The carcass was recovered from near Amkatoni camp under Bagori Range of the World Heritage Site.
So far, 13 rhinos have died due to drowning in the current wave of floods which have so far also claimed lives of 15 hog deer, two wild boars and two snakes, park officials said.
Meanwhile, nine rhino calves separated from their mothers due to the floods have been rescued and being looked after at the Centre of Wildlife Rehabilitation and Conservation at Panbari near KNP, said CWRC Director Rathin Barman.
There are 16 animal corridors on the NH-37 through which various types of animals from the park cross over to Karbi Anglong hill during floods, officials said.
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The rising water level of the mighty Brahmaputra river has brought 85 per cent of KNP area under flood, submerging 117 of the 120 forest camps there and snapping road connectivity.
Country boats are the only means of communication for the KNP guards and others, the officials said.
Meanwhile, the All Assam Students Union (AASU) has demanded the union forest and environment ministry take needful steps to protect the forest wealth - both flora and fauna - in the "unprecedented situation".