Diversion Headworks
MODULE III
DIVERSION HEAD WORKS
A hydraulic structure which supplies water to the off taking canal is called a head work.
Head works are of two types.
1.Storage head works
2.Diversion head works.
1.Storage head works. It stores water during the period of excess supplies in the river and releases it when demand overtakes available supplies.
1.Diversion head works
It serves to divert the required supply in to the canal from the river.
A diversion head works serves the following purposes.
1. It raises the water level in the river so that commanded area can be increased.
2. It regulates the intake of water in to the canal.
3. It controls the silt entry in to the canal.
4. It reduces fluctuations in the level of supply in the river.
5. It stores water for tiding over small periods of short supplies.
COMPONENT PARTS OF DIVERSION HEAD WORKS
A diversion head work consists of the following component parts
1.Weir or barrage
2.Divide wall or divide groyne
3.Fish ladder
4.Pocket or approach channel
5.Scouring sluices
6.Silt prevention devices
7.Canal head regulator
8. River training works. (marginal bunds and guide banks)
Causes of failure of Weirs and their remedies.
1. Piping.
Water seeps under the base of the weirs founded on permeable soils. When the flow lines emerge out at the D/S end of the impervious floor of the weir the exit gradient may exceed a certain critical value for the soil. In that case the surface soil starts boiling and is washed away by the percolating water. With the removal of the surface soil there is further concentration of flow lines in to the resulting depression and still more soil is removed. This process of erosion thus progressively works backwards the upstream and results in the formation of a channel or pipe underneath the floor of the weir, causing its failure.
Remedies 1
1. Providing sufficient length of impervious floor so that path of percolation is increased and the exit
DIVERSION HEAD WORKS
A hydraulic structure which supplies water to the off taking canal is called a head work.
Head works are of two types.
1.Storage head works
2.Diversion head works.
1.Storage head works. It stores water during the period of excess supplies in the river and releases it when demand overtakes available supplies.
1.Diversion head works
It serves to divert the required supply in to the canal from the river.
A diversion head works serves the following purposes.
1. It raises the water level in the river so that commanded area can be increased.
2. It regulates the intake of water in to the canal.
3. It controls the silt entry in to the canal.
4. It reduces fluctuations in the level of supply in the river.
5. It stores water for tiding over small periods of short supplies.
COMPONENT PARTS OF DIVERSION HEAD WORKS
A diversion head work consists of the following component parts
1.Weir or barrage
2.Divide wall or divide groyne
3.Fish ladder
4.Pocket or approach channel
5.Scouring sluices
6.Silt prevention devices
7.Canal head regulator
8. River training works. (marginal bunds and guide banks)
Causes of failure of Weirs and their remedies.
1. Piping.
Water seeps under the base of the weirs founded on permeable soils. When the flow lines emerge out at the D/S end of the impervious floor of the weir the exit gradient may exceed a certain critical value for the soil. In that case the surface soil starts boiling and is washed away by the percolating water. With the removal of the surface soil there is further concentration of flow lines in to the resulting depression and still more soil is removed. This process of erosion thus progressively works backwards the upstream and results in the formation of a channel or pipe underneath the floor of the weir, causing its failure.
Remedies 1
1. Providing sufficient length of impervious floor so that path of percolation is increased and the exit