Evaluation of drought on agricultural land-use change: A case study of coastal districts, Ben Tre province

Abstract

Ben Tre is a coastal province in the Mekong Delta heavily affected by negative impacts of climate change and sea level rise, such as freshwater shortage and increased salinity intrusion during the dry season. This research aimed to develop a remote sensing approach, using time series data to assess drought development for the coastal districts (Ba Tri, Binh Dai, and Thanh Phu) in Ben Tre province. The Temperature Vegetation Dryness Index (TVDI) was analyzed based on the time-series Landsat 8 OLI data, which were obtained continuously from 2009 - 2019 to evaluate drought changes over time. The drought maps of 2009 and 2019 were established and the results showed that there were four levels of drought, including non-drought, slight drought, moderate drought and severe drought. Areas with non-drought and slight drought were reported at 5.65% and 35.34% (about 6,098 ha and 38,146 ha), respectively; while about 53.14% and 5.87% of the study areas were classified as moderate and severe drought (about 57,354 ha and 6,332 ha), respectively. The assessment of fluctuations in the period 2009-2019 showed that the areas of non-drought and slight drought tended to decrease while the areas of moderate and severe drought increased. The drought was positively related to agricultural land-use change as shown by the following formula log_e(P_i/(1 - P_i)) = 7.985 * TVDI - 6.746. Drought tended to decrease in the areas where the bare land was changed to lands for perennial crops, rice crops and aquaculture, while drought tended to increase in land-use types of rice and annual crops.