1) The document analyzes the changing trends of hydrological and morphological parameters of the Surma and Kushiyara river systems in Bangladesh through statistical analysis of hydrological data, morphological modeling using HEC-RAS, and GIS analysis. 2) Field data from 2011-2014 was used to calibrate and validate hydrodynamic models of the two river systems to investigate patterns of cross-sections and sediment transport. 3) The models show changes in bed levels and bank shifting for the Kushiyara River but not the Surma River, and can be used to predict future changes to cross-section patterns.

1. Journal of Modern Science and Technology
Vol. 6. No. 1. March 2018 Issue. Pp.113-123
113
Assessment of Hydro-Morphological Change of
Surma-Kushiyara River System
Md. Sabbir Mostafa Khan 1*
and Purnima Das2
Bangladesh stands on a thick alluvial deposit. It is the result of
deltaic activity of the Ganges and the Brahmaputra. These main
rivers, their tributaries and distributaries control its hydrological and
morphological behavior. The morphology of a river channel is a
function of a number of processes and environmental conditions,
including the composition and erosion possibility of the bed and
banks (e.g., sand, clay, bedrock).This study analyzes the changing
trends of hydrological and morphological parameters of Surma and
Kushiyara river system. The field of research is focused on rive
hydrology and river morphology.
Keywords: Erosion; Deposition; Sedimentation.
1. Introduction
Channel morphology is the result of mutual interactions of four broad categories
ofvariables such as fluid dynamics (which include velocity, discharge, roughness and
shear stress), channel characteristics or channel configuration (e.g. channel width,
channel depth, channel slope, channel shape, channel pattern etc.), sediment load
and Bed and bank materials (composition and character i.e. coarse, fine, medium
etc.). The theory of river sedimentation and morphological processes are among the
most complex and least understood phenomena in nature (Alam et al. 2007). In this
case, measurement of sediment concentrations at certain location would depend of
course on local flow conditions, but also on conditions upstream and on the flow
history. Field surveys, with the purpose of understanding the process, would then
include very large amount of information. To collect the data and analyze it would be
a very costly and time-consuming task. In that respect, mathematical modeling is an
alternate tool to understanding the detail physical processes in the nature.
Mathematical modeling has been introduced as a tool to interpret the information
provided by the field data in an integrated way. The mathematical models enable
interpolation and extrapolation in space and time based on the observations from the
field and on the understanding of the physical processes and their interaction to the
extent that of its incorporation in the model. Various 1-D, 2-D and 3-D hydrodynamic
and sediment modules are in use in water engineering sector.
In this case the Analysis process includes statistical analysis of hydrological data like
water level and discharge, morphological analysis by using HEC-RAS 1D model and
cooperation of GIS and HEC-GeoRAS. The application of GIS and HEC-GeoRAS
______________________
1
Dr. Md. Sabbir Mostafa khan, Professor, Department of Water Resources Engineering, Bangladesh
University of Engineering and Technology (BUET), Dhaka, Bangladesh,
Email: sabbirkhanbuet@gmail.com
2
Purnima Das, Graduate Student, Department of Water Resources Engineering, Bangladesh
University of Engineering and Technology (BUET), Dhaka, Bangladesh,
Email: pinkiwre10@gmail.com

