Co-evolution of riparian vegetation and channel dynamics in an aggrading braided river system, Mount Pinatubo, Philippines

2015 ◽  
Vol 40 (8) ◽  
pp. 1101-1115 ◽  
Author(s):  
Karen B. Gran ◽  
Michal Tal ◽  
Emily D. Wartman
Keyword(s):  
Riparian Vegetation ◽  
River System ◽  
Braided River ◽  
Mount Pinatubo ◽  
Channel Dynamics

scholarly journals DEVELOPMENT OF A FLOOD RISK ASSESSMENT MODEL FOR A BRAIDED RIVER SYSTEM

2017 ◽  
pp. 25
Author(s):  
Mustafa Kemal Cambazoglu ◽  
Cheryl Ann Blain
Keyword(s):  
Risk Management ◽  
Flood Risk ◽  
Channel Model ◽  
River System ◽  
Flood Risk Management ◽  
High Flow ◽  
Water Levels ◽  
Pearl River ◽  
Braided River ◽  
River Channels

The aim of this study is to construct a modeling system that will assist flood risk management strategies in a coastal plain braided river system. The model configuration consists of a hydrodynamic model (ADCIRC) of the river basin that receives tidal forcing at the open boundary and river discharge forcing at upstream flux boundary. An unstructured mesh model resolving the Pearl River channels at higher resolution from the coastline to approximately 75km inland to upstream reaches of the river has been constructed. The modeling system produces water levels and currents throughout the Lower Pearl River Basin. Initial sensitivity analysis efforts on the channel model include consideration of low-flow, average-flow, and high-flow scenarios. Model results were found to be slightly sensitive to slope of river channels and bottom friction to control stability in predictions. The model results were shown to be highly sensitive to the bathymetry of the model that controls the discharge capacity of the narrow river channels and the channel model resulted in elevated currents and water levels under high flow conditions. A channel discharge capacity analysis was conducted and the results showed the need to construct a floodplain mesh around the channel model with more realistic bathymetry and topography so that the flooding scenarios could be modeled with wetting and drying capability of ADCIRC. An initial attempt to develop such a floodplain mesh has been made with preliminary results and more comprehensive validation of the developed floodplain modeling system will extend to reproducing events associated with the historical Hurricane Isaac that impacted the region in 2012. This modeling system will provide an important tool to decision makers that could be used in future flood risk management and mitigation efforts.

scholarly journals Sedimentary facies analysis of the fluvial systems in the Siwalik Group, Karnali River section, Nepal Himalaya, and their significance for understanding the paleoclimate and Himalayan tectonics

2016 ◽  
Vol 51 ◽  
pp. 11-26 ◽  
Author(s):  
Ashok Sigdel ◽  
Tetsuya Sakai
Keyword(s):  
River System ◽  
Precipitation Pattern ◽  
Braided River ◽  
River Section ◽  
Meandering River ◽  
Braided Rivers ◽  
Facies Associations ◽  
Siwalik Group ◽  
Himalayan Tectonics ◽  
Flood Flow

Fluvial sediments of the Siwalik successions in the Himalayan Foreland Basin are one of the most important continental archives for the history of Himalayan tectonics and climate change during the Miocene Period. This study reanalyzes the fluvial facies of the Siwalik Group along the Karnali River, where the large paleo-Karnali River system is presumed to have flowed. The reinterpreted fluvial system comprises fine-grained meandering river (FA1), flood-flow dominated meandering river with intermittent appearance of braided rivers (FA2), deep and shallow sandy braided rivers (FA3, FA4) to gravelly braided river (FA5) and finally debris-flow dominated braided river (FA6) facies associations, in ascending order. Previous work identified sandy flood-flow dominated meandering and anastomosed systems, but this study reinterprets these systems as a flood-flow dominated meandering river system with intermittent appearance of braided rivers, and a shallow sandy braided system, respectively. The order of the appearance of fluvial depositional systems in the Karnali River section is similar to those of other Siwalik sections, but the timing of the fluvial facies changes differs. The earlier appearance (3-4 Ma) of the flood-flow dominated meandering river system in the Karnali River section at about 13.5 Ma may have been due to early uplift of the larger catchment size of the paleo-Karnali River which may have changed the precipitation pattern i.e. intensification of the Indian Summer Monsoon. The change from a meandering river system to a braided river system is also recorded 1 to 3 Ma earlier than in other Siwalik sections in Nepal. Differential and diachronous activities of the thrust systems could be linked to change in catchment area as well as diachronous uplift and climate, the combination of which are major probable causes of this diachronity.

