scholarly journals Sediment Flow Characteristics in The Upper Slope of Volcanic Landscapes With Dryland Agriculture

2021 ◽  
Vol 6 (3) ◽  
pp. 241
Author(s):  
La Ode Hadini ◽  
Junun Sartohadi ◽  
M. Anggri Setiawan ◽  
Djati Mardiatno ◽  
Nugroho Christanto
Keyword(s):  
Water Level ◽  
Soil Loss ◽  
Average Rate ◽  
Discharge Rate ◽  
Measurement Data ◽  
Flow Characteristics ◽  
Suspended Sediments ◽  
Dryland Agriculture ◽  
Creative Commons ◽  
Sediment Flow

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

scholarly journals The Simplified of Suspended Sediment Measurement Method in Natural River (Case study of Kuning River in Yogyakarta, Indonesia)

2019 ◽  
Vol 5 (3) ◽  
pp. 243
Author(s):  
Bambang Yulistiyanto ◽  
Bambang Kironoto ◽  
Bangun Giarto ◽  
Mariatul Kiptiah ◽  
Muhammad Lutfi Tantowi
Keyword(s):  
Suspended Sediment ◽  
Cross Sections ◽  
Suspended Sediment Concentration ◽  
Flow Characteristics ◽  
Preventive Measure ◽  
Suspended Sediments ◽  
Sediment Concentration ◽  
Middle Part ◽  
Sediment Discharge ◽  
Sediment Flow

The accumulation of suspended sediment reduces the capacity in the river and deteriorates the water quality. Kuning  River in Yogyakarta is one of the main rivers in Yogyakarta, Indonesia, which is currently facing the issue of suspended sediments. To reduce the effect of suspended sediment and determine a preventive measure, hence, it is necessary to study the characteristics of the suspended sediment flow. Therefore, this study aims to investigate the suspended sediment flow characteristics, i.e. the velocity, and the concentration profiles at specific points in the transverse direction of the channel as well as the correlation of the suspended sediment discharge. Thirty (30) profiles of velocity and suspended sediment concentration were measured at six different points along the Kuning River. Opcon probe was used to measure suspended sediment concentration, while the propeller current meter was used to measure mean point-velocity profiles. Results of this study show the suspended sediment discharge ratio, defined as  are higher in the middle part of the channel than the one near the edge of the channel. The position of z/B where the values of  1 occurs at z/B = 0,19 and z/B = 0,75, which depend on the irregularity of the channel cross-sections. For practical purposes, the depth-averaged velocity and suspended sediment concentration can be determined from 1, 2 and/or 3 points measurement at y = 0,2D, 0,4D and 0,8D.

Effect of the Fish-Bone Dam Angle on the Flow Mechanisms of a Fish-Bone Type Dividing Dike

2020 ◽  
Vol 54 (3) ◽  
pp. 58-67
Author(s):  
Jia Ni ◽  
Linwei Wang ◽  
Xixian Chen ◽  
Luan Luan Xue ◽  
Isam Shahrour
Keyword(s):  
Water Level ◽  
Longitudinal Velocity ◽  
Flow Characteristics ◽  
Fish Bone ◽  
Flume Experiments ◽  
Lateral Velocity ◽  
Engineering Structures ◽  
Flow Mechanisms ◽  
River Training ◽  
Large Velocity Gradient

AbstractFish-bone type dividing dikes are river engineering structures used for river training and to protect a mid-channel bar from scour. The flow characteristics around fish-bone type dividing dikes are very complicated, especially near its fish-bone dam. To understand the flow and scour processes associated with fish-bone dams, this paper conducts a numerical simulation of flow characteristics for different fish-bone dam angles. Based on the Yudaizhou fish-bone type dividing dike of the Dongliu Waterway, a 3-D numerical model is established via Flow-3D to simulate the flow characteristics around a fish-bone type dividing dike, which is verified by flume experiments. Based on the results, the effects of different fish-bone dam angles on water level and velocity distribution are investigated. With increasing fish-bone dam angle, the longitudinal and lateral gradients of the water level gradually decreased, and the variation degree of the longitudinal velocity also decreased; however, the variation degree of the lateral velocity increased. Vortex areas formed around the fish-bone dam and the downstream zone of the dike. A large velocity gradient was found around the dike, and the downstream vortex area decreased with increasing fish-bone dam angle.

