College of Resources and Environment, Gansu Agricultural University, Lanzhou 730070, China.
College of Management, Gansu Agricultural University, Lanzhou 730070, China.
Ying Yong Sheng Tai Xue Bao. 2021 Feb;32(2):649-660. doi: 10.13287/j.1001-9332.202102.012.
As one of the extreme climatic events, the frequency and intensity of drought have great impacts on regional water resource. Water is a main limiting factor for plant growth in arid and semi-arid regions. Therefore, it is of great scientific significance to explore the spatiotemporal variations and future tendency of drought for the ecological environment in the Loess Plateau. Based on grid data of monthly precipitation and temperature from 1986 to 2019, we calculated standardized precipitation evapotranspiration index (SPEI) and drought frequency. The spatiotemporal patterns and its variations were analyzed at the seasonal and annual scales in the Loess Plateau using the Mann-Kendall test and Sen's slope estimation method. Finally, the future trend of drought was analyzed in the Loess Plateau by the NAR neural network combined with Hurst index. Results showed that the trend of aridification became more significant in the Loess Plateau, and that the frequency of droughts events exhibited great spatial variations at the interannual and seasonal scales during the study period. Specifically, the highest frequency of drought in the interannual, spring and winter was found in the southeast and west of the Loess Plateau, whereas the frequency of drought in summer and autumn was higher in the northwest. The frequency of moderate drought was the highest in summer compared with other seasons while the frequency of slight drought was the highest in interannual and other seasons. The Loess Plateau showed a trend of aridification in spring and summer, but this trend in autumn and winter became weaker in most areas of the study area. The SPEI value in the interannual, spring, and summer exhibited a decline trend in a future period in the Loess Plateau. The aridification would be enhanced. The Hurst index value was the largest and the persis-tence of its change remained stronger in summer. The possibility of continuous drought in summer would be higher than that in other seasons in the future.
作为极端气候事件之一，干旱的频率和强度对区域水资源有重大影响。水是干旱和半干旱地区植物生长的主要限制因素。因此，探索黄土高原干旱的时空变化及其未来趋势，对生态环境具有重要的科学意义。本研究基于 1986-2019 年月均降水和气温格网数据，计算标准化降水蒸散指数（SPEI）和干旱频率，采用 Mann-Kendall 检验和 Sen 斜率估计法，分析黄土高原季节性和年际尺度的时空格局及其变化。最后，利用 NAR 神经网络结合 Hurst 指数分析黄土高原未来干旱趋势。结果表明，黄土高原的干旱化趋势更加显著，且在研究期间，年际和季节性干旱事件的频率具有较大的空间变异性。具体而言，黄土高原东南部和西部年际、春季和冬季干旱频率最高，而西北部夏季和秋季干旱频率较高。年际、夏季和秋季干旱以中度干旱为主，春季和冬季以轻度干旱为主。黄土高原春、夏季呈干旱化趋势，但研究区大部分地区秋、冬季干旱化趋势减弱。未来黄土高原年际、春季和夏季 SPEI 值呈下降趋势，干旱化将加剧。夏季的 Hurst 指数值最大，其变化的持续性更强。未来夏季连续干旱的可能性高于其他季节。
