Equation development for resistance coefficient estimation for selected rivers in the highland areas of Malaysia / Susie Nadya David Asen
At present state-of-knowledge, the selection of roughness coefficients for natural rivers still remains chiefly-an-art and is merely done by referring to typical tabulated values listed in any hydraulic textbooks or handbook manuals alongside with photographs of rivers which the values are mostly...
| Main Author: | |
|---|---|
| Format: | Thesis |
| Language: | English |
| Published: |
2010
|
| Subjects: | |
| Online Access: | https://ir.uitm.edu.my/id/eprint/4269/ |
| _version_ | 1848802752666271744 |
|---|---|
| author | David Asen, Susie Nadya |
| author_facet | David Asen, Susie Nadya |
| author_sort | David Asen, Susie Nadya |
| building | UiTM Institutional Repository |
| collection | Online Access |
| description | At present state-of-knowledge, the selection of roughness coefficients for natural rivers
still remains chiefly-an-art and is merely done by referring to typical tabulated values
listed in any hydraulic textbooks or handbook manuals alongside with photographs of
rivers which the values are mostly unjustified for rivers in other areas of different
conditions. Computations that are based solely on assumptions or predictions from
secondary sources often result to error in hydraulic design. Despite various studies
conducted to quantify the Manning’s n values for various river conditions as happening
in developed countries, Malaysia is still lack of such activities. Thus, the present study
attempts to derive an equation to estimate the roughness coefficient for rivers
specifically located in the highland areas of Malaysia because a proper understanding on
rivers should start from its nearest source by ensuring that extensive field database from
these rivers are made available for proper quantification of the bed roughness coefficient
which would be very useful for future planning of the rivers. Comprehensive field
measurements at 29 rivers located in the highland areas throughout Malaysia were
conducted which involve data collection and laboratory analysis over an extended period
of time. The newly collected database was used to evaluate the existing resistance
equations to obtain Manning, Darcy-Weisbach and Chezy resistance coefficients.
Suitability checking was carried out by comparing the results of the calculated velocity
(Vcalc) with the measured velocity (Vmeas) obtained from field measurements. 30 existing
resistance equations were evaluated and checked for their discrepancy ratios within
range of 0.5 to 2.0, which none of the equations exceed 50% passing. Therefore,
development of an equation was carried out using 77 data. The new equation; f =
1.309(R/d50)-1.86E-03(RS/d50)0.048 presented here was developed through the Multiple
Linear Regression Analysis, was found suitable to estimate the Darcy-Weisbach
resistance coefficient for rivers in the highland area having water-surface slope, So(%)
ranging from 0.1 to 5.7 and bed material grain size ranging from 1mm to 3072mm.
Suitability test was carried out again to validate the equation with 24 holdout samples
which then the discrepancy ratio obtained a percentage of 58.33%. |
| first_indexed | 2025-11-14T21:28:21Z |
| format | Thesis |
| id | uitm-4269 |
| institution | Universiti Teknologi MARA |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-14T21:28:21Z |
| publishDate | 2010 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | uitm-42692022-04-21T04:21:11Z https://ir.uitm.edu.my/id/eprint/4269/ Equation development for resistance coefficient estimation for selected rivers in the highland areas of Malaysia / Susie Nadya David Asen David Asen, Susie Nadya TA Engineering. Civil engineering River, lake, and water-supply engineering At present state-of-knowledge, the selection of roughness coefficients for natural rivers still remains chiefly-an-art and is merely done by referring to typical tabulated values listed in any hydraulic textbooks or handbook manuals alongside with photographs of rivers which the values are mostly unjustified for rivers in other areas of different conditions. Computations that are based solely on assumptions or predictions from secondary sources often result to error in hydraulic design. Despite various studies conducted to quantify the Manning’s n values for various river conditions as happening in developed countries, Malaysia is still lack of such activities. Thus, the present study attempts to derive an equation to estimate the roughness coefficient for rivers specifically located in the highland areas of Malaysia because a proper understanding on rivers should start from its nearest source by ensuring that extensive field database from these rivers are made available for proper quantification of the bed roughness coefficient which would be very useful for future planning of the rivers. Comprehensive field measurements at 29 rivers located in the highland areas throughout Malaysia were conducted which involve data collection and laboratory analysis over an extended period of time. The newly collected database was used to evaluate the existing resistance equations to obtain Manning, Darcy-Weisbach and Chezy resistance coefficients. Suitability checking was carried out by comparing the results of the calculated velocity (Vcalc) with the measured velocity (Vmeas) obtained from field measurements. 30 existing resistance equations were evaluated and checked for their discrepancy ratios within range of 0.5 to 2.0, which none of the equations exceed 50% passing. Therefore, development of an equation was carried out using 77 data. The new equation; f = 1.309(R/d50)-1.86E-03(RS/d50)0.048 presented here was developed through the Multiple Linear Regression Analysis, was found suitable to estimate the Darcy-Weisbach resistance coefficient for rivers in the highland area having water-surface slope, So(%) ranging from 0.1 to 5.7 and bed material grain size ranging from 1mm to 3072mm. Suitability test was carried out again to validate the equation with 24 holdout samples which then the discrepancy ratio obtained a percentage of 58.33%. 2010 Thesis NonPeerReviewed text en https://ir.uitm.edu.my/id/eprint/4269/1/TM_SUSIE%20NADYA%20ANAK%20DAVID%20ASEN%20EC%2010_5%201.pdf David Asen, Susie Nadya (2010) Equation development for resistance coefficient estimation for selected rivers in the highland areas of Malaysia / Susie Nadya David Asen. (2010) Masters thesis, thesis, Universiti Teknologi MARA. <http://terminalib.uitm.edu.my/4269.pdf> |
| spellingShingle | TA Engineering. Civil engineering River, lake, and water-supply engineering David Asen, Susie Nadya Equation development for resistance coefficient estimation for selected rivers in the highland areas of Malaysia / Susie Nadya David Asen |
| title | Equation development for resistance coefficient estimation for selected rivers in the highland areas of Malaysia / Susie Nadya David Asen |
| title_full | Equation development for resistance coefficient estimation for selected rivers in the highland areas of Malaysia / Susie Nadya David Asen |
| title_fullStr | Equation development for resistance coefficient estimation for selected rivers in the highland areas of Malaysia / Susie Nadya David Asen |
| title_full_unstemmed | Equation development for resistance coefficient estimation for selected rivers in the highland areas of Malaysia / Susie Nadya David Asen |
| title_short | Equation development for resistance coefficient estimation for selected rivers in the highland areas of Malaysia / Susie Nadya David Asen |
| title_sort | equation development for resistance coefficient estimation for selected rivers in the highland areas of malaysia / susie nadya david asen |
| topic | TA Engineering. Civil engineering River, lake, and water-supply engineering |
| url | https://ir.uitm.edu.my/id/eprint/4269/ |