River training work of river venkatapura

2. Contents
• Introduction
• Erosion and scouring
• Protective measures
• Literature review
• IS code design recommendation
• Study area
• Tools and techniques used
• Morphometric analysis
• steady flow
• Result and discussion
• Conclusion
• Reference

3. INTRODUCTION
• River silting and scouring are frequant problems in
meandering course.
• The Structures like dike, groyne, Bandalling.
• To reduce the velocity,deflecting the flow away from
the bank safety,increase flow depth(Navigation)
• The comparative study needed for satisfies required
velocity/flow depth for B/C

4. Objectives of river training work
• To know the river from changing its course
• To protect flooding of settlement area by safe
passing flood discharge
• To analyse Morphometric charecterstics of the
watershed
• To minimize scouring or erosion of river bank
• To ensure effect disposal of sediment load

5. Silting and scouring process
Fig 1:Typical silting and scouring process at river bend
• Silting(deposition)
• Scouring(erosion)

6. Preventive measures
Fig 2: Rip rap revetment Fig 3:Geobag revetment
Fig 4: Concrete precast block revetment

7. Literature view
Name of the author Title of the paper Date of
publication
Tools and methedology
Jens Kiesel et.el Application of a
hydrological-hydraulic
modelling cascade in
lowlands for investigating
water and sediment fluxes
in catchment, channel and
reach
30 sep 2013 Simulation of water and sediment
fluxes from the catchment to the reach
scale. Using SWAT(ArcGis
extension),HEC RAS and ADH.
Naveen Naidu Maddukuri
et.el
Design of embankment
and bank protection works
for hilly rivers
June 2015 the present study the flood
embankments and bank protection
measures are designed for hilly river in
different reaches by using predicted
water levels for 100 years return
period. Predicted water levels are used
to finalize the top level of the
embankments by adding sufficient free
board in the vulnerable reaches.The
predicted water level for 100 yr
discharge HEC-RAS
Amir Hamzeh Haghiabi and
Ehsan Zaredehdasht
Evaluation of HEC-RAS
Ability in Erosion and
Sediment Transport
Forecasting
March 2012 The authors studied sedimentation
analysis in Mollasani river station(Iran)
using HEC RAS 4
Md. Mostazur Rahman MODELING FLOOD
INUNDATION OF THE
JAMUNA RIVER
March, 2015 The study is conducted for extension
of floodplain and inhundation map of
Jamuna river using Bathymetry and
HEC RAS

8. IS code design recommendation
As per IS 14262-1995, “Planning and design guideline for revetment”
• Weight of stone on horizontal bed is
W=0.023
𝑆 𝑎
(𝑆 𝑎−1)3 𝑉6 (1)
‘W’ weight of stone in kg, Sa specific gravity of stone, and ‘V’ mean velocity of water in m/s
over the vertical under reference.
• Correction factor ‘K’ for computing weight of stone on sloping face may be obtained
from the following equation:
K = 1 −
𝑠𝑖𝑛𝜃2
𝑠𝑖𝑛𝛷2 (2)
Where,
θ = angle of bank slope with horizontal, and Φ= repose of material of protection.
• Size of the stone ‘Ds’, may be determined from the following relationship:
Ds =0.124
3 𝑊
𝑆𝑠
(3)
where
W = weight of stone in kg, and SS = specific gravity of stones.
• Minimum thickness of protection layer is required to withstand the negative head created
by velocity. This may be determined by the following relationship:
T=
𝑉2
2𝑔(𝑆𝑠−1)
(4)
Where, T = thickness of protection layer in m,V=velocity in m/s

9. Study area
Fig 5:Location map of Venkatapura watershed

10. • Venkatapur river originating from the Western Ghats near Bhatkal and
flows in Bhatkal and Sagar taluk before reaching to Arabian sea.
• Its basin spreads (74°35 E to 74° 40’ E longitude and 140 0 to 140 10 N)
having area 348 km2 and It flows for a length of 26.4 km before joining the
Arabian Sea near Shirali .
• Hydrometerologic features are watershed has uniform rainfall pattern of
300 cm per year and 90% of the rainfall occurs in 4 months June, July,
August and September, July being the peak of the monsoon.
• Geologically, the area consists of Pre-Cambrian gneisses and granites
constituting the major parts of the basin. In the coastal plain gneisses and
granites are capped by laterite. Wherever laterite capping is not found, it is
covered by Quaternary sediments of marine /estuarine process.
• Geomorphic features along the coast such as beach ridges, wave-cut
platform, paleoriver channels, terraces in the lower part of the river,
migration of river channels and abandoned channels, shifting of river
mouths, coast-perpendicular faults and embankments leading to sediment
traps, and backwater-lagoon systems.