scholarly journals What Discharge Is Required to Remove Silt and Sand Downstream from a Dam? An Adaptive Approach on the Selves River, France

Water ◽  
2019 ◽  
Vol 11 (2) ◽  
pp. 392 ◽  
Author(s):  
Rémi Loire ◽  
Loïc Grosprêtre ◽  
Jean-René Malavoi ◽  
Olivier Ortiz ◽  
Hervé Piégay
Keyword(s):  
Water Level ◽  
Suspended Sediment Concentration ◽  
Suspended Sediments ◽  
Sediment Concentration ◽  
Small Rivers ◽  
Management Approach ◽  
Sand Transport ◽  
Environmental Objectives ◽  
Operational Information ◽  
Operational Tests

An increasing number of scientific studies are tackling the management of discharges downstream of dams for environmental objectives. Such management is generally complex, and experiments are required for proper implementation. This article present the main lessons from a silt sand removal experiment on a bypassed reach of a dam on the Selves River (164 km²), France. Three four-hour operational tests at maximum discharge (10, 15, and 20 m3/s) were carried out in September 2016 to determine the discharge required for transporting as much silt and sand as possible without remobilizing coarser sediments. In September 2017, an additional flow release was performed over 34 h at 15 m3/s. Suspended sediment concentration and water level were recorded throughout the releases. Monitoring at the reach scale was supplemented by morphological measurements. The results demonstrate that a discharge of approximately 10 m3/s enables significant transport of suspended sediments (SS), whereas a discharge of 15 m3/s enables significant sand transport. The results provide operational information on silt and sand transport applicable to other small rivers. This study represents an important contribution to the relatively sparse existing body of literature regarding the effects of water releases and sediment state. Our study also demonstrates that it is possible to successfully undertake water releases in small rivers with an adaptive management approach.

scholarly journals Numerical and Experimental Investigation of External Characteristics and Pressure Fluctuation of a Submersible Tubular Pumping System

Processes ◽  
2019 ◽  
Vol 7 (12) ◽  
pp. 949 ◽  
Author(s):  
Yan Jin ◽  
Xiaoke He ◽  
Ye Zhang ◽  
Shanshan Zhou ◽  
Hongcheng Chen ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Pressure Fluctuation ◽  
High Efficiency ◽  
Pressure Pulsation ◽  
Guide Vane ◽  
Measurement Data ◽  
Flow Characteristics ◽  
Measuring Point ◽  
Pumping System ◽  
Impeller Outlet

This paper presents an investigation of external flow characteristics and pressure fluctuation of a submersible tubular pumping system by using a combination of numerical simulation and experimental methods. The steady numerical simulation is used to predicted the hydraulic performance of the pumping system, and the unsteady calculation is adopted to simulate the pressure fluctuation in different components of a submersible tubular pumping system. A test bench for a model test and pressure pulsation measurement is built to validate the numerical simulation. The results show that the performance curves of the calculation and experiment are in agreement with each other, especially in the high efficiency area, and the deviation is minor under small discharge and large discharge conditions. The pressure pulsation distributions of different flow components, such as the impeller outlet, middle of the guide vane, and guide vane outlet and bulb unit, are basically the same as the measurement data. For the monitoring points on the impeller and the wall of the guide vane especially, the main frequency and its amplitude matching degree are higher, while the pressure pulsation values on the wall of the bulb unit are quite different. The blade passing frequency and its multiples are important parameters for analysis of pressure pulsation; the strongest pressure fluctuation intensity appears in the impeller outlet, which is mainly caused by the rotor–stator interaction. The farther the measuring point from the impeller, the less the pressure pulsation is affected by the blade frequency. The frequency amplitudes decrease from the impeller exit to the bulb unit.