Early Sevier orogenic deformation exerted principal control on changes in depositional environment recorded by the Cretaceous Newark Canyon Formation

2020 ◽  
Vol 90 (9) ◽  
pp. 1175-1197
Author(s):  
Anne C. Fetrow ◽  
Kathryn E. Snell ◽  
Russell V. Di Fiori ◽  
Sean P. Long ◽  
Joshua W. Bonde
Keyword(s):  
North American ◽  
Global Climate ◽  
Sedimentary Basins ◽  
River System ◽  
Structural Deformation ◽  
Braided River ◽  
Thrust Belt ◽  
North American Cordillera ◽  
The North

ABSTRACT Terrestrial sedimentary archives record critical information about environment and climate of the past, as well as provide insights into the style, timing, and magnitude of structural deformation in a region. The Cretaceous Newark Canyon Formation, located in central Nevada, USA, was deposited in the hinterland of the Sevier fold–thrust belt during the North American Cordilleran orogeny. While previous research has focused on the coarser-grained, fluvial components of the Newark Canyon Formation, the carbonate and finer-grained facies of this formation remain comparatively understudied. A more complete understanding of the Newark Canyon Formation provides insights into Cretaceous syndeformational deposition in the Central Nevada thrust belt, serves as a useful case study for deconvolving the influence of tectonic and climatic forces on sedimentation in both the North American Cordillera and other contractional orogens, and will provide a critical foundation upon which to build future paleoclimate and paleoaltimetry studies. We combine facies descriptions, stratigraphic measurements, and optical and cathodoluminescence petrography to develop a comprehensive depositional model for the Newark Canyon Formation. We identify six distinct facies that show that the Newark Canyon Formation evolved through four stages of deposition: 1) an anastomosing river system with palustrine interchannel areas, 2) a braided river system, 3) a balance-filled, carbonate-bearing lacustrine system, and 4) a second braided river system. Although climate undoubtedly played a role, we suggest that the deposition and coeval deformation of the synorogenic Newark Canyon Formation was in direct response to the construction of east-vergent contractional structures proximal to the type section. Comparison to other contemporary terrestrial sedimentary basins deposited in a variety of tectonic settings provides helpful insights into the influences of regional tectonics, regional and global climate, catchment characteristics, underlying lithologies, and subcrop geology in the preserved sedimentary record.

Organic matter processing and soil evolution in a braided river system

CATENA ◽  
2015 ◽  
Vol 126 ◽  
pp. 86-97 ◽  
Author(s):  
Nico Bätz ◽  
Eric P. Verrecchia ◽  
Stuart N. Lane
Keyword(s):  
Organic Matter ◽  
River System ◽  
Braided River ◽  
Soil Evolution ◽  
Organic Matter Processing

scholarly journals THE OCCURRENCE OF PALAEOZOIC CONGLOMERATIC ROCKS IN EAST JOHOR, PENINSULAR MALAYSIA

2015 ◽  
Vol 1 (2) ◽  
Author(s):  
Sugeng Sapto Surjono ◽  
Mohd Shafeea Leman ◽  
Kamal Roslan Mohamed ◽  
Che Aziz Ali
Keyword(s):  
Marine Environment ◽  
Debris Flows ◽  
Depositional Environment ◽  
River System ◽  
Peninsular Malaysia ◽  
Late Carboniferous ◽  
Braided River ◽  
Late Permian ◽  
Shallow Marine ◽  
Shallow Marine Environment

Conglomeratic rocks in East Johor are found in the separately three formations that are the Murau, Tanjung Leman and Linggiu Formations. The Murau Formation is characterized by cobble to boulder grained breccia with very angular to angular and disorganized clasts. It was deposited by fan-delta system in the sub-aerial to shallow marine environment. The Tanjung Leman Formation consists of pebble to cobble grained conglomerate with rounded to subrounded and organized clasts. It was deposited by braided river system in the sub-aerial environment. Both formations outcropped in eastern coastal of Johor. The rudaceous rocks of the Linggiu Formation consist of pebble to cobble-sized clasts with sub angular and disorganized texture. It present as subordinate rocks within sandstone dominant in the central part of East Johor and was deposited by debris flows in the shallow marine environment. All these rudaceous rocks were interpreted as Palaeozoic in age ranging from Late Carboniferous to Late Permian. Those rudaceous rocks indicated that since Late Carboniferous, palaeogeography of East Johor was a continent with subaerial to shallow marine depositional environment. Keywords: Conglomerate, Palaeozoic, East Johor, subaerial, shallow marine.

scholarly journals Sedimentation style of a Pleistocene kame terrace from the Western Sudety Mountains, S Poland

Geologos ◽  
2010 ◽  
Vol 16 (2) ◽  
pp. 101-110 ◽  
Author(s):  
Małgorzata Pisarska-Jamroży ◽  
Katarzyna Machowiak ◽  
Dariusz Krzyszkowski
Keyword(s):  
Ice Sheet ◽  
River System ◽  
High Energy ◽  
Braided River ◽  
Braided Rivers ◽  
Mountain Valley ◽  
Sedimentary Succession ◽  
Sudety Mountains ◽  
S Poland ◽  
Lithofacies Association

