The Sarasvati River (Sanskrit: सरस्वती नदी sárasvatī nadī) is one of the chief Rigvedic rivers mentioned in ancient Hindu texts. The Nadistuti hymn in the Rigveda (10.75) mentions the Sarasvati between the Yamuna in the east and the Sutlej in the west, and later Vedic texts like Tandya and Jaiminiya Brahmanas as well as the Mahabharata mention that the Sarasvati dried up in a desert.
Here you can find more information on it.
Article : Recent Research on the Sarasvati River by Stephen Knapp
180 Page eBook : SARASVATI RIVER by Dr. S. Kalyanaraman
Article : Saraswati – the ancient river lost in the desert by A. V. Sankaran
And if you want a brief information read this presentation by Dr. V. Raja Bandaru