气候变化下冬小麦生育期水分亏缺特征变化及其对旱灾风险影响评估研究

The process and total amount of crop water demand have changed due to climate change. In the meantime, temporal-spatial distribution of precipitation and water resources has been different from it was before, leading to the change of water replenishment and expenditure process of crops. Identifying the water shortage change characteristics during the crop growth period in the context of climate change is the key basis to establish targeted and accurate irrigation system. Besides, water shortage in the context of climate change will cause the change of regional drought and drought risk characteristics. Thus, identifying chained transfer process from water shortage to drought disaster and evaluating the effects on drought disaster risk is a necessary precondition for the drought risk management. This project will take Luanhe River Basin in North China where drought events occurs frequently as study area and typical crop winter wheat as investigated subject. Through numerical simulation and time series analysis, water shortage change characteristics during the winter wheat growth period will be revealed. Based on this, scenario simulation and prototype observation experiment will be used to identify the chained transfer process of “water shortage-hazard-affected body-drought disaster”, so as to establish drought disaster risk assessment model of winter wheat. With the model, the effect of water shortage on risk can be assessed both in the past and future. This project will provide direct scientific basis and technological support for drought comprehensive response of Luanhe River Basin.

受气候变化影响，作物需水时间节律和总量有所改变，降水及水资源的时空分布格局也异于以往，从而导致作物水分的补给过程和支出过程均发生变化，识别气候变化下作物生育期内水分亏缺特征变化是制定靶向性和精准性灌溉制度的关键依据。此外，气候变化下的水分亏缺变化会导致区域旱灾风险特征有所改变，识别从缺水到旱灾的链式传递过程，评估作物生育期内水分亏缺特征变化对旱灾风险的影响是干旱风险管理的前提。本项目以位于华北地区干旱事件频发的滦河流域为研究区，以典型农作物冬小麦为研究对象，通过数值模拟和时间序列分析技术，揭示冬小麦生育期内水分亏缺特征变化；在此基础上，通过多情景模拟和原型观测试验，识别“缺水-承灾体-旱灾”链式传递过程，构建冬小麦旱灾风险评估模型，评估过去50年和未来30年冬小麦生育期水分亏缺特征变化对旱灾风险的影响。通过本项目研究，将为滦河流域干旱综合应对提供直接科学依据和技术支撑。

本项目以位于华北地区干旱事件频发的滦河流域为研究区，以典型农作物冬小麦为研究对象，开展气候变化下冬小麦生育期水分亏缺特征变化及其对旱灾风险影响评估研究。主要成果如下：.（1）滦河流域冬小麦生育期干旱时空变化规律.1960-2013年间滦河流域干旱率年际变化较大，平均干旱率为19.1%。1960s、1980s和2000s，干旱形势较为严峻，多年平均干旱率为23.6%、22.8%和21.5%，是1960-2013年期间多年平均值的1.1-1.3倍；上游多伦、围场和下游迁西等地区干旱程度加剧，上游沽源和隆化等地区干旱程度有所缓解；干旱事件主要集中在中上游围场、隆化、多伦和沽源等地区；对于长历时的干旱，多生在围场和承德，高强度的干旱多发生在源头的沽源。.（2）滦河流域冬小麦生育期干旱灾害风险分布.在中等干旱、严重干旱和极端干旱影响下，冬小麦产量的减产分别为13.7%、33.6%和57.8%；旱灾风险评估结果表明，滦河流域干旱灾害风险相对较高的地区主要位于上游的沽源县、丰宁满族自治县、多伦县、围场满族蒙古族自治县、中游的隆化县、承德县和平泉县；中游右岸地区和下游平原地区干旱灾害风险相对较低。流域内约有57.8%的耕地位于中等及以上风险区。.（3）滦河流域未来冬小麦生育期干旱灾害风险预估.在未来预估时段，滦河流域中风险区和高风险区的面积有所扩张，在中游左岸地区（承德以北）尤为明显，在RCP2.6、RCP4.5和RCP8.5情景下，位于中高及以上风险区的耕地占总耕地面积的58.7%、62.8%和56.0%，为6108.6km²、6542.1 km²和5832.9 km²，分别为基准期（1961-1990年）的2.18倍、2.33倍和2.08倍。风险增加的地区主要分布在承德、隆化、滦平、遵化等地区。