Conference PaperPDF Available

A Case Study of the River Training Work of Padma River: Assessment of Local Slope Protection Measures

Authors:

Abstract and Figures

This study aspires to represent a wholesome advertence on the River Training Work (RTW) of Padma River (Bangladesh) based on an in-situ observation, scrutinizing the process weighing it against various river slope protection criteria. Geotextile bags and Cement Concrete (CC) blocking are the main features for slope protection in this project where selection of proper gradation of fine aggregate (to be used inside the bags, D50>O90), selection of coarse aggregate and fine aggregate to be used for CC Blocking, proper placement of geotextile bags and CC blocks along the slope with varying depth from the river bank are important parameters to be fulfilled with respect to Standard C.F values. Based on the sieve analysis and Atterberg limit test, identification of fine sand (to be used inside the bags) and river bank soil type was made respectively. A mathematical model is used to observe the stability of slope using these slope protection measures against adverse embankment failure. The result shows the methodology adopted by Bangladesh Water Development Board (BWDB) partially meets the standard criteria for river bank protection (when wave velocity ≤3ms-1).
Content may be subject to copyright.
Proceedings of Civil and Water Resources Engineering Conference,
3-4 November 2017, BIAM Foundation, 63 Eskaton, Dhaka, Bangladesh
ISBN: 978-1-925488-52-4
A Case Study of the River Training Work of Padma River:
Assessment of Local Slope Protection Measures
Md. Enayet Chowdhury1; Ahmed Hossain2; H.M.Muktadir3
ABSTRACT
This study aspires to represent a wholesome advertence on the River Training Work (RTW) of Padma River
(Bangladesh) based on an in-situ observation, scrutinizing the process weighing it against various river slope
protection criteria. Geotextile bags and Cement Concrete (CC) blocking are the main features for slope
protection in this project where selection of proper gradation of fine aggregate (to be used inside the bags,
D50>O90), selection of coarse aggregate and fine aggregate to be used for CC Blocking, proper placement of
geotextile bags and CC blocks along the slope with varying depth from the river bank are important parameters
to be fulfilled with respect to Standard C.F values. Based on the sieve analysis and Atterberg limit test,
identification of fine sand (to be used inside the bags) and river bank soil type was made respectively. A
mathematical model is used to observe the stability of slope using these slope protection measures against
adverse embankment failure. The result shows the methodology adopted by Bangladesh Water Development
Board (BWDB) partially meets the standard criteria for river bank protection (when wave velocity 3ms-1).
Introduction
The Padma is acknowledged as a major river in Bangladesh arising from river bifurcation of the Ganges being
the main distributary of it. In terms of average annual discharge, the Padma is classified as the third largest river
in the world, only surpassed by the Congo and Amazon (Schumm and Winckley, 1994). The Padma possesses a
catchment area of 1.57 million km2. Strenuous southwest monsoon precipitation (June to October) induces the
fluid circulation of the Padma. Off that period, the drift is mainly associated with the base flow and snow
melting in the Himalayas. Length averaged width of the river is about 10.5 km, while annual maximum erosion
rate may transcend 1,000 m/year (Figure 1) [1], illustrating the location of highly erodible and less erodible bank
materials along symmetric slopes of the river (Figure 2) [1]. Such phenomenon catalyzes the urgency of an
observant River Training Work (RTW) for the Padma. Bangladesh Water Development Board (BWDB) is the
corresponding authority for this project under Ministry of Water Resources, Government of the People’s
Republic of Bangladesh.
Methodology Adopted for the River Training Work
1. For Revetment constructed slope dimension is 1V:3.5H, but practically Non-Dredged Natural Slope is
maintained because of the inefficiency of Cutter Suction Dredgers for under water work scopes.
RipRap Dumping which induces dumping of boulders- a rock fragment with size greater than 25.6 cm
and Geotextile Bags- produced from stitching high strength geotextile fabric and Cement Concrete
(CC) Blocking are used for wave protection.
