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 Chittagong on Karnaphuli

Karnaphuli River | Southeast Bangladesh

Date of acquisition:    November 9th, 2023  |  04:32:29 UTC

Sensor: Sentinel-2 L2A

Coordinates:     ca.22.22°N, 91.81°E

Chittagong (Bengali: চট্টগ্রাম) is a city in southeastern Bangladesh; the administrative center of the district and region of the same name, the second largest city in the country and the country’s main port. Chittagong and its surrounding areas have a population of more than 6.5 million. Chittagong is an important industrial and financial center. It is the country’s largest port, handling up to 80% of Bangladesh’s total exports and imports, and one of the largest in the entire Indian subcontinent. The city is located on the right bank of the Karnaphuli River (Bengali কর্ণফুলি), which has a total length of 180 km. It flows into the Bay of Bengal about 15 km south of the city.
Nearly half of the world’s decommissioned ships are disposed of in Chittagong. The local ship recycling facility is said to be the largest in the world. The shipbreaking yards near Chittagong are located on a seven-kilometer stretch of beach about 15 kilometers northwest of Chittagong.
The satellite image shows many small and medium-sized vessels on the Karnaphuli River in the Chittagong area, possibly hundreds of ships anchored in the Bay of Bengal, north of the mouth of the Karnaphuli River, and many large vessels in the Bay of Bengal, west of the mouth of the Karnaphuli river.
It is interesting to observe the image using the Normalized Difference Water Index (NDWI)  for the Sentinel-2 bands ((B3 – B8)/(B3 + B8)). The position and composition of the ships change very dynamically, as can be seen in the animation over several days. This also shows how large the influence is on the water colour caused by the ships by resuspension and swirling the water. The ships produce clear plumes of suspended matter and the  area with the highest density of ships is much more turbid than other regions.

Fig. 1: RGB
Fig. 2: NDWI
Images contain modified Copernicus Sentinel Data [2023].