The proton chemical shift of supercritical water is analyzed by computer simulations with emphasis on its relationship to the number of hydrogen bonds per water molecule and the dipole moment of a water molecule. The chemical shift is shown to be proportional to the number of hydrogen bonds, and the dipole moment of a water molecule at supercritical states is estimated within the simple point charge (SPC)- like and TIP4P-like frameworks of the water intermolecular potential model. The dipole moment can then be used to construct an effective potential model suitable for simulating supercritical water. The radial and orientational correlations in supercritical water are examined using the effective potential model.