Nittrouer Charles A.

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Nittrouer
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Charles A.
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  • Article
    Sediment dynamics in the lower Mekong River : transition from tidal river to estuary
    (John Wiley & Sons, 2015-09-23) Nowacki, Daniel J. ; Ogston, Andrea S. ; Nittrouer, Charles A. ; Fricke, Aaron T. ; Van, Pham Dang Tri
    A better understanding of flow and sediment dynamics in the lowermost portions of large-tropical rivers is essential to constraining estimates of worldwide sediment delivery to the ocean. Flow velocity, salinity, and suspended-sediment concentration were measured for 25 h at three cross sections in the tidal Song Hau distributary of the Mekong River, Vietnam. Two campaigns took place during comparatively high-seasonal and low-seasonal discharge, and estuarine conditions varied dramatically between them. The system transitioned from a tidal river with ephemeral presence of a salt wedge during high flow to a partially mixed estuary during low flow. The changing freshwater input, sediment sources, and estuarine characteristics resulted in seaward sediment export during high flow and landward import during low flow. The Dinh An channel of the Song Hau distributary exported sediment to the coast at a rate of about 1 t s−1 during high flow and imported sediment in a spatially varying manner at approximately 0.3 t s−1 during low flow. Scaling these values results in a yearly Mekong sediment discharge estimate about 65% smaller than a generally accepted estimate of 110 Mt yr−1, although the limited temporal and spatial nature of this study implies a relatively high degree of uncertainty for the new estimate. Fluvial advection of sediment was primarily responsible for the high-flow sediment export. Exchange-flow and tidal processes, including local resuspension, were principally responsible for the low-flow import. The resulting bed-sediment grain size was coarser and more variable during high flow and finer during low, and the residual flow patterns support the maintenance of mid-channel islands.
  • Technical Report
    Coastal Ocean Processes : a science prospectus
    (Woods Hole Oceanographic Institution, 1992-04) Brink, Kenneth H. ; Bane, John M. ; Church, Thomas M. ; Fairall, Christopher W. ; Geernaert, G. L. ; Hammond, D. E. ; Henrichs, S. M. ; Martens, C. S. ; Nittrouer, Charles A. ; Rogers, D. P. ; Roman, Michael R. ; Roughgarden, J. D. ; Smith, R. L. ; Wright, L. Donelson ; Yoder, James A.
    CoOP (Coastal Ocean Processes) is an organization meant to study major interdisciplinary scientific problems in the coastal ocean. Its goal is "to obtain a new level of quantitative understanding of the processes that dominate the transformations, transport and fates of biologically, chemically and geologically important matter on the continental margin". Central to obtaining this understanding will be advances in observing and modeling the cross-shelf component of transport. More specific objectives are to understand 1) cross-margin exchanges, 2) air sea exchanges, 3) benthic-pelagic exchanges, 4) terrestrial inputs and 5) biological and chemical transformations within the water column. CoOP research will be carried out primarly through a series of process-oriented field studies, each involving about two years of measurements. Each of these field studies is to be initiated and defined through a community workshop. In addition to the process studies, CoOP will also involve modeling, long time series, exploratory studies, remote sensing, technological innovation, data archiving and communications. A CoOP pilot study has been approved for funding by the National Science Foundation, and funding will begin in 1992. The CoOP science effort is thus already underway.