Irrigation Methods and Efficiencies

Irrigation practices today are characterized by the necessity to irrigate "by all means" leaving little room for proper irrigation system management. Where village communities were able to organize themselves in a peaceful manner and received assistance in the rehabilitation of destroyed (intakes) or obsolete (conveyance canals) irrigation structures, irrigation is mostly practiced in the traditional way: operation and maintenance of the schemes as well as water distribution are managed on a communal basis under the supervision of mirabs, and disputes over water rights are solved by vakils. In many other cases where communities share the same water resource for the irrigation of their individual fields but are ruled by different "authorities", farmers are less fortunate and struggle to make their irrigation scheme some how operational.

About 85 per cent of all crops in Afghanistan are grown under irrigation. Canal irrigation is by far the most commonly used method of irrigation in Afghanistan. Canals in Afghanistan irrigate nearly 75% or 1.9 million ha of land. As is evident from Figure, the proportion of canal-irrigated land is much greater than any other form of irrigation. Most of the canal-irrigated land is located in the north, west, and southwest of the country. These canals primarily get water from the snowmelt rivers in the region. At different locations along the river, small diversion structures are installed to divert water from river to the irrigation canals. These diversions are both open or gate fitted. Newly build Logar dam and a typical gate fitted diversion point is shown in Figures. From these canals, water is diverted to small irrigation channels (watercourses). According to the water laws of 1981, the amount of water given to each farmer is determined according to its area under cultivation, the kind of crop, the irrigation regime, the water rights document, the local practice and amount of water present in the main source. However, these regulations are not strictly followed and water distribution is mainly done on informal agreements among the farmers.

In traditional as well as in modern irrigation schemes the dominant irrigation method is basin/border irrigation for cereals and furrow irrigation for vegetables and grapes. Farmers usually lack knowledge about crop water requirements and over-irrigation of crops is a common practice. Overall efficiency is only about 25 to 30 per cent for both modern and traditional irrigation schemes due to the following reasons:

• high conveyance losses in traditional schemes with earth canals,
• high operation losses in modern schemes with lined conveyance canals,
• high on-farm distribution losses (over-irrigation, poorly leveled land) in both traditional and modern schemes.

Additionally, there is usually a waste of irrigation water in traditional schemes during the first half of the growing season due to unregulated flood water entering the conveyance canal, and a shortage of water during the second half when river flow decreases to its annual minimum.

Due to low water use efficiencies and lack of inputs, crop yields are very low. Present drought conditions have caused further reduction in crop yields e.g. average yield of wheat was about 1.1 tons/ha in 1978 as compared to 0.8 tons/ha of today. In Table 10, total area, production and yields of different cereal crops for 1978 are presented. The total area (irrigated+rainfed) under cereal crops was about 3.39 million ha. The total cereal production was 4.15 million tones of which 2.65 million tones was only wheat.

Area of irrigated land (ha), irrigated by different irrigation schemes in Afghanistan

New Dam on the Logar River

A typical gate fitted canal intake

Cultivated area, production and yields of different cereals in 1978

Source: Water Resources Management in Afghanistan: The Issues and Options by Asad Sarwar Qureshi, IWMI, Working Paper 49