ABSTRACT
Indonesia is one of the countries blessed with a large potential of water resources. The seasons change every six months. The dry season (June to September) is influenced by the Australian continental air masses, while the wet season (December to March) is the result of the Asian and Pacific Ocean air masses. During the twentieth century, rainfall reduced with 2 to 3" in Indonesia. Almost all of this reduction occurred during the months from December to February. The precipitation patterns have also changed. The changes in the wet and the dry season also affect the water availability, with decreasing rainfall during critical times of the year that may result in drought risk and uncertainty in water availability. Subak irrigation schemes, related to which is the term of Irrigation Planning Criteria, called Irrigation Area- are an example of water resources management, distribution and supply of irrigation water in a perfect vision on the social welfare in the river basin.
