Synthesis study of evapotranspiration evolution in the Mekong Delta induced by land use and land cover changes in the decades of 1990-2020

Evapotranspiration (ET) plays a key role in the water cycle and balance, and its estimation is of paramount importance in hydrological studies. This variable is also strongly influenced by the land use and land cover (LULC). This study use a synthesis approach to analyse the relationship between ET variation and LULC transformation in the period 1990-2020. The study area represents a major agricultural region in the Mekong Delta of Vietnam between the Mekong and Bassac rivers. The multivariate dataset was ingested into the hydrological model Soil and Water Assessment Tool to examine the multidecadal ET evolution across the study region. The ET evolution is investigated together with LULC changes to identify the primary drivers of the ET change. The results reveal an increase in landscape fragmentation together with a decrease in ET. The reduction in ET is associated with the decrease in water surfaces corresponding to upstream dam operations and with the construction of new urban areas. In the coastal area, a conversion from natural areas (i.e., mangroves cover) to aquaculture has been observed, leading to a slight increase in ET.