Canal Headwork - Types & Locations
Definition: Any hydraulic structure which
supplies water to the off taking canal.
Diversion head-work provides an obstruction across a river, so that the water level is raised and water is diverted to the channel at required level. The increase water level helps the flow of water by gravity and results in increasing the commanded area and reducing the water fluctuations in the river. Diversion head-work may serve as silt regulator into the channel. Due to the obstruction, the velocity of the river decreases and silt settles at the bed. Clear water with permissible percentage of silt is allowed to flow through the regulator into the channel. To prevent the direct transfer of flood water into the channel.
Functions of a Headwork a headwork serves the following purposes
*.A headwork raises the water level in the river
*.It regulates the intake of water into the canal
*.It also controls the entry of silt into the canal
*.A headwork can also store water for small periods of time.
*.Reduces fluctuations in the level of supply in river
Types of Head works
1.Storage headwork
2.Diversion headwork
Component parts of Diversion Headwork Types of Diversion head works
1.Temporary:
2.Spurs Bunds
3.Permanent
Components
1.Weir or Barrage
2.Divide Wall
3.Fish Ladder
4.Approach Canal
5.Silt prevention device
6.Canal head regulator
7.River training works
Location of head works
1.Rocky Stage
2.Sub mountainous or boulder stage: boulder or gravel
3.Alluvial plan
Rocky stage: River steep slope, high velocity
Advantages:
1.Good foundation at shallow depth
2.Comparatively silt free water for turbines
3.High head for hydro-electric work
Disadvantages:
1.Long ---- length of canal. In reach soil is good for agriculture.
2.More cross damage works
3.More falls (ground steep gradient - lined to permit high velocity)
4.Costly head regulator excluding shingle
5.Frequent repairs of the weirs.
Sub mountainous or boulder stage: boulder or gravel
Advantages:
1.Less training works
2.Suitable soil for irrigation available
3.Availability of construction material locally.
4.Falls can be utilized for power generation
Disadvantages:
1.It has a strong sub-soil flow as a result
2.Reduce in storage and damage floor downstream
3.More percolation loss from canal
4.More x-drainage works
5.Less demand of water at head reaches (more idle length of canal)
Alluvial plan:
1.x- section of river alluvial sand silt
2.Bed slope small, velocity gentle
3.No idle length of canal
4.less x- drainage works
5.Comparatively less sub soil flow
Disadvantages:
1.Cost of headwork is more due to poor foundation
2.More river training works
3.Problem of silt in canal
Diversion head-work provides an obstruction across a river, so that the water level is raised and water is diverted to the channel at required level. The increase water level helps the flow of water by gravity and results in increasing the commanded area and reducing the water fluctuations in the river. Diversion head-work may serve as silt regulator into the channel. Due to the obstruction, the velocity of the river decreases and silt settles at the bed. Clear water with permissible percentage of silt is allowed to flow through the regulator into the channel. To prevent the direct transfer of flood water into the channel.
Functions of a Headwork a headwork serves the following purposes
*.A headwork raises the water level in the river
*.It regulates the intake of water into the canal
*.It also controls the entry of silt into the canal
*.A headwork can also store water for small periods of time.
*.Reduces fluctuations in the level of supply in river
Types of Head works
1.Storage headwork
2.Diversion headwork
Component parts of Diversion Headwork Types of Diversion head works
1.Temporary:
2.Spurs Bunds
3.Permanent
Components
1.Weir or Barrage
2.Divide Wall
3.Fish Ladder
4.Approach Canal
5.Silt prevention device
6.Canal head regulator
7.River training works
Location of head works
1.Rocky Stage
2.Sub mountainous or boulder stage: boulder or gravel
3.Alluvial plan
Rocky stage: River steep slope, high velocity
Advantages:
1.Good foundation at shallow depth
2.Comparatively silt free water for turbines
3.High head for hydro-electric work
Disadvantages:
1.Long ---- length of canal. In reach soil is good for agriculture.
2.More cross damage works
3.More falls (ground steep gradient - lined to permit high velocity)
4.Costly head regulator excluding shingle
5.Frequent repairs of the weirs.
Sub mountainous or boulder stage: boulder or gravel
Advantages:
1.Less training works
2.Suitable soil for irrigation available
3.Availability of construction material locally.
4.Falls can be utilized for power generation
Disadvantages:
1.It has a strong sub-soil flow as a result
2.Reduce in storage and damage floor downstream
3.More percolation loss from canal
4.More x-drainage works
5.Less demand of water at head reaches (more idle length of canal)
Alluvial plan:
1.x- section of river alluvial sand silt
2.Bed slope small, velocity gentle
3.No idle length of canal
4.less x- drainage works
5.Comparatively less sub soil flow
Disadvantages:
1.Cost of headwork is more due to poor foundation
2.More river training works
3.Problem of silt in canal
Comments
Post a Comment