The position was lying vacant for more than five months after Australian Neil Hawgood resigned from the post last November.
New Zealand's Anthony Thornton was the first choice candidate to replace Hawgood but failed to join because of medical issues.
Hockey India then proposed Arhens' name to the Sports Authority of India as he was second on the shortlist submitted by the federation and the SAI approved the Canadian's appointment early last month itself.
Ahrens landed here on Monday.
"Ahrens' appointment was finalised early last month. It took him some time to clear all his paper works with his past employer. He came to Delhi on Monday and it has been two days he has started training the girls," Hockey India President Narinder Batra said.
Before taking up the India job, Ahrens was the technical director of junior hockey with Vancouver Hawks and was looking after their under-18 development programme.
Ahrens' first assignment with the Indian women's tea will be the Hockey World League Semi-finals to be held in Antwerp, Belgium from June 20 to July 5.

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