The turbulent Brahmaputra and Barak rivers along with their overflowing tributaries continued to submerge vast tracts in Assam, affecting 2.26 lakh people in six districts and prompting the Army to remain alert.

Army's Four Corps based in Sonitpur district has sent a letter to state Home Commissioner that over eight trained battalions of the National Disaster Relief Force with specialised relief and rescue equipment were in readiness to assist whenever required.

Prohibitory orders under Section 144 CrPC have been imposed in the national highway adjoining Kaziranga National Park, home to the one-horned rhino, limiting vehicular speed to 40 kmph.

The move was to protect animals from being knocked down while crossing the highway in search of highland.

The first wave of floods of the Brahmaputra during this monsoon affected the districts of Lakhimpur, Dhemaji, Sibsagar and Dibrugarh in Upper Assam's Brahmaputra Valley and Cachar, Karimganj and Hailakandi in South Assam's Barak Valley, overrunning vast tracts of human habitation and farm land.

According to the Central Water Commission, the water level was above the danger mark at Dibrugarh and Jorhat in Upper Assam, river Katakhal at Matizuri Point in Hailakandi and Kushiyara at Karimganj in Barak Valley.

Submerged highways were affecting smooth movement of vehicular traffic, sources said, adding, the floods inundated over 21,500 hectares of agricultural fields with standing crops.

Although flowing above the red mark, the rivers were registering a falling trend in Dibrugarh district and in Dhemaji where 25 villages with a population of 11057 were affected, sources said.