Means Of Irrigation In Pakistan
The following means of irrigation are practiced in various areas of our country:
1.Wells or Tube-wells:
This is one of the oldest methods of irrigation which is being used from ancient times in our country.Well irrigation is quite common in pledmont areas of North Eastern mountains and in the vicinity of rivers where the water-table is high.They are found all over the plain where canal water is not available and water table is high enough for their construction.Many shallow wells are dug by hand the areas where the water table is not far below the surface of the earth .The water is then lifted by “Charas” or “Persian wheels” driven by oxen or camels.
In areas where the water table is low and cheap electric power is available ,tube wells are used;due to shortage of canal irrigation water ,government is encouraging the farmers to dig more and more tube wells.
Irrigation from rivers is an ancient practice.It was being carried before the birth of christ in various areas of our country,but the modern system of large perennial canals was introduced by the Britishers.The first modern canal in Punjab was opened in 1859;it was taken out from river Ravi at madhopur (Gurdaspur district,India).After that a number of canals have been taken out from various rivers and our country has got one of the most excellent systems of irrigation in the world.The canals found in our country may be divided into the following types:
Those canals which supply water to their commanded areas throughout the year are known as perennial canals.To regulate the supply dams and barrages have been built.Most of the canals of our country are of this type.
(b)Non Perennial Canals:
Such canals runs only during the summer and the rainy season .They are closed down during winter months when there is not enough water in the rivers.Some of the canals from Sutlej ,the Sidhnal canals from Ravi and Haveli canals from Chenab are of this type.Only one crop can be harvested in the commanded areas of such types of canals.
(c) Inundation or Flood Canals:
These canals work only during the rainy season,when the rivers have a plenty of water .Because no dam or barrage is built at their head ,their construction cost being low,they also help in reducing the flood water and save the area from many dangers.Many old canals from the Indus and Chenab are of this type.
In Baluchistan short underground canals called Karez have been built to carry the water which soaks into the ground at the foot of the mountains to the fields and villages .As the canals are underground no water is wasted by evaporation.In Queta and Pashin districts this system is very popular and a large area of this region is irrigated by the Karez system.
The irrigated area is served by more than 40 major canal commands.Main canals start from a barrage or dam or weir on a river.A barrage feeds one or more main or link canals.A number of minor tributaries feed out of the main canal and these in turn,serve a number of outlets to the farmers water-courses each of which irrigates between 60 and 240 hectares.
There are three major groups of canal system :
(i) Canals on upper Indus Tributaries
(ii) Systems on the Indus
(iii) Systems west of the Indus.