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

  1. Infiltration galleries
  2. Springs
  3. Karez.

1. Infiltration Galleries.

  • 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.

Infiltration galleries.

  • 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 provid with man holes for inspection and maintenance.
  • Infiltration galleries are not use for getting water for irrigation purposes.

2. Springs.

  • 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:

(a) Artesian springs

(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 fissur.
  • Gravity spring develops when ground water table gets exposed due to ups and downs in the surface.

(a) Artesian spring (b) and (c) surface springs.


  • 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.

3. Karez.

  • 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.