黄土高原气象干旱和农业干旱特征及其相互关系研究

选择标准化降水指数(SPI)和植被状态指数(VCI)分别作为评价黄土高原气象干旱和农业干旱的指标,使用干旱频率和Sen斜率分析了黄土高原地区干旱的分布特征与变化趋势,并探讨了气象干旱与农业干旱的相关性。结果表明:①黄土高原西部干旱频率总体上高于东部。气象干旱和农业干旱变化趋势在空间上表现有所不同,黄土高原西部、北部气象干旱呈不显著减缓趋势,东部和南部呈不显著加重趋势,但绝大部分地区的农业干旱呈减缓趋势,尤其是400 mm等降水量一线两侧区域。②季节上,黄土高原夏季和秋季气象干旱频率较高,春季和冬季气象干旱频率相对较低。黄土高原农业干旱频率春季最高,夏季其次,VCI对农业干旱实时监测的适用性更强。③不同季节,农业干旱滞后气象干旱的时间长短不同,冬季滞后约2个月,春季滞后约1个月,夏季和秋季滞后少于1个月。黄土高原一熟制种植区的SPI-12值与VCI值具有较好的正相关性。研究结果可以为黄土高原的干旱监测和预警、干旱区划以及干旱灾害风险评估提供科学依据。

Meteorological and Agricultural Drought Characteristics and Their Relationship Across the Loess Plateau

In recent years, the combined effects of climate change and soil and water conservation measures have led to more complex drought conditions in the Loess Plateau, which has caused huge agricultural and socioeconomic losses. In this paper, standardized precipitation index (SPI) and vegetation condition index (VCI) are selected as indicators to evaluate the meteorological and agricultural droughts on the Loess Plateau, respectively. The distribution characteristics and trends of droughts in the Loess Plateau are analyzed using drought frequency and Sen slope, and the correlation between meteorological drought and agricultural drought is also discussed. The results show that: 1) The drought frequency in the western Loess Plateau is generally higher than that in the east. The trends of meteorological droughts are different from that of agricultural droughts in space. The meteorological droughts in the western and northern Loess Plateau show no significant slowing down trends, and the meteorological droughts in the eastern and southern Loess Plateau show no significant increasing trends. However, the agricultural droughts in most areas are slowing down, especially in the areas on both sides of the line with a rainfall of 400 mm. 2) The frequency of meteorological drought in summer and autumn is higher than that in spring and winter. The frequency of agricultural drought is the highest in spring and the second in summer. VCI is more suitable for real-time monitoring of agricultural drought. 3) In different seasons, the lag time of agricultural drought to meteorological drought is different. The lag time is about 2 months in winter, 1 month in spring, and less than 1 month in summer and autumn. There is a good positive correlation between SPI-12 and VCI in one-harvest regions of the Loess Plateau. The results can provide scientific basis for drought monitoring and early warning, drought regionalization and drought disaster risk assessment in the Loess Plateau.