Hi, I believe that you need first to investigate and find out what the cause of shrinking is before you can predict its future trends. This is an issue of lake water ballance or budget. Similar sudies are available in the literature. Hope this helps.

I agree with the response of Dr. Pang. You need to investigate the causes for the fall in water level and thereby shrinkage in the water spread area of the lake. One has to study the historical data on the hydrological and developmental activities of the region and understand the spatial and temporal variation of its effect on the lake. Then try to extrapolate the same for future scenario. 

Dear Ahmad

Actually, the lake might not disappear. We must study the relationship between surface and subsurface water bodies. Probably, the evaporation process is responsible of this water loss and the drop in water level. Another reason might be is due to the decrease of ground water table. These are the two expected reasons. One must study the factors that control the equilibrium formula of water input and discharge.

Regards