scholarly journals The Potential of Small Mountain River Systems for Paleoenvironmental Reconstructions in Drylands—An Example from the Binaloud Mountains in Northeastern Iran

Geosciences ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 448
Author(s):  
Azra Khosravichenar ◽  
Morteza Fattahi ◽  
Hamideh Amini ◽  
Hans von Suchodoletz
Keyword(s):  
River System ◽  
Large River ◽  
Alluvial Fan ◽  
Small Rivers ◽  
River Systems ◽  
Mountain Ranges ◽  
Geomorphological Mapping ◽  
Fluvial Dynamics ◽  
Local Tectonics ◽  
Numerical Dating

Fluvial sediments are valuable paleoenvironmental archives of the Quaternary. Since besides environmental factors they are also affected by local tectonics or intrinsic processes, large instead of small catchments should be studied. In drylands covering ca. 45% of the global terrestrial surface large river systems are generally missing, and most river systems are small rivers originating from mountain ranges. Their sediments are potentially interesting paleoenvironmental archives, but are often affected by intensive tectonics. During this study, to obtain a robust regional paleoenvironmental signal a small river system in the southwestern Binaloud Mountains in semi-arid NE Iran was exemplarily studied with a combined approach that encompassed both alluvial fan and catchment. By using geomorphological mapping and numerical dating, fluvial aggradation followed by incision was independently identified in larger areas or in different parts of the river system ca. 95–88 ka, 40 ka, 20 ka, around/after the Pleistocene/Holocene transition and possibly ca. 2.6 ka. These could be linked with regional and over-regional paleoenvironmental data. Furthermore, large boulders on the alluvial fan suggest anthropogenic destabilisation of the catchment during the last decades. Despite strong local tectonics the fluvial dynamics was mostly controlled by paleoenvironmental changes and human activity. This indicates that despite their small size, such river systems form valuable paleoenvironmental archives in drylands where other archive types are largely missing.

scholarly journals The potential of small mountain river systems for paleoenvironmental reconstructions in drylands - An example from the Binaloud Mountains in northeastern Iran

2021 ◽  
Author(s):  
Azra Khosravichenar ◽  
Morteza Fattahi ◽  
Hamideh Amini ◽  
Hans von Suchodoletz
Keyword(s):  
River System ◽  
Large River ◽  
Alluvial Fan ◽  
Small Rivers ◽  
River Systems ◽  
Mountain Ranges ◽  
Geomorphological Mapping ◽  
Fluvial Dynamics ◽  
Local Tectonics ◽  
Numerical Dating

<p>Fluvial sediments are valuable paleoenvironmental archives of the Quaternary. Since besides environmental factors they are also affected by local tectonics or intrinsic processes, large instead of small catchments should be studied. In drylands covering ca. 45% of the global terrestrial surface large river systems are generally missing, and most river systems are small rivers originating from mountain ranges. Their sediments are potentially interesting paleoenvironmental archives, but are often affected by intensive tectonics. During this study, to obtain a robust regional paleoenvironmental signal a small river system in the southwestern Binaloud Mountains in semi-arid NE Iran was exemplarily studied with a combined approach that encompassed both alluvial fan and catchment. By using geomorphological mapping and numerical dating, fluvial aggradation followed by incision was independently identified in larger areas or in different parts of the river system ca. 95–88 ka, 40 ka, 20 ka, around/after the Pleistocene/Holocene transition and possibly ca. 2.6 ka. These could be linked with regional and over-regional paleoenvironmental data. Furthermore, large boulders on the alluvial fan suggest anthropogenic destabilisation of the catchment during the last decades. Despite strong local tectonics the fluvial dynamics was mostly controlled by paleoenvironmental changes and human activity. This indicates that despite their small size, such river systems form valuable paleoenvironmental archives in drylands where other archive types are largely missing. </p>

scholarly journals CONTRIBUTION OF LARGE RIVER SYSTEM ON WATER LEVEL DUE TO A STORM

2018 ◽  
pp. 14
Author(s):  
Abdul Al Mohit ◽  
Yoshihiko Ide ◽  
Mitsuyoshi Kodama ◽  
Masaru Yamashiro ◽  
Noriaki Hashimoto
Keyword(s):  
Water Level ◽  
Water Discharge ◽  
Interaction Model ◽  
River System ◽  
Large River ◽  
Water Levels ◽  
Sea Surface ◽  
Surface Elevation ◽  
Small Rivers ◽  
Open Boundary

