Abstract:
The live storage capacity of a reservoir which is the utilizable storage gets reduced due to continuous sedimentation from the catchment since impounding. The reservoirs are used for flood control, irrigation, hydropower production, water supply for industries and multi-functional utilization. Proper monitoring of sedimentation is required for efficient water utilization. Hirakud reservoir is impounded in 1957. After 62 years of operation for proper monitoring of the reservoir, a cost effective measure has been adopted, without adopting the conventional hydrographic surveys. Therefore, in the present study, an attempt has been made to assess the quantity of sediments in Hirakud reservoir from its catchment area by using Soil and Water Assessment Tool (SWAT). The result of the SWAT model have been found in good agreement during calibration (R2=0.772, NSE =0.655, PBIAS=15) and validation (R2=0.85, NSE= 0.83, PBIAS= -16.9) periods. The quantity of sedimentation has been found to be 39.35 Mm3/year. Further, the remote sensing technique has been applied to estimate water spread area for different time periods (2016 to 2018) of maximum level and minimum level and some intermittent level of Hirakud reservoir. SWAT model results have been compared with results obtained in remote sensing based water spread area estimation. Comparing with the original capacity of the reservoir in 1957 which was 8135 Mm3 and capacity in the year 2016 to 2018 was found to be 5406.54 Mm3. The total reduction in capacity is 2729 Mm3 in 62 years which gives amount of sedimentation 44.01 Mm3/year, which gives a 10% higher value. It means the deposition of sediments comes from higher intensity of rainfall, which doesn’t coincide with SWAT model result which runs on daily basis runoff simulation.
