scholarly journals Analisis Kavitasi pada Saluran Transisi dan Peluncur Pelimpah Bendungan Kluet – Model Fisik Skala 1:60

2021 ◽  
Vol 28 (2) ◽  
pp. 173-178
Author(s):  
Imam Faudli ◽  
Azmeri Azmeri ◽  
Cut Dwi Refika
Keyword(s):  
Flow Velocity ◽  
Water Pressure ◽  
Steep Slope ◽  
Side Channel ◽  
Velocity Flow ◽  
River Region ◽  
In Series ◽  
Level 3 ◽  
Transition Channel ◽  
Local Water

River Region of  Baru-Kluet has a steep slope contour and high rainfall so that it is vulnerable to flooding while during the dry season rice fields experience drought due to lack of water. Therefore, a dam is built to mitigate these issues. The spillway is a flow-control component in the dam which is used to improve regulation and enlarge the flow rate that will cross the spillway building. Spillway that has a steep slope is vulnerable to hydraulic behavior called cavitation. The experiment was carried out at the River and Coast Laboratory of Syiah Kuala University, Indonesia. This study aims to determine the value of the damage cavitation index interval in each series and discharge variation. Cavitation index analysis method used formula of ratio between local water pressure and flow velocity. Flow velocity and pressure at each outflow discharge was collected from the experiment. The results of the damage cavitation index interval in the 0 series and the modified series are located at level 1 for the transition region, level 3 for the launcher region and level 2 for the launcher region of modified series. It is found that the change in series 0 to a modified series with extending width in the side channel, lowering the elevation of side channel, and displacement sill in the transition channel with the aim of reducing the flow velocity. This change still has the possibility of cavitation damage, but it is much safer than the cavitation results of the 0 series. High quality of materials or concrete are not recommended because they are expensive and economically unfeasible, therefore the use of slot aeration/aerator is a suitable option for this case. Keyword: Dam, spillway, cavitation, model test.  

scholarly journals PENGARUH VEGETASI TERHADAP TAHANAN ALIRAN PADA SALURAN IRIGASI

2019 ◽  
Vol 2 (2) ◽  
pp. 107-113
Author(s):  
I.E. Sulastri Sihotang ◽  
Eldina Fatimah ◽  
Masimin Masimin
Keyword(s):  
Flow Velocity ◽  
Field Observation ◽  
Flow Resistance ◽  
Grid Method ◽  
Flow Depth ◽  
Secondary Channel ◽  
Irrigation Channel ◽  
Velocity Flow

Irrigation channel in D.I. Timbang Deli, Deli Serdang district Sumut province has a total area of 520 Ha and a 5000 meter long secondary channel. Irrigation channel in D.I. Timbang Deli overgrown vegetation at the base and wall of the channel so it is expected to affect roughness. The objective of the study was the flow resistance with the variation of vegetation volume to the variation of the discharge. The method used in this study is field observation by measuring flow velocity, flow depth and vegetation volume (VT) on trapezoidal tract width of 3.75 m and height of 0.90 m along 154 m. Measurements were performed on 3 points of upstream, middle and downstream channels and 5 transverse dots X1 through X5 4 times with D1 debit variation of 1.32 m³/s and D2 of 0.98 m³/s. The dominant vegetation channels are rigid. Measurement velocity using current meter while for vegetation volume (VT) using grid method. The results showed that vegetation volume VT0 (0,00 m³/0,00%), VT1 (52,417 m³/21,14%), VT2 (70,7921 m³/24,51%) and VT3 (83,053 m³/30,42%). It is seen that the increase in vegetation volume can affect the flow resistance. The result of measurement increased the resistance of flow to VT0 0,052, VT1 equal to 0,062 with percentage 16,13%, VT2 equal to 0,108 with percentage 51,85% and VT3 equal to 0,122 with percentage 57,37% atD1. Meanwhile, at D2 there is an increase of flow resistance to VT0 by 0,044, VT1 is 0,052 with percentage 15,38%, VT2 equal to 0,058 with percentage 24,14% and VT3 equal to 0,070 with percentage 37,14%. This shows that the flow resistance VT0 is smaller than the flow resistance VT1, VT2 and VT3. From the above results are expected to conduct O P channels by surrounding communities and related government.

