本文探討漢代水、旱、蝗、疫造成饑饉、荒歉的災害史，及其與治亂興 衰的關係。全文分三部分：一，利用文獻分析及統計，得出兩漢災荒的時間 分布，以掌握各時期頻率的變化。二，以重大災害密集爆發為基準，呈現兩 漢災荒史的4 個關鍵段落。三，藉由不同段落之間的比較，剖析災荒與政治 經濟體制的關聯。以武帝元封四年（107 BC）「關東流民二百萬口」、王莽 時期（11-24）農業崩潰與「陰陽錯謬」的關係，以及東漢安帝（106-125 在 位）「水旱十載」3 次事件為例，釐清自然和人為因素在兩漢災荒史上的作 用，及所隱含的意義。
簡述本文論旨：一，災荒的發生頻率及程度輕重牽涉到兩漢治亂興衰，其間關係複雜，不能簡單的對應。二，氣候變化可以解釋災荒的發生，無法解釋造成破壞的程度。三，秦漢農業的全面崩潰與大蝗災密切相關，但蝗災是農業崩潰的結果，而非原因。四，王莽時期河患、枯旱霜蝗等災害無法解釋為其滅亡的主要理由；漢末之傾穨亦復如此。五，基於史實分析比較證明，良好的政治經濟體制得以減除災荒所造成的破壞，而決定朝代興亡的大規模災害，以人禍的因素居多。

This article explores the history of floods, droughts, locusts, epidemics and other disasters, and their relationship with the vicissitude of the empire in the Han dynasty (202 BC-AD 220). This article is divided into three parts: the first touches upon the time distribution of the Han disasters and famines, as well as its frequency changes in each period; the second analyzes the complex disasters in four key periods; and the third discusses three great events and their causes and consequences, including the 2 million eastern refugees in the reign of Emperor Wu, the full collapse of agriculture in the Wang Mang period, and the “Ten Years of Serious Disasters” in the reign of Emperor An of the Eastern Han.
This article intends to make the following arguments: (1) changes in disaster frequency did not simply correspond to the vicissitude of the Han dynasty; (2) the climate change can be accountable for the occurrence of famines, but it cannot explain why it caused so much damage; (3) the collapse of the Qin and Han agriculture was closely related to several big locust plagues, but these plagues were the result of the agricultural failure instead of the cause of it; (4) the Yellow River flood and natural disasters could not be used as valid reasons to explain the fall of Wang Mang’s regime; and (5) good political-economic institutions could reduce the natural disasters’ damages, but it is usually man-made factors that played the role behind the disaster-caused massive destructions.