The Kaziranga National Park and Tiger Reserve in Assam state is home to the world's largest population of the endangered one-horned rhinos, which faced extinction just two decades ago.
Around 2,500 out of the world’s total population of 3,000 one-horned rhinos live in the park.
The intense rain has caused the Brahmaputra River, which flows through Tibet, India and Bangladesh to burst its banks and has killed at least 84 people and displaced more than 2.75 million since May.
Authorities managed to save one exhausted rhino which had strayed onto a motorway on Saturday.
Park authorities said on Sunday, around 85 per cent of the park - over 430 sq km (130 sq miles) - is under water at present.
As well as the rhinos, the park said 36 hog deer, three wild buffalo, one python, seven wild boar, two swamp deer, one sambar deer and two porcupines have also died due to drowning.
A further 15 hog deer reportedly died after getting hit by vehicles on roads close to the park, while trying to escape flood waters, the Hindustan Times reported.
“The flood situation remains critical with most of the rivers flowing menacingly above the danger mark,” Assam water resources minister Keshab Mahanta told Reuters.
Rescue teams are facing the double challenge of rising flood waters and trying to maintain social distancing to protect people from the coronavirus as villagers driven from their homes huddle in shelters.
“It’s hard to enforce social distancing when people are being ordered to move away from the rising waters,” said Sanghamitra Sanyal, a member of the northeastern state's flood management force.
“We're urging people to at least cover their mouth and nose with a piece of clean cloth.”
Officials warned that the water level in the Brahmaputra river was expected to rise by 11 cm (4.3 inches), two weeks after it burst its banks swamping more than 2,500 villages.
Assam, famous for its tea plantations, is hit by flooding every rainy season despite flood-control efforts.
Rights groups accuse corrupt officials of siphoning off funds meant for flood projects, resulting in shoddy construction of embankments which are often breached.
Additional reporting by Reuters
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