Abstract:

Based on the observations at 17 typical stations and the monthly outputs of 25 CMIP5 models, the impact of climate change on summer maize net irrigation water requirement in Henan province in China during 2021-2050 was assessed. Firstly, the daily maximum temperature, minimum temperature and precipitation in the future period (2021-2050) under the RCP4.5 scenario were generated by using the quantile mapping method and the weather generator BCC/RCG-WG 3.0. Then the difference between the crop water requirement and the effective precipitation in growth stages (namely, the net irrigation water requirement, NIWR) was calculated and compared to the baseline period (1961-2000). The results show that in the whole growth period, annual mean temperature and precipitation could increase by 1.8℃ and 3.6%, respectively, which might lead to increases in both water requirement (5.1%) and effective precipitation (1.5%). The projected future NIWR is likely to increase by 5.6%. Due to the temperature increase and precipitation decrease in sowing-jointing stage, the NIWR could increase by 21.3%. In jointing-milk maturity stage, the increased effective precipitation (3.0%) is not enough to offset the increased crop water requirement (5.1%) derived from temperature increase, the NIWR could still increase by 3.4%. However, in milk maturity-maturity stage, the NIWR decreases by 1.4% with a more increase of 8.2% in effective precipitation and a less increase (7.4%) in water requirement. The NIWR could increase in every growth stage at Sanmenxia, Mengjin, Luanchuan and Xixia stations in the western and southwestern of study area.

Key words: summer maize, climate change, net irrigation water requirement (NIWR), weather generator