A new numerical method to approximate root water uptake fluxes in a mixed-dimensional 1D-3D setting

2021 ◽  
Author(s):  
Timo Koch ◽  
Hanchuan Wu ◽  
Kent-André Mardal ◽  
Rainer Helmig ◽  
Martin Schneider
Keyword(s):  
Analytical Solutions ◽  
Water Pressure ◽  
Numerical Test ◽  
Three Dimensional ◽  
Root Water Uptake ◽  
Richards Equation ◽  
Soil Pressure ◽  
Approximation Accuracy ◽  
Flux Approximation ◽  
Local Water

<p>1D-3D methods are used to describe root water and nutrient uptake in complex root networks. Root systems are described as networks of line segments embedded in a three-dimensional soil domain. Particularly for dry soils, local water pressure and nutrient concentration gradients can be become very large in the vicinity of roots. Commonly used discretization lengths (for example 1cm) in root-soil interaction models do not allow to capture these gradients accurately. We present a new numerical scheme for approximating root-soil interface fluxes. The scheme is formulated in the continuous PDE setting so that is it formally independent of the spatial discretization scheme (e.g. FVM, FD, FEM). The interface flux approximation is based on a reconstruction of interface quantities using local analytical solutions of the steady-rate Richards equation. The local mass exchange is numerically distributed in the vicinity of the root. The distribution results in a regularization of the soil pressure solution which is easier to approximate numerically. This technique allows for coarser grid resolutions while maintaining approximation accuracy. The new scheme is verified numerically against analytical solutions for simplified cases. We also explore limitations and possible errors in the flux approximation with numerical test cases. Finally, we present the results of a recently published benchmark case using this new method.</p>

Landslide susceptibility mapping using GIS and Remote Sensing: A case study of the Rangamati District, Bangladesh

2020 ◽  
Author(s):  
Afruja Begum ◽  
Md Shofiqul Islam ◽  
Md. Muyeed Hasan
Keyword(s):  
Remote Sensing ◽  
Water Pressure ◽  
Research Work ◽  
Slope Angle ◽  
Steep Slope ◽  
Landslide Susceptibility Mapping ◽  
Dominant Factor ◽  
Natural Phenomenon ◽  
Slope Aspect ◽  
Gis And Remote Sensing

Abstract The landslide is a natural phenomenon and one of the most commonplace disasters in the Rangamati Hill tract area which appeals for better forecasting and specify the landslide susceptible zonation. This research work examines the application of GIS and Remote Sensing techniques based on different parameters such as altitude, slope angle, slope aspect, rainfall, land-use land-cover (LULC), geology and stream distance by heuristic model to identify the landslide susceptible zones for the study area. Among the parameters, rainfall, steep slope, geology and LULC are the dominant factor that triggering the landslide. Clayey or silty soils of the study area during heavy and prolong rainfall behave a flow of debris due to water pressure within the soil, resulting landslides. Steep slope has greater influences for weather zones of the rock-masses for susceptible landslides. Result and field observation indicate that the population density and LULC has a vital effect on landslide within the study area. However, landslide susceptible zones were created based on the susceptibility map of the study area which shows that about 19.43% of the area are at low susceptible zone, 56.55% of the area are at medium susceptible zone, 19.19% of the area are in the high susceptible zone and 4.81% of the area is at the very high susceptible zone.

