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Lecture – 18: River Training Work

Welcome, all of you for these interesting lectures here we will not talk much about mathematics talk about the art of river training work it is a combination of science and art and with the experience of hydraulic engineers, sediment specialist and river engineers they try to train the rivers for different purposes. So, looking that most of the experience in the United States of America that is what I will share today.

And some of the advanced country how they have been managing the floods and they how they have been making the river is navigable so that they can use as inland waterways. So, the basic idea of that what the experience is there and most probably I will be following this book the river engineering by M. S. Petersen that is the books we are following it and partly we are following its river mechanics books.

This is the engineering concepts though mostly you know it when you construct a any river training works it is a combinations of geotechnical engineering combination of hydraulic engineers and new constructions materials. So, it is it is not a just a river engineering this is a combinations of geotechnical engineering river specialist and also the advanced techniques geotechnical techniques what nowadays we have been using it.So that is the reasons is a quite introductory levels but then many new things are coming it like geotextile materials and all geotube and all the things water is coming off but I will just highlight it what is the experience of the rivers engineering works in the united states of America.

Let me look at the next figures which are very interesting figures slides were showing to us
before that this is a content what I will talk about inland navigation projects in the United
States of America and we will talk about the lock and dams configurations what is there at
the introductory levels. Then we will talk about Dredging’s the floodway’s even we will talk
about the river closures at the end we will have a case studies on Brahmaputra rivers that is
what the impact of the bridge constructions on fluvial morphology that is the case study that
is what will present at the last.
Now if you look at that points if you look at this Ohio river navigations projects which is way
back in 1979 by the U.S army Corps of engineers if you look at this rivers and you can look
at this all these dam and locks ok so if you look at that from upstream to down streams how
many series of the cascading dam and lock structures are there and this is for the longitudinal
profiles distance versus elevations.
And if you look at that for each project, they have a like Montgomery projects who is having
the elevations 682 Mel dahl projects the elevations 485 and you have McAlpine project 420
meters elevations and the Uniontown is 342. So if you look at this longitudinal profiles of the
rivers and the intervention structures you can see that more than 15 structures are there which
was constructed way back just after the world war I and world war II this is the channels is a
navy 9 feet navigation channels which is very famous for transporting the coals from the
upstream to the downstream locations.
And it has been designed for fleet of the 10 barges and that period you used to carry about 60
million tons of the traffic. So, you can understand it after the World War I and World War II
these projects the river navigation projects play vital roles for economic growth in the United
States of America because they constructed a series of the dam structures so that throughout
the years, they can have a 9 feet navigation channels.
The depth of the feet will be 9 feet because of that they construct a series of dam structures if
you can look at the series of dam structures and that ponding elevations you can see it. So,
this is the way they make it the river is a navigable and throughout the rivers throughout theseasons they have a 9 feet navigation channel flow or the river flow more than that. So that is
what they have designed it and that is what is took it almost 30 to 40 years to construct all
these major structures makes this river each river was navigable and it has been a navigable
river that is what if you see that the major interventions what is done in Ohio river
navigations projects.
(Refer Slide Time: 06:13)
Similar way if you look at this Arkansas river navigation project which is part of USA is part
of the Mississippi river basins and if you look at the reservoirs you can see that series of the
reservoirs okay all are the cascading reservoirs and the dam and the locks. So, all these are
cascading reservoirs and all again if I plot the longitudinal profiles here the unit in some
miles and we have the elevations and you can see this the dam structures each dam structures
having a number and each number having this lock and dam positions.
So they have the ponding and they also have a keeping these waters ponding waters at the
different levels and the lock and dam structures so that the any navigations can flow smoothly
from upstream to downstream and it can carry the significant amount of though it can
transport the significant amount of the upstream coal or other materials. So they make this
river is navigable and based on these a cascading the dam and lock structures and that is what
if you can see it and that is what it is made them to make it one of the successful projects to
connecting the rivers no doubt.
There are the advantage and disadvantages like it has certainly helped the flood protections
the bank erosions but the sedimentation was the bigger issue but that is what the strategy is?How to maintain the cascading segmentations because of the series of the cascade dams?
Those are the issues still the many of the engineer’s hydraulic engineers are trying to find out
the solutions how to optimally use the cascading dams’ project so that you can reduce the
sedimentations.