1 Undergraduate Student, Dept. of Civil Engineering, Bangladesh University of Engineering and Technology
(BUET), Dhaka-1000, Bangladesh (corresponding author). E-mail: enayet108@gmail.com, Phone:
+8801684919608
2 Undergraduate Student, Dept. of Civil Engineering, Bangladesh University of Engineering and Technology
(BUET), Dhaka-1000, Bangladesh. E-mail: ahmed.hossain100@gmail.com
3 Undergraduate Student, Dept. of Civil Engineering, Bangladesh University of Engineering and Technology
(BUET), Dhaka-1000, Bangladesh. E-mail: muktadir_tanvir@yahoo.com
A Case Study of the River Training Work of Padma River: Assessment of Local Slope Protection Measures
Md. Enayet Chowdhury1; Ahmed Hossain2; H.M.Muktadir3
2. For Embankment construction of Dredged Slope using Cutter Suction Dredgers and later compacted
by Roller.
3. Geotextile Bags (Figure 3) are of dimension 1250×1000×3mm and Standard Weight (without
moisture by Tender) is 800kg, 250kg and 125kg. Sieve Analysis Specification by tender is 90% of the
filled sand must be retained on the standard #100 U.S sieve. A Total Station (Figure 9) is used to set up
the Cardinal Directions where the Geotextile bags will be Dumped [at 1m interval, 4 bags per layer, (6
bags per layer in deeper section): (Figure 4)] and set the Burge parallel to the Dumping Direction. Bags
are stitched by a Machine (Figure 6).
4. Cement Concrete (CC) Blocking (Figure 5) dimensions for dumping: 45×45×45 cm3 and 35×35×35
cm3 and for Placing (in the embankment): 45×45×30 cm3 Coarse aggregate and fine aggregate should
have a nominal diameter of 40~50mm and fineness modulus 1.5 respectively. Portland Composite
Cement (PCC) is used.
Figure 1: Erosion along the Padma River (CEGIS, 2014)
Figure 2: Location and extent of Low and Highly
Erodible bank materials along the Padma
River (CEGIS, 2005)
(3)
(4)
(5)
(6)
Figure*: (3) Geotextile Bags; (4) Dumping of bags in cardinal directions set up by Total Station; (5)
Cement Concrete (CC) Block; (6) Stitching of Geotextile Bags; (7) Steel CC Block Casting; (8) Geotextiles
Bags above water in layers; (9) Total Station *Photos by Authors.
(7)
(8)
(9)
Proceedings of Civil and Water Resources Engineering Conference,
3-4 November 2017, BIAM Foundation, 63 Eskaton, Dhaka, Bangladesh
ISBN: 978-1-925488-52-4
Table 1: Properties of Geotextiles used for Bags
(Oberhagemann, K., Hossain, M.M., 2010)
Evaluation of Local Slope Protection Criteria
1. Fine Sand used inside the Geotextile bags must be retained being allowed by the Opening Size, O90
(see Table 1) of the bag. Soil sample collected from the site, exhibits a median diameter, D50 of
0.24mm (>standard O90) (see Figure 10). It fulfills the standard criteria (Oberhagemann, K. and
Hossain, M.M., 2010). It retains 95.76% material (from Figure 10) (>90%) on #100 U.S Standard
Sieve, which satisfies standard set up by Bangladesh Water Development Board (BWDB). Moreover,
the bags are dumped in multiple-layer coverage (Figure 8) to prevent Winnowing Failure (Melville and
Coleman, 2000), a failure due to loss of fines through gaps between the bags.