Coastline Change and Erosion-Accretion Evolution of the Sandwip Island, Bangladesh

2019 ◽  
pp. 434-447
Author(s):  
Al Emran ◽  
Md. Abdur Rob ◽  
Md. Humayun Kabir
Keyword(s):  
Water Depth ◽  
Water Pressure ◽  
Steep Slope ◽  
Erosion Processes ◽  
Coastline Change ◽  
The North ◽  
Topographic Slope ◽  
North Eastern ◽  
Near Shore ◽  
Different Parts

The study tries to analyze the morphological and hydrological changes and to establish their relationship in the Sandwip Island through the integration of Remote Sensing (RS) and Geographic Information Systems (GIS). The study concludes from the recent 30 years' data that the different parts of the island response different cycle of coastline change associated with hydrological dynamics. The resulted net loss of the coastline is about 6.98 km (0.23 km/y) and the net loss of the coastal area is about 23.99 km2 (0.8 km2/y). The erosion processes (increase in the water depth near shore) were active along the western and the south-western shores. This erosion of the island is facilitated by the steep slope of the bank, high tidal water pressure and loose bank materials. In contrast, the accretions (decrease in the water depth near shore) were taken place in the larger parts of the northern and the north-eastern shores of the island. This is due to the backwash sediment deposition with the favor of gentle topographic slope along shores.

scholarly journals Waves of Accelerated Motion in a Glacier Approaching Surge: the Mini-Surges of Variegated Glacier, Alaska, U.S.A.

1987 ◽  
Vol 33 (113) ◽  
pp. 27-46 ◽  
Author(s):  
Barclay Kamb ◽  
Hermann Engelhardt
Keyword(s):  
Flow Velocity ◽  
Pressure Wave ◽  
Water Pressure ◽  
Water System ◽  
Pressure Rise ◽  
Strain Wave ◽  
Overburden Pressure ◽  
Flow Acceleration ◽  
Accelerated Motion ◽  
Velocity Peak

AbstractPeriods of dramatically accelerated motion, in which the flow velocity increases suddenly from about 55 cm/d to a peak of 100–300cm/d and then decreases gradually over the course of a day, occurred repeatedly during June and July 1978–81 in Variegated Glacier (Alaska), a surging-type glacier that surged in 1982–83. These “mini-surges” appear to be related mechanistically to the main surge. The flow-velocity peak propagates down-glacier as a wave at a speed of about 0.3 km/h, over a reach of about 6 km in length. It is accompanied by a propagating pressure wave in the basal water system of the glacier, in which, after a preliminary drop, the pressure rises rapidly to a level greater than the ice-overburden pressure at the glacier bed, and then drops gradually over a period of 1–2 d, usually reaching a new low for the summer. The peak velocity is accompanied by a peak of high seismic activity due to widespread fresh crevassing. It is also accompanied by a rapid uplift of the glacier surface, amounting to 6–11 cm, which then relaxes over a period of 1–2 d. Maximum uplift rate coincides with the peak in flow velocity; the peak in accumulated uplift lags behind the velocity peak by 2 h. The uplift is mainly due to basal cavitation driven by the high basal water pressure, although the strain wave associated with the mini-surge motion can also contribute. Basal cavitation is probably responsible for the pulse of high turbidity that appears in the terminal outflow stream in association with each mini-surge. In the down-glacier reach, where the mini-surge waves are attenuating, the observed strain wave corresponds to what is expected for the propagating pulse in flow velocity, but in the reach of maximum mini-surge motion the strain wave has a form quite different, possibly related to special features in the mini-surge initiation process from that point up-stream. The flow acceleration in the mini-surges is due to enhanced basal sliding caused by the high basal water pressure and the consequent reduction of bed friction. A preliminary velocity increase shortly before the pressure wave arrives is caused by the forward shove that the main accelerated mass exerts on the ice ahead of it, and the resulting preliminary basal cavitation causes the drop in water pressure shortly before the pressure wave arrives. The mini-surge wave propagation is controlled by the propagation of the water-pressure wave in the basal water-conduit system. The propagation characteristics result from a longitudinal gradient (up-glacier increase) in hydraulic conductivity of the basal water system in response to the up-glacier increase of the basal water pressure in the mini-surge wave. The mini-surge waves are initiated in a succession of areas situated generally progressively up-glacier during the course of the summer season. In these areas, presumably, melt water that has accumulated in subglacial (?) reservoirs is released suddenly into the basal water system immediately below, generating a pressure rise that propagates down-stream from there. Relationships of the mini-surges to the main surge are seen in the role of high basal water pressure in causing the rapid glacier motion in both phenomena, in the pulse-propagation features of both, and in the high outflow turbidity associated with both. The mini-surges of Variegated Glacier have a strong resemblance to movement and uplift events observed in Unteraargletscher and Findelengletscher, Switzerland. This bears on the question whether the mini-surges are a particular characteristic of surge-type glaciers prior to surge.