2. Khan & Das
114
helped in calculating Bank-line shifting of the study area. The Unsteady models were
run for the year 2012 both for the Surma and Kushiyara river system. The Manning’s
n value for Surma River was 0.03. In addition, for Kushiyara River the value was
0.013. The model is used to investigate the pattern of the cross-section. The
sediment transport model was run for 2012 year and was used to investigate the
pattern of the cross-section. The model shows remarkable changes in the bed level
in the case of Kushiyara River and shows no such changes in the Surma River.
Moreover, the model can be used for predicting the changed pattern of the cross-
sections using the predicted discharge data of the Surma-Kushiyara river system.
In this paper, Section 1 deals with Introduction while Section 2 focuses on Literature
Review and Section 3 contains Methodology. Results and discussion are provided in
Section 4 and Conclusion is in Section 5.
2. Literature Review
Surma-Meghna River System is one of the three major river systems of Bangladesh.
It is the longest river (669 km) system in the country. It also drains one of the world's
heaviest rainfall areas (e.g. about 1,000 cm at Cherapunji, Meghalaya, India). East of
Brahmaputra-Jamuna River system is Surma-Meghna River System. The Surma
originates in the hills of Shillong and Meghalaya of India. The main source is Barak
River, which has a considerable catchment in the ridge and valley terrain of Naga-
Manipur hills bordering Myanmar. Barak-Meghna has a length of 950 km of which
340 km lies within Bangladesh. On reaching the border with Bangladesh at Amalshid
in Sylhet district, Barak bifurcates to form the steep and highly flashy rivers Surma
and kushiyara. Surma flows west and then southwest to Sylhet town. From there it
flows northwest and west to Sunamganj town. Afterward it maintains a course
southwest and then south to Markuli to meet Kushiyara. The joint flow goes upto
Bhairab Bazar as the Kalni. Environmental Impact Assessment case study of Surma
–Kushiyara River has been studied for this analysis. Morphological analysis of
Surma- Kushiyara is a very new study. Due to great changes experienced by the
river system, it has been subject to investigation and studies. Gupta(2012)described
the effect of tectonics and meandering in the moderately paced avulsion of the
Ganga-Bhagirathi system to the present Ganga-Padma using the Landsat program.
The study revealed that gradient advantage and bend upstream of bifurcation does
not result in modeled avulsion as observed in small and medium rivers and large
rivers in tectonically active regions. A tectonic uplift results in a modeled avulsion
period consistent with historical observations. The study also showed that backwater
effect and high sediment mobility keepboth bifurcated channels active to attain an
Ana branching pattern. The backwater effect was found to play an important role for
sustaining the anabranch plan form of many of the largest rivers of the world by the
said study. Reza (2016) expanded on the theory of the fluvial morphological
characteristics of the Padma River in northwestern Bangladesh. Morphological and
morpho-dynamic maps of the Padma River were prepared using remote sensing
techniques. Sinuosity ratio, braided index and island percentage of the study area
were estimated for the years of 1977, 1989 and 2000respectively. Outcomes of this
study obtained from investigating satellite remote sensing imagery provide valuable
information about the bank erosion, channel shifting of fluvial morphology of the
Padma River, and recommended some protective measures. Hossain et al. (2013)
assessed morphological changes of the Ganges River using satellite images. Using

3. Khan & Das
115
eight dry season satellite images of Landsat MSS (1973-1984), Landsat TM(1993-
2003), and IRS LISS (2009), this study assessed morphological changes of the
Ganges River within Bangladesh. The results indicate that both the left and the right
banks of Ganges have changed significantly due to varying erosion and accretion
rates that had occurred. On a whole, the left bank was more prone to accretion while
the right bank to erosion. Baca (2015)described the process due to the nature of the
Ganges River, integration of cultural connectivity is becoming ever more prominent.
Climate change has also exposed the need for the creation and revising of trans-
boundary water sharing agreements. Be it through the interference of flow due to
dams, the unhealthful interaction between the river and the floodplain, or the
increased variability of the river due to climate change, the river, and its
management is more tumultuous than ever. The theory of the part of the old
Brahmaputra River, off taking from Jamuna is located under the district of
Mymensingh and partially under the district of Tangail, Jamalpur, Sherpur and
Netrokona (Alam et al. 2007). Analyzing the image of part of the old Brahmaputra
River among the year 1997 and 2004, it is found that Significant changed has been
occurred in north east part of Mymensingh sadarupazila and less change is found in
the lower part which is close to the Mymensingh town where China Bangladesh
Friendship Bridge (Shambhuganj Bridge) has been constructed. Transportation of
sediment is the major contributing factor of morphological changes.Rouf
(2011)described the process of hydro-morphological characteristics and water
quality parameters of Shitalakhya River. In this study, the variation of cross sectional
area, maximum depth and top width at different sections for different period was
observed and it was found that rivers show negligible shifting of channel from one
bank to the other. This is the theory usedon the river Ganga at Varanasi for
calculating amount of meandering in the form of change of sinuosity at two
consecutive bends (Singh, SM 2014). For this purpose10 years of satellite imagery
data has been analyzed of the Ganga River, using Arc GIS combined with historical
data. The result shows that sinuosity varies from 1.66 to1.26 and silt deposition of
two bends varies from 4.52 to 3.14 and 3.4 to 2.42 respectively. Laz (2012)described
the process of Simulation of sediment transport rate at the river Jamuna and
variation of bed level along the river by using a two dimensional morphological
model. Non- cohesive sediment transport module of Delft 3D Flow is used for the
simulation used in the study. Result shows that erosion takes place in the channel
bed, the deposition mainly takes place on the adjacent char areas, and both its width
and area are increased. It is also evident that the channel has beenshifted
westwards of the reach due to shifting of the bank line of the river and the zones of
higher velocity has higher sediment transport capacities causing more erosion.
Begum (2009) described the process of the siltation observed in Mongla portand
developed a hydrodynamic and a sediment model of Pasur river system using HEC-
RAS. From the model it was found that, both siltation and erosion occurred in the
Mongla port area and erosion was prominent at the downstream of Mongla port
(near downstream of Danger Khal). Based on the study of the literature review this
study will focus on the hydro morphological change of the Surma-Kushiyara River
system by HEC-RAS model and GIS software.