2. The hydrodynamic stability of the protective elements on slopes can be assessed by the equation
(Stevens, 2006)
C.F = u2/ (2gk) (1)
= (𝛾𝑠-𝛾)/ 𝛾 (2)
Table 3: Atterberg Limit Test result for the
Embankment soil sample of Padma
(ASTM D4318 and D2487-11)
Numerical
Values
34.86
28.77
6.09
From equation of A-Line,
PI=0.73(LL-20)=10.89; that implies the soil
sample is Low Plastic Silt (ML)
Properties
Test Standards
Test Values
Opening size, O90
EN ISO 12956
0.06mm and
0.08mm
Mass Per Unit Area
BS EN 965
400 g/m2
CBR Puncture
Resistance
EN ISO 12236
4000N
Elongation at
Maximum Force
(MD)
EN ISO 10319
60% and 100%
Elongation at
Maximum Force
(CMD)
EN ISO 10319
40% and 100%
Permeability
EN ISO 11058
2×10-3 ms-1
UV Resistance
ASTM D4355C
70% of original
strength
0
10
20
30
40
50
60
70
80
90
100
0.010.1110
Percent Finer
Sieve Opening Diameter (mm)
Grain Size Distribution
Figure 10: Sieve Analysis Result of the Sand of
Geotextile Bags in the Padma
(ASTM D 422-63 R02)
Figure 11: C.F Coefficients required for displacement
of protective elements on slopes
(Stevens and Oberhagemann, 2006)
A Case Study of the River Training Work of Padma River: Assessment of Local Slope Protection Measures
Md. Enayet Chowdhury1; Ahmed Hossain2; H.M.Muktadir3
Here, u=velocity of water over the element; g= gravitational acceleration (9.81 m/s2); k= (V0/A) = effective
thickness of the element; V0=volume of element; A=area over which hydrodynamic forces act; 𝛾𝑠=density of the
particles; 𝛾=density of water; C=coefficient; F=adjustment factor to account for issues not directly addressed in
the analysis.
Table 2: C.F Calculation for Concrete Block (for Normal Weight Concrete, 𝛾𝑠=150 lb/ft3, 𝛾=62.5 lb/ft3, =1.4;
from Eq. 2)
Dimension
(cm3)
Weight
(in Kg)
V0 (m3)
A (m2)
k (m)
u** (ms-1)
C.F
Standard***
(Figure 11)
C.F
(from
Eq. 1)
45×45×45
218.78
0.091
0.61* (1)
0.15
3
2.86
2.19
35×35×35
103.02
0.043
0.12* (2)
0.35
3
1.35
0.93
45×45×35
170.10
0.061
0.41* (3)
0.15
3
2.22
2.17
*Number of Susceptible Surfaces: for (1) =3; for (2) =1; for (3) =2
**Median Velocity by rivers in Bangladesh (Oberhagemann, K., Hossain, M.M., 2010)
***A linear relationship is assumed between the weight of protective elements and C.F standard values
From Table 2, it is scrutinized that every block dimension has a C.F value, not exceeding the standard one. This
represents the elements will not be removed by this median velocity range (Oberhagemann, K., Hossain, M.M.,
2010). But blocks (2) and (3) should not be used under water, for having calculation with less number of
susceptible surfaces. Moreover, the bank-failure mechanism of Padma is associated with formation of tension
cracks described as Slab-Type Rotational Failure (Hossain, M.B. et al., 2010)
Conclusions
Slope protection measures set up by Bangladesh Water Development Board (BWDB) successfully meet (for
Geotextile Bags) and partially meet (for CC Blocks) the standard values recognized above for the Padma.
However, during monsoon, the velocity, u may exceed 3ms-1 benchmark and rise up to as high as 4.5 ms-1,
which is enough to move protective elements in the slope, but by dumping the elements in close proximity
allows better prevention against wave attack. Jute Geotextile Bags are biodegradable, used in this project. But
concrete block may create an adverse effect in the river atmosphere. Bioengineering technique should be mostly
appreciated by the concerned authority for this type of river bank protection which is environment friendly.