11. Fig 6: Digital elevation model(DEM) of SRTM 30m resolution

12. TOOLS AND TECHNIQUES
Tools and software Purpose source
SRTM 30 meter DEM data For morphometric and to take river
cross section export to HEC RAS
www.earthexplorer.com
Arc GIS 10.1v To carry out area, perimeter,stream
order, relief etc(morphometric
parameter), interpolation rainfall and
discharge
ESRI(Environmental Systems Research
Institute )
HEC RAS 5.0.3 Unsteady analysis and sediment
transport
US army corps engineer’s

13. ArcGIS 10.1V
• ArcView GIS developed by Environmental Systems Research Institute (ESRI) is a
powerful and easy tool to create and use maps, view spatial data and perform spatial
analysis. ArcView GIS is equipped with excellent graphical user interface (GUI),
which enables visualization, exploring and the analysis of spatial data.
• ArcView GIS is capable of displaying, viewing, editing vector dataset called shape
files It has also the facility to display tables, charts, layouts associated with the
shape The processing, modeling, visualization and interpretation of grid based
raster data can be performed using the spatial analyst extension.
• Arc hydro tool is used for watershed delination which include flow direction, flow
accumulation, stream to feature and other tools are used for watershed delinate upto
sixth order definition.

14. HEC-RAS and HEC-GeoRAS
Fig 7:Interface method of GIS linkage by HEC-GeoRAS
• HEC GeoRAS is ArcGIS extension is useful for river floodplain mapping and very important tool for
exporting DEM river section to HEC RAS.
• For effective operation of geometry, the section should be in projected geographic system.
• The geometric data created is shown in below figure.

15. Fig 8:Construction of river geometry in HEC-GeoRAS
Fig 9:Imported cross section in Hec ras

16. Fig 10:Exported cross section in HEC RAS at of station 12712.37(U1)

17. Morphometric analysis
Fig 8: Flow chart of morphometric analysis
MORPHOMETRY
Linear Aspects Areal aspects Relief Aspect
 Stream order
 Stream length
 Bifurcation ratio
 Stream length
ratio
 Drainage pattern
 Form factor
 Elongation ratio
 Compactness
ratio
 Stream frequency
 Circularity ratio
 Basin relief
 Relative ratio
 Relative relief
 Ruggedness
number

18. • Drainage density is the average length of streams per unit area within the basin Drainage density may be
thought of as an expression of the closeness of the spacing of channels. The drainage density of the
watershed is 2.503 which is moderate
Drainage density(Dd)=
𝐿 𝑢
𝐴
(4)
• Stream Frequency (F): Defined stream frequency as the number of stream segments of all orders per unit
area of the basin. High stream frequency is favoured in regions of impermeable subsoil and steep gradients.
Higher the stream frequency, faster is the surface run-off and therefore less time for infiltration.The stream
frequency of Venkatapur watershed 5.62 (No of streams/per sq.km) which is moderate
Stream frequency(F)= ∑
𝑁 𝑢
𝐴
(5)
• Bifurcation Ratio (Ru): The ratio of number of streams of any given order (Nu) to the number of streams in
the next higher order (Nu+1) is called bifurcation ratio
Ru= Nu/Nu+1
• Channel Sinuosity (S): Sinuosity is a quantitative index of stream meandering and a distinctive property of
channel pattern. It is related to the morphological, sedimentological and hydraulic characteristics of stream
channels.
S=
𝑆 𝐿
𝐿 𝑏
(6)
• Elongation Ratio (Re): It is defined as the ratio between the diameter of a circle of the same area as the
drainage basin to the maximum length of the basin (Lb).
Re=
2 𝐴/𝛱
𝐿 𝑏
(7)
• Circularity Ratio (Rc): Circulatory ratio is the ratio of the basin area (A) to the area of the circle of basin
perimeter (P) . It is the measure of the degree of circularity of the given basin.
Rc =
4𝜋𝐴
𝑃2 (8)

