What are the reasons for the great change in the caste system?

There is a great change in the caste system because of various factors such as,
(i) The efforts of political leaders and social reformers like Jotiba Phule, Gandhiji, B.R. Ambedkar etc.
(ii) Social Economic changes, also brought a change in the caste system.
(iii) The old concept of caste heirarchy is also coming down because of economic development, urbanisation increase in literacy rate, occupational mobility etc.
(iv) The provision of Indian Constitution like, prohibition on caste discrimination, untouchability, also led to a change in caste system.