1784~1787 Drought Occurrence over East China in a Warm Climatic Background

Abstract

This paper presents the 1784--1787 successive drought events in the farming land of east China as a case study done in such a way that the dryness sitation is reconstructed in the context of historical works and documents by drawing the dynamic development of disaster--hit and food famine zones on an annual basis. Results show that the rerrible events took place dominantly in 1784--1786 for the years 49th-51th of Qianlong Emperor of Qing Dynasty, covering the provinces of Liaoning, Inner Mongolia, Shanxi, Shaanxi, Shandong, Henan, Anhui,Hubei (to the north of the Yangtze River),and later extending into Jiangxi, Hunan, Fujian, Guangdong, Guangxi, Sichuan and Gansu, with the maximum seventy lasting 5 years in the lower valleys of the Yellow River where drought was relieved as late as the autumn of 1788, which was given in local chronicles and confirmed by the Weather Record of that time as another meteorological dataset, As indicated for Suzhou in the Record, the number of wet days were 28 days, reconstructing the total rainfall of 174 mm for June-August, 1785 as the sub--maximum in that century, arriving at an anomaly near -60% and smaller than the climatic extremum in the past 50 years. This article present tabulated description of the drying up of the rivers and lakes in that time over the research region, showing that the seventy has never been experienced in modern times. The drought events occurred a climatic warming background, i. e., in a warm phase of the Little Ice Age, as revealed by the reconstructing winter temperature series of Shanghai for the last 500 years. In comparison to the reconstructed curve of northern temperatures in history, the study droughts fall into a stage of warm climate. Also, the historical recording shows that the extensive band of east China saw no snowfall in 1784-1786 in succession even in the normally snow--rich provinces of Jiangsu and Anhui, and we find warm winter to be in 1778 and 1779. Moreover, the work discloses that the droughts are related to sunspot activities and El Nino episodes: they happened in the week--4 low--valued span of the activities and the year of 1785 as the prime period of the events was in the year before the 1786 event. The resulting drought features in east China are in good agreement with relevant studies. It is noted that the long--term drought disasters were followed by large--scale food famine, which was relieved by the government and with the aid of the act to help refugees from the populace. However, locust plagues and epidemic diseases ensued, with the affected regions given in a diagram for 1784--1786 calamities. The 1784-1787 drought study can be used for reference in our future combat against drought.