19. • Form Factor (Rf): Form factor is the ratio of the basin area (A) to the square of the maximum
length of the basin (Lb)
Rf=
𝐴
𝐿 𝑏
2 (8)
• Compactness Constant (Cc): Compactness constant can be calculated by using the formula:
Cc=0.2821 P/A2 (9)
• Relief Ratio (Rh): defined relief ratio as the total relief (H) of watershed divided by maximum
length of the watershed (Lb). It is an indicator of the potential energy available to move water
and sediments down the slope.
Rh=
𝐻
𝐿 𝑏
(10)
• Ruggedness Number (RN): It is defined as the product of the total relief (H) and drainage
density (Dd). It gives an idea of overall roughness of a watershed.
RN=
H×Dd
100
(11)
• Relative Relief (Rr): It is the ratio of the total relief (H) to the perimeter (P) of the watershed.
Low relief ratio is indicative of gentle topography while high relief ratio is characteristic of
steep slopes.
R =
𝐻
𝑃
(12)

20. Result(Morphometric analysis)
• The SRTM 30m resolution Digital elevation model of study area extracted from
www.earthexplorer.com website.
• ArcGis 10.1 commands such as fill sink,flow direction, flow accumulation ,stream to features
to convert raster data into Vector data and there after general dimensions of watershed is
obtained in attribute table.
• The fig shows Drainage map of Venkatapura river Watershed upto 6th order streams shown
below
Fig 7:Drainage map of Venkatapur watershed

21. Table1:Basin parameter
Table 2:Morphometric charecterstics of Venkatapur watershed
Basin Parameter Dimension
Area 348km2
Perimeter 81.63km
Length 26.01km
Width 16.9km
Max elevation 812m
Min elevation 0m
number of
stream
Total
length(km)
BF
rati
o
mean
length(m)
cumulative
length(m)
length
ratio
drainage
density(Km/
km2)
1395 463.23 0.332 463.23
2.503
459 193.62 3.04 0.421 656.85 1.2703
82 100.88 5.6 1.230 757.73 2.916
15 62.9 5.47 4.193 820.63 3.408
3 38.032 5 12.67 858.662 3.023
1 12.44 3 12.44 871.102 0.981
Form
factor(Rf)
compactness
coefficient
Circularity
ratio
Elongation
ratio
Constant of channel
maintence
Channel
Sinuocity
0.5 1.234 0.65 0.809 0.4 2.09
Table 3: Morphometric characterstics of Venkatapur river(Areal Aspect)
Relief ratio Relative relief max
relief(H)(meter)
Ruggedness
number
0.000312 0.0000994 812 0.00203
Table 4:Morphometric Charecterstics of Venkatapur(Relief aspect)

22. Morphometric analysis graph
Fig 8:mean stream length(log scale) v/s stream order Fig 9:stream number(log scale) v/s stream order
• The drainage density of the watershed is 2.503 which is moderate .
• The average bifurcation ratio of the Venkatapur River watershed is 4.42. The bifurcation ratio between 2nd
and 3rd order streams is distinctly high (5.6) indicating a strong control of the structure of the underlying
rocks on the development of these higher order streams. Similarly, the ratio between 3rd and 4th order
streams is also relatively high (5.4).
• The channel sinuosity values is 2.09 which indicate presence meandering course.
• For Venkatapur watershed the circularity ratio is 0.809 which represent strong relief and steep ground .
• The form factor for the watersheds is 0.51 indicating moderately flat nature of all the basins .
• . The constant of channel maintenance value for the entire Venkatapur River basin is 0.4 (Table 4) meaning
0.40 km2 of surface area is required to maintain each kilometre of channel length. The compactness ratio is
1.234 (from table 6).
1
10
100
1000
10000
0 2 4 6 8
Numberofstreams
Stream order
Venkatapura watershed
0.1
1
10
100
0 1 2 3 4 5 6 7
meanstreamlength
stream order
Venkatapura watershed

