Tunnels of hope
US spy satellites often point to lines of mounds in the arid south and east Afghanistan surrounded by greenery. What they, in fact, hide is one of world's ancient technological marvels to harvest water known as karez (or qanats). In ancient times, farmers in eastern and southern Afghanistan built this network of underground irrigation channels to use the scarce groundwater for irrigation. "Recovering of the karez is crucial to the country's livelihood," says Abdullah Qaderdan from the Ngo Arc (Afghan relief committee) in Jalalabad.
The karez system evolved in northwestern Iran some 3,000 years ago. By 714 BC, the system spread to Egypt, Afghanistan and far away south India. It is an unlined tunnel with shafts in equal intervals and brings water to the surface using gravity. First, a well is dug to the water level and then lines of shafts are dug to enable removal of soil. Water travels down through tunnels to farm fields on lower plains. Some of karez stretch for several kilometres underground. Farmers construct and manage such structures through users' groups. Karez is labour and maintenance-intensive. The silt must be cleaned annually and hauled to the shaft surface. It takes many years to construct a karez, but the operating cost is low. A karez can irrigate 10-20 hectares (ha) of land. There are some 6,500 karez in Afghanistan and can irrigate about seven per cent of land.
Besides irrigation, these tunnels have also been used as hideouts. Afghan fighters dug caves in the shafts' sides to hide weapons and people. Osama bin Laden created a network of crisscrossing tunnels and fortified underground bunkers.
In India, this system is still exists in Kerala and in few districts in Madhya Pradesh. In Kerala's Kasargod district there are around 400 karez, known as surangams in local parlance. Surangams resemble karez both in structure and spread. This system has been very effectively used for domestic and agriculture purposes in dry areas of northern Malabar. Interestingly, one survey found that more than half of these structures were constructed between 1977-97.