Changes of Rice Water Demand and Irrigation Water Requirement in Southeast China under Future Climate change

In this paper, Rice water requirement and irrigation water requirement in Kunshan Irrigation and Drainage Experiment Station in 2046-2065 and 2081-2100 are forecasted based on the projected meteorological data of CGCM3.1 under SRA1B and SRB1 scenarios. Rice water requirements are estimated by using crop coefficient approach. Reference evapotranspiration are calculated by FAO Penman-Monteith method. Moreover, the irrigation water requirements are simulated by calibrated ORYZA2000 model. The results show that both crop water requirement and irrigation water requirement present upward trend in the future. In 2046-2065, the rice water requirement and irrigation water requirement increase by more than 2% and 5% under SRA1B and SRB1 scenarios, respectively. In 2081-2100, the rice water requirement and irrigation water requirement increase by more than 5% and 15% under SRA1B and SRB1 scenarios, respectively. Furthermore, the temperature rise may be the main reason for the increase in crop water requirement, while significant increase of irrigation water requirement should be attributed to combined action of rising temperature and a slight decrease in precipitation.