@article{fdi:010079083,
  title = {{A} quasigeoid-derived transformation model accounting for land subsidence in the {M}ekong delta towards height system unification in {V}ietnam},
  author = {{V}u, {D}. {T}. and {B}ruinsma, {S}. and {B}onvalot, {S}ylvain and {R}{\'e}my, {D}ominique and {V}ergos, {G}. {S}.},
  editor = {},
  language = {{ENG}},
  abstract = {{A} vertical offset model for {V}ietnam and its surrounding areas was determined based on the differences between height anomalies derived from 779 {G}lobal {N}avigation {S}atellite {S}ystem ({GNSS})/levelling points and those derived from a dedicated high-resolution gravimetric-only quasigeoid model called {GEOID}_{LSC}. {F}irst, the deterministic transformation model to effectively fit the differences between the quasigeoid and {GNSS}/levelling heights was based on a third-order polynomial model. {S}econd, the residual height anomalies have been interpolated to a grid employing {L}east-{S}quares {C}ollocation. {F}inally, the distortions were restored to the residual grid. {T}his model can be used for combination with a gravimetric quasigeoid model in {GNSS} levelling. {T}he quality of {GNSS}/levelling data in {V}ietnam was analyzed and evaluated in this study. {T}he annual subsidence rate from {ALOS}-1 was also used to analyze the effects of subsidence on the quality of {GNSS}/levelling data in the {M}ekong {D}elta. {F}rom this we made corrections to improve the accuracy of {GNSS}/levelling data in this region. {T}he offset model was evaluated using cross-validation technique by comparing with {GNSS}/levelling data. {R}esults indicate that the offset model has a standard deviation of 5.9 cm in the absolute sense. {B}ased on this offset model, {GNSS} levelling can be carried out in most of {V}ietnam's territory complying third-order levelling requirements, while the accuracy requirements for fourth-order levelling networks is met for the entire country. {T}his model in combination with the developed gravimetric quasigeoid model should also contribute to the modernization of {V}ietnam's height system. {W}e also used high-quality {GNSS}/levelling data and the determined quasigeoid model to determine the geopotential value {W}-0 for the {V}ietnam {L}ocal {V}ertical {D}atum. {T}he gravity potential of the {V}ietnam {L}ocal {V}ertical {D}atum is estimated equal to <mml:semantics>{W}0{LVD}</mml:semantics> = 62,636,846.81 +/- 0.70 m(2)s(-2) with the global equipotential surface realized by the conventional value {W}-0 = 62,636,853.4 m(2)s(-2).},
  keywords = {quasigeoid ; {GNSS} ; levelling ; gravity potential ; local vertical datum ; {VIET} {NAM} ; {MEKONG} {DELTA}},
  booktitle = {},
  journal = {{R}emote {S}ensing},
  volume = {12},
  numero = {5},
  pages = {art. 817 [21 p.]},
  year = {2020},
  DOI = {10.3390/rs12050817},
  URL = {https://www.documentation.ird.fr/hor/fdi:010079083},
}