Day John W.

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Day
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John W.
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  • Article
    Deltas in arid environments
    (MDPI, 2021-06-16) Day, John W. ; Goodman, Reed ; Chen, Zhongyuan ; Hunter, Rachael ; Giosan, Liviu ; Wang, Yanna
    Due to increasing water use, diversion and salinization, along with subsidence and sea-level rise, deltas in arid regions are shrinking worldwide. Some of the most ecologically important arid deltas include the Colorado, Indus, Nile, and Tigris-Euphrates. The primary stressors vary globally, but these deltas are threatened by increased salinization, water storage and diversion, eutrophication, and wetland loss. In order to make these deltas sustainable over time, some water flow, including seasonal flooding, needs to be re-established. Positive impacts have been seen in the Colorado River delta after flows to the delta were increased. In addition to increasing freshwater flow, collaboration among stakeholders and active management are necessary. For the Nile River, cooperation among different nations in the Nile drainage basin is important. River flow into the Tigris-Euphrates River delta has been affected by politics and civil strife in the Middle East, but some flow has been re-allocated to the delta. Studies commissioned for the Indus River delta recommended re-establishment of some monthly water flow to maintain the river channel and to fight saltwater intrusion. However, accelerating climate impacts, socio-political conflicts, and growing populations suggest a dire future for arid deltas.
  • Preprint
    Sinking deltas due to human activities
    ( 2008-12-26) Syvitski, James P. M. ; Kettner, Albert J. ; Overeem, Irina ; Hutton, Eric W. H. ; Hannon, Mark T. ; Brakenridge, G. Robert ; Day, John W. ; Vorosmarty, Charles J. ; Saito, Yoshiki ; Giosan, Liviu ; Nicholls, Robert J.
    The world’s population living on low-lying deltas is increasingly vulnerable to flooding, whether from intense rainfall, rivers or from hurricane-induced storm surges. High-resolution SRTM and MODIS satellite data along with geo-referenced historical map analysis allows quantification of the extent of low-lying delta areas and the role of humans in contributing to their vulnerability. Thirty-three major deltas collectively include ~26,000 km2 of area below local mean sea level and ~96,000 km2 of vulnerable area below 2 m a.s.l. The vulnerable areas may increase by 50% under projected 21st Century eustatic sea level rise, a conservative estimate given the current trends in the reduction in sedimentary deposits forming on the surface of these deltas. Analysis of river sediment load and delta topographical data show that these densely populated, intensively farmed landforms, that often host key economic structures, have been destabilized by human-induced accelerated sediment compaction from water, oil and gas mining, by reduction of incoming sediment from upstream dams and reservoirs, and from floodplain engineering.
  • Article
    Impacts of coastal infrastructure on shoreline response to major hurricanes in southwest Louisiana
    (Frontiers Media, 2022-04-27) Cadigan, Jack A. ; Bekkaye, Jasmine H. ; Jafari, Navid H. ; Zhu, Ling ; Booth, Ashley R. ; Chen, Qin ; Raubenheimer, Britt ; Harris, Brian D. ; O’Connor, Chris ; Lane, Robert ; Kemp, G. Paul ; Day, Jason N. ; Day, John W.
    The Rockefeller Wildlife Refuge, located along the Chenier Plain in Southwest Louisiana, was the location of the sequential landfall of two major hurricanes in the 2020 hurricane season. To protect the rapidly retreating coastline along the Refuge, a system of breakwaters was constructed, which was partially completed by the 2020 hurricane season. Multi-institutional, multi-disciplinary rapid response deployments of wave gauges, piezometers, geotechnical measurements, vegetation sampling, and drone surveys were conducted before and after Hurricanes Laura and Delta along two transects in the Refuge; one protected by a breakwater system and one which was the natural, unprotected shoreline. Geomorphological changes were similar on both transects after Hurricane Laura, while after Delta there was higher inland sediment deposition on the natural shoreline. Floodwaters drained from the transect with breakwater protection more slowly than the natural shoreline, though topography profiles are similar, indicating a potential dampening or complex hydrodynamic interactions between the sediment—wetland—breakwater system. In addition, observations of a fluidized mud deposit in Rollover Bayou in the Refuge are presented and discussed in context of the maintenance of wetland elevation and stability in the sediment starved Chenier Plain.