But no doubt this type of extensive river training works for navigable the channels navigable
for making the navigable channels so that there will be a two-way traffic movement of the
vessels can be done it that is what this thing and many of the text is very clearly said that
because of these are the projects was the after the world war II gives us a boom to the
economy of the United States of America. So that is the point what we to know it.
(Refer Slide Time: 09:04)
The same way if you look at that that means what is the locks and dams you can understand it
say locks and dams. So basically, it is required to dams you know it is required to sustain a
adequate navigation step that is what is 9 feet depth of the water minimum that should be
there and the locks is to allow the ships to navigate in a rivers steepened by artificial cut-offs.
So if you look at this figures, this is the part of the rivers this is the left bank this is the right
bank and you can see these are the spillway gates and the stilling basins and there are the gate
piers are there and if you take the cross sections you can see with a gate upper pool lower
pool and the stilling basins with the baffles will be there spillway crest and the riverbed.
So if you look at that so more detail we are not going it mostly you can get any hydraulic
engineering’s how to design all the aspects the how to design the spill gate how to design thestilling basins, the gate piers and spillway gates that is not we are discussing here but that is
the arrangement for a barrage or the dams to flow through that. But to passing through the
ship okay we need to have a lock arrangement.
So, if you can see there is a lock arrangement this is the lock chain this is the upper gate this
is the lower gate this is a lower lock approach this is the lower guard while an upper guard.
So, ships come from these goes to this lock chambers then goes through this. So, this is the
arrangement many of the things there will be the one side the dam another side will be the
lock arrangement which facilitates a ship to pass through those ones within having the upper
and lower with the storage and the lower lock approach.
We will talk more details in the next slides. So, if you look at that must be spaced to maintain
the navigation step throughout the pools and the river navigation project lock is generally
located near the bank at one hand that is what is you can see the peak to minimize the adverse
effect of the spillway discharge on traffic. So that is the basic ideas and you can just see that
the lock and dam basic features which may vary from location to locations.
It may vary the design of the spillway stilling basins and all the most difficult things of lock
and dam arrangement will have a locks with you have upper lock approach lock chambers
lower lock tools and there are upper guard wall and you have a lower gate you will have a
lower guard walls which is facilitates the ships to go through these lock arrangements and the
gates will be gate and the piers to maintain this your pool depth that is the idea the maintain
the pool depth that is what is necessary to have the gate and you have the also the lock.
So this is the typical arrangement but it varies from depending upon the geology depending
upon the site locations, depending upon economy and we try to make it differently but typical
structures like this will have the arrangement for the spillway and the gate arrangements for
storing and having the pool of water depth and there will be facility of the lock which
facilitates the ships can pass through these ones.
(Refer Slide Time: 13:11)Now if you look at next part you can see that is a lock arrangements you can see this upper
lock and the lower locks you can see it and it facilitates this is the lock arrangements its opens
and closes and that is the reasons the locks is adequate depth for the navigations gain access
to the lower or the higher water levels on either side of the dam it is have open chambers it
has a gate at the offer to fill up fill the waters and you have a lower pool which is discharge
the waters.
So that is what we do it is a costly its expensive and it depend upon how much time its take
the fill this the chambers the larger filling times emptying times that is what also matters how
locking times we do it when the ships goes through these lock systems.
(Refer Slide Time: 14:09)Now if you look at very interesting figures which is given through the P. Julien book on river
engineering and the chapters which is a river mechanics book. So, if you look at that if you
can try to understand these figures very interesting figures which is showing it how do we
have arrangement for a lock system. There will be upper pool there will be the lower pool and
you have the lock chambers.
So that is there and you have upper gate and the lower gate for to do this filling this is the
filling valve. So, if you look at the water can come from upper pool can get into the from the
lock floor it can get into this lock chambers then you will have the lower pools and you have
the lift okay you have lower gate sill. Now if you see that a ship enters the ship enters to the
pool that is time, we upper go gate is open and that is what it enters into that and that time it
has a closed here.
And the ship enters to the chambers to the lower chambers. As soon as also the water is
extract from this so that it can goes below down okay to the levels of the lower pool that is
what its arrangements again the water goes out from these and the ships goes down. As it
goes down it comes too closer to the same level of the lower pool. At that time, we close this
gate, open this gate that is what initially close it still goes to that regions.
Then we open the gate and the ship pass through it then you have these things it is very
mechanical way of arrangements. But you know it needs to design the all the structures like
gate these filling valve arrangements with a filling chamber. All it depends upon how much
time it takes to filling the chambers, emptying the chambers and based on that we designed
these lock chambers upper pool and lower pool and also filling value and emptying valves.