Motor cortical activity during drawing movements: single-unit activity during sinusoid tracing

1992 ◽  
Vol 68 (2) ◽  
pp. 528-541 ◽  
Author(s):  
A. B. Schwartz
Keyword(s):  
Average Rate ◽  
Discharge Rate ◽  
Arm Movement ◽  
Discharge Pattern ◽  
Movement Direction ◽  
Cortical Cells ◽  
Preferred Direction ◽  
Constant Direction ◽  
Motor Cortical ◽  
Tuning Function

1. This study examines the neuronal activity of motor cortical cells associated with the production of arm trajectories during drawing movements. Three monkeys were trained to perform two tasks. The first task ("center----out" task) required the animal to move its arm in different directions from a center start position to one of eight targets spaced at equal angular intervals and equal distances from the origin. Movements to each target were in a constant direction, and the average rate of neuronal discharge with movements to different targets varied in a characteristic pattern. A cosine tuning function was used to map each cell's discharge rate to the direction of arm movement. This function spanned all movement directions, with a peak firing rate in the cell's preferred direction. 2. The second task ("tracing" task) required the animal to trace curved figures consisting of sine waves of different spatial frequencies and amplitudes. Both the speed and direction changed continuously throughout these movements. The cosine tuning function derived from the center----out task was used to model the activity of the cell during the tracing of sinusoids in the second task. Sinusoidal data were divided into 20-ms bins; instantaneous direction, speed, and discharge rate were analyzed bin by bin. This provided a way to compare directly the tuning parameters during a task with constant direction to a task where the direction varied continuously. 3. Movement direction as it changed during the tracing task was an important factor in the discharge pattern of cells that had discharge patterns that could be represented by the cosine tuning function. 4. The modulation of discharge rate during figure tracing depended on both the cell's preferred direction and the orientation of the figure. The activity of cells with preferred directions perpendicular to the axis of the sinusoidal figure was most modulated, whereas the activity of those cells with preferred directions aligned to the figure's axis was least modulated. 5. The cells with modulated activity tended to have firing rates that differed from the predicted cosine tuning function during the sinusoidal movements for those portions of the trajectory where the movement direction was in the cell's preferred direction. 6. Finger speed during figure tracing varied inversely with path curvature with the same relation that has been found during human drawing. To assess the relation of instantaneous speed to discharge rate, the component of the discharge pattern related to direction was subtracted from the total discharge.(ABSTRACT TRUNCATED AT 400 WORDS)

scholarly journals Holocene relative shore-level changes and Stone Age palaeogeography of the Pärnu Bay area, eastern Baltic Sea

The Holocene ◽  
2019 ◽  
Vol 30 (1) ◽  
pp. 37-52 ◽  
Author(s):  
Triine Nirgi ◽  
Alar Rosentau ◽  
Hando-Laur Habicht ◽  
Tiit Hang ◽  
Tõnno Jonuks ◽  
...  
Keyword(s):  
Baltic Sea ◽  
Water Level ◽  
Sea Level ◽  
Average Rate ◽  
Stone Age ◽  
Shore Level ◽  
Bay Area ◽  
Shore Displacement ◽  
Ancylus Lake ◽  
Eastern Baltic

The shore displacement and palaeogeography of the Pärnu Bay area, eastern Baltic Sea, during the Stone Age, were reconstructed using sedimentological and archaeological proxies and GIS-based landscape modelling. We discovered and studied buried palaeochannel sediments on the coastal lowland and in the shallow offshore of the Pärnu Bay and interpreted these data together with previously published shore displacement evidence. The reconstructed relative shore-level (RSL) curve is based on 78 radiocarbon dates from sediment sequences and archaeological sites in the Pärnu Bay area and reported here using the HOLSEA sea-level database format. The new RSL curve displays regressive water levels at −5.5 and −4 m a.s.l. before the Ancylus Lake and Litorina Sea transgressions, respectively. According to the curve, the total water-level rise during the Ancylus Lake transgression (10.7–10.2 cal. ka BP) was around 18 m, with the average rate of rise about 35 mm per annum, while during the Litorina Sea transgression (8.5–7.3 cal. ka BP), the water level rose around 14 m, with average rate of 12 mm per annum. During the short period around 7.8–7.6 cal. ka BP, the RSL rose in Pärnu, but probably also in Samsø (Denmark), Blekinge (Sweden) and Narva-Luga (NE Estonia–NW Russia), faster than the concurrent eustatic sea level calculated from the far-field sites. The palaeogeographic reconstructions show the settlement patterns of the coastal landscape since the Mesolithic and provide new perspective for looking Mesolithic hunter-fisher-gatherer settlement sites on the banks of the submerged ca. 9000 years old river channel in the bottom of the present-day Pärnu Bay.

