Aflaj are the main source of irrigation water in Oman, besides wells. They have been utilised in agriculture as well as for domestic purposes since ancient times. This system of irrigation engineering is a legacy of the rich Omani heritage, and this complicated architectural system reflects the Omani civilisation through centuries.
Falaj has been an integral part of Omani social life for a long time. Omanis are still emotionally connected to their falaj and it is an integral part of their present and past. The history of it dates to the times when people started building villages and towns.
Falaj is a channel dug in the ground or built on the surface, tapping underground water. The water flows through channel naturally.
The water flow of aflaj is more or less constant all year round and varies according to the amount of rainfall and drought conditions.
The main structure of the falaj consists of the mother well with a depth of 65 to 200 feet, the main channel, and the access shafts that are built every 50 to 60m along the channel.
The average water flow of the falaj is about 9 gal/sec which is adequate to irrigate a large number of hectares permanently. Water distribution is fairly complicated but rather efficient to ensure fair and adequate water supply for all farming lands.
There are two types of aflaj in Oman: Ghaily falaj, which are dug close to the ground surface and normally open channels. The water of this kind of aflaj comes from wadi (valley) bottom which accumulates after rainfall or through higher water table that leak to lower ground levels of wadis. This type represents 55 per cent of the total number of aflaj. They are around 4 metres deep and two kilometres long. Ghail Aflaj dry out after long periods of drought.
The other type of aflaj is Iddi or Daudi, which is underground canals and connectedto the mother well where the underground water flows and runs through covered channels to the irrigated lands. The depth of these canals is around 50m and may reach a length of 12 kilometres. It consists 45 per cent of the total aflaj and is the main and permanent source of water in many Omani regions.
Omanis set up this system hundreds of years ago to distribute water to manage farming lands.
The Ministry of Water Resources carry out maintenance of aflaj and add modern irrigation techniques to increase the flow of water.
There are many aflaj in the country noted for their abundance of water. Falaj Darass in Nizwa and Fardhag falaj in Wadi Bani Khalid are examples.
see article OMAN DAILY