Was the Brahmaputra River created by Lord Brahma?

Question

I want to know that was the river Brahmaputra created by Lord Brahma or any other God?

Answer 1

Chapter 81 (Kāmarūpamāhātmyavarṇana) of Kālikāpurāṇa (English Translation Link) describes the origin of the river Brahmaputra in the following way.

I'm providing the Summarized English Translation of the translated Hindi text

Forermerly in the vicinity of the Nilāchala hills were situated many kuṇḍas, like the Apunarbhavakuṇḍa (named such because the person who bathed here would never be reborn again), bathing in which people were obtaining permanent residence in svarga directly after death by the grace of it's presiding deity, Bhagavatī Kāmākhyā. Indra complained to Prajapati Brahmā that svarga was getting overpopulated with people bathing in those kuṇḍas & Yama complained that sinners were evading justice by bathing there. So Brahmā made humanity forget about the tīrtha-māhātmya of the Yonipīṭha & proceeded there to conceal the sacred kuṇḍas of the site.

On the way, he was hit by the arrows of Kāmadeva on seeing a ṛṣipatnī named Amoghā & deposited his seed on that spot. That seed was implanted in Amoghā's womb by her husband, a sage named Śāntanu, which led to the birth of Lauhitya. Lauhitya's physical appearance was that of a boy of crimson-red complexion wearing blue-garmets & gem-studded garland, holding a book & a lotus in his right arms, a spear & flag in his left arms, seeated on a dolphin & surrounded by a mass of clear water, so Śāntanu had him placed inside a artificially constructed kuṇḍa (identified as Paraśurāmakuṇḍa of south-eastern Aruṇācala Pradeśa from where the river Lohita originates) in the mountains. This Lauhitya-kuṇḍa was visited by Paraśurāma on his quest to relieve himself from the sin of matricide, incurred when his father, the sage Jamadagni ordered him to kill his mother Reṇukā for masturbating at the site of a copulating Gandharva couple. Paraśurāma, on being relieved from matricide after bathing in it, decided to make the waters of Lauhitya-kuṇḍa available to the massess. So he carved out a channel out of the Lauhitya-kuṇḍa into the sea which inadvertedly passed through Kāmarūpa-kṣetra & submerged the kuṇḍas of Yonipiṭha within its waters. The channel dug by Paraśurāma became the river Lauhitya aka Brahmaputra.

On a sidenote, a legend is prevalent among Hindus of eastern Bengal that while approaching near the sea, Lauhitya was distracted by the beauty of a local rivulet named Śitalakhyā & deviated from the channel carved by Paraśurāma to merge with her, which caused Paraśurāma to stop dragging his plough (with which he had been carving out Brahmaputra's channel till then) & cursed Lauhitya to lose his sin-relieving properties. However on Lauhitya's request, he decreed that Lauhitya would possess his sin-relieving powers only on the 8th day of the bright fortnight in the month of Caitra. On that day, Hindus of eastern Bengal gather in large numbers at the banks of the old riverbed of Brahmaputra at Laṅgalabandha (where Paraśurāma is believed to have pronounced the curse on Lauhitya), situated in Nārāyaṇagañja district of present day Bāṇglādeśa to take bath in the river uttering the following pranāma-mantra

ब्रह्मपुत्र महाभाग शान्तनोः कुलनन्दन । अमोघागर्भसम्भूत पापं लौहित्य मे हर ।। त्वं ब्रह्मपुत्र भुवनतारण तीर्थराज गम्भीरनीर परिपूरित सर्वदेह । त्वद्दर्शन हरतु मे भवघोरदुःखं संयोगतः कलियुगे भगवन्नमस्ते ।।

Answer 2

No, the Brahmaputra river was not created by Brahma.

It was actually created by Parashuram.

Parashuram, after beheading his mother, found his axe sticking to his palm because he had committed a sin.

To relive the sin, he went to several places, but without any success.

Finally, he went to Manasarovar, where he could relieve himself of the sin.

He then decided to make way for the water in the sarovar to go to various places on the earth as a river. The river is Brahmaputra.