Model Study for Upgrading of Sungai Belibis Pump Sump

2015 ◽  
Vol 802 ◽  
pp. 617-622 ◽  
Author(s):  
M.A.Z. Mohd Remy Rozainy ◽  
A.W. Khairy ◽  
Ismail Abustan ◽  
Mohd Mustafa Al Bakri Abdullah
Keyword(s):  
Water Level ◽  
Flow Rate ◽  
Flow Characteristics ◽  
Worst Case ◽  
Pump Flow ◽  
Model Study ◽  
Swirl Angle ◽  
Pump Flow Rate ◽  
Pump Sump ◽  
Model Features

Experimental study of hydraulic physical model investigates the flow characteristics in the pump sump. The model features four pumps (7.91 L/s for pump 1 and 2, and 4.74 L/s for pump 3 and 4) with a total of 9 cases of study. Different values of water depth (180mm, 200mm, and 300mm) and pump flow rate (15L/s, 20L/s, and 25L/s) were conducted. Velocity measurements at the dividing cross section were obtained by an Acoustic Doppler Velocimeter (ADV), pump flow rate by flow meter (Dyna Handheld Transit Time Ultrasonic Flow Meters) and swirl angle in the suction intakes were measured by a vortimeter/rotometer. No vortices were occurred near the suction intake at the high and medium water level conditions. In the low water level condition with high flow rate (25L/s), vortex Type 4 or 5 were observed near the suction intake and this condition is unacceptable. Since this condition indicate the presence of vortices more than Types 2 and an uneven flow through the suction intake, this can be categorized as the worst case and not recommended for pump sump operation.

Stratigraphy of the Sixteen Mile Creek lagoon, and its implications for Lake Ontario water levels

1988 ◽  
Vol 25 (8) ◽  
pp. 1175-1183 ◽  
Author(s):  
J. E. Flint ◽  
R. W. Dalrymple ◽  
J. J. Flint
Keyword(s):  
Water Level ◽  
Lake Michigan ◽  
Drainage Basin ◽  
Average Rate ◽  
Lake Ontario ◽  
Open Water ◽  
Water Levels ◽  
Beach Sand ◽  
Water Level Fluctuations ◽  
Lake Outlet

The sequence of units (from the base up) in the Sixteen Mile Creek lagoon (Lake Ontario) mimics the longitudinal sequence of surficial environments: pink silt—overbank (flood plain – dry marsh); bottom sand—stream channel and beach; orange silt—marsh; gyttja—wet marsh and very shallow (deltaic) lagoon; and brown and grey clay—open-water lagoon. This entire sequence accumulated over the last 4200 years under slowly deepening, transgressive conditions caused by the isostatic rise of the lake outlet. Land clearing by European settlers dramatically increased the supply of clastic sediment and terminated the deposition of the organic-rich silty clays (gyttja) that make up most of the lagoon fill.Because the gyttja and beach sand are interpreted to have accumulated in water depths of less than 0.5 m, the elevation–time plot of 14C dates from these units can be used to reconstruct a very closely constrained lake-level curve. The data indicate that water levels have risen at an average rate of 0.25 cm/a over the last 3300 years as a result of differential, isostatic rebound. Superimposed on this trend are water-level oscillations with amplitudes on the order of 1 m and periods of several hundred years. These oscillations are synchronous and in phase with water-level fluctuations in Lake Michigan, and with a variety of other climatic variations in North America and Europe. We propose, therefore, that the water-level oscillations are a result of long-term, climatically produced variations in precipitation in the Great Lakes drainage basin.

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