研究期間：10105~10112;According to the report of Agriculture and Food Agency, the comprehensive food self-sufficiency rate has decreased to 32% year by year with high risk of food security. This value is also lower than our neighbor countries, such as Japan or Korea, which had similar eating preference. The effect of climate change made mass hazards in the whole world. The hydrology record data also showed the pattern of long term drought and short time mass rainfall. That also increased the risk of worldwide food supply chain. In Taiwan, paddy rice is always the most important crop. However, the same paddy irrigation area has mix crop in the same time, such as paddy and upland crop, or pure large area vegetable field is not rare. To understand the irrigation factors effect of food security. This research will establish the study area irrigation system with Vensim model and simulate with real rotation irrigation operation system. To discuss the crop output effect and water allocation under local seasonal irrigation supply condition and mix crop area distribution. The result data can provide the policy office as background data or pre-study to make more accurate decisions about the subject of drought season, food security of agriculture irrigation, reliability of climate change or renew water allocation policy.