scholarly journals Investigation of Ultrasound-Measured Flow Velocity, Flow Rate and Wall Shear Rate in Radial and Ulnar Arteries Using Simulation

2017 ◽  
Vol 43 (5) ◽  
pp. 981-992
Author(s):  
Xiaowei Zhou ◽  
Chunming Xia ◽  
Gandy Stephen ◽  
Faisel Khan ◽  
George A. Corner ◽  
...  
Keyword(s):  
Shear Rate ◽  
Flow Velocity ◽  
Flow Rate ◽  
Wall Shear Rate ◽  
Velocity Flow ◽  
Measured Flow ◽  
Wall Shear

scholarly journals Experimental Study on the Effect of Triangular Plate Barrier Height on Flow Velocity Distribution in Open Channels

2021 ◽  
Vol 2 (2) ◽  
pp. 31-36
Author(s):  
Lhiung Phung Hwa
Keyword(s):  
Velocity Distribution ◽  
Flow Velocity ◽  
Open Channel ◽  
Pitot Tube ◽  
Closed Channel ◽  
Velocity Flow ◽  
Velocity Changes ◽  
Automatic Tool ◽  
Data Collection Technique ◽  
Narrow Opening

Open and closed channel flow flows are distinct, the flow in the channels will constantly change. The flow will also be altered if the water level or flow velocity changes. It was found that employing the Pitot Tube Portable yielded findings identical to those calculated by other methods. A water transfer system is made up of natural or artificial structures via which water is moved from one site to another. The carrier building may be open or closed, depending on whether you want to utilize it as a shipping or receiving location. An open channel with a relatively narrow opening at the top is known as an open conduit. The speed data collection technique is carried out vertically, with a review point as illustrated above. The velocity of the flow was measured using a Pitot Tube Portable Automatic tool. The results are entered into the Froude number (fr) after each review point to determine the type of velocity flow at each Review point. The normal flow velocity distribution pattern emerges at the measurement sites of 450 cm, 500 cm, and 550 cm.

scholarly journals Short-term velocity and water-pressure variations down-glacier from a riegel, Storglaciären, Sweden

1998 ◽  
Vol 44 (147) ◽  
pp. 359-367 ◽  
Author(s):  
Brian Hanson ◽  
Roger LeB. Hooke ◽  
Edmund M. Grace
Keyword(s):  
Water Pressure ◽  
Spatial Coherence ◽  
Drainage System ◽  
Pressure Rise ◽  
Surface Velocity ◽  
Storm Events ◽  
Pressure Cycle ◽  
Large Water ◽  
Local Water ◽  
Subglacial Drainage

AbstractDuring the 1991 94 summer held seasons, time-correlated measure-merits of water pressure and surface speed were made over and down-glacier from a major riegel on Storglaciären, Sweden. Measurements were made at sub-hourly time-scales in order to discern details in the diurnal cycle. Large water-input events, typically associated with rain storms, produced coherent, lagged surface-velocity responses that could be understood in terms of till deformation or decoupling, and these have been discussed elsewhere. The consequences of smaller diurnal water-pressure events w ere more enigmatic, in that acceleration of ice flow generally preceded the onset of the local water-pressure rise. From consideration of these data and other work done on the hydrology of Storglaciären, we infer that the ice in this area is generally pushed from behind via a relaxation in extensional strain across the riegel. Hence, accelerations occur in response to increases in water pressure that occur up-glacier and that precede local water-pressure rises. In addition, following a period of large storm events, surface speeds became more spatially coherent and were in phase with the diurnal water-pressure cycle. This suggests that the large water-pressure events lead to a spatially more homogeneous subglacial drainage system. Sliding laws need to take into account such temporal changes in spatial coherence of the subglacial drainage system.

