An extraordinary period of low-magnitude floods coinciding with the Little Ice Age: Palaeoflood evidence from central and western India

Fluvial archives include slackwater flood deposits (SWD), which not only preserve information about centennial- to millennial-scale changes in the flood regime conditions, but also provide information on climate variability and extreme climatic events. The present study is based on SWD evidence from six large rivers in central and western India. A remarkable feature that has emerged from the palaeoflood analyses is that the evidence of large floods between circa 14th and 19th century AD is generally missing. Considering the manner in which the rivers build the palaeoflood sequences in stable bedrock gorges, the striking and conspicuous absence of flood deposits of this period indicates a significantly reduced frequency of large floods. Since modern floods on these rivers are the result of severe cyclonic storms, the absence of large palaeofloods not only implies a sharp decline in the frequency of flood-producing severe cyclonic systems, but also an overall decrease in the summer monsoon intensity. Interestingly, this period of less frequent large floods (ca. 14th-19th century AD) approximately coincides with the Little Ice Age (1300 to 1850 AD), which was characterized by relatively cool and dry conditions, and a weakening of the Indian summer monsoon.