4. 3. Methodology
For the study different sets
level) and topographic data as
up the model preprocessing G
DEMs are increasingly used
landscapes and landforms, a
comprises of a resolution of
measured with respect to the
projected on to the Banglades
Figure 2: C
After taking the DEM of Bang
The DEM of Sylhet is clipped
Toolbox. After clipping the DE
Raster to TIN tool is to create
does not deviate from the in
done by using the Raster to T
Khan & Das
s of data named hydrologic data (discharge
as Digital Elevation Model (DEM) data were u
GIS data was necessary.
Figure 1: Study Area
d for visual and mathematical analysis of
, as well as modeling of surface processes
of 30m x 30m. The elevation of the DEM
e mean sea level. All the data in the DEM
esh Transverse Mercator (BTM).
Clipping the DEM of Sylhet Division
gladesh, the Shape file of Sylhet division is s
ed from the whole DEM using the Clipping
EM, it is converted to the TIN format. The pu
te a Triangulated Irregular Network (TIN) wh
input raster by more than a specified Z tole
TIN tool in the Arc Toolbox.
116
ge and water
e used. To set
of topography
es. The data
M has been
M have been
s superposed.
g Tool in Arc
purpose of the
hose surface
olerance. It is

5. Figur
For the preparation of channe
To create 1D geometry we us
floodplain. The goal of this
generate a HEC-RAS import
sections. This extraction com
river centerline, cross-section
upstream and downstream sid
Figure 4: Drawing River Ce
C
For setting up an unsteady h
versus time has been consid
Surma River, Kanaighat (SW
discharge station. Flow hydrog
Upstream Boundary Condition
24.887°
, Long. 92.190°
) has
Kushiyara River. Flow hydrog
Upstream Boundary Condition
Khan & Das
re 3: Transforming DEM to TIN
nel geometry, preprocessing was done in HE
used the bathymetric grid only and excluded
s section was to develop the spatial data
rt file with a 3-D river network and defined
mprises of several steps. These are develo
ions, riverbanks, and flow path lines as sh
side of the flood plain respectively.
enterline, Bank Lines, Flow Path and Cros
Cut Lines for Surma River
hydrodynamic model, a flow hydrograph o
idered as Upstream Boundary Condition. In
W266; Lat. 25.004°
, Long. 92.270°
) is th
rograph of the year 2013 of this station has be
ion. The flow hydrograph of station Sheola (S
s been used as Upstream Boundary Cond
graph of the year 2011 of this station has be
on. A stage hydrograph of water surface elev
117
EC-GeoRAS.
ed the nearby
ta required to
ed 3-D cross
elopment of a
shape files of
oss-Section
of discharge
In case of the
the upstream
been used as
(SW173; Lat.
ndition of the
been used as
vation versus