scholarly journals A novel permanent gauge-cam station for surface flow observations on the Tiber river

2016 ◽  
Author(s):  
Flavia Tauro ◽  
Andrea Petroselli ◽  
Maurizio Porfiri ◽  
Lorenzo Giandomenico ◽  
Guido Bernardi ◽  
...  
Keyword(s):  
Flow Velocity ◽  
Large Scale ◽  
Surface Flow ◽  
Video Data ◽  
Engineering Practice ◽  
Surface Hydrology ◽  
Flow Monitoring ◽  
Tiber River ◽  
Scale Particle ◽  
Local Water

Abstract. Flow monitoring of riverine environments is crucial for hydrology and hydraulic engineering practice. Besides few experimental implementations, flow gauging relies on local water level and surface flow velocity measurements through ultrasonic meters and radars. In this paper, we describe a novel permanent gauge-cam station for large scale and continuous observation of surface flows, based on remote acquisition and calibration of video data. Located on the Tiber river, in the center of Rome, Italy, the station captures one-minute videos every 10 min over an area oriented along the river cross-section of up to 20.6 × 15.5 m2. In a feasibility study, we demonstrate that accurate surface flow velocity estimations can be obtained by analyzing experimental images via particle tracking velocimetry (PTV). In medium illumination conditions (70–75 lux), PTV leads to velocity estimations in close agreement with radar records and is less affected by uneven lighting than large scale particle image velocimetry. Future efforts will be devoted to the development of a comprehensive testbed infrastructure for investigating the potential of multiple optics-based approaches for surface hydrology.

EFFECTS OF UPSTREAM SLOPE OF CLAY CORE AND HEIGHT OF THE ROCK FILL DAMS AGAINST HYDRAULIC FRACTURING

2016 ◽  
Vol 78 (8-5) ◽  
Author(s):  
Didiek Djarwadi ◽  
Kabul Basah Suryolelono ◽  
Bambang Suhendro ◽  
Hari Christady Hardiyatmo
Keyword(s):  
Hydraulic Fracturing ◽  
Water Pressure ◽  
Steep Slope ◽  
Upstream Face ◽  
Statistical Research ◽  
Element Analysis ◽  
Rock Fill ◽  
Clay Core ◽  
Base Width ◽  
Made In

Hydraulic fracturing in rock fill dams may occur in case where the upstream face of the clay core experiencing tension cracks due to the arching effects and water pressure from the reservoir. One of the causes of arching effects was the steep slope of the upstream clay core. A statistical research on the dam experiencing with hydraulic fracturing indicated that rock fill dams with un-compacted rock fill embankment zone with narrow and steep slope of core, where the ratio between height against base width of core > 2 were considered much more likely for hydraulic fracturing to occur, while if the ratio was between 1 to 2 were considered likely to occur. This paper investigates the height limitation of the rock fill dams on the ratio of the height against the base width of core of 2.00 and 2.50, which represent the conditions of more likely and much more likely hydraulic fracturing to occur. The clay cores were obtained from five (5) major dams in Indonesia; Batubulan, Batutegi, Pelaparado, Sermo and Wonorejo dams, where their heights vary from 37 m to 125 m. The variation of the clay core embankment materials was made in six (6) various fine contents, and compacted at their optimum moisture contents. Analysis was made on the modeled rock fill dam using finite element analysis with coupling of the stress, the deformation and the seepage analyses. The hydraulic fracturing may occur in case the vertical effective stresses in the upstream face of clay core were less than the water pressure from the reservoir. The results indicated that the maximum dam height with no hydraulic fracturing was governed by the percentage of fines in the clay core and the ratio of the height to the base width of the clay core. The clay core that consists of more fine contents, and smaller ratio of height against the base width of the clay core of the dam has greater resistance against hydraulic fracturing.  

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