干旱传递机理及综合干旱评估方法

Drought risk facing the world under changing environment would be even more severe. It pose a threat to water supply security and food security. The Shiyang river basin in Hexi Corrider is selected as the study area. Based on the water cycle process and SWAT model, the factors of the water cycle will be simulated. the standard groundwater drought index (SGI) will be built. The methods of run theory，clustering analysis and extreme-point symmetric mode decomposition(ESMD) were then used to identify the dynamic characteristics of Spatiotemporal trend of the drought. The cross wavelet analysis and non-linear function model were utilized to examine the respond correlations and propagation between hydrological、groundwater、 agricultural and meteorological droughts. A multivariable comprehensive drought index (SPRSGI) will developed which utilize information from hydroclimatic variables, including precipitation, runoff, groundwater and soil moisture as indicators variables. And an assessment method for comprehensive drought is put forward. Through this research, The method of SGI and SPRSGI will be proposed. Spatiotemporal dynamic evolution law of different types of drought and drought transfer mechanism will be revealed. The transfer threshold of the meteorological drought to hydrologic、groundwater and agriculture drought will be obtained. The method to evaluate comprehensive drought will be put forward. The problems of groundwater distribution of standardized drought index, the threshold of droughts propagation and dimension disaster in building SPRSGI will be solved. Through the combination of theoretical innovation and practical application, enrich and develop the drought index theory. It will provide scientific guidance to the decision of drought control and mitigation and water resources management in northwest arid area.

变化环境下全球面临的干旱风险更加严峻，给水资源安全及粮食安全带来巨大挑战。以西北旱区石羊河流域为研究区，基于SWAT水文模型，模拟干旱评估需要的水循环要素演变过程；构建标准地下水干旱指数（SGI），采用游程理论、聚类分析和极点对称模态分解方法识别和评估干旱时空动态演变特征；采用交叉小波、转移概率及非线性函数建立气象干旱与水文干旱、地下水干旱以及农业干旱的响应关系及传递关系；构建综合反应气象、水文、地下水及农业干旱的多变量综合干旱指数。通过研究，提出SGI和综合干旱指数的构建方法，揭示干旱的时空动态演变规律以及不同类型干旱的传递机理，界定气象干旱向水文、地下水以及农业干旱传递的阈值，提出综合干旱评估方法。解决SGI构建中地下水分布的拟合函数优选、干旱传递阈值以及综合干旱指数构建的维数灾问题。通过理论创新与实践应用相结合，丰富和发展干旱指数理论，为研究区防旱减灾以及水资源管理调控提供科学依据。

变化环境下全球面临的干旱风险更加严峻，给水资源及粮食安全带来挑战。针对西北气象站点稀疏、地下水最优拟合函数和干旱传递机理尚不明晰以及干旱指数难以全面反映干旱特征等问题，评估了提高SWAT模型模拟精度的遥感数据，模拟了水循环要素；优选了地下水位拟合函数，提出了地下水干旱指数SGI构建方法；完善了干旱三维识别方法及干旱事件对匹配准则，采用copula函数等建立气象-水文/农业干旱的非线性响应关系，推导了基于贝叶斯网络的干旱传递概率模型；构建并验证了多变量综合干旱指数，分析了综合干旱特征。扩展研究了农业/水文干旱预测模型，预估了未来中国干旱的演变趋势。.研究发现提高高寒山区水文模拟精度的遥感数据为CHIRPS日降水与CFSR温度数据，基于降水与海拔关系的改进ADW插值方法可提高日降水空间插值精度；黑河地下水位最优拟合函数为Beta分布，SGI呈先下降后回升和持续下降2种变化趋势；近10年地下水干旱发生频率在河西走廊、六盘山区和青海南部等区较高，而在陕南、柴达木盆地、青海湖和新疆等区较低；气象-地下水干旱的传递时间主要为1~6个月和19~24个月；获得的气象-农业/水文干旱特征变量间的最优响应关系，可回答触发不同程度农业/水文干旱的气象干旱阈值；提出的非一致性综合气象水文干旱指数NMHDI、混合干热指数BDHI、综合水文干旱指数SGRI等多种综合干旱指数方法，能更全面反映干旱的特征；构建的4C-vine和BMAViC模型分别对中国夏季农业干旱和黄河上游水文干旱的预测效果明显优于MG模型；不考虑CO2浓度影响的干旱指数高估了未来干旱发生状况，考虑CO2升高的SZI[CO2]识别的中国未来干旱在西北地区南部、内蒙古和青藏高原西部呈下降趋势，在华中和华南则呈明显上升趋势。结果丰富和发展了干旱指数与传递理论，为研究区干旱预警、防旱减灾以及水资源管理调控提供科学依据。