Evolution of soil erosion and sedimentation vulnerability of Western Himalayan Lake Sukhna, India

Sukhna lake is an important man-made lake located at the foot of Siwalik Hills near Chandigarh. It has been used for irrigation, drinking, recreation, tourism, and biodiversity etc. The lake storage capacity is reducing owing to high rate of erosion from the lake catchment. This study was carried out to find out the recent sedimentation rate within the lake, to compute the life expectancy, and to develop conservation measures to control the sedimentation in lake. Sediment deposition profiles of the lake have been prepared to understand the sediment deposition pattern in the lake. The sediment mass balance approach has been applied to estimate rate of sedimentation in the lake during different time intervals. The sediment mass balance approach shows that the recent rate of sedimentation into the lake varies in the range of 5.15 ha-m/y to 18.30 ha-m/y with an average value of 7.01 ha-m/y during the period of 2003-2012. The computed life expectancy of the lake with the current estimated sedimentation rate is 76 years and will fill up completely with sediments by 2090. The Garde and Kothyari model predicted the sediment yield is significantly lower by 39.52%. The results indicate that the sedimentation rate has reduced from 50 ha-m/y during the 1960s to 7.01 ha-m/y during 2003-2012 due to various conservation measures such as extensive reforestation, plantation, and construction of various sediment detention structures in the lake catchment.