华北平原地下水超采区冬小麦-夏玉米种植模式旱灾风险时空特征研究

Natural disasters such as droughts are the main reasons for crop yield losses. Study on the cause mechanism and spatio-temporal patterns of drought risk is of great significance for grain security. In this study, the North China Plain with severe groundwater overdraft and agricultural droughts was selected as a typical area. We study the risk features of drought disaster in North China Plain by employing the spatial analysis of GIS, the crop model simulation and field experiments. Based on the differences of rainfall and water sensitivity in different growth stages of crops, we set up different irrigation scenarios such as total rainfed and low-volume irrigation, and we simulate the drought-induced crop yield loss using the APSIM model and field experiment. A technical framework was established to quantitatively assess the drought risk of winter wheat-summer maize cropping system from two perspectives of "dividing different growth stages" and "dividing different planting areas" in North China Plain. The results can indicate the vulnerable growth stages of winter wheat-summer maize, and identify the high risk areas with high-intensitive, high frequency, and big yield loss of droughts. This study can provide a reference for cropping pattern optimization and groundwater protection in North China Plain.

旱灾是造成作物减产的主要自然灾害，开展旱灾风险成因机制和时空特征研究，对于稳定作物生产和粮食安全具有重要意义。本研究选择地下水严重超采和干旱灾害频发的华北平原为典型区，采用GIS系统空间分析、作物模型模拟和田间试验相结合的研究方法，分析华北平原典型种植模式与区域水资源的时空匹配协调特征；基于作物不同生育阶段的降水量和水分敏感性差异，设置完全雨养和低量灌溉等不同干旱情景，运用APSIM模型模拟并结合田间试验分析作物受旱减产的过程机制；构建以作物水分亏缺胁迫和最终产量损失为核心的旱灾风险评价技术流程，从“分生育期”和“分种植区”两个维度开展华北平原地下水超采区冬小麦-夏玉米种植模式旱灾风险时空特征研究；揭示导致作物受旱减产的关键生育期阶段，识别旱灾强度大、发生频率高和产量损失重的高风险种植区域，为华北平原粮食主产区因地制宜调整作物种植结构，有效缓解地下水压力和实现可持续丰产提供一定科学依据。

水资源短缺和干旱灾害频发严重威胁华北平原粮食安全。冬小麦-夏玉米是华北平原主导种植模式，研究其干旱灾害的成因机制和时空特征, 对于稳定区域粮食生产和农业可持续发展有重要意义。本项目综合运用作物模型模拟、GIS系统分析和田间试验相结合的研究方法，分析评估华北平原冬小麦-夏玉米种植模式的旱灾风险时空特征。研究构建了作物水分亏缺指数（CWDI）和干旱风险指数（AI）等定量化评价指标，分析了冬小麦-夏玉米不同生育期的水分亏缺特征及其敏感性差异, 揭示了华北平原冬小麦-夏玉米水分供需的空间分布规律及其变化趋势，阐明了近几十年气候变化影响下华北平原冬小麦-夏玉米干旱灾害风险的时空格局。研究表明, 冬小麦生育期内需水量和干旱风险很高，年均水分亏缺量达264mm。冬小麦拔节–抽穗阶段的干旱风险最高, 其次是抽穗-成熟阶段，且气温是影响冬小麦生育后期干旱程度的关键因子。从空间上看，河北省东南部特别是保定、沧州、衡水等黑龙港流域地区面临非常严重的干旱风险。相比而言，夏玉米生育期内有效降水和作物需水的耦合度较高，灌溉需水量较少（全生育期仅为79 mm），其干旱风险处于较低水平。本研究识别出了冬小麦-夏玉米干旱灾害的高风险区域及其关键生育期阶段，研究成果可为华北平原调整优化灌溉管理制度及农田抗旱减灾提供参考依据。