6. time was used as the dow
Sunamganj Station (SW269;
of the Model. Stage hydrograp
a Downstream Boundary C
(SW270; Lat. 24.691°, Long.
Condition of the Kushiyara Ri
was used as a Downstream B
Figure 5: Surma Riv
For Surma-Kushiyara river sys
calibrate the Kushiyaraand Su
2014 has been used to valid
value of 0.030 for main cha
channel of Kushiyara River ha
Figure 6:Calibratio
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.00
WS
ELEVATION,
M
Calibrat
Khan & Das
wnstream boundary condition. For the Su
; Lat. 25.071°
, Long. 91.410°
) is at the down
raph of the year 2013 of Sunamganj station w
Condition. The stage hydrograph of Mar
g. 91.390°) has been used as Downstream
River. Stage hydrograph of the year 2011 of
Boundary Condition.
iver Schematic in HECRAS Geometry Edi
ystem, the data of year 2011 and 2013 has b
Surma River respectively and the data of ye
lidate Kushiyara and Surma River System
hannel of Surma river and n' value of 0.01
have been fixed.
tion of the Kushiyara River (‘n’ value 0.013
DATE
ration graph of 2011 for the Kushiyara
Observed Wat
Simulated wat
118
Surma River,
wnstream end
was used as
arkuli Station
am Boundary
of this station
ditor
been used to
ear 2012 and
. Finally, `n'
.013 for main
13)
ved Water Level(m)
ated water level (m)

7. Figure 7: Calibr
Finally, `n' value of 0.030 for
main channel of Kushiyara Riv
Figure 8: Validatio
0.00
2.00
4.00
6.00
8.00
10.00
12.00
WS
ELEVATION,
M
Cali
0.00
1.00
2.00
3.00
4.00
5.00
6.00
7.00
8.00
9.00
10.00
WS
ELEVATION,
M
Valida
Khan & Das
ration of the Surma River (‘n’ value 0.03)
r main channel of Surma River and n' value
iver have been fixed.
tion of the Kushiyara River (‘n’ value 0.013
DATE
libration graph of 2013 for the Surma
Observed Wate
Simulated Wate
DATE
dation graph of 2012 for the Kushiyara
Observed Wate
Simulated Wat
119
e of 0.013 for
13)
ed Water Level (m)
ed Water Level (m)
ed Water Level(m)
ted Water level (m)

8. Figure 9: Valida
Sediment modeling is deve
unsteady flow data and sedim
RAS can perform mobile bed
flow series data. Quasi-uns
temperature file. For sedimen
data. In this study, this tempe
the year of 2012. For sedim
depth, Sediment transport f
method are required. The obs
m. Therefore, the maximum
three boundary conditions: Ra
In this study, equilibrium load
file, quasi-unsteady flow and
January 2012 to 29 Decem
considered to show changing
Figure 10: Eroding Cros
0.00
2.00
4.00
6.00
8.00
10.00
12.00
WS
Elevation,
m Validatio
Khan & Das
dation of the Surma River (‘n’ value 0.03)
veloped for selected reach of Ganges R
diment data sets required to build up this m
ed sediment routing computations with quas
nsteady flow data includes boundary con
nt transport mechanics, HEC-RAS requires
erature was assumed as 25 degrees Celsius
ment transport analysis Selection of maxim
formulas, Sediment sorting method and
bserved maximum erosion at the thalweg is
erodible depth is set to 15 m. HEC-RAS
Rating curve, Sediment load series, and equi
d is used as boundary condition. After definin
nd sediment data, sediment model is simul
mber 2012. Upstream and downstream s
g bed level of those river.
osssection at Kushiyara River for Upstrea
Downstream Station
Date
Validation graph of 2014 for the Surma
Observed Wat
Simulated Wa
120
River. Quasi
model. HEC-
asi- unsteady
onditions and
s temperature
ius throughout
mum erodible
d fall velocity
s less than 15
S model has
uilibrium load.
ning geometry
ulated for 1st
stations are
eam and
ved Water Level (m)
ated Water Level (m)

9. Figure 11: Non-Eroding
The model result showed rem
and bed remain unchanged fo
Khan & Das
g Crosssection at Surma river for Upstrea
Downstream Station
markable changes in the bed level for Kushiy
for Surma River.
121
eam and
iyara River

