SBR- Content.pmd - INBO

State of the Basin Report - 2003Irrigation schemes in Cambodia largely rely onthe use of receding flood waters as the sourceof irrigation water. This kind of rice productionis known as recession rice and is graduallyreplacing lower yielding traditional floatingrice. Pumping is also a major feature ofCambodian irrigation. Traditionally this wasdone manually, but petrol-propelled pumps aregradually becoming more common. Manualpumping for a lift of 0.5 m requires labour ofabout three to four work hours per day for oneha of flood recession rice. This labourrequirement is approximately 40-50 percenthigher than that needed for automated pumping.Planting of a second irrigated rice crop in the dry season occurs in only approximately 10 percent ofthe total wet season rice production area. Limited ability to control water constrains the furtherexpansion of second season cropping. 34In Lao PDR, the use of irrigation expanded rapidly over the 1990s, with the government reportingan eight-fold increase in irrigated rice area during this decade. 35 However, the irrigation area islargely confined to the relatively affluent lands of the Mekong corridor, and remains a rarity in theupland areas. The increase in irrigation use in the lowlands is partly due to a move away from a fewlarge, government-managed schemes, in favour of numerous small farmer-managed arrangements. 36The creation of water user associations, and a related legal framework to support them, has alsobeen important. 37In Northeast Thailand, where farming methods remain comparatively traditional, irrigation ratiosare much lower than in other parts of the country. 38 Various large-scale irrigation projects have beenconstructed on the Chi and Mun Rivers, but local opposition to dam projects has made it difficultfor the government to undertake further large- and medium-scale developments. 39 Furthermore,water scarcity is a major concern. Water shortages prevent full utilisation of existing irrigationworks in the dry season, and there are even reports of water shortages in the rainy season. 40There are huge variations in scale and type ofirrigations schemes in the LMBIrrigation comprises 80-90 percent of all waterabstractions in the LMBIrrigation is extremely important in the Viet NamMekong Delta region, and enables the very highproductivity of agriculture in this area. More thanhalf of the total area of the delta is flooded duringthe rainy season. 41 Irrigation therefore plays acritical role because it allows farmers to storewater for use in intensive rice cropping duringthe flood free period. Irrigation schemescontributed to the tripling of food productionbetween 1975-1995 and over the last 15 years,almost all the low-yielding floating rice (estimatedat half a million hectares in 1995) has beenreplaced by irrigated rice. The rapid rise inirrigation development in Viet Nam is the resultof intensive investment in irrigation, related flood- and salinity-control works, and the market-orientatedDoi Moi economic reforms. Government planning and management of irrigation has been decentralised,with autonomous provincial authorities now financing many irrigation activities. In the Central Highlands,irrigation is less developed than in the delta, with upland rice and coffee being the main irrigated crops.154