So this these are very typical figures and quite interestingly its indicating for us the how a
lock arrangement is there for the navigation properties that is what is showing that so that is
what is here the same thing is telling it here that locks admits the water fill the chambers from
the upper and discharge to the lower pool to empty the lock. Okay the overlock gates are the
open for the two to move into the lock chambers the upper lock gates and filling valves are
then closed.
The emptying valves are open to bring the water surface in the lock down to the level of the
lower pool it is the same things what I discuss it and the lower lock gates are then open thentwo moves out of the lock chambers into the lower pool. So, this is a very nice arrangement
how do a ship goes from upper pool to lower pool through a navigational lock that is the very
interesting things is there and we have a navigational lock arrangement typical navigational
lock arrangement.
(Refer Slide Time: 17:59)
Now more details you can see its figures it is quite you can get it nowadays you have a
google images are there you can see this the gate so and you can see this how the ship is
passing through it and how these great openings are happening it all you are like you can
understand it nowadays you all have a the google is a source of information nowadays you
can get all sorts of information’s how the lock can get and how the civil engineering
structures are there for dams and the locks arrangements it is not that difficult.
(Refer Slide Time: 18:41)Now if you look it that way the next part is nowadays, we have been advocating that dredging
a river okay dredging a pond what is that how much cost effective it is those things I am not
going details but very introductory levels I will talk about the dredging towards the river
management. So, if you look at that the so often, we have the sedimentations of the rivers that
because of natural sedimentation river the river aggradations happens it the river becomes
more shallower and shallower or we confine the river.
As we confine the river the more the sedimentation happens in aggradations happens so
because of the aggradations happens it rework flow carrying capacity decreases. So, flow
carrying capacity decreases so that is what it happens it because of embankments because of
confining the rivers because having the levees we also confine the rivers because of that there
will be the sedimentations.
Okay there will be the sedimentations so if you do not remove that sedimentations no doubt
the carrying capacity of a river decreases with the time. So, decreases with that and that may
be slowly it will have the dangers to the embankment where the flood protection structures
what we have so the basic idea is that to dredge that materials means remove that digging and
remove this river bed or widening the river.
So, we can increase the width of the river or increase the depth of the rivers that is what you
call its deepening or widening the navigation channels or the river channels okay. So that to
have more carrying capacity so we basic idea is to increasing more carrying capacities of the
rivers so that it so the equipment generally we use either the dredges are defined it is a
mechanical time or the sorry dredges are generally two types one is mechanical type other is
hydraulic types.
In mechanical dredges we have bed materials which is have a dipper or bucket to this thing i
will show the figures for that the hydraulic dredges is a pick of the dredge materials by means
of suctions pipe and the pumps okay when you talk about hydraulic dredges that means it is
just pump the bed materials okay and it have a suction pipe and it have the pumps and it has a
disposal part. But in a case of mechanical grazers it is a dipper and it is having a bucket that
is what it helps us to dig the materials and remove this material from the bed.
(Refer Slide Time: 21:36)Now if you look at that dipper dredges if you look at this dredges part there is fixed it here
and there is a top hinged buckets are there and dipper arms are there and drag hoist is there
just it is dipping that things okay with the buckets we are just removing it we can just
understand it way we dig a soils okay the dig soils okay that that the concept will follow it
and this is what the river bed.
So, we can have a dipper or we can have buckets you can have a dig the soils and as you dig
the soils then you can take it okay and to make it stable. So you can put this main spud so fix
this dredges and take this bed materials from that okay that is what we do it basically excited
hard compacted materials blasted rocks we can all do it nowadays technologies are there or
the dredges having very high end dredges are there we can actually dredge the rivers with
having this part.
It can operate very little guidance space and accurately control the near the bridge locations
like the structures okay you can accurately dredge the critical locations like a bridge location
you have a bridge pier you have a bridge abutment those are the critical structures we can use
this type of structures to dredge the materials.
(Refer Slide Time: 23:14)Now if you look at the bucket dredges so which is you can see it is a the bucket concept is
there and that bucket chain is there the ladder is there and buckets are moving like this and
there are the ladder of pivot and the dumping of these materials and you have this ladder
hosting wire side wires and the head wires. So, if you look at that these are all mechanical
components what I am talking about and as a river engine is, we try to know it how much of
dredging can happen it because of these bucket dredges.
