scholarly journals ANALISIS KECEPATAN JATUH SEDIMEN PADA SUNGAI CIBEET, JAWA BARAT

2021 ◽  
Vol 5 (1) ◽  
pp. 45
Author(s):  
Kevin Wijaya Warsito ◽  
Wati Astriningsih Pranoto
Keyword(s):  
Conceptual Understanding ◽  
Settling Velocity ◽  
Soil Mechanics ◽  
River Estuary ◽  
Sediment Concentration ◽  
Water And Sediment ◽  
Sediment Research ◽  
Hydraulics Laboratory ◽  
The Relationship ◽  
Optimum Salinity

Cibeet River is one of the branch of the Citarum river in West Java province with a length of 101 km. Cibeet River is one of the rivers supplying water and sediment to the West Tarum irrigation channel or known as the Kalimalang. In this research, the sample used was in the form of mud taken at the Cibeet River Estuary. This research is focused on settling velocity which is a parameter for sedimentation in order to improve numerical modeling and conceptual understanding of sediment dynamics, especially mud. Sediment research is carried out in the Soil Mechanics laboratory and Hydraulics laboratory. Bottom withdrawal tube experiments were carried out using 5 types of salinity and 6 kinds of sediment concentrations. The purpose of the study was to obtain settling velocity and compare laboratory results with the Stokes law approach and compare the relationship between settling velocity with sediment concentration and salinity. The optimum salinity is obtained at 15 ‰, and the optimum sediment concentration at 4700 ppm with an average fall speed of 37,28 mm / s. The results from the laboratory are not in accordance with the Stokes law due to the influence of flocculation from the cohesive nature of the mud sediment, so that using the Stokes law approach cannot calculate the velocity of falling sediment on the mud. Keywords: concentration; salinity; sediment; settling velocity AbstrakSungai Cibeet merupakan salah satu anak sungai dari sungai Citarum di provinsi Jawa Barat dengan panjang 101 km. Sungai Cibeet merupakan salah satu sungai pemasok air dan sedimen ke saluran irigasi Tarum Barat atau dikenal sebagai Kalimalang. Pada penelitian ini, sampel yang digunakan berupa lumpur yang diambil di Muara Sungai Cibeet. Penelitian ini difokuskan pada kecepatan jatuh sedimen yang merupakan parameter untuk sedimentasi demi meningkatkan permodelan numerik dan pemahaman konsep dari dinamika sedimen terutama lumpur.  Penelitian ini dilakukan di laboratorium Mekanika Tanah dan laboratorium Hidrolika, memakai bottom withdrawal tube, dilakukan dengan menggunakan 5 macam jenis salinitas dan 6 macam konsentrasi sedimen.  Penelitian ini membandingkan antara hasil laboratorium dengan pendekatan yaitu hukum Stokes serta membandingkan hubungan antara konsentrasi sedimen dengan salinitas. Untuk salinitas didapat optimum pada saat 15‰, dan konsentrasi sedimen yang optimum pada saat 4700 ppm dengan kecepatan jatuh rata-rata 37,28 mm/s. Hasil dari laboratorium tidak sesuai dengan pendekatan hukum stokes dikarenakan adanya pengaruh flokulasi dari sifat sedimen lumpur yang kohesif, sehingga menggunakan pendekatan hukum stokes tidak bisa untuk menghitung kecepatan jatuh sedimen pada lumpur.

The More, the Merrier? Roles of Device-Student Ratio in Collaborative Inquiries and Its Interactions With External Scripts and Task Complexity

2021 ◽  
pp. 073563312110107
Author(s):  
Cixiao Wang ◽  
Huixiao Le
Keyword(s):  
Conceptual Understanding ◽  
Repeated Measures ◽  
Task Complexity ◽  
Mainland China ◽  
Fifth Grade ◽  
Learning Context ◽  
Simple Task ◽  
Fifth Grade Students ◽  
Main Effect ◽  
The Relationship

In collaborative learning, the intuition “the more device, the merrier” is somehow widely acknowledged, but little research has investigated the relationship between device-student ratio and the learning outcome. This study aims to investigate not only the main effect of different device-student ratio, also to identify the moderators in the learning context including task complexity, external script availability and students’ familiarity to the collaboration settings. A three-round quasi-experiment was conducted in a primary school in mainland China, 130 fifth-grade students from four classes participated. Group worksheet including conceptual understanding and problem-solving tasks were used to collect participants’ inquiry performance. Repeated measures ANOVA was employed in data analysis. Findings indicate that 1:m device-student ratio could be beneficial, and external scripts, and prior collaboration experience could moderate such effect. The different effect of 1:m device-student ratio to 1:1 is only significant in the situation when students are faced with relatively simple task, and the effect size is larger when external script is present. When the task is more complicated, such effect of device-student ratio would only emerge after a period of collaboration. This finding challenged the intuition that one-to-one device-student ratio could be better. Related discussions and recommendations to teaching were made.

