sediment flow
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Author(s):  
Eder A. S. Sá ◽  
Ildegardis Bertol ◽  
Silvio L. Rafaeli Neto ◽  
Daiane T. Schier

ABSTRACT Water erosion is influenced by climate, soil, soil cover and soil conservation practices. These factors can be modified by natural (especially climate) and/or anthropogenic (especially soil, soil cover and conservation practices) actions. The relief factor also influences the water erosion and can also be partially modified by anthropic action. This study aimed to evaluate the impact of anthropogenic action due to the introduction of soil crop in no-tillage system on water erosion, and on the consequent flow of sediments in the water. The study was carried out in the Marombas river basin with an area of 3,939 km², using the Soil Water Assessment Tools (SWAT) model. The calibration and validation of the model for sediment production was carried out with a historical series of synthetic data. The data from this series were estimated by linear regression from sediment value load and the average daily flow obtained punctually in the basin’s outlet. The SWAT model was calibrated on a daily scale with data from 1979 to 1989 and was validated with data from 1994 and 1997. The SWAT model was suitable to represent the average daily flow and sediment flow in the Marombas watershed. The hypothesis of reduced sediment production with increasing soil crop in no-tillage system was accepted.


2021 ◽  
Vol 6 (3) ◽  
pp. 241
Author(s):  
La Ode Hadini ◽  
Junun Sartohadi ◽  
M. Anggri Setiawan ◽  
Djati Mardiatno ◽  
Nugroho Christanto

Increasing population densities and food demands are major factors contributing to the widespread use of agricultural drylands in upper volcanic slope areas. This phenomenon poses a high risk of severe erosional events that are environmentally hazardous. Therefore, this study aims to analyze the sediment flow characteristics, based on the relationship between sediment flow and water level as well as the sediment discharge rate and soil loss. Field surveys were conducted to determine the soil measurement, slope morphology and dryland cover characteristics. The sediment flow was evaluated at the gully outlet, where 169 suspension data pairs for the modeling and 130 suspension data pairs for the validation, as well as the bed load, water level, rainfall and water flow characteristics were obtained. Tables and figures were subsequently used to represent the measurement data and analysis results for the correlation between the flow rate effects, sediment and soil loss on the water surface. The results showed that the sediment flow in volcanic landscape slopes with dryland agriculture were possibly characterized by the polynomial relationship, using the suspension discharge model, Qs=0.0322Q2+6.0625Q–1.2658. Under this condition, the average rate of soil loss in the form of sediment load and erosion rate of the catchment area occurred at 953.53 and ​​1,657.94 ton/ha/yr, respectively. Furthermore, the sediment sources in the soil loss were believed to originate from 83% of the suspended sediments and 17% bed loads. Keywords: Discharge; Dryland; Landscape; Sediment; Volcano Copyright (c) 2021 Geosfera Indonesia and Department of Geography Education, University of Jember   This work is licensed under a Creative Commons Attribution-Share A like 4.0 International License


Water ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 3283
Author(s):  
Norio Harada ◽  
Kana Nakatani ◽  
Ichiro Kimura ◽  
Yoshifumi Satofuka ◽  
Takahisa Mizuyama

Improvements in sediment retarding basin design are required to mitigate flood damage caused by bed load and wood debris outflow in lower river reaches. We used a scaled sediment retarding basin model to optimize our basin design, with the goal of improving sediment and wood debris transport and capture. Changes to the structural dimensions and elements of the sediment retarding basin were assessed under experimental debris flow conditions. The results obtained from the experiments and simulations were in good agreement regarding sediment flow and containment. The proposed one-dimensional model is useful for showing the effects of flow conditions within a sediment retarding basin on sediment transport.


2021 ◽  
Vol 3 (4) ◽  
pp. 15-23
Author(s):  
Silta Yulan Nifen ◽  
Afif Dzaky Almy

Batang Kuranji is a river located in Kota Padang. The high rainfall and human factors that cause changes in characteristics, especially in the upstream area make the water from the flow of kuranji stems in the rainy season often overflows, and cause flash floods, therefore built Check Dam at the head of the river batang kuranji to prevent the shallowing of the riverbed. Thisresearch aims toreview the structure of the Check Dam 3 building on Batang Kuranji in the city of Padang. This study refers to SNI 2851:2015 with rainfall data for 15 years used from 2005 to 2019, with batu busuk observation station and rice fields obtained from PSDA. Luas DAS is obtained from ArcGIS Applications. Dari hydroligi analysis obtained rainfall plan (R100th) 153,152 m3/dt with Gumbel method, Discharge flood plan for the 100 year anniversary period used Haspers method obtained (Q100th) 165.19 m3/dt. The type of Check Dam that is planned is the type of pelimpah (head work) with a height of Check Dam 8.5 m. Tilt of the body at the upstream 0.6, the distance between the main dam and sub dam 25.2 m, the thickness of the apron floor 1.6 m, with an estimated volume of sediment flow that can be accommodated by 14797.6 m3. The stability of the Check Dam construction was obtained at a value of 3.43 >1.5 and a sliding of 1.53 > 1.5 with a safety coefficient of 1.5, so that the construction of the Check Dam was stable.


