Complex sentence: The lake receives water from an endorheic basin of 5700 square km catchment area, which is not a part of the Ganga river basin area but is geographically a separate land locked river basin.
Split into simpler sentences: The lake receives water from an endorheic basin with 5700 square km catchment area. It is not part of the Ganga river basin area and is geographically a separate land locked river basin.