Understanding the land use/land cover dynamics and impacts of human activities in the Mekong Delta over the last 40 years

The Mekong Delta is the third largest delta in the world, and a globally recognized agricultural production zone and biodiversity hotspot. In recent decades, land use and land cover (LULC) in the Mekong Delta has undergone tremendous changes due to increasing anthropogenic activities. However, accurate and long-term LULC mapping products for the entire delta are scarce. This study aims to use the Landsat and Chinese HJ-1B satellite images for nearly 40 years to detect the spatiotemporal dynamics of LULC in the Mekong Delta applying the classification and regression trees (CART) technique and analyze its driving factors. Seven main LULC categories were identified with an overall accuracy of 89–94%. We generated seven LULC maps of the whole Mekong Delta from 1979 to 2015 at a 30 m spatial resolution. The results showed that the area of aquaculture and residential land increased, while the area of mangroves, planting land, other forests, wasteland, and unused land decreased from 1979 to 2015. The planting land has been the dominant land use type in the delta since 1979, and still occupied over 72% of the delta area in 2015. The change to aquaculture is most pronounced in all LULC categories, with its percentage of area in the delta increasing to 19% in 2015. With the transformation of large-scale inland planting land into aquaculture ponds, aquaculture has become the second largest land use type following the planting land in the Mekong Delta from the late 20th century. Although the mangrove area showed only slight reduction during 1979–2015, the degree of patch fragmentation increased significantly. We found that the rapid changes of the LULC were mainly driven by economic development and land policies. This study gives insights into LULC dynamics and provides a valuable dataset for regional sustainable development planning and ecological assessment in the Mekong Delta.