Relationship between Drought and Precipitation Heterogeneity: An Analysis across Rain-Fed Agricultural Regions in Eastern Gansu, China

Suping Wang,Yuanpu Liu,Yu Zhang,Jinsong Wang,Qiang Zhang

doi:10.3390/atmos12101274

Abstract

Based on daily meteorological data from 55 meteorological stations in eastern Gansu from 1960 to 2017, the characteristics of the drought process and precipitation heterogeneity were analyzed, and the relationship between drought and precipitation heterogeneity was evaluated. Results showed that there were 1–3 drought processes in the study area every year. Drought processes in the eastern and north-central regions were more frequent than those in other regions. Droughts were mainly manifested as intra-seasonal droughts, especially across the spring and summer. PCD (Precipitation Concentration Degree, the concentration degree of the precipitation at a certain time) ranged from 0.2 to 0.7 in the area. PCD increased in spring and autumn but decreased in summer and winter for most regions from 1960 to 2017. PCP (Precipitation Concentration Period, the shortest time which the precipitation was concentrated in) was from late April to early May in spring, mid-to-late July in summer, mid-September in autumn, and late January in winter. In the last 58 years, PCP has remained consistent in most regions, varying by approximately 10 days. In addition to insignificant changes in winter, the days with light and moderate rain presented a declining trend, especially in summer and autumn. The larger the PCD, the fewer the days with light and moderate rain, and the stronger the drought intensity. However, in the east-central region, the larger the PCD in autumn, the weaker was the drought intensity. This difference is related to the PCP and the evapotranspiration. Additionally, the later the PCP, the stronger was the drought intensity, particularly in summer and autumn. When PCD was ≥0.5 in spring and ≥0.4 in summer, the PCP was after May and August in spring and summer, respectively. Droughts appeared in 28–56% of periods when seasonal precipitation was above normal. When PCD was ≥0.5 in autumn and PCP was in early and middle September, droughts appeared in 7% of periods when precipitation was above normal. Our results show that although less precipitation is the leading influencing factor of drought in the dry rain-fed agricultural areas, the influence of precipitation heterogeneity should be also considered for the prediction and diagnosis of seasonal drought.

Highlights

Drought is the most common and serious meteorological disaster in China and globally [1,2,3,4]
Our results show that less precipitation is the leading factor of Current drought monitoring and prediction focus mainly on the precipitation amount within a period, such as the percentage of precipitation anomaly (Pa), the standardized precipitation index (SPI), and even the standardized precipitation evapotranspiration index (SPEI) [35]
Our results show that less precipitation is the leading factor of drought in the dry rain-fed agricultural areas of northern China, the impacts of precipitation heterogeneity are significant

Summary

Introduction

Drought is the most common and serious meteorological disaster in China and globally [1,2,3,4]. Drought disaster loss accounts for over 15% of total natural disasters every year in China [5]. Drought areas can be as high as 57% of the total natural disaster area [6]. In China, the response is more sensitive, as droughts show a trend of increasingly larger affected areas, greater frequency, and aggravated disasters in the recent half-century [7,8]. In the 30 years, drought in China is predicted to become more frequent and serious [10]

Methods

Results

Conclusion