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 multiple disciplines in water cycle science and applications. The study domain covers a major agricultural region in the Mekong Delta of Vietnam between the Mekong and Bassac rivers. This region has increasingly suffered water-related risks, such as drought along with salinity intrusion. A synthesis approach is used with the integration of different types of land use and land cover (LULC) data in 1990-2020. The multivariate dataset was ingested into a hydrological mode (i.e. the Soil and Water Assessment Tool) to examine the multidecadal ET evolution across the study region 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.