Rapid sedimentation history of Rewalsar Lake, Lesser Himalaya, India during the last fifty years - Estimated using 137Cs and 210Pb dating techniques: A comparative study with other North-Western Himalayan Lakes

The pristine Himalayan lakes are under threat due to higher sedimentation, ecological degradation and pollution, especially due to human interference. The higher Sedimentation reduces the depth and size of these lakes. This study is aimed at understanding the last similar to 50 years record of sedimentation and shift in sedimentation fates in the Rewalsar Lake, Himachal Pradesh, India. An effort has also been made to identify the natural, such as geological, especially lithology and catchment slope and rainfall, etc. and anthropogenic factors that could have governed the fluctuation in the sedimentation rates. A comparative study of some of the north-western Himalayan lakes has also been performed. The sedimentation rate of the Rewalsar Lake was measured on top 2 meter core samples using isotopes of Cs-137 and Pb-210 dating techniques. Our study reveals that the Rewalsar Lake experienced an average sedimentation rate of 3.35 cm/year during the last similar to 50 years which is the highest in comparison to the other lakes in the north-western Himalayan region. The 3.92 cm/year of rapid sedimentation rate was observed during ca. 1995 to 1963 AD and 2.78 cm/year after 1995 AD. The study reveals that the enhanced human interference in the catchment area of the Rewalsar Lake is responsible for this rapid sedimentation.