Precipitation change in western China during Qing Era reconstructed with the official document data

清代官方文献中发现了大量的“降水资料”，保存在“中国第一史料”中。结果发现，“降水数据”并不是所谓的降雨量，而是雨水对表层土壤的渗透深度。通过现场观测和试验，建立了降水与入渗深度之间的关系式，将文献资料转化为降水资料。结果表明，降水量的季节变化和面积分布与目前大体一致。另一方面，自19世纪初以来，总金额一直在下降。然而，得出的结论是，对于最近的水资源短缺，人类活动比这样的气候变化更负有责任。

Enormous amount of "precipitation data" was found in official documents in Qing Dynasty, preserved in the First Historical Archives of China. It was found that the "precipitation data" are not the so called precipitation but the penetration depth of rain water into the surface soil. With in situ observations and experiments, hence, a relation between precipitation and the penetration depth was established, with which the document data were converted into precipitation data. As the results, it was found that the seasonal variation and areal pattern of precipitation were roughly consistent with those at present. The total amount, on the other hand, has decreased since the early 19th century. It was concluded, however, that for the recent water shortages, the human activities are more responsible than such a climate change.