Characteristics of the onset, cessation, and length of the rainy season in typical mountainous areas in China

ABSTRACT: Variation in the onset, cessation, and length of the rainy season (ORS, CRS, and LRS, respectively) influences crop growth and food security. In this study, we used the cumulative precipitation anomaly method, spline interpolation, Mann-Kendall trend test, and linear regression to investigate the ORS, CRS, LRS, and rainfall amount during the rainy season (ARS), and their temporal trends, for the Taihang Mountains (THM), the Hengduan Mountains (HDM), and the Qian-Gui Karst Mountains (KSTM) in China from 1961-2013. The results showed that the rainy season began first in the KSTM, followed by the HDM and the THM. The coefficients of variation for the ORS, CRS, LRS, and ARS in the THM had the highest values of the 3 mountainous areas, and therefore agricultural production in the THM faces higher risks. From 1961-2013, both the ORS and CRS showed tendencies of becoming earlier, and ARS showed decreasing trends. The decreasing trend magnitudes for the LRS and ARS in the KSTM were the largest of the 3 typical mountainous regions. Furthermore, ORS occurred later, CRS occurred earlier, LRS became shorter, and ARS decreased significantly in the north of the KSTM compared to the south. The results of this study may aid planning and decision makers in making adequate preparations to prevent risks and failures, and may help farmers optimize their production activities.