Flash floods can be extremely harmful to agriculture, especially in a climate-vulnerable country like Bangladesh. This study looked at the damage caused by the August 2024 flash flood in Feni district using satellite images. Two types of satellite data were used: Landsat satellite imagery and Sentinel-1 SAR radar imagery. The research focused on how much crop was lost due to flooding. Two important tools NDVI (which shows plant health) and VCI (which shows how vegetation is doing compared to normal) were used before and after the flood. A new index called DVDI (Disaster Vegetation Damage Index) was created from NDVI and VCI to measure how badly crops were affected. The study found that about 81.95% of the crops were lost, which matched closely with 79.60% reported by the Department of Agricultural Extension (DAE). The strong match shows that the satellite method is reliable. Also, NDVI showed that 196.81 km² of vegetation was lost, and 156.14 km² turned into water. These findings show how modern satellite tools can quickly assess crop loss, helping in disaster response and food security. Such methods support Bangladesh’s goals for zero hunger (SDG 2) and climate-smart agriculture. Future studies can make these tools even better.