水是增加食物生产的最重要因素之一。即使短期的干旱也往往引起显著减产,而长期干旱能导致作物全部失收。灌溉是人工供水,以使干旱地区能进行农业生产,使半干旱或半湿润地区消除干旱威胁。因此,在解决日益增多的人口的粮食问题中灌溉有其重要作用。即使在雨量充沛的地区,也可能由于一年中雨量分布不均匀,以致只有进行灌溉,才能进行复种。 Water is one of the most important factors in increasing food production. Even short-term droughts often result in significant yield cuts, while prolonged droughts can lead to the total loss of crops. Irrigation is a man-made supply of water to enable agricultural production in arid regions and to eliminate the threat of drought in semi-arid or sub-humid lands. Therefore, irrigation plays an important role in solving the food problem of a growing population. Even in areas with heavy rainfall, the uneven distribution of rainfall throughout the year may result in multiple cropping only when irrigation is carried out.