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The Water Institute produces a range of scientific publications. In this way, we contribute to the state of the science, communicating cutting edge ideas to a broad technical audience.

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Sources of organic matter in sediments of the Colville River delta, Alaska: A multi-proxy approach

posted on 08.13.2015

Mead Allison, Author

Thawing of permafrost and subsequent release of organic carbon in the warming Arctic has great potential to influence carbon cycling between the land and ocean. Here, we investigated temporal and spatial differences of organic carbon sources in sediments of Colville River delta and the adjacent Simpson Lagoon, Alaska (USA) over the last ∼50 years, using a multi-proxy approach (lignin, fatty acids, sterols, bulk and compound-specific 13C isotopes). Stations closer to the river mouth showed greater inputs of soil and litter-derived terrestrial material based on the terrestrial inputs indicator (Λ8), soil biomarker (3,5-Bd), and degradation index ([Ad/Al]v), as well as stronger and more frequent watershed-flushing events, coupled with Colville River discharge events, than stations in the lagoon. Values of Λ8, 3,5-Bd, and [Ad/Al]v in sediments ranged from 0.75–2.69, 0.02–0.44 mg/100 mg OC, and 0.23–0.85, respectively. The increase of terrestrial inputs in sediments near the delta for the last ∼50 years is most likely due to increase of river discharge under warmer temperatures in recent decades. Coastal erosion and inputs from other river sources (e.g., Kuparuk and Mackenzie Rivers) also contribute to the organic carbon in sediments of the delta. Rudimentary fatty acid indices reflected two distinct groups of bacteria in these sediments. Additionally, the sterol biomarker 24-ethylcholest-5-en-3β-ol is useful to track peat inputs in the Arctic. Click here to view the full publication. 

An Examination of Froude-Supercritical Flows and Cyclic Steps On A Subaqueous Lacustrine Delta, Lake

posted on 08.13.2015

Mead Allison, Author

Density-driven submarine flows, including turbidity currents, play an important role in the transfer of sediment into deep water. These bottom-hugging flows often produce flow-transverse bedforms along their path. A sedimentological and geophysical survey of the Stehekin River delta in Lake Chelan, Washington, reveals a downslope-elongate field of bedforms on the delta foreset associated with hyperpycnal discharges of the Stehekin River. An analysis of the bedform morphologies, delta geometry, and density contrast between lake and river water suggests that these hyperpycnal flows are Froude-supercritical. The bedforms are likely cyclic steps, flow-transverse bedforms that are bounded by stable hydraulic jumps between alternating subcritical and supercritical flow regimes. The ability to examine the three-dimensional bed configuration produced by natural density-driven flows adds valuable information to the body of experimental work focused on the behavior of cyclic steps in flumes. Click here to view the full publication. 

High rates of organic carbon burial in fjord sediments globally

posted on 05.05.2015

Mead Allison, Author

The deposition and long-term burial of organic carbon in marine sediments has played a key role in controlling atmospheric O2 and CO2 concentrations over the past 500 million years. Marine carbon burial represents the dominant natural mechanism of long-term organic carbon sequestration. Fjords—deep, glacially carved estuaries at high latitudes—have been hypothesized to be hotspots of organic carbon burial, because they receive high rates of organic material fluxes from the watershed. Here we compile organic carbon concentrations from 573 fjord surface sediment samples and 124 sediment cores from nearly all fjord systems globally. We use sediment organic carbon content and sediment delivery rates to calculate rates of organic carbon burial in fjord systems across the globe. We estimate that about 18 Mt of organic carbon are buried in fjord sediments each year, equivalent to 11% of annual marine carbon burial globally. Per unit area, fjord organic carbon burial rates are twice as large as the global ocean average, and fjord sediments contain twice as much organic carbon as biogenous sediments underlying the upwelling regions of the ocean. We conclude that fjords may play an important role in climate regulation on glacial–interglacial timescales. Click here to view the full publication. 

Riverside morphological response to pulsed sediment diversions

posted on 03.21.2017

Ehab Meselhe, et. al., Author

This paper in Geomorphology shows how researchers used numerical modeling of the lower Mississippi River informed by detailed field observations to produce information about how the riverbed changes in response to a diversion of large quantities of water and sediment. The study suggests that removing a significant amount of water through a diversion leads to the build of sediment near and downstream from the diversion.