scholarly journals The Response of Turbidity Maximum to Peak River Discharge in a Macrotidal Estuary

Water ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 106
Author(s):  
Yuhan Yan ◽  
Dehai Song ◽  
Xianwen Bao ◽  
Nan Wang
Keyword(s):  
River Discharge ◽  
Recovery Time ◽  
Morphological Evolution ◽  
Spring Tide ◽  
River Estuary ◽  
Sediment Concentration ◽  
Ocean Model ◽  
Turbidity Maximum ◽  
Sediment Supply ◽  
Three Dimensional Model

The Ou River, a medium-sized river in the southeastern China, is examined to study the estuarine turbidity maximum (ETM) response to rapidly varied river discharge, i.e., peak river discharge (PRD). This study analyzes the difference in ETM and sediment transport mechanisms between low-discharge and PRD during neap and spring tides by using the Finite-Volume Community Ocean Model. The three-dimensional model is validated by in-situ measurements from 23 April to 22 May 2007. In the Ou River Estuary (ORE), ETM is generally induced by the convergence between river runoff and density-driven flow. The position of ETM for neap and spring tides is similar, but the suspended sediment concentration during spring tide is stronger than that during neap tide. The sediment source of ETM is mainly derived from the resuspension of the seabed. PRD, compared with low-discharge, can dilute the ETM, but cause more sediment to be resuspended from the seabed. The ETM is more seaward during PRD. After PRD, the larger the peak discharge, the longer the recovery time will be. Moreover, the river sediment supply helps shorten ETM recovery time. Mechanisms for this ETM during a PRD can contribute to studies of morphological evolution and pollutant flushing.

Temporal variation in the weight-size relationship of the mangrove crab Ucides cordatus L. (Decapoda: Ucididae) in relation to its life cycle phases

2014 ◽  
Vol 64 (4) ◽  
pp. 333-342 ◽  
Author(s):  
Marcos de Miranda Leão Leite ◽  
Cynthia Yuri Ogawa ◽  
Carla Ferreira Rezende ◽  
José Roberto Feitosa Silva
Keyword(s):  
Life Cycle ◽  
Condition Factor ◽  
River Estuary ◽  
Total Weight ◽  
Northeastern Brazil ◽  
Annual Life Cycle ◽  
Ucides Cordatus ◽  
Mangrove Crab ◽  
Significant Difference ◽  
The Relationship

The relationship between weight and size of individuals can be used to evaluate the status of a population, which is particularly useful for natural populations that are being exploited. Ucides cordatus occurs on the Atlantic coast of the American continent, from Florida (USA) to Santa Catarina (Brazil). This species is economically very important, most of all in the Northeastern area of Brazil, as well as in the Dominican Republic and Suriname. The objective of this study was to analyze life phases (‘fattening’, ‘matumba’, ‘milk-crab’, ‘maturation’ and ‘walking’) by use of the weight-length relationships, as well as temporal variations in this condition factor for each sex of U. cordatus. For this purpose, individuals were sampled monthly for twenty-four months at the Jaguaribe River estuary, Ceará State, Northeastern Brazil. The relationship between total weight and cephalothorax width was established using regression analysis, adjusted by a power equation. The dynamics of the condition factor were analyzed for each sex using the variation of its averages related to annual life cycle; this was done for each of the previously-mentioned phases. The relationship between total weight and cephalothorax width showed an isometric growth in males and negative allometric growth in females suggesting that, for the same reference size, males are heavier than females. When considering the average of the female condition factors, these were greater than those for males during the annual life cycle, except during the ‘maturation’ phase, which is the phase with a higher demand of energetic reserves for males. Annual variation of the condition factor in females presented no significant difference.

scholarly journals Learning with Leaflet of Electronegativity (LoEN): Enhancing Students' Understanding on Electronegativity, Chemical Bonding, and Polarity

2021 ◽  
Vol 10 (1) ◽  
pp. 60-68
Author(s):  
E. Erlina ◽  
C. Cane ◽  
D. P. Williams
Keyword(s):  
High School ◽  
Undergraduate Students ◽  
Conceptual Understanding ◽  
Chemical Bonding ◽  
Theoretical Basis ◽  
Classroom Discussion ◽  
Paired Sample ◽  
Full Color ◽  
Before And After ◽  
The Relationship

