OTHER SOURCES OF GROUND WATER

OTHER SOURCES OF GROUND WATER

Besides different types of wells following may also sometimes becomes source of water for irrigation.

1. Infiltration galleries
2. Springs
3. Karez.

• They are horizontal or nearly horizontal tunnels which are construct through water bearing strata along the river banks to collect the inflow of ground water from river.
• They are also know horizontal wells.
• The galleries are made of bricks, or stones.

• The galleries are laid at some longitudinal slope so that the water collect in the gallery is led out of gallery under gravity flow.
• Galleries are provide with man holes for inspection and maintenance.
• Infiltration galleries are not use for getting water for irrigation purposes.

• When ground water automatically comes to the surface and starts flowing it is call a spring.
• Springs are found in hills.
• They also supply very little quantity of water and as such are not adopt for irrigation purposes.
• Springs may be class into following three types:

(b) Gravity or shallow springs

(c) Surface springs.

• In the case of artesian springs underground water comes to the surface under hydraulic pressure.
• This spring is form when an aquifer lying under an impervious layer gets punctur or some how fissure.
• Gravity spring develops when ground water table gets exposed due to ups and downs in the surface.

• Surface spring is developed when an impervious stratum which is supporting the ground water reservoirs is out cropped.
• Formation of various springs is given in Fig. 8.22.

• In it a tunnel laid along the hill side to tap water from under ground springs.
• The tunnel has some longitudinal slope.
• As it lies in hard stratum it is

• usually not line
• . Water from Karez is led into an open channel at its down stream end and used as deemed suitable.
• Such tunnels are existing in Baluchistan and North West frontier in Pakistan.