23. HEC RAS steady flow analysis
The HEC RAS hydraulic analysis is carried out with some assumptions in geometric and
hydraulic design
 The flow cannot surpass over ridge line(i.e drawn by flow path line) under any condition.
 The main channel Manning’s roughness assumed with clean water with more of stone and
weeds(n=0.035) .For bank region it is considered sluggish reach with weedy pools(0.07).
 The hydraulic coefficient assumed under gradual transition condition
(contraction=0.1,expansion=0.3).
Table 5 :Input steady flow data on upstream, tribuatary,downstream
Where, RS-river station,Tribute_r-tributary, U1-upstream ,down_1-downstream
channel sinuiosity of the study area devided into 3 parts,they are upstream, downstream and tributery to
understand meandering range given in below table
River Reach RS 10yr 50yr 100yr
1 Venk_rive_r Tribute_r 4718.953 89.89 129.2 170.6
2 Venk_rive_r U1 12712.37 1191.8 2005.72 2352
3 Venk_rive_r down_1 3303.86 1281.69 2134.82 2600

24. Table 6: Channel sinuiosity of the study reaches
• It(Table 6) indicates no serious meandering process (Sn<1.5) but heavy rainfall event
can bring significant amount flow discharge which has to tackle by bank protection
structure.
• Steady flow analysis is carried out for entire 32 cross sections(fig 9) taking boundary
condition at extreme stations of upstream, tributary ,downstream are 12712.37, 4718.953
and 3303.86 respectively for 10, 50 and 100 year return period shown in table 5
• The main purpose of the carryouting steady flow analysis is to know change in water
surface and corresponding velocity at every sections.
• After successfully performing steady flow analysis over the cross sections, there found
critical cross section are found which are either changed it’s course or overtopped the
bank for 100 year return period as shown in below.
Upstream (U1) Downstream (down 1) Tributary(tribute_r)
Channel length(km) 10.23 4.803 5.378
Axial length(km) 8.89 3.988 3.873
Sinuosity(Sn) 1.15 1.204 1.39

29. Fig 10:Sections failed by over topping(100 year discharge) on left V/S After
embanked the same river section on right

30. The hydraulic character of river before and after emabankment
Table 7:The hydraulic charecterstics of river reach before(left) and after(right)
embankment

31. Fig:Longitudinal profile of the of the river sections after steady flow analysis of upstream,
tributary,downstream(from top to bottom)

32. Tab 8: Comparison of water level with and without embankment
River station(m) Without Embankment/levee With embankment/levee
Water level(m) Velocity(m/s) Water level(m) Velocity(m/s)
River upstream
12712.37 73.64 2.84 73.2 5.04
12175.28 73.51 1.36 73.67 1.41
11480.65 71.35 5.66 71.32 5.9
10816.76 66.18 5.27 66.91 5.34
9932.472 62.2 1.79 62.25 2.03
9092.963 61.49 2.24 61.48 2.27
7753.97 57.8 3.96 57.75 4.09
6843.212 52.31 5.33 52.09 5.78
5927.746 48.3 2.33 48.3 2.35
5400.00 47.46 1.83 47.51 1.83
5051.678 44.29 4.97 44.26 5.19
4414.588 41.71 1.97 41.95 2.16
River tributery
4718.953 68.64 2.29 68.64 2.37
4438.698 67.03 2.39 67.00 2.6
4120.435 64.35 2.84 64.35 3.11
3695.72 57.99 2.89 57.95 3.26
3316.854 54.57 1.65 54.59 1.69
2911.719 52.09 2.95 52.06 3.29
2626.436 47.96 2.04 47.92 2.19
2289.148 46.28 1.9 46.27 2.01
1992.299 44.21 1.96 44.21 2.08
1746.644 41.59 3.22 41.57 3.59
1310.275 41.68 0.73 41.8 0.72
868.2799 41.16 2.25 41.5 1.58
361.3945 41.26 0.42 41.52 0.43
River downstream
3303.86 40.71 3.16 41.02 3.03
2765.18 38.53 5.33 38.52 5.78
2253.075 36.29 1.2 36.4 1.19
1523.352 35.92 2.37 35.98 2.48
1033.829 33.95 5.29 34.04 5.25
604.5525 30.99 5.96 30.94 6.16
206.2838 28.61 3.54 28.86 3.55

