O.P. Mathur did his M.Sc. in Geology from the Banaras Hindu University, Varanasi, U.P. in 1962. During 1962-63 he was lecturer in geology at M.B. College, Udaipur, Rajasthan. In 1963-64 he worked as an engineering geologist with the U.P. Irrigation Department and was engaged in the geological investigation for the construction of the Tehri Dam on the river Bhagirathi. In December 1964 the author joined the Geological Survey of India and remained engaged in geological mapping on the aerial photographs for iron ore investigation in the Sikar and Jhunjhunu districts of Rajasthan. In 1972 the author opted for the newly created Central Ground Water Board and worked for the ground water exploration in western Rajasthan and hydrogeological mapping in the Dungarpur district in south Rajasthan. From 1975 to 1978 the author worked in the UNDP Project of the Central Ground Water Board on the Ghaggar River Basin and was associated with the Artificial Recharge studies. From 1978 to 1985 the author worked in the North-Western Region of the Central Ground Water Board, Chandigarh, and conducted a number of short-term water supply investigations in addition to other ground water studies. From 1985 till his retirement in 1997 as Director, he remained as officer in charge of the state Unit Office, Western Region, Central Ground Water Board, Jodhpur, Rajasthan and supervised hydrogeological studies of the Unit Office. Presently the author residents at Udaipur.