Habitat Characterization for Submerged and Floating-Leaved Aquatic Vegetation in Coastal River Deltas of Mississippi and Alabama

2016 ◽  
Vol 56 (4) ◽  
pp. 454-472 ◽  
Author(s):  
H.J. Cho ◽  
P.D. Biber
2016 ◽  
Vol 2 (5) ◽  
pp. e1501768 ◽  
Author(s):  
Vamsi Ganti ◽  
Austin J. Chadwick ◽  
Hima J. Hassenruck-Gudipati ◽  
Brian M. Fuller ◽  
Michael P. Lamb

River deltas worldwide are currently under threat of drowning and destruction by sea-level rise, subsidence, and oceanic storms, highlighting the need to quantify their growth processes. Deltas are built through construction of sediment lobes, and emerging theories suggest that the size of delta lobes scales with backwater hydrodynamics, but these ideas are difficult to test on natural deltas that evolve slowly. We show results of the first laboratory delta built through successive deposition of lobes that maintain a constant size. We show that the characteristic size of delta lobes emerges because of a preferential avulsion node—the location where the river course periodically and abruptly shifts—that remains fixed spatially relative to the prograding shoreline. The preferential avulsion node in our experiments is a consequence of multiple river floods and Froude-subcritical flows that produce persistent nonuniform flows and a peak in net channel deposition within the backwater zone of the coastal river. In contrast, experimental deltas without multiple floods produce flows with uniform velocities and delta lobes that lack a characteristic size. Results have broad applications to sustainable management of deltas and for decoding their stratigraphic record on Earth and Mars.


2021 ◽  
Vol 13 (22) ◽  
pp. 4549
Author(s):  
Sergey Chalov ◽  
Kristina Prokopeva ◽  
Michał Habel

This study presents detailed suspended sediment budget for the four Siberian river deltas, representing contrasting conditions between Northern and Southern environments. Two of the studied rivers empty their water and sediments into the marine located in the permafrost zone in the Arctic region (Lena and Kolyma), and the other two (Selenga and Upper Angara) flow into Lake Baikal located in the steppe and forest-steppe zone of Southern Siberia. For the first time, these poorly monitored areas are analyzed in terms of the long-term and seasonal changes of spatial patterns of suspended sediment concentrations (SSC) over distributaries systems. Remote sensing reflectance is derived from continuous time series of Landsat images and calibrated with the onsite field measurements of SSC. Seasonal variability of suspended sediment changes over deltas was captured for the period from 1989 to 2020. We identify significant variability in the sedimentation processes between different deltas, which is explained by particularities of deltas networks and geomorphology and the existence of specific drivers—continuous permafrost impact in the North and abundant aquatic vegetation and wetland-dominated areas in the South. The study emphasizes that differences exist between Northern and Southern deltas regarding suspended sediments transport conditions. Mostly retention of suspended sediment is observed for Southern deltas due to sediment storage at submerged banks and marshlands located in the backwater zone of the delta during high discharges. In the Northern (arctic) deltas due to permafrost impacts (melting of the permafrost), the absence of sub-aquatic banks and river to ocean interactions of suspended sediment transport is mostly increased downwards, predominantly under higher discharges and along main distributary channels. These results shine light on the geochemical functions of the deltas and patterns of sequestering various metals bound to river sediments.


2008 ◽  
pp. 68-75 ◽  
Author(s):  
G. S. Taran

In the Ob river floodplain between the mouths of its tributaries Vakh and Tym (within the limits of Aleksandrovskiy district of Tomsk region), phytocoenoses belonging to 9 associations and 2 communities of Braun-Blanquet classification vegetation classes are listed. Class Lemnetea is represented by associations Ricciocarpetum natantis (Segal 1963) Tx. 1974, Lemnetum trisulcae Soó 1927, Stratiotetum aloidis Miljan 1933; class Potametea is done by asso­ciations Potametum perfoliati Koch 1926, Myriophylletum sibirici Taran 1998, Myriophylletum verticillati Soó 1927, Potametum graminei Koch 1926, Potametum pectinati Carstensen 1955, Nymphoidetum peltatae (All. 1922) Bellot 1951, as well as Sagittaria natans and Potamogeton natans—Ceratophyllum demersum communities. The syntaxa distribution in Western Siberia and adjoining territories is characterized.


2019 ◽  
pp. 91-94
Author(s):  
T. M. Lysenko ◽  
V. Yu. Neshatayeva ◽  
Z. V. Dutova

The International conference “Flora and conservation in the Caucasus: history and current state of knowledge” dedicated to the 130-year anniversary of the Perkalsky Arboretum took place at 22–25 of May 2019 in Pyatigorsk (Stavropol Territory) on the base of the Pyatigorsk Museum of local lore and natural history. The participants were from 11 cities of Russia and 7 Republics of the Caucasus and represented 14 institutions. Proceedings of the conference were published by the beginning of the meeting the book of abstracts includes 49 papers on the study of vascular plants, bryophytes, lichens and fungi, plant communities, as well as the protection of rare and endangered species, unique plant communities, and ecological problems in the Caucasus. The following geobotanical topics were highlighted in 13 papers: forest communities (3 reports), meadow and steppe vegetation (2), xeric open forests (2), communities of ecotone areas (1), structure of populations of rare plant species (3), as well as the history and current status of nature protected areas (2). The great emphasis has been focused on the study of floristic composition and plant populations. Thus, the conference showed that very few studies от vegetation are currently carried out in the Caucasus, and a lot of districts are not affected by the research. The greatest attention is paid to forest vegetation while meadow, steppe, alpine heath and xerophytic communities are studied rather poorly. Besides, there are “white spots” — mire, floodplain and aquatic vegetation. In nowadays, when the anthropogenic impact on the plant cover of the Caucasus is intensively increasing, it is especially important to study natural undisturbed communities preserved in protected natural areas. Another important issue is the conservation of the unique vegetation cover of the whole Caucasus. Thus, the study of vegetation of this region opens a wide field for researchers using various methods of modern plant science.


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