References
[1] General Economics Division, Planning Commission, Government of Bangladesh (2015), Bangladesh Delta Plan
2100 Formulation Project: River System Management” Dhaka.
[2] Hossain, M.B., Sakai, T., Hossain, M.Z., 2010, “River Embankment and Bank Failure in Bangladesh: A Study on
Geotechnical Characteristics and Stability Analysis”, Proc. of International Conference on Environmental Aspects of
Bangladesh (ICEAB10), Japan, Sept. 2010
[3] Melville, B.W., Coleman, S.E., 2000. Bridge Scour. Water Resources Publication
[4] Oberhagemann, K., Hossain, M.M., 2010 “Geotextile bag revetments for large rivers in Bangladesh”, Geotextiles
and Geomembranes, doi:10.1016/j.geotexmem.2010.12.003
[5] Schumm A., and Winckley B.R., 1994, The Variability of Large Alluvial Rivers, ASCE Press, New York
[6] Stevens, M.A., Oberhagemann, K., 2006. Special Report 17: Geobag Revetments, Prepared for Jamuna-Meghna
River Erosion Mitigation Project, Bangladesh Water Development Board, May.
[7] Stevens, M.A., 2006. Special Report 19: Morphology Mission Report. Prepared for Jamuna-Meghna River
Erosion Mitigation Project, Bangladesh Water Development Board, May.
... ( Chahinian et al., 2005;Chowdhury et al., 2017). Liu et al. (2013) discussed infiltration regulation under sustained and small intensity rainfall. ...
... Other measurement techniques such as mini-disk infiltrometer or artificial rainfall simulator (Chowdhury et al., 2017). ...
... The waves thus formed eventually hit the embankment toe and slopes. The high hydraulic loads exerted on the embankment cause erosion and if there is overtopping, the physical structure of the embankment is destroyed (Chowdhury, Hossain and Muktadir, 2017). The presence of continuous borrow-pits on a river or seaside induces undercutting of the embankment toes and slopes due to complete inundation of the riverbank or seashore during the monsoon and thus inundated induce a parallel water current to flow along very near the embankment toes and slopes, thereby eroding the surfaces . ...
... The Padma River in central Bangladesh is approximately 100 km long and flows in a south-east direction from the confluence of the Jamuna (or Brahmaputra) and the Ganges to join the upper Meghna River, below which point it is known as the Lower Meghna [1]. In terms of average annual discharge, it is classified as the third largest river in the world, only surpassed by the Congo and Amazon [2]. Strenuous southwest monsoon precipitation (June to October) induces the fluid circulation of the Padma. ...
Article
A well and exact documentation of the methodology and novel implementations of a river training work can pave the way for future economic, established and cost effective paradigm to work with. The paper describes contemporary practice for river training works, as well as site specifics, obstacles, costs involved and management exercises, along the Padma River, the main distributary of the river Ganges. A map of the riverbank erosion along the study area is provided in order to extract proper and useful information about the morphological nature of the river. Then the technical aspects for bathymetric survey along with the application procedure used for dumping and placing of geo-bag and CC block along the riverbank for its protection is described. After that, some of the concerns and challenges that were encountered by the team, which was working there, are discussed. It was found that the project would have benefited if the technical and instrumental risks in addition to the uncertainty of workers were taken into account beforehand. A cost analysis table is also provided to give information about the estimated expenditure for future projects.
... Obtained fines were added to each of three base sand samples, S-1, S-2 and S-3 in varying amount (0, 3, 5, 8, 10 and 15% by weight). The gradation curve ( Figure 2) shows a median diameter, D50 of 0.25 mm, which is close to the median diameter of the soil sample collected from Padma river (D50 = 0.24 mm) used inside the geotextile bags (Chowdhury, Hossain and Muktadir, 2017). Pertinent physical properties of the three base samples are presented in Table 1. ...