Sedimentation style of a Pleistocene kame terrace from the Western Sudety Mountains, S PolandThe depositional conditions of kame terraces in a mountain valley were analysed sedimentologically and petrologically through a series of kame terraces in the Rudawy Janowickie mountains. The kame terraces comprise five lithofacies associations. Lithofacies association GRt, Sp originates from deposition in the high-energy, deep gravel-bed channel of a braided river. Lithofacies association GC represents a washed out glacial till. Probably a thin layer of till was washed out by sandy braided rivers (Sp). The fourth association (Fh, Fm) indicates a shallow and quite small glaciomarginal lake. The last association (GRt, GRp) indicates the return of deposition in a sandy-bed braided channel. The petrography of the Janowice Wiekie pit and measurements of cross-stratified beds indicate a palaeocurrent direction from N to S. The Janowice Wielkie sedimentary succession accumulated most probably during the Saalian (Odranian, Saale I, Drenthe) as the first phase of ice-sheet melting, because the kame terrace under study is the highest one, 25-27 m above the Bóbr river level. The deposits under study are dominated by local components. The proglacial streams flowed along the margin of the ice sheet and deposited the kame terrace. The majority of the sedimentary succession was deposited in a confined braided-river system in quite deep channels.

scholarly journals Australia's earliest tetrapod swimming traces from the Hawkesbury Sandstone (Middle Triassic) of the Sydney Basin

2020 ◽  
Vol 94 (5) ◽  
pp. 966-978 ◽  
Author(s):  
Roy M. Farman ◽  
Phil R. Bell
Keyword(s):  
Fossil Record ◽  
Middle Triassic ◽  
New South ◽  
River System ◽  
Braided River ◽  
South Wales ◽  
The World ◽  
Body Fossil ◽  
Insight Into ◽  
Shed Light

AbstractThe Hawkesbury Sandstone (Hawkesbury Series, Sydney Basin) on the southeastern coast of New South Wales, Australia, preserves a depauperate but important vertebrate tetrapod body-fossil record from the Early and Middle Triassic. As with many fossil sites around the world, the ichnological record has helped to shed light on the paleoecology of this interval. Herein, we investigate historical reports of a trackway pertaining to a putative short-tailed reptile found at Berowra Creek in the 1940s. Reinvestigation of the surviving track-bearing slabs augmented by archival photographs of the complete trackway, suggests that these impressions, which consist primarily of didactyl tracks (plus less common monodactyl and tridactyl traces), represent the earliest example of a swimming tetrapod found in Australia. Another isolated specimen (possibly from a nearby locality at Annangrove) appears to represent similar didactyl swim traces of a second, larger individual. Although the identities of the trackmakers are unknown, the Berowra Creek individual had an estimated body length of between ~80 cm (short-coupled) and 1.35 m (long-coupled), and produced the subaqueous trackway while travelling upslope (against the current) on a sandbar within a braided river system of the Hawkesbury Sandstone. These trackways partially resemble amphibian swim traces in the so-called Batrachichnus C Lunichnium continuum, but appear to represent a unique locomotion trace. This reanalysis of the Berowra Creek trackway provides insight into the locomotion of tetrapods of the Triassic Hawkesbury Series, which remains a poorly understood aspect of their life history.

scholarly journals Influence of flood regime on riparian vegetation dynamics in rivers with alternate bars

2018 ◽  
Vol 40 ◽  
pp. 02025 ◽  
Author(s):  
Camille Jourdain ◽  
Nicolas Claude ◽  
Germain Antoine ◽  
Pablo Tassi ◽  
Florian Cordier
Keyword(s):  
Vegetation Cover ◽  
Riparian Vegetation ◽  
Steady Increase ◽  
River Channels ◽  
Vegetation Development ◽  
Flood Peak ◽  
Channel Dynamics ◽  
Alternate Bars ◽  
Morphodynamic Modeling ◽  
Vegetation Encroachment

Throughout the 20th century, many rivers worldwide have undergone important riparian vegetation encroachment, which can be problematic in terms of flood risks and biodiversity. Nowadays, controlled floods is often considered as a management option in anthropized rivers, with the aim of limiting vegetation encroachment within river channels, as well as maintaining a diverse habitat by reactivating natural channel dynamics. In this context, this study aims at investigating the influence of different flood regimes on river bar vegetation development and dynamics, focussing on alternate bar systems which are typically found in embanked streams. This question has been addressed through two-dimensional bio-morphodynamic modeling of a simplified gravel bed river reach. Four hydrological scenarios with different flood peak discharges have been run for 50 years. For all scenarios, a steady increase in vegetation cover strongly impacts the evolution of bar morphology, until a relatively stable equilibrium is reached after one to three decades. Numerical results suggest that vegetation development on bars is associated to an increase in bar wavelength and a decrease in bar width. Higher peak flood discharges lead to narrower and longer bars, and a longer adjustment duration. When vegetation cover is fully developed, interannual flood variability seems crucial to maintain bedform and vegetation turnover.

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