I want to know if we can analyse the permanancy of sandbars from a satellite image? Whether the formation of the sandbar is permanent or temporary.
Yes. It is definitely possible. Sandbars are formed from gradual sediment deposition. It is possible to analyse spatio-temporal variability using satellite images of different time periods. What is your criteria to call a sandbar permanent? As per my knowledge a spit or sandbar can gradually develop into a lagoon or island. You can depict this change over time.
For your purpose, the best bet available is AWiFS-1 or AWiFS-2 data of Resourcesat-1 (IRS P6) & Resourcesat-2 respectively. It is the most widely used sensor for natural resource studies in India, with a revisit period of 5 days at a good resolution. You can calculate total area of the sandbar in multiple images of different times and compare it to infer the temporal increase.
Otherwise, You can always use MODIS data which is freely available if you just want to observe the change. You can observe the beach as a whole, but not individual aggregation of sandbars. Hope this helps.