Seawater circulation in coastal aquifers : processes and impacts
Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012.
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| Format: | Thesis |
| Language: | eng |
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Massachusetts Institute of Technology
2013
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| Online Access: | http://hdl.handle.net/1721.1/78141 |
| _version_ | 1811079594821812224 |
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| author | Karam, Hanan Nadim |
| author2 | Charles Harvey. |
| author_facet | Charles Harvey. Karam, Hanan Nadim |
| author_sort | Karam, Hanan Nadim |
| collection | MIT |
| description | Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012. |
| first_indexed | 2024-09-23T11:17:30Z |
| format | Thesis |
| id | mit-1721.1/78141 |
| institution | Massachusetts Institute of Technology |
| language | eng |
| last_indexed | 2024-09-23T11:17:30Z |
| publishDate | 2013 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/781412019-04-12T11:28:23Z Seawater circulation in coastal aquifers : processes and impacts Karam, Hanan Nadim Charles Harvey. Massachusetts Institute of Technology. Dept. of Civil and Environmental Engineering. Massachusetts Institute of Technology. Dept. of Civil and Environmental Engineering. Civil and Environmental Engineering. Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Civil and Environmental Engineering, 2012. Cataloged from PDF version of thesis. Includes bibliographical references (p. 150-154). This thesis explores the subterranean domain of chemical cycling in coastal oceans abutting permeable aquifers, where transport through sediments is dominated by advection, rather than diffusion. We investigate the mechanisms by which seawater circulates in the subsurface over a range of spatio-temporal scales, and the chemical reactions to which this circulation is coupled. Seawater circulation in coastal aquifers is driven by salinity variations in pore water as well as by the effects of temporally variable forcings at both terrestrial (variable recharge) and marine (tides, waves and secular sea level changes) boundaries. It is coupled to the transport of biogeochemically reactive species through the subsurface and their exchange between the sediments and the water column. Our understanding of how different forcing mechanisms interact to determine spatial scales and residence times of subsurface seawater circulation, as well as temporal patterns and rates of aquifer-surface water exchange has thus far been very limited. The large range in the spatial and temporal scales of flow dynamics associated with different forcings challenges our ability to comprehensively observe and monitor their associated seafloor fluxes. In this thesis, we present a novel, homemade instrument for high-resolution, long-term monitoring of seafloor fluxes, designed to address this challenge. Two-year deployments of several such instruments at Waquoit Bay, MA, produced the most comprehensive datasets on seafloor fluxes available to date, multiplying the length of published time series by tenfold. The length and integrity of the datasets permit the use of spectral analysis to investigate distinct frequency components of seafloor fluxes and quantify their relationship to various forcing mechanisms. The temporal and areal coverage of the datasets allow us to distinguish the contributions of different forcings to observed fluxes, as a function of distance from shore and season. Furthermore, we discuss new insight derived from the data into the physics underlying observed seafloor fluxes and their associated subsurface circulation processes. Additionally, we describe results from an independent but related project to characterize chemical dynamics associated with seawater circulation in beach sand at Waquoit Bay. We present evidence for the important contribution of this circulation to the nitrogen budget of the Bay. by Hanan Nadim Karam. Ph.D. 2013-03-28T18:07:42Z 2013-03-28T18:07:42Z 2012 2012 Thesis http://hdl.handle.net/1721.1/78141 829233092 eng M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. http://dspace.mit.edu/handle/1721.1/7582 154 p. application/pdf Massachusetts Institute of Technology |
| spellingShingle | Civil and Environmental Engineering. Karam, Hanan Nadim Seawater circulation in coastal aquifers : processes and impacts |
| title | Seawater circulation in coastal aquifers : processes and impacts |
| title_full | Seawater circulation in coastal aquifers : processes and impacts |
| title_fullStr | Seawater circulation in coastal aquifers : processes and impacts |
| title_full_unstemmed | Seawater circulation in coastal aquifers : processes and impacts |
| title_short | Seawater circulation in coastal aquifers : processes and impacts |
| title_sort | seawater circulation in coastal aquifers processes and impacts |
| topic | Civil and Environmental Engineering. |
| url | http://hdl.handle.net/1721.1/78141 |
| work_keys_str_mv | AT karamhanannadim seawatercirculationincoastalaquifersprocessesandimpacts |