why does narmada and tapti river does not form delta?

Answer 1

Because mountain ranges lie on both sides of the rivers which extend upto a place which is hardly 80 Kms from the sea .So there is not enough space(or plains) for delta formation.Moreover the slope of the river may be more when it descends and enters the sea along the above 80 Kms route thereby not allowing any delta formation.

Answer 2

Tapti River

Answer 3

there are several reasons, not enough sediment being flushed down river, deep water drop offs and strong currents washing the sediments away hence no buildup at the outflow sites, there are more