Ans: Karez:
Below the surface of land, small canals or covered water courses are dug
which are called Karez. Underground canals in Balochistan are used for
irrigation. Water is collected in underground canals in the mountain valleys.
This water is then transported to the land to be cultivated so as to prevent
water loss through evaporation. Such underground canals are found in the
base of mountains. Karez is mostly made in those areas where water is
scarce and the process of evaporation is more. Groups of people make
karez so that water can be used and not lost through becoming water
vapours. To keep such underground canals clean, blocks are placed at
intervals (below the ground), which can be removed when necessary for
cleaning purposes.