Previous research has reported that many high-school and undergraduate students have difficulty explaining the relationship between polarity and electronegativity even though they may be familiar with the concept of polarity. This study aims to address these misconceptions using a leaflet and assess its effectiveness using questionnaires and concept testing.  A simple, colorful printable leaflet was produced and distributed to students in Indonesia. The Leaflet on Electronegativity (LoEN) provided students with an overview of the theoretical basis of the concepts and guidance on applying these principles. The leaflet format is cheap and easy to mass-produce, which is an important factor given the limited access to other types of appropriate learning resources in Indonesia. The leaflet formed the basis of a classroom discussion activity. Visualization is known to play an important role in constructing students' conceptual understanding, so the leaflet made extensive use of diagrams to explain relevant concepts. The leaflet was printed in full color to make it visually appealing and facilitate student learning. Students were tested before and after learning with the LoEN. A Paired-sample t-test using SPSS is used to compare the pretest and posttest scores to measure the effectivity of the LoEN.A statistically significant improvement in scores (p = 0.000) was achieved, which indicates that using the LoEN in the classroom helps students understand the topic. Also, students' positive responses signify that the LoEN provides an engaging way to learn the concepts.

scholarly journals Response of Variation of Water and Sediment to Landscape Pattern in the Dapoling Watershed

2022 ◽  
Vol 14 (2) ◽  
pp. 678
Author(s):  
Chong Wei ◽  
Zhiqiang Zhang ◽  
Zhiguo Wang ◽  
Lianhai Cao ◽  
Yichang Wei ◽  
...  
Keyword(s):  
Landscape Pattern ◽  
Sediment Yield ◽  
Landscape Heterogeneity ◽  
Swat Model ◽  
Landscape Patterns ◽  
Land Resource ◽  
Low Carbon ◽  
Water And Sediment ◽  
The Relationship ◽  
Runoff And Sediment Yield

The relationship between water-sediment processes and landscape pattern changes has currently become a research hotspot in low-carbon water and land resource optimization research. The SWAT-VRR model is a distributed hydrological model which better shows the effect of land use landscape change on hydrological processes in the watershed. In this paper, the hydrological models of the Dapoling watershed were built, the runoff and sediment yield from 2006 to 2011 were simulated, and the relationship between landscape patterns and water-sediment yield was analyzed. The results show that the SWAT-VRR model is more accurate and reasonable in describing runoff and sediment yield than the SWAT model. The sub-basins whose soil erosion is relatively light are mostly concentrated in the middle reaches with a slope mainly between 0–5°. The NP, PD, ED, SPIIT, SHEI, and SHDI of the watershed increased slightly, and the COHESION, AI, CONTAG, and LPI showed a certain decrease. The landscape pattern is further fragmented, with the degree of landscape heterogeneity increasing and the connection reducing. The runoff, sediment yield and surface runoff are all extremely significantly negatively correlated with forest, which implies that for more complicated patch shapes of forest which have longer boundaries connecting with the patches of other landscape types, the water and sediment processes are regulated more effectively. Therefore, it can be more productive to carry out research on the optimization of water and soil resources under the constraint of carbon emission based on the SWAT-VRR model.

The relationship between settling velocity grading and the characteristics of the contributing catchment

1996 ◽  
Vol 33 (9) ◽  
pp. 135-142 ◽  
Author(s):  
J. Naomi Tyack ◽  
Peter D. Hedges ◽  
Robert P. M. Smisson
Keyword(s):  
Wastewater Treatment ◽  
Settling Velocity ◽  
Careful Selection ◽  
Predictive Tool ◽  
Regression Techniques ◽  
Research Relationships ◽  
Water Companies ◽  
The Relationship ◽  
Dry Weather Flow ◽  
Selection Of

A method for measuring the settling velocity gradings of both storm and dry weather flow (DWF) sewage was investigated. This method was then used experimentally to determine whether a relationship exists between the settling velocity grading of a sewage as it enters a treatment works and the characteristics of the contributing catchment. The problems associated with the collection of data on the characteristics of the contributing catchments are discussed. These include the availability of up to date information within the water companies and the time consuming nature of collecting full sets of information for a particular wastewater treatment works. An S-shaped curve was fitted to all the settling velocity gradings produced during the research. Relationships relating the curve constants to the catchment characteristics were derived using multiple regression techniques. The methodology was proved, but the model was not sensitive enough to be used successfully as a predictive tool without further analysis involving either more sites and/or a more careful selection of the test sites.

Sign in / Sign up

Export Citation Format

Share Document