Linking the bottom to the top in aquatic ecosystems: mechanisms and stressors of benthic-pelagic co

posted on 05.01.2015

Melissa Baustian , Author

Linkages between benthic and pelagic habitats occur in both freshwater and marine systems across multiple spatial and temporal scales, and are influenced by a number of chemical, biological, and physical forces. We identified three major mechanisms of benthic-pelagic coupling: (1) organism movement, (2) trophic interactions, and (3) biogeochemical cycling. We also explore the implications of several stressors, including invasive species and climate change that will inevitably impact the linkages between benthic and pelagic habitats. We identify critical research gaps that need to be addressed to quantify the habitat coupling of these ecosystems. We advocate for more collaboration among scientists with expertise in benthic and pelagic habitats in both freshwater and marine ecosystems to fully understand the cycles, interactions, processes, and functions of benthic-pelagic coupling in ecosystems. Finally, we suggest targeted research needs for better capturing of cross-ecosystem linkages in aquatic ecology. Click here to view the full publication. 

Proposed best modeling practices for assessing the effects ofecosystem restoration on fish

posted on 03.17.2015

Denise Reed, Shaye Sable, et al., Author

Large-scale aquatic ecosystem restoration is increasing and is often controversial because of the economic costs involved, with the focus of the controversies gravitating to the modeling of fish responses. This paper presents a scheme for best practices in selecting, implementing, interpreting, and reporting of fish modeling designed to assess the effects of restoration actions on fish populations and aquatic food webs. Previous best practice schemes that tended to be more general are summarized, and they form the foundation for our scheme that is specifically tailored for fish and restoration. Click here to view the full publication. 

An Overview of Cyberinfrastructure to Support the Coastal Modeling Community in the Gulf of Mexico

posted on 09.25.2014

Ehab Meselhe, Joao Pereira, Author

Twilley, R.R., S. Brandt, D. Breaux, J. Cartwright, J. Chen, G. Easson, P. Fitzpatrick, K. Fridley, S. Graves, S. Harper, C. Kaiser, A. Maestre, M. Maskey, W. McAnally, J. McCorquodale, E. Meselhe, T. Miller-Way, K. Park, J. Pereira, T. Richardson, J. Tao, A. Ward, J. Wiggert and D. Williamson.  2014.  Simulation Management Systems developed by the Northern Gulf Coastal Hazards Collaboratory (NG-CHC):  An overview of cyberinfrastructure to support the coastal modeling community in the Gulf of Mexico.  Advances in Coastal and Marine Resources: Remote Sensing and Modeling edited by Charles W. Finkl, Antonio H.F. Klein, and Christopher Makowski. Coastal Research Library (CRL) series. To view this publication, click here.

Community Resettlement Prospects in Southeast Louisiana

posted on 09.23.2014

Scott Hemmerling, Author

Christopher Dalbom, Program Manager of the Tulane Institute on Water Resources Law & Policy; Scott A. Hemmerling, Associate Director of Human Dimensions of the Water Institute of the Gulf; and Joshua A. Lewis, Research Analyst, Tulane/Xavier Center for Bioenvironmental Research (2014). “Community Resettlement Prospects in Southeast Louisiana: A Multidisciplinary Exploration of Legal, Cultural, and Demographic Aspects of Moving Individuals and Communities.” An Issue Paper of the Tulane Institute on Water Resources Law & Policy. To view this publication click here.

Diversion of Mississippi River Water Downstream of New Orleans, La to Maximize Sediment Capture

posted on 08.20.2014

Mead Allison, Ehab Meselhe, Author

Allison, M.A., Ramirez, M.T., Meselhe, E.A. (2014) "Diversion of Mississippi River Water Downstream of New Orleans, Louisiana, USA to Maximize Sediment Capture and Ameliorate Coastal Land Loss," Water Resources Management, June 2014. To view this publication click here

Bed Forms Resistance Dependency on Numerical Model Grid Size Spatial Resolution

posted on 08.22.2014

Ehab Meselhe, Author

El Kheiashy, K., McCorquodale, J., Georgiou, I., Meselhe, E. (2014).  "Bed Forms Resistance Dependency on Numerical Model Grid Size Spatial Resolution," Journal of Spatial Science, April 2014.