SBR- Content.pmd - INBO

State of the Basin Report - 2003global economic integration, and as socialattitudes change. However, the shifttoward commercialisation is occurringmuch more slowly in remote and highlandregions and will probably requiresubstantial government or donorassistance and investment. Cambodia andLao PDR have the double challenges ofensuring food security and movingtowards market-oriented, commercialagriculture, which is likely to ensure thatthe process of change is slow in thesecountries.In Northeast Thailand and Cambodia, tobacco isa major cash crop3.2 IrrigationIrrigation is any process other than natural rainfall that supplies water to crops and other cultivatedplants. The main crop under irrigation in the LMB is rice, and most of the data on irrigated cropsrefer in reality to irrigated rice. The use of irrigation is increasing in the lowland areas of the basin,not only as a means of allowing dry season and even third season rice crops, and dry season orperennial cash-crops, but also to provide extra water for wet season production.More attention is also being paid to improving the efficiency of existing schemes throughrehabilitation, water management and institutional strengthening. Despite these developments, theLMB irrigation ratio (irrigated area over cultivated area) is still low by international standards. In1998, the ratio was estimated at 7-10 percent, as compared with 45 percent for the whole of Asia. 27There are, however, significant differences in the extent of irrigation in the basin, with the VietNam Delta, for example, irrigating approximately 60 percent of crops. 28There are huge variations in the scale and type of irrigationschemes in use across the basin. The largest individual schemeis the 50,000 ha Lam Pao project in Thailand, while thesmallest are simple manual lift operations, irrigating less thana hectare. The most basic systems provide only supplementarywater during the wet season, while more intensive schemeshave the capacity to grow two to three crops per year. Majortypes of irrigation systems include: the use of gravity to divertrivers, lakes, or streams to provide supplementary water inthe wet season, with no storage; the pumping of water fromrivers in the wet or dry season, with no storage; the use ofpumps or gravity to divert water from streams, rivers andrunoff into reservoirs for use in dry or wet season irrigation;and the storage of receding flood waters in reservoirs for usein preparing land for cropping and wet or dry seasonirrigation. 29Only 10 percent of LMB land isirrigated compared to an average of45 percent for AsiaIrrigation systems in LMB currently face significantchallenges that complicate balancing the increasing demandfor irrigation water with requirements to conserve waterresources. Studies show that water is lost while flowing152