@article{fdi:010092318,
  title = {{A} multi-method approach to flood mapping : reconstructing inundation changes in the {C}ambodian {U}pper {M}ekong {D}elta},
  author = {{O}rieschnig, {C}. and {V}enot, {J}ean-{P}hilippe and {M}assuel, {S}ylvain and {E}ang, {K}.{E}. and {C}hhuon, {K}. and {L}un, {S}. and {S}iev, {S}. and {B}elaud, {G}.},
  editor = {},
  language = {{ENG}},
  abstract = {{A}s in many tropical deltas globally, annual floods shape the livelihoods of the largely rural population in the {C}ambodian {M}ekong delta. {A}gricultural cycles are keyed to the flood arrival, peak, and recession, and fish populations depend on inundated floodplains for their regeneration. {H}owever, as factors like climate change and hydropower infrastructure development are altering the {M}ekong's hydrology, the inundation dynamics of its deltaic floodplains are shifting as well. {S}everal studies have assessed the general changes of river discharge and flood extent on a basin- or delta-wide scale. {Y}et the sustainable development of this region is relying on dynamics at more local and specific scales, which have not been addressed so far.





{T}his paper presents a methodology to track the evolution of hydrological regimes and associated inundations in tropical deltas such as the upper {M}ekong delta in {C}ambodia, where it is applied over the past 30 years. {D}ata scarcity and heterogeneity of the environment in this region necessitated the use of combined approaches. {W}e established a link between water levels measured in situ and flood maps derived from optical and radar satellite images ({S}entinel-1 and -2).{T}he robustness of the link was assessed using {S}entinel, {L}andsat imagery and the {T}an{DEM}-{X} (12 m) elevation model. {T}his water level-flood link ({WAFL}) was then used to reconstruct a daily time series of inundation extents reaching back to the beginning of hydrological measurements in 1991 (30 years). {O}n this basis, changes in the incidence, duration, and spatial distribution of floods were analysed.





{T}he results indicated that {WAFL} can be used to reconstruct inundation maps with an overall robustness of 87% in comparison to historical inundation maps derived from remote sensing imagery. {C}omparisons of {WAFL}-derived flood extents with {L}andsat images further underscored the significant role of local infrastructure, sedimentation dynamics, and land cover to explain changes in inundation dynamics. {WAFL}-based analyses revealed that inundation durations have decreased by an average of 19 days when comparing the periods before and after 2008, which was identified as a break point in the hydrological time series. {F}urthermore, a drastic decrease in inundation the annual frequency with which individual pixels are flooded can be detected during the first half of the traditional flood season, with an average of -21% in early {A}ugust, negatively impacting water-based livelihoods, from agriculture to fisheries.},
  keywords = {{CAMBODGE} ; {ZONE} {TROPICALE} ; {MEKONG} {DELTA} ; {BASSAC} {RIVIERE}},
  booktitle = {},
  journal = {{J}ournal of {H}ydrology},
  volume = {610},
  numero = {},
  pages = {127902 [28 ]},
  ISSN = {0022-1694},
  year = {2022},
  DOI = {10.1016/j.jhydrol.2022.127902},
  URL = {https://www.documentation.ird.fr/hor/fdi:010092318},
}