Every ryot having a right of occupancy shall be entitled to claim an abatement. of the rent previously paid by him, if the area of the land has been diminished by diluvion or otherwise or if the value of the produce or the productive powers of the land have been decreased by any cause beyond the power of the ryot or if the quantity of land held by the ryot has been proved by measurement to be less than the quantity for which rent has been previously paid by him;