2021 ◽  
Author(s):  
Andrei Kedich ◽  
Maxim Uspensky ◽  
Anatoly Tsyplenkov ◽  
Sergey Kharchenko ◽  
Valentin Golosov

<p>The highland cirques mostly created by nivation and glacial exaration take large areas in mountains and have a significant role in the sediment transit of the basins. The approximate view on the connection of cirques and low levels in the sediment flow could be given with the sediment connectivity index analysis. We study the spatial distribution of the index for typical ice cirque – the Koiyavgan cirque near the join of the Main Caucasus Range and its offshoot (the Gumachy range). This area is located in the tops of the Adyl-Su valley (left side of the Baksan river basin). In August 2020, we got a high-resolution orthophoto image (13+ cm) and digital elevation model (27+ cm) from aerial photography. The territory located in the elevation range from 3230 to 4022 m. Geological conditions: gneiss, metamorphic shale and basic dark coloured igneous rocks. There is no developed vegetation cover. Typical post-glacial cirques topography includes (top-down): mountain tops, very steep bedrock slopes, colluvial footslopes and fans, cirques bottom (moraine ridges with dividing valleys, craters from melting of the in-moraine covered ice etc.) with fluvial, avalanche and creep post-shaping, and bottom surface break as analogue of riegels in glacial trough valleys. The connectivity index (CI) after Cavalli et al. [2013] is very dependent on initial DEM resolution, from the method for filling mistaken depressions, from window size for computing intermediate geomorphometric variables (e.g. roughness index), from choice in flow impedance variable, from area coverage and terrain diversity and others. We compute connectivity index with the parameters: 1) DEM resolution – 27 cm; 2) impedance variable – terrain roughness index (standard deviation of elevation) with window 7*7 cells; 3) standard filling method used in the ArcMap (filling local depression without any limitations on maximum depth); 4) range of impedance values before normalization (partially related to area coverage) is from 0 to 72 m. In the some buffers from the channel network the connectivity index generally grows in the top-down direction. Greatest spurt of the CI values relates to the cirques low border - the riegel (3300 m asl). There are two levels characterised with low values of the CI: 3550 m and 3750 m. The first one is backside of cirques bottom with relatively low flow accumulation area and low-moderate slopes (0-25°), the second one is mountain tops with high steep slopes, but with lowest flow accumulation. For different geomorphodynamical zones the threshold of IC where sediment transit turns into sediment accumulation has differ values: for example, -2.3 for colluvial fans and -2.5 for alluvial fans (p-value for differences significance « 0.01). Maximum values of CI (quantile: the top-95%) for accumulative positions again are -1.27 and -0.72. Its means, those accumulative processes areas with different mechanics of the deposition may be delineated with using non-constant CI values only. The potential of sediment flow connectivity modelling for high mountain isn’t exhausted, but its application needs wide discussion and calibration.<br>The study was supported by the Russian Science Foundation (project No. 19-17-00181).</p>


2021 ◽  
Author(s):  
Hugo Fagundes ◽  
Fernando Fan ◽  
Rodrigo Paiva ◽  
Vinicius Siqueira ◽  
Diogo Buarque ◽  
...  

<p>Suspended sediments (SS) have an important role in the maintenance of several ecosystems by supplying them with nutrients. On the other hand, erosion and sediment transport can carry pollutants and pesticides, contributing to the negative impacts on the aquatic biota. Besides that, sediment supply for the rivers is often a driver to geomorphologic changes occurring in the rivers. Erosion and sediment rates in South America are considerably high in comparison to northern continents in the world. In this study we modeled the natural (non affected by reservoirs) spatio-temporal dynamic of suspended sediments in South America, including deposition rates in floodplain areas, using the sediment continental model MGB-SED SA. The model performance was evaluated aga inst 595 in-situ stations; 80 sites using results from regional studies; and 51 sites using results from a global sediment model. For most places, model performance analysis shows a better agreement between simulated and observed (in-situ) data than when results were compared to regional studies and a global model data. A better representation of sediment flow in rivers and floodplains was possible due to the use of hydrodynamic river routing. Based on MGB-SED SA estimates, South America delivers to the oceans 1.00×10<sup>9</sup> t/year of SS. The bigger suppliers are the Amazon (4.36×10<sup>8</sup> t/year), Orinoco (1.37×10<sup>8</sup> t/year), La Plata (1.11×10<sup>8</sup> t/year), and Magdalena (3.26×10<sup>7</sup>) rivers. Around 12% (2.40×10<sup>8</sup> t/year) of SS loads reaching the rivers are stored in the floodplains, showing the importance of these regions.  </p>


2021 ◽  
Author(s):  
NAHLA Naji HILAL ◽  
Marijana Hadzima Nyarko

Abstract Recycling plastic waste to obtain new materials such as concrete or mortar seems to be one of the best solutions for disposing of plastic waste. Second, in the construction industry, due to the increasing costs of landfills and the lack of a natural large aggregate, the increased interest in crushed ceramics is significant. The third type of waste that is dealt with in this article is tea ash because tea is the second most consumed beverage in the world and large amounts of waste are generated. This article attempts to develop the appropriate characteristics of self-compacting concrete by adding the following waste materials: plastic waste, tea waste and collapsed ceramics. In this paper, Fresh and hardened properties of self-compacting concrete with waste materials were investigated. The diameter and time of sediment flow, segregation, L-box ratio, and density of freshly compacted concrete mixtures were measured. Moreover, both 7, 14, and 28-day bending strength and 7 and 28-day bending strength of hardened self-compacting concrete samples were measured. The results proved the possibility of using plastic waste, tea waste and collapsed ceramics in self-compacted concrete, because they do not significantly reduce the hardened and fresh properties of self-compacted concrete.


Energy ◽  
2021 ◽  
Vol 218 ◽  
pp. 119522
Author(s):  
Bao Guo ◽  
Yexiang Xiao ◽  
Anant Kumar Rai ◽  
Quanwei Liang ◽  
Jie Liu

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