Bangladesh is a riverine country in South Asia, which contain about 700 big or small rivers. The major Ganges- Brahmaputra-Meghna river system makes the coast of Bangladesh more complex and disaster vulnerable area. This river system may or may not have its impact on the height of the water level due to a storm. This area is a suitable place for research, but there is no such mention of suitable research conducted in this area. Worth mentioning works done by some scholars are Dube et al. (2004), Agnihotri et al. (2006). All the works are important to the Bay-River interaction for the storm surge simulation, but these studies were also limited by the lack of a representation of proper geometry of the river system. Some of them considered idealized river system with constant water depth and some of them did not consider the proper tidal resume. The present study is a step towards the development of an operational surge forecasting nonlinear Bay-River interaction model that incorporates the major river system with realistic geometry. Both the bay and river model equations are discretized by finite difference method with central in space and forward in time and are solved by a conditionally stable, semi-implicit manner on a staggered Arakawa C-grid system. A stable tidal condition was made by forcing the sea level with the most energetic tidal constituent, M2 , along the southern open boundary of the parent model (Bay model). The developed model was applied to foresee sea-surface elevation associated with the catastrophic cyclone 1991 and a recent cyclone MORA 2017 along the coast of Bangladesh. We also investigated how the river influences the sea surface elevation with and without fresh water discharge. We also intend to investigate the effect of river discharge with sediment. It is observed that the water levels are found to be influenced by the river system.

An evaluation of hydrometric monitoring across the Canadian pan-Arctic region, 1950–2008

2011 ◽  
Vol 42 (6) ◽  
pp. 479-490 ◽  
Author(s):  
Theo J. Mlynowski ◽  
Marco A. Hernández-Henríquez ◽  
Stephen J. Déry
Keyword(s):  
River System ◽  
Arctic Region ◽  
The Arctic ◽  
Small Rivers ◽  
Labrador Sea ◽  
Hudson Bay ◽  
Water Regulation ◽  
River Systems ◽  
Influence Of Water

This study evaluates the hydrometric monitoring maintained within the Canadian pan-Arctic and is based on the hydrometric gauges closest to northern seas for 76 river systems throughout 1950–2008. Monitoring is quantified by compiling time series of total gauged area and discharge values from the available hydrometric records. We further evaluate the quality of hydrometric data by examining the availability of hydrometric records, the continuity of individual records, and the influence of water regulation on river systems. The maximum gauged area of the Canadian pan-Arctic was 64% in 1990 before it slowly decreased to 56% in 2008. Larger river systems typically had the most hydrometric data available, though each river system had an average of 46% of their records available. In 1998, a maximum of 22 river systems had more than 30 years of continuous records, which is the maximum attained throughout the study period. For future improvements in hydrometric monitoring, additional gauges on relatively small rivers will need to be deployed. We suggest new gauges should be implemented in the Eastern Hudson Bay, Ungava Bay and Labrador Sea basins in spite of the tremendous need for more in the Arctic Archipelago.

scholarly journals Decadal-Scale Variations of Thalweg Morphology and Riffle–Pool Sequences in Response to Flow Regulation in the Lowermost Mississippi River

Water ◽  
2019 ◽  
Vol 11 (6) ◽  
pp. 1175 ◽  
Author(s):  
Chia-Yu Wu ◽  
Joann Mossa
Keyword(s):  
Mississippi River ◽  
Management Strategies ◽  
River System ◽  
Temporal Variations ◽  
Large River ◽  
Sediment Supply ◽  
Flood Events ◽  
River Systems ◽  
Decadal Scale ◽  
River Control

The lowermost Mississippi River (LMR) is one of the largest deltaic systems in North America and one of the heavily human-manipulated fluvial river systems. Historic hydrographic surveys from the mid-1900s to the early 2010s were used to document the thalweg morphology adjustments, as well as the riffle–pool sequences. Extensive aggradation was observed during 1950s to 1960s, as the Atchafalaya River was enlarging before the completion of the Old River Control Structure (ORCS). Following the completion of the ORCS, reductions in sediment input to the LMR resulted in net degradation of the thalweg profile patterns since the mid-1960s except for the 1992–2004 period. Different flood events that supplied sediment might be the cause of upstream aggradation from 1963–1975 and net aggradation along the entire reach from 1992–2004. Furthermore, the change pattern of thalweg profiles appear to be controlled by backwater effects, as well as the Bonnet Carré spillway opening. Results from riffle–pool sequences reveal that the averaging Ws ratios (length to channel width) are 6–7, similar to numerous previous studies. Temporal variations of the same riffles and pools reveal that aggradation and degradation might be heavily controlled by similar factors to the thalweg variations (i.e., sediment supply, backwater effects). In sum, this study examines decadal-scale geomorphic responses in a low-lying large river system subject to different human interventions, as well as natural flood events. Future management strategies of this and similar river systems should consider recent riverbed changes in dredging, sediment management, and river engineering.

scholarly journals Distribution and degradation of terrestrial organic matter in the sediments of peat-draining rivers, Sarawak, Malaysian Borneo

2019 ◽  
Author(s):  
Ying Wu ◽  
Kun Zhu ◽  
Jing Zhang ◽  
Moritz Müller ◽  
Shan Jiang ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Total Nitrogen ◽  
River System ◽  
Small Rivers ◽  
C3 Plants ◽  
Terrestrial Organic Matter ◽  
River Systems ◽  
Diagenetic Alteration ◽  
Malaysian Borneo

