Development of prediction models of the change of agricultural water use in the Asia monsoon region

Integrated models of meteorology, hydrology and water resources are developed, which is based on hydrological process and water user patterns that are peculiar to Asia Monsoon Areas. In addition, simulation of the prediction of water resources change is carried out under scenarios of the future. Target areas are monsoon and semi-arid zones, especially the Mekong River, which is facing controversial water resources problems. The check-points of the model is maintained and proofed by 'the generation and simulation of past natural variation and human modification.' In the starting 3 years, restoration and generation of dispersed and scattered part of the original data are performed. What is more, observation watersheds are installed on areas with typical hydro-meteorology, land-use and water use and monitoring is resumed. Based on the above information, water circulation and water use processes are modeled, which are peculiar to the Asia Monsoon. In the following 2 years, those models and technologies are integrated. In addition, causes, results and effects of the past floods and water uses are evaluated and the countermeasures on those changes are proposed. In this paper, especially, various kinds of paddy cultivation and irrigation and drainage patterns are practiced in the Mekong River Basin. Among those, an irrigation pattern, that is, water circulation process with inundation and irrigation combined, which is not defined and formulated concretely due to the lack of various hydrologic data, is focused and modeled. In addition, based on the information of the sub-topics such as historical flood data, the change of land-use, irrigation water use, the relation between the level of irrigation practices and water circulation is examined and a model to evaluate the effect of artificial agricultural activities and its development on basin wide water circulation is developed. The difference and distribution of various irrigation patterns in the basin are defined and an integrated modeling with inundation, irrigation and drainage models combined is carried out. At the same time, an estimation method for inundated areas and rice-cropping patterns and periods, is developed using satellite data. When performing studies, field visits, field observation and various data collection are carried out with the help of many local and/or international organizations such as Mekong River Commission, SRHMC, SIWRP in Vietnam, RID, DEDP, JIRCAS in Thailand, DI, DMH of MAFF in the Lao PDR, and DHRW, DI of MWRM in Cambodia.