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Irrigation and drainage
Evolution of irrigation development
The irrigation potential is about 413 700 ha. Irrigation development dates back to the end of the eighteenth century. The Kerian irrigation schemes were the first large schemes to be constructed, in 1892. Since the formation of the Department of Irrigation and Drainage in 1932, irrigated areas for rice cultivation have progressively increased. By 1960, about 200 000 ha had been developed, the emphasis then being on supplementing rainfall for single crop cultivation.
During the 1960s and early 1970s, the introduction of double cropping of rice cultivation required the development of adequate water resources for the second cropping season. During the 1980s, the priority for irrigation took on a new dimension with the need to rationalize rice cultivation and increase its productivity. The Government developed a policy to concentrate efforts on irrigation development in eight large irrigation areas, designated as granary areas and totalling 210 552 ha. They are the irrigated areas of Kada, Seberang Muda Perai, Trans Perak, Northwest Selangor, Kerian-Sungai Manik, Besut and Kemasin-Semarak.
In 1994, Malaysia had over 932 irrigation schemes covering 340 717 ha, comprising the above eight granary schemes (210 552 ha), 74 mini-granary schemes (29 507 ha) and 850 non-granary schemes (100 658 ha) (Table 4 and Figure 3). The non-granary schemes are scattered throughout the country and their size varies between 50 and 200 ha. In 1994, 92 percent of the full control equipped area was irrigated by surface water and 8 percent by groundwater (Figure 4). Surface irrigation and localized irrigation accounted for 340 600 ha and 117 ha respectively (Figure 5).
In addition, there are 21 970 ha, which are inundation and control drainage schemes. The total irrigation area was an estimated 362 687 ha in 1994.
In the major irrigation schemes, flooding or basin irrigation is practiced on rice fields, and the water depth is controlled individually by farmers. Major irrigation schemes are designed with proper farm roads to cater for farm mechanization especially for ploughing and harvesting.
Role of irrigation in agricultural production, the economy and society
Irrigation is predominately for rice cultivation and, to a minor extent, for vegetables and cash crops. Rice cultivation is mostly carried out by individual farmers working on small plots of about 1-1.5 ha. In 2006, the total harvested irrigated cropped area on the full control irrigation area was about 382 000, of which 95 percent was rice, 3.1 percent sugarcane, 1.6 percent vegetables and 0.3 percent groundnuts (Table 4 and Figure 6).
In 1999 irrigation efficiency was around 35-45 percent with a water productivity index for rice of about 0.2 kg/m│. The average yield for irrigated rice was 4 tonnes/ha in 1995.
Status and evolution of drainage systems
In 1994, the total drained area was 940 600 ha. About 600 000 ha were drained for oil palm cultivation, using public funding for smallholders. Most of the irrigation schemes (340 600 ha) are provided with separate drainage facilities.