What was done
The authors conducted geomorphic studies of slackwater deposits in the bedrock gorges of the Tapi and Narmada Rivers of central India that allowed them to assemble a 2000-year chronology of large floods on the Narmada River and a much shorter chronology of floods on the Tapi River.

What was learned
With respect to the Tapi River, the authors report that "since 1727 at least 33 large floods have occurred on the Tapi River and the largest on the river occurred in 1837."  With respect to large floods on the Narmada River, they report at least 9-10 floods between the beginning of the Christian era and 400 AD; between 400 and 1000 AD they document 6-7 floods, between 1000 and 1400 AD about 8-9 floods, and after 1950 AD three more such floods.  In addition, on the basis of texture, elevation and thickness of the flood units, they conclude that "the periods 400-1000 AD and post-1950 AD represent periods of extreme floods."

What it means
What do these findings imply about the effects of global warming on central India flood events?  The post-1950 period would be claimed by climate alarmists to have been the warmest of the past millennium; and it has indeed experienced some extreme floods, as noted by the authors of this study.  However, the flood characteristics of the 400-1000 AD period are described in equivalent terms; and this was a rather cold climatic interval known, in fact, as the Dark Ages Cold Period [see, for example, McDermott et al. (2001) and Andersson et al. (2003)].  In addition, the most extreme flood in the much shorter record of the Tapi River occurred in 1837, near the beginning of one of the colder periods of the Little Ice Age.  Hence, there would appear to be little correlation between the flood characteristics of the Tapi and Narmada Rivers of central India and the thermal state of the global climate.

References
Andersson, C., Risebrobakken, B., Jansen, E. and Dahl, S.O.  2003.  Late Holocene surface ocean conditions of the Norwegian Sea (Voring Plateau).  Paleoceanography 18: 10.1029/2001PA000654.

McDermott, F., Mattey, D.P. and Hawkesworth, C.  2001.  Centennial-scale Holocene climate variability revealed by a high-resolution speleothem ð¹⁸O record from SW Ireland.  Science 294: 1328-1331.