab framework, Sequence takes into account key geological processes, including:
- Tectonics and Faulting: How Earth's shifting crust affects sediment buildup
- Sea Level Changes: The rise and fall of ocean levels over time
- Sediment Compaction: How layers of sediment become compressed under pressure
- Storms and Floods: The major events that move and deposit large amounts of sediment
Because sediment transport happens in bursts---often during major storms or floods---Sequence simplifies this process by calculating long-term trends rather than simulating every individual event. It does this using mathematical equations that approximate how sediment moves and settles over time, focusing on thousands to millions of years rather than day-to-day changes.
Tracking Sediment Properties and Predicting Offshore Freshwater
Beyond modeling where sediment is deposited, Sequence also tracks the geotechnical properties of these layers---such as their permeability (how easily water can flow through sediment). This is particularly important for understanding offshore freshwater reservoirs trapped beneath the seafloor.
Freshwater can become stored in sediment layers offshore, especially when sea levels rise and flood former land surfaces. By using Sequence's permeability data, scientists can feed this information into fluid flow models, which predict how and where freshwater is stored beneath the ocean. This research helps:
- Identify offshore freshwater sources, which could be valuable for water-scarce coastal regions
- Improve predictions of groundwater movement, which affects coastal water resources
- Understand how past sea level changes influenced freshwater storage, informing future climate change projections
Why is This Important?
By modeling how sediment layers form, Sequence can help scientists reconstruct Earth's past environments and predict how coastlines and underwater landscapes might changein the future. This research is useful for:
- Understanding how sea level changes have shaped coastal areas over time
- Predicting the impact of climate change on sediment deposition and erosion
- Informing coastal management strategies to protect against erosion and flooding
- Supporting energy and resource exploration, such as locating offshore freshwater, oil, or gas reserves
Sequence is designed to be modular and adaptable, allowing researchers to customize and improve the model by adding new components. By making this tool widely available, scientists can continue refining our understanding of how Earth's landscapes evolve over geological time.
Last Modified: 03/07/2025
Modified by: Eric Hutton
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