The RVI result shows irregularity. The value range of waterbody shows higher while vegetation shows lower. why is that?

I have calculated RVI using Sentinel-1 using SNAP software, The equation i followed for preparing RVI includes:

  1. Apply Orbit
  2. Radiometric caliberation (for sigma0_VV & sigma0_VH)
  3. Multilooking
  4. Speckle Filtering (lee Sigma)
  5. Terrain correction
    For RVI calculation, First prepared DOP using the mentioned equation

DOP = Sigma0_VV / Sigma0_VV + Sigma0_VH

Then I calculated RVI,
RVI = Sqrt (DOP) x (4 x Sigma0_VH) / (Sigma0_VV + Sigma0_VH).

The result ranging from 0 to 1.5. But the result shows that WATERBODIES shows HIGHER values and VEGETATION shows LOWER values. Why is it like that? Anyone help me with the solution? Why my range extents 1 ?

DOP, please decipher

Degree of Polarizarion (DOP) = Sigma0_VV / Sigma0_VV + Sigma0_VH