33. River training embankment design
The descriptive design computation of protection work for sloping bank as per
IS 14262-1995 is given below:
1. Velocity = 3.33m/s, 2.12m/s and 4.26m/s(average velocity flow under no
embankment condition at reach upstream,tribuatery and downstream
respectively)
2. Bank slope (θ) = 2 H:1 V (26.560)
3. Angle of internal friction of soil of bank material(Φ) = 350 (gravel mixed
wih sand)
4. Specific gravity of boulder stones (Sa) = 2.65
5. d50 stones being used for filling crates =175mm (for example as per
specifications, the stones of size 125mm to 225mm are proposed(assumed).
Therefore ,d50 is assumed as 175mm(125+225)/2)( Naveen Naidu et.el,2015)
• At unstable section(Fr>1) provide extra 10cm or 0.1m thickness of stone
pitching of crates then corresponding reach thickness

34. Table 9:design parameter of the designed embankment
Parameter Upstream
(2H:1V)
Upstream @
turning
Upstream
unstable section
Tributery
(2.5H:1V)
Tributery
@turning
Tributery
unstable
section
Downstream
(3H:1V)
Downstream
@ turning
Discharge intensity(q)
m3/s/m
32.74 32.74 32.74 9.41 9.41 9.41 56.61 56.61
Peak discharge(Q) m3/s 7910.3 7910.3 7910.3 1268 1268 1268 14530 14530
Weight of the crates(W)
kg
166.22 166.22 180.8 9.56 9.56 11.5 569.84 569.84
Correction factor(K) 0.62 0.62 0.62 0.76 0.76 0.76 0.84 0.84
Thickness of crate (m) 0.4 0.4 0.5 0.2 0.2 0.3 0.6 0.6
Volume of crate (m3) 0.093 0.093 0.11 0.0053 0.0053 0.007 0.32 0.32
Scour depth,Dmax(m) 6.08 6.08 6.08 3.54 3.54 3.54 9.39 9.39
Width of apron (m) 9.12 9.12 9.12 5.31 5.31 5.31 14.08 14.08
Quantity of stones
(m3/m)
21.75 21.75 24.5 6.60 6.60 7.2 57.71 57.71
Thickness of apron (m) 0.4 0.4 0.5 0.2 0.2 0.3 0.6 0.6
Volume crates for
apron(m3)
0.1 0.1 0.12 0.01 0.01 0.02 0.3 0.3
Weight of stones for
apron(kg)
109.2 109.2 125 7.27 7.27 9 478.66 490
Top width of
embankment(m)
3 15 3 3 15 3 3.5 15
Size of crate for
apron(m) × 2
0.2× 0.2 × 1.25 0.2× 0.2 × 1.25 0.3× 0.3 × 1.25 0.1× 0.1 × 0.8 0.1× 0.1 × 0.8 0.15 × 0.15 × 0.8 0.32×0.32 ×1.5 0.32×0.32 ×1.5

35. Fig 11:Embankment with 2H:1V for upstream reach
Fig12:Embankment with 2H:1V for upstream reach at turning
Fig13:Embankment with 2H:1V for upstream reach at unstable section

36. Fig 14:Embankment with 2.5H:1V for tributary reach
Fig 15:Embankment with 2.5H:1V for tributary reach at turning
Fig 16:Embankment with 2.5H:1V for tributary reach at unstable section

37. Fig17: Embankment with 3H:1V for downsream reach
Fig 18: Embankment with 3H:1V for downstream reach at turning

38. Fig 19: Perspective view of Venkatapura river confluence after embankment

39. Conclusion
• Construction of embankment of directly associated with socio-economic growth of
society(CWC,2013)
• It is to be observed that construction embankment increases velocity of flow for same
discharge and are taken by inerodible material(abrasive resistance) of the embankment.
• Adding sufficient free board of atleast 1-1.5m height above the HFL.
• The of the top width of embankment can be kept around 3-3.5 m and at turning 15m based on
type of land use behind the embankment.
• Dense packing of crates to achieve max density for safty against ill effect of high velocity of
water
• The time to time inspection and maintenance of embankment is required for efficient working
of the structure upto it’s design life

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