Article
Full-text available
This study establishes a mathematical relationship between angle of internal friction, fines content and maximum or minimum dry density for non-plastic fines. Sand samples of three different fineness moduli (1.3, 1.5 and 1.7) were used and six different percentages (0, 3, 5, 8, 10, 15% by weight) of fines content were simulated for each fineness modulus. Direct Shear Test, Maximum Index Density Test and Minimum Index Density Test were performed on the corresponding samples. Results from laboratory tests were used as numerical inputs in the software, assigned in three distinct variables. Among 120 completely different combinations with respect to degrees of independent variables and variables allocation in X, Y and Z data, some combinations were chosen to validate with data available in the existing literature on the basis of goodness of fit parameters. Among them, two equations (generated from polynomial surface fitting) of third-order polynomial mostly converged with the validation data. It seems that the proposed equations can perform satisfactorily to estimate any of the variables considered when the other two are known.
Article
Since the late 1990s, riverbank revetments constructed of sand-filled geotextile bags (geotextile bags) have been developed in Bangladesh in response to the lack of traditional erosion-protection materials, particularly rock. After independence in 1971 and the related loss of access to quarries, rock was replaced by concrete cubes, but those are expensive and slow to manufacture. Geotextile bags on the other hand, first used as emergency measures during the second half of the 1990s, can be filled with local sand and therefore provide the opportunity to respond quickly to dynamic river changes.Geotextile bags also provide the potential for substantial cost reduction, due to the use of locally available resources. The use of the abundant local sand reduces transport distance and cost, while local labor is used for filling, transporting, and dumping of the 75–250kg bags. Driven by the need for longer protection, the idea of using geotextile bags for permanent riverbank protection emerged in 2001. Eight years of experience have enabled systematic placement of geotextile bag protection along about 12km of major riverbanks at a unit cost of around USD 2M per km. By comparison, concrete-block revetments cost around USD 5M per km. In addition, there are strong indications that geotextile bags perform better than concrete blocks as underwater protection, largely due to their inherent filter properties and better launching behavior when the toe of the protected underwater slope is under-scoured.This article reports the outcome of the last eight years of development work under the ADB-supported Jamuna-Meghna River Erosion Mitigation Project (ADB, 2002), implemented by the Bangladesh Water Development Board. Besides substituting geotextile bags for concrete blocks as protective elements, the project involved development of a comprehensive planning system to improve the overall reliability and sustainability of riverbank protection works.
Bangladesh Delta Plan 2100 Formulation Project: River System Management
General Economics Division, Planning Commission, Government of Bangladesh (2015), "Bangladesh Delta Plan 2100 Formulation Project: River System Management" Dhaka.
River Embankment and Bank Failure in Bangladesh: A Study on Geotechnical Characteristics and Stability Analysis
  • M B Hossain
  • T Sakai
  • M Z Hossain
Hossain, M.B., Sakai, T., Hossain, M.Z., 2010, "River Embankment and Bank Failure in Bangladesh: A Study on Geotechnical Characteristics and Stability Analysis", Proc. of International Conference on Environmental Aspects of Bangladesh (ICEAB10), Japan, Sept. 2010
  • B W Melville
  • S E Coleman
Melville, B.W., Coleman, S.E., 2000. Bridge Scour. Water Resources Publication
The Variability of Large Alluvial Rivers
  • A Schumm
  • B R Winckley
Schumm A., and Winckley B.R., 1994, The Variability of Large Alluvial Rivers, ASCE Press, New York
Special Report 17: Geobag Revetments, Prepared for Jamuna-Meghna River Erosion Mitigation Project
  • M A Stevens
  • K Oberhagemann
Stevens, M.A., Oberhagemann, K., 2006. Special Report 17: Geobag Revetments, Prepared for Jamuna-Meghna River Erosion Mitigation Project, Bangladesh Water Development Board, May.
Special Report 19: Morphology Mission Report. Prepared for Jamuna-Meghna River Erosion Mitigation Project
  • M A Stevens
Stevens, M.A., 2006. Special Report 19: Morphology Mission Report. Prepared for Jamuna-Meghna River Erosion Mitigation Project, Bangladesh Water Development Board, May.