On Origin of name Nehru

How the surname Kaul became Nehru is best explained by Frank Moraes in his book, 'Jawaharlal Nehru A Biography': “We were Kashmiris". 

"Over two hundred years ago, early in the eighteenth century, our ancestor came down from that mountain valley to seek fame and fortune in the rich plains below. Those were the days of the decline of the Moghal Empire after the death of Aurungzeb, and Farrukhsiar was the Emperor. Raj Kaul was the name of that ancestor of ours and he had gained eminence as a Sanskrit and Persian scholar in Kashmir. He attracted the notice of Farrukhsiar during the letter’s visit to Kashmir, and, probably at the Emperor’s instance, the family migrated to Delhi, the imperial capital, about the year 1716. A jagir with a house situated on the banks of a canal had been granted to Raj Kaul, and, from the fact of this residence, ‘Nehru’ (from nahar, a canal) came to be attached to his name. Kaul had been the family name; this changed to Kaul-Nehru; and, in later years, Kaul dropped out and we became simply Nehrus.”