10. Khan & Das
122
4. Results and Discussion
Morphological change is a very complex phenomenon and plays an important role in
gaining knowledge of rivers. In this study, a successful hydrodynamic and
morphological model has been developed and run for Surma and kushiyara River
System. Hydrodynamic model of 1D river was established for the Surma and
Kushiyara Rivers. Calibration Model for Surma was done for 2013 and for Kushiyara,
was done for the year 2011.It was based on the data availability of the rivers. The
Calibration Models was established for Surma River for Manning’s n value of 0.03.In
addition, for Kushiyara River the value was 0.013. Validation Model for Surma was
done for 2014 and for Kushiyara, was done for 2014.It was also based on the data
availability of the rivers. Calibration and validation of the model show good
correlation between the observed and simulated data. Two unsteady models were
run for 2012 year and were used to investigate the pattern of the cross-section. The
sediment transport models were run for 2012 year and were used to investigate the
pattern of the cross-section. The model result and observed results showed
remarkable changes in the bed level of Kushiyara River and no changes in Surma
River. Moreover, the model can be used for predicting the changed pattern of the
cross-sections using the predicted discharge data of these rivers.
5. Conclusion
In this analysis, an average 25degree Celsius temperature was used for a whole
year. In practice, however, there is monthly variation of average temperature, so
using the same temperature for the 1-year-run is not justifiable. To obtain esult that
is more precise HEC-RAS 2-D model or DELFT-3D model can be used.
Due to the lack of sediment data, an equilibrium sediment load for all the cross
sections was considered. However, in nature sediment load varies according to river
velocity, river width, scouring, flow disruption due to structures etc. If proper
sediment load series data were available, the model result would be more realistic.
The model result showed remarkable changes in the bed level for Kushiyara River
and bed remain unchanged for Surma River. This type of model can be used for any
other rives. Using this model, we can identify the characteristics of a specific river.
This type of morphological assessment studies can give us an idea of proper river
training works, constructing embankments where this type of structure is needed and
future policy- making.
This specific model is different because for the first time it has been constructed for
Surma-Kushiyara and it identifies any characteristics required.
References
Alam, JB, Uddin, M, Ahmed, UJ, Cacovean, H, Rahman, HM,Banik, BK and Yesmin,
N 2007, ‘Study of Morphological Change of River Old Brahmaputra and Its
Social Impacts by Remote Sensing’, Geographia Technica, No.2, viewed 19
February 2017, <http://technicalgeography.org/pdf/2_2007/gt_2_2007.pdf>
Baca, EA 2015, ‘The Ganges River: Symbology, Sustainability, and The Confluence
of Cultural and Fluvial Connectivity’, BSc thesis, Texas State University, San
Marcos, Texas.

11. Khan & Das
123
Begum, M 2009, ‘Study of Siltation of Mongla Port Using HEC-RAS 4.0’,BSc thesis,
Bangladesh University of Engineering and Technology, Dhaka, Bangladesh.
Gupta, N 2012, ‘Channel planform dynamics of the Ganga-Padma system, India’,
PhD thesis, University of Southampton, Southampton, United Kingdom.
Laz, OU2012, ‘Morphological Assessment of a Selected Reach of Jamuna River by
Using DELFT3D Model’, MSc thesis, Bangladesh University of Engineering and
Technology, Dhaka, Bangladesh.
Reza, A and Islam, MT 2016, ‘Assessment of Fluvial Channel Dynamics of Padma
River in Northwestern Bangladesh’, Universal Journal of Geoscience, Vol. 4,
No. 2, Pp. 41-49.
Rouf, T 2011, ‘A Study on Hydro-Morphology and water quality of Shitalakha River’,
BSc thesis, Bangladesh University of Engineering and Technology, Dhaka,
Bangladesh.
Singh,SM 2014, ‘Morphology Changes of Ganga River over time at Varanasi’,
Journal of River Engineering, Vol. .2, Issue. 2, viewed 22 February 2017,
<http://www.scijour.com/page/download-KZgwhmHl2eU.artdl>