So basically, the bucket dredges use the interchangeable buckets okay that is what you can
see the chain of the buckets are there and different operational propose you can have a
different type of buckets okay. An open bucket can have a 9-meter cube or volume of the bed
materials then close to the rest and emptied. So, because then it is closed then emptied so that
is the process goes on. Okay, so it is very interesting so we have the dredges with a bucket
which can have a dredge the bed materials as a bucket and try to store it here okay store it
here.
(Refer Slide Time: 24:43)So that is same way if you talk about the hopper dredges which is basically it is a selfpropelled sea going vessels maintenance dredging’s we are progressing deepening by
successive passes okay. Most of the times what we do it readings a progressive deepening it
is not like in a one day we do it okay that is the idea of a river engineering is not that do a
deepening in one time okay you do a progressive deepening you can understand it how the
river response is helping it.
Otherwise the dredging of the channels dredging of a of seafronts does not make the sense
that is the reasons we do progressive deepening okay or we do a maintenance dredging. We
do the dredging’s just to maintaining the 9 feet depth or maintaining the draft requirements
we do not go for high level of dredging things. So, it collects the connected materials in
through the channel bottom through a suction pipe stored in the hoppers okay that is what is
there.
This is the suction pipe and it also stores in the hoppers the dredges are emptied by opening
the bottom doors dumping of this entire content of the few seconds okay. It takes the
dredging materials and then dumps it and come back it that is what the hopper dredge okay
hopper dredge is there and you can see that dredged part and taking these materials and filling
the digged materials and dumped the dredging materials after where we have to dispose the
dredging materials that is what we look at.
(Refer Slide Time: 26:32)Same way if you look at that dustpan dredges okay very interesting part you can see this
dredger is just like a dustpan okay you can see in any house how you remove the dust okay;
we use the dustpan the exactly same concept we have the dustpan dredge. The basic idea is
that is a pressure water jet that loosens the bottom materials wide flare flat suction lines
intake for sedimentary removals okay that is there.
Two components first components are having the pressure water jet which loses the bottom
materials the bed materials. The second one is that it has a flat suction line intake okay that is
what is that flat suction line intake okay so that is the take the sedimentary from that this
normally discharge into the open water through a relatively short pipeline up to 30-meterlong or a longer dispenser line requires a boosting pump.
So, you can dump it within 30 meters or if you do not want to deposit do the disposals within
the 30 meters you can have a booster pump okay. So, because it is a mix of the sediment and
the waters you can use a booster pump to dispose at a far a distance or a location where you
want to do the disposals. So if you look at this dustpan dredge is very interesting dredges part
ok it is have a that it has a two component one is a pressure water jets that loosens the
bottoms then we have a white flat flared and flat suction intake.
And you need to have a booster pump if you want to take the dredge materials beyond the 30
meters you can have the booster pumps okay. More mechanical designs and all the things we
are not going here but these are things we can use it like a alluvial rivers where you have avery loose sand and the silt materials or the clay materials which we can loosens with help of
pressure water jets.
Then we can suctions line take the sediment from that and you can dispose it because you
have a booster pump on that these are things we can do it and which is necessary now when
you talk about making national waterways of our country to navigable may be the dredger is
can be used for some of the dredgers to do a maintenance dredging’s.
(Refer Slide Time: 29:25)
Let I show the figures how we have same way you have the cutter head dredge okay. So that
is a suctions pipe cutter head and you have the dredge so it is a cutting okay that is the
reasons it is the most efficient and versatile. It is having a rotating cutter around the suction
pipe intakes okay it is cutting the thing and it has dig and pump the alluvial materials
including the compacted clay and the hardpans.
Okay so because it is having a cutting tools okay that means is a cutter head is there that is
what into like a you have the very hardpan the clay materials are there that is what you want
to remove it you can use these things because it has a rotating cutter okay around the suction
pipe intakes and that is what it helps to do remove these compacted layers and the hardpan
formation.
Generally, it have a cutter head baskets, ladder suctions line. A-Frame, H-frame, Pumps,
gantry, spuds, and a pipeline up to 90-centimetre diameters okay pipelines can have. So, if
you look at this the basic structures what is there in these things. Nowadays thesetechnologies are there many of our country maintaining national waterways we have been
also using maintenance dredges.
(Refer Slide Time: 30:57)
Let I put it how a river like Arkansas rivers we have been using different strategies to make
the river navigable it is not only solutions of the dredging the rivers. If you look at these
rivers very interesting river which is 1972 way back in United States of America how they do
the maintenance dredging’s. How they have the river training works so if you look at the
levee structures you can see that they are very far away there is a levee structures that is what
is to protect the flood plain.
