Author(s): Pan Chen
Linked Author(s):
Keywords: Water resources; Climate change; Culture; Stalagmites; Rainfall
Abstract: A reconstruction of Holocene rainfall is presented for middle reaches of the Yangtze River, China, based on an existing high-resolution δ18O record. The existing record is from Heshang Cave (30°27′N, 110°25′E; 294 m) and can be interpreted as a record of local rainfall. This is further confirmed by the high correction between δ18O and smoothed rainfall data from the instrumental record at Yichang weather station. It is of great significance to study the water resources variation of the middle reaches of the Yangtze River as it is the worst flood and drought areas of the whole basin since ancient times due to its special hydrological condition. Besides, the region is also an ideal study site of the impact of climate change on water resources because it is located in a climate transition zone where its south downstream areas of the Yangtze river is near the tropics and its north upstream areas is near temperate zone. This Holocene rainfall record can be used to test the water resources variation and its response to climate change. This study reveals that the record mainly follows solar variability, but the variation of 9500-6300 year before present (yr B. P., relative to 1950 A. D. ) may be also influenced by the North Atlantic climate for a broad similarity to the δ18O record of Greenland ice cores. Significant centennial-scale fluctuations also occur, with notable dry periods at 500, 1000, 2700, 3500, 4200, 6000, 8200 B. P. and wet period at 4000 B. P. Dry event at 8200 B. P. in the record is mainly caused by weak solar activity, which would result in increasing float ice, declining temperature differences between the land and sea, and weakening monsoons. Dry event at 4200 B. P. might be related with weak solar activity, which would lead to a southward shift of the ITCZ (The Intertropical Convergence Zone) and dry/cool events at mid and low latitude areas in the Northern Hemisphere. These events might also have an important impact on the human civilization progress. For example, 4200 B. P. event, to a great extent, might shake the foundations of the culture, and then prehistoric abnormal floods at 4000 B. P. further accelerated the collapse of the culture.
Year: 2013