1 Water Resource Engineering Assignment Naba Kumar Bhaumik, B.Tech Civil Engg. ,09BTCENG021 Question 2: - Discuss in detail about canal, their types & importance. Give full description of at least 5 canals in India. Answer 2: - Classification of canals Based on the type of land in which they are constructed- I. Alluvial Canal- The soil which is formed by the agency of water over a course of time is called alluvial soil. A river before joining the sea, gets divided into a number of streams forming which is called as river delta. In the deltaic region, a river carries heavy charge of silt, which gets deposited on the adjoining lands, as and when the river overflows its banks during the flood season. This process of silt deposition continues over long periods of time, resulting in formation of alluvial soil. Hence the soil which is formed by continuous deposition of silt is called alluvial soil. Example- Indo-Gangetic plane in India. The rivers passing through alluvial areas have a tendency to shift courses. The river bed consist of sand of considerable thickness, and is therefore permeable. Whenever an irrigation structure is to be constructed on such a river, special precautions and design methods are to be adopted. Most of the north Indian rivers, which pass through alluvial soil, do pose these problems. II. Non-Alluvial Canal- Mountainous regions may go on disintegrating over a period of time, resulting in the formation of a rocky plain area, called non-alluvial area. It has an uneven topography, and hard foundation. The rivers passing through such areas have no tendency to shift courses and they do not pose much problems for designing irrigation structures over them. Canals passing through such areas are called Non- alluvial canals. Based on size/source - 1. Main canal – Main canal generally carries water directly from the river or reservoir. Such a canal carries heavy supplies and is not used for direct irrigation except in exceptional circumstances. Main canals act as water carriers to feed supplies to branch canals and major distributaries. Assignment- 1
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1. Farakka Barrage Project Feeder Canal- The Farakka Barrage Project is designed to serve the need of preservation and maintenance of the Kolkata Port by improving the regime and navigability of the Bhagirathi-Hoogly river system. The Farakka Barrage Project includes the following:-
A 2245 metre long barrage across the river Ganga with rail-cum-road bridge, necessary river training works and a head regulator on the right side.
A 213 metre long Barrage across the river Bhagirathi at Jangipur and Navigation Lock beside it.
Feeder Canal of 1133 cumec (40,000 cuses) carrying capacity and 38.38 km long, taking off from the Head Regulator on the right bank of the Farakka Barrage.
Navigation works such as locks, lock channels, shelter basins, control towers, navigation lights and other infrastructure.
33.79 Km. Left Afflux Bundh of Farakka Barrage 16.31 Km. long Left Afflux Bundh of Jangipur Barrage.
Two road-cum- rail bridges two road bridges across the Feeder Canal. A number of Regulators at different locations in both Murshidabad and
Malda Districts. Bagmari Syphon at RD 48.0 of Feeder Canal The jurisdiction of Farakka Barrage Project has been extended upto
Rajmahal including Diara in the upstream (40 Km from the Farakka Barrage) and upto Jalangi in the downstream (80 km from the Farakka Barrage) for carrying out anti-erosion protection works.
Image: Sluice gates of the ‘Farakka Barrage Project’
2. Indira Gandhi Canal Indira Gandhi Canal starts from the Harike Barrage at Sultanpur, a few kms. below the confluence of the Sutlej and Beas rivers in Punjab state. Rajasthan Canal near Giddarbaha, Punjab. Irrigation facilities to the north-western region of Rajasthan, a part of the Thar Desert. It consists of the Rajasthan feeder canal (with the first 167 km in Punjab and Haryana and the remaining 37 km in Rajasthan) and 445 km of the Rajasthan main canal which is entirely within Rajasthan. This canal enters into Haryana from Punjab near Lohgarh village of Haryana, then running in western part of district Sirsa it enters into Rajasthan near Kharakhera village (Tehsil: Tibbi, District: Hanumangarh) of Rajasthan. The IGNP traverses seven districts of Rajasthan: Barmer, Bikaner, Churu, Hanumangarh, Jaisalmer, Jodhpur, and Sriganganagar.
