资源环境科技发展态势分析平台

Understanding past climate variability is important for obtaining better predictions of future changes. Documentary records are high temporal resolution proxies that can be used to reconstruct aspects of the climate, such as precipitation. Vicuna Mackenna developed a compilation of historical climatic events between the 16(th) and 19(th) centuries using chronicles from Spanish colonizers and town council records. The objective of this work was to classify dry and wet periods beginning in the 16(th) century using records from Vicuna Mackenna by generating a precipitation index based on events in the documentary evidence (e.g., epidemics, pro pluvia rogations, and infrastructural damage) into a simple annual precipitation index on an ordinal scale. The index used a three-term classification scale, with 0 representing normal years, 1 representing wet years, and -1 representing dry years. The documentary records were not substantial enough to identify wet/dry periods during the 16(th) and 17(th) centuries. However, it was possible to identify dry and wet years described by conquerors and settlers that first arrived in the study area. During the 18(th) century, two long periods of drought were identified: 1705 to 1718 and 1770 to 1797. During these droughts, people organized rogations to the Virgen and different saints in desperation due to the lack of water. Finally, during the 19(th) century, technological improvements in measuring precipitation made it possible to identify intermittent dry and wet periods with higher resolution and precision, and these events could be related to the El Nino-Southern Oscillation (ENSO).