Abstract. Tropical peatlands are one of the largest pools of terrestrial organic carbon (OCterr); however, our understanding of the dynamics of OCterr in peat-draining rivers remains limited, especially in Southeast Asia. This study used bulk parameters and lignin phenols concentrations to investigate the characteristics of OCterr in a tropical peat-draining river system (the main channel of the Rajang and three smaller rivers) in the western part of Sarawak, Malaysian Borneo. The depleted δ13C levels and lignin composition of the organic matter indicates that the most important plant source of the organic matter in these rivers is woody angiosperm C3 plants, especially in the three small rivers sampled. The diagenetic indicator ratio (i.e., the ratio of acid to aldehyde of vanillyl phenols (Ad / Al)v) increased with decreasing mean grain size of sediment from the small rivers. The selective sorption of acid relative to aldehyde might explain the variations in the (Ad / Al)v ratio. The (Ad / Al)v ratio appears to be related to the C / N ratio (the ratio of total organic carbon to total nitrogen) in the Rajang and small rivers, where slower degradation of OCterr and a higher total nitrogen percentage (TN%) were observed, compared to other river systems. Most of the OCterr discharged from the Rajang and small river systems was material derived from woody angiosperm plants with limited diagenetic alteration before deposition, and so could potentially provide significant carbon to the atmosphere after degradation.

scholarly journals The Isotope Hydrology of a Large River System Regulated for Hydropower

2014 ◽  
Vol 31 (3) ◽  
pp. 335-349 ◽  
Author(s):  
C. Soulsby ◽  
C. Birkel ◽  
J. Geris ◽  
D. Tetzlaff
Keyword(s):  
River System ◽  
Large River ◽  
Isotope Hydrology

scholarly journals Effects of Weir Construction on Phytoplankton Assemblages and Water Quality in a Large River System

2018 ◽  
Vol 15 (11) ◽  
pp. 2348 ◽  
Author(s):  
Hae-Jin Lee ◽  
Hae-Kyung Park ◽  
Se-Uk Cheon
Keyword(s):  
Water Quality ◽  
Chlorophyll A ◽  
River System ◽  
Large River ◽  
Anthropogenic Factors ◽  
Centric Diatom ◽  
Nakdong River ◽  
Biological Variables ◽  
Physical Chemical ◽  
The Nakdong River

Flow regulation is one of the most common anthropogenic factors affecting rivers worldwide. In Korea, 16 weirs were constructed along four major rivers from 2009 to 2012. This study aimed to elucidate initial changes in physical, chemical, and biological variables after the construction of consecutive weirs on the Nakdong River, a major large river system. Water quality variables and phytoplankton cell densities were investigated at eight representative sites and compared with the data recorded before the weir construction. There were spatial and temporal changes in the hydraulic retention time (HRT), total phosphorus (TP), and chlorophyll a concentrations among the eight weir sections. HRT increased after the weir construction, while TP and chlorophyll a tended to decrease from the middle to lower section of the Nakdong River. Furthermore, differences were observed in the phytoplankton community composition between 2006–2007 and 2013. There was a marginal decrease in the duration of centric diatom (Stephanodiscus hantzschii) blooms after weir construction. However, Microcystis aeruginosa proliferated more extensively during summer and autumn than it did before the weir construction. Our results suggest that changes in hydrological factors, in response to consecutive weir construction, may contribute to greater physical, chemical, and ecological variability.

Chutes and ladders and other games we play with rivers. II. Simulated effects of translocation on white sturgeon

2006 ◽  
Vol 63 (1) ◽  
pp. 176-185 ◽  
Author(s):  
Henriette I Jager
Keyword(s):  
Fish Species ◽  
Simulation Study ◽  
River System ◽  
Genetic Effects ◽  
White Sturgeon ◽  
Acipenser Transmontanus ◽  
River Systems ◽  
Short Segment ◽  
River Fragmentation ◽  
Demographic Effects

Restoring connectivity is viewed as an important recovery option for fish species adversely affected by river fragmentation. This simulation study quantified the genetic and demographic effects of translocation on metapopulations of white sturgeon (Acipenser transmontanus) inhabiting a series of long (source) and short (sink) river segments. Genetic effects were predictable; upstream translocations increased introgression and downstream translocations had no effect. Demographic results suggest that indiscriminant efforts to reconnect populations may do more harm than good. Simulated river systems with high interspersion of long and short segments and a long segment far upstream tended to benefit most from translocation, but only when narrow screening or downstream passage was also provided below the river segment receiving fish. When combined with narrow screening, upstream translocation to a long segment subsidizing several downstream short segments produced the best results. Downstream passage outperformed narrow screening only when the translocation recipient was a short segment in a river system with low interspersion and no long, upstream river segment. This model-based evaluation of reconnection options has helped to refine ideas about restoring populations in fragmented rivers by predicting which options benefit riverine metapopulations as a whole.

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