After the construction of the Indira Gandhi Canal, irrigation facilities were available over an area of 6770 km² in Jaisalmer district and 37 km² in Barmer district. Irrigation had already been provided in an area of 3670 km² in Jaisalmer district.
The canal has transformed the barren deserts of this district into rich and lush fields. Crops of mustard, cotton, and wheat now flourish in this semi-arid north-western region replacing the sand there previously.
Image: The Rajasthan Canal-A part of the ‘Indira Gandhi Canal’
Image: Indira Gandhi Canal Rajasthan Canal at Lohgarh
Question 3: - Differentiate between the following:-
Answer 3: -
1. Weir and Barrage
2. Barrage and Dam Barrage Dam
1. A barrage is an artificial obstruction at the mouth of a tidal watercourse used to increase its depth or maintain a separation between fresh and salt water or reduce the risk of tidal flooding up the river.
2. In case of a barrage, its entire length across the river i.e. between the banks is provided with gates having their bottom sill near the river bed level. Thus, the storage behind the barrage is solely created by the height of the gates.
1. A dam is a barrier across flowing water that obstructs, directs or slows down the flow, often creating a reservoir, lake or impoundment.
2. The dam on the other hand has
spillway gates almost near its top level and the storage behind the dam is mainly due to the height of concrete structure and partially due to the gate height.
Weir Barrage
1. An impervious barrier which is constructed across a river to raise the water level on the upstream side is known as a weir. Here the water level is raised up to the required height and the surplus water is allowed to flow over the weir. Generally it is constructed across an inundation river.
1. When adjustable gates are installed over a weir to maintain the water surface at different levels at different times is known as a barrage. The water level is adjusted by operating the gates or shutters. The gates are placed at different tiers and these are operated by cables from the cabin. The gates are supported on piers at both ends. The distance between the pier to pier is known as Bay.
3. Gravity weir and Non-Gravity weir Gravity weir Non-Gravity weir
1. When the weight of the weir (i.e. its body and floor) balances the uplift pressure caused by the head of the water seeping below the weir, it is called a gravity weir.
1. If the weir floor is designed continuous with the divide piers as reinforced structure, such that the weight of concrete slab together with the weight of divided piers, keep the structure safe against the uplift; the structure may be called as a Non gravity Weir.
4. River regulator & Canal regulator
River regulator Canal regulator 1. It is the same as canal regulator but in this case it is used for a river. It is much bigger and efficient than that of a river regulator
1. A suitably designed regulator at the head of a canal is provided to regulate the supplies entering the canal as well as to control silt entry into the canal. It can also be used as a calibrated meter for assessment of the discharge entering the canal. Head regulators are provided at the head of a canal off-taking from a river or a branch canal taking-off from a main canal or a distributary sub distributary taking-off from a branch canal or a distributary itself as a case may be.
1. Silt excluder consists of a number of under tunnels resting on the floor of the silt pocket. Top floor of the tunnels is at the level of sill of the head regulator. Its main purpose is to prevent the entry of silt into the canal
1. Silt ejector or extractor is provided in the main canal few metres downstream of the head regulator. The device is a curative measure.
It consists of a horizontal diaphram placed slightly above the canal bed. Canal bed there is slightly depressed and curved walls as shown in the figure below are constructed to have tunnels to dispose of extra silt. Velocity decreases and this silt is deposited below the diaphram and this deposited silt is carried to river downstream or to a low depression
1. The length of the weir should be as that of a normal weir constructed across a river to raise its level and divert the water into the canal.
2. A weir which stores water for tiding
over small periods of short supplies is called a storage weir.
1. The length of such a weir must be such that the quantity of water estimated as the maximum flood discharge likely to enter from the catchment into the tank, can be disposed of with a depth of water over the weir equal to the difference between the Maximum Water Level(MWL) and the Full Tank Level(FTL).