law: 15. Amendment of schemes.
  The Authority shall not make any material change in the scheme approved under sub-section (5) of section 14 without the prior approval of the Central Government.
  Explanation.
  For the purposes of this section, "material change" means an increase in the cost of the scheme by more than twenty per cent. of its cost or a change in the benefit and cost ratio which either makes the cost component in the ratio exceeds the benefit or reduces the benefit component by more than twenty per cent.