And they have given and half rivers space okay that is not the levee is just parallel to the
rivers that is not the concept. You see that levee were constructed so far away river has one
space like for exit pool these the positions they have given enough space that cut-off rivers
which are morphologically cut-off and they put a cut-off thing are here. So, if you try to
understand it the first, they have given enough space to the rivers confined the river through
the left levee and the right level and that is what is designing it.
If you look at that and within that they try to look at all these geomorphological variability in
terms of river cut-offs, meanders though the history of the rivers tell about the morphology of
the river tells about what are the space of the rivers that is not a big issue we can use a series
of satellite data’s we can find out the river space and we can design what could be the space,
what will be the layout for the levee.Okay the second part is that if you look at there is a lock and dam structures here there are the
series of the spur things are there see there are the series of the spur and there are series of the
spur structures are there to confine the river or divert the river from that not only that there is
a Trench fill revetment okay. So again, I am talking about is a Trench fill revetment there is a
trench in that they have filled the revetment that is what is there the Trench fill revetment see
this well designs the Trench fill revetments are there.
After doing so much things okay having the levee the spur the pile structures are all sort of
spur structures still, they need to find out the depth they want to have a major dredge. So, this
is the dredges materials okay so it is not only the dredging is a solution for that they construct
they confine the rivers they know to have a stage wise confinements like the levee is a higher
discharge confinement then within the inline structures are there which is confining it with
having this protective like a Trench filled revetment.
We have all spur structures still it is not possible to get the 9 feet depth of water that is the
reasons they maintain the dredging’s this is the maintenance dredging that is a combinations
of the all these river training works have been followed by the United States of America to
maintain this river navigable it is not that easy that is what the point is to highlight it and that
is what it is happening this how these structures are there how the they construct the cut-off
they construct the levee they construct the all the river training work the Trench fill revetment
and also where they need a major dredged work
So, the dredging or the minima at the last option is there to dredge the river and that is what
they try to look it where they can do it where they cannot get the 9 feet depth of water for
river navigations. That is my idea to convey you.
(Refer Slide Time: 35:13)Let us come to talk about the floodway’s okay many of the times you know it that we have
the discharge is much higher order when you talk about 10 year flood, 100 year flood and
when you talk about the flood we should not talk about only the fixed discharge okay we can
talk about peak discharge also we should talk about the flood volume how much of flood
volume is coming how much volume of water is coming for that specific flood of 100 years
10 years or 5 years.
So, if you can try to understand it then naturally the river has one space it has one flood plain
but with the times, we have enclosed the part of the flood plains. So, we have constructed the
embankment we have constructed the series of the dam structures like for example of
Hirakud dam projects okay which is one of it was one of the largest dam early 70s 50s 1950s
and 60s and these time structures store as enough waters.
So that storage can reduce the flood peak and the flood volume the down streams of this step
projects that is what is the strategy to us there but there are new studies coming it that you
can have a float flood storage you can have a very low laying area you can store the waters
and many of the time they call it as the floodway’s or the flood divergence or the many of in
in Germany they talk about flood folders.
So basically, the low laying areas which are designed to store the excess flood waters, return
period of 10 years, 100 years or 2 year return period flood. So nearby the area the depression
areas near the rivers where you can store and after it is that is the reasons you can have a
series of the wetlands and you can design the wetlands such a way that they can store thefloodwaters during the 2 years or 10 years or 100 year floods that is what the idea is to
commit and that is what it to design it the things.
So there should be outlet the spillway and we should have a control devices okay so to
manage this we should have a control devices okay so you can have a control of gate
arrangement and all synchronized you have to manage the floods so that you can store the
waters in a low depression area, man made reservoirs are you can store the flood wave waters
in a less vulnerable part of the things that is what we stretch it basically its emergencies for
the high flood it contains high proportion of sediment load.
But you should know it when you do the flood managements there are also the huge sediment
loads how do we manage that sediment loads and that is what as a river engineers we
engineers we should look it we you can store the waters for the time being during the flood
periods then you can release it but what happened to the sediments whether that one is going
to deposit and as it deposits it has advantage for agriculture or not those cost benefit analysis
needs to be done it to look at the flood storage during the extreme flood like 2 years, 10
years, 100 years floods and that is where we manage it to have a different type of storage
mechanisms.