Impact of climate change on cotton production and water consumption in Shiyang River Basin

Based on the COSIM cotton model associated with the climate change scenario produced by the UK Hadley Centre regional climate model-PRECIS (Providing Regional Climates for Impacts Studies), the cotton production and water consumption were simulated in Shiyang River Basin under A2 (concentration on the economic development) and B2 (concentration on the sustainable development) emission scenarios, and the potential of enlarging cotton cultivation scope in SRB was discussed. Finally, the impact of future climate change on cotton production in SRB was analyzed based on the proposed adaptation measures such as adjusting sowing date, breeding the new cotton variety and adopting different irrigation amount. The results showed that the cotton growth stages would prolong and the yield would obvious increase by 2080s（2071-2100）in Minqin under future emission climate change scenarios, and the yield under A2 scenario would be higher than that under B2 scenario, but the increase rate under B2 scenario would be faster than that under A2 scenario. The risk of cultivating cotton would reduce with the decrease of variation coefficient of cotton yield. The reference crop evapotranspiration, water consumption and water use efficiency would obvious increase by 2080 in Minqin, which demonstrated water requirement of cotton tended to rise and water productivity per unit would increase. The risk of cotton drought would rise with the increase of variation coefficient of reference crop evapotranspiration and water consumption.WUE of cotton tended to more stable with the decrease of variation coefficient of WUE. The cotton could natural grow in Wuwei under future A2 and B2 emission scenarios, and cotton would obtain high yield under A2 scenario, which demonstrated the cotton cultivation scope would be expanded and there was a certain potential for cotton production in future SRB when only climate change was considered. If keeping other managements unchanged, the sowing date was delayed under A2 scenario or advanced under B2 scenario, the cotton yield would increase. Breeding the early-mid maturing cotton variety into SBR, the cotton yield would obvious increase under A2 scenario but decrease under B2 scenario, which indicated that there could be some risks on breeding the new variety in the future climate scenarios. If irrigation amount decreased under A2 and B2 emission scenarios, the cotton yield would obvious decrease, which demonstrated the risk of cotton production would rise if irrigation amount was insufficient and production water use gave place to ecological water use in future SRB.