Earthquakes, floods, sea-level rise and sudden shifts in river courses threaten many of the 150 million Bangladeshis living in the low-lying Brahmaputra River delta. Scientists from Lamont-Doherty, Dhaka University and other institutions have begun a five-year project to understand the hazards and the possible hidden links among them. Lamont geophysicist Michael Steckler keeps us up to date on the work.
The last part of our river work was on the Jamuna River, as the Brahmaputra is called south of where if diverges from its former course. It shifted up to 100 km to this course about 200 years ago. We visited Sirajganj where an embankment protects the city from the migrating river and Aricha near the confluence of the Jamuna and Ganges. We ended our journey by standing with one foot in each of these two great rivers.
We traveled to the Brahmaputra River, one of the most active on the planet, to continue our fieldwork. We visited two places while working our way downstream and saw the rapid changes in the river bank and chars (islands). At one ghat (dock) the river had eroded a mile of the coast while in the other it added a similar amount. The chars had moved, appeared, disappeared and reemerged. In this changing environment, the resilient Bangladeshi char people shifted and adapted with the land.
For the final part of my journey, we will be visiting numerous sites, mainly on the main rivers of Bangladesh. The samples and field data will ground truth and calibrate satellite data improving our analyses. We first stopped at an area that had converted from shrimp farming to rice, then spent two days on the mighty Ganges River.
Due to the speed at which the two Scotts were able to repair the compaction meter, I found myself with two extra days in Dhaka. Besides numerous quickly planned meetings, I got to see the celebration of the arrival of Bengali Spring and the growing protest movement against the light sentence for Islamists convicted of collaboration during the 1971 revolution. This Occupy Dhaka has tangled traffic in an already clogged city.
I headed east to Comilla for 4 days to train 6 Dhaka University students and graduates to use the resistivity imaging system we bought for the project. The system will send electric currents into the ground to map the distribution of sand and muds. The 1000s of measurements will create a catscan-like image of the rocks under the profiles. Together we all learned what worked and didn’t in Bangladesh.
Able to drive again, we wrapped up the last few days of the conclave with more outcrop geology, drilling wells through the sediments, 3D filming and a barbeque. The conclave turned to be an extremely successful means of getting us excited due to the tremendous cross-fertilization that occurred.
A two day general strike disrupted our field plans, but Bangladeshis are adept at adapting to any change. We walked the local outcrops one day and hired a small pickup truck the next and managed to accomplish our goals despite the political turmoil.
Our project studying the Ganges-Brahmaputra Delta in Bangladesh consists of many components studying different tectonic and sedimentary aspects of the geology. To bring all the parts together, we are holding a meeting we are calling the “conclave” in NE Bangladesh. We are jointly visiting places that can help us to develop an integrated understanding of the basin.
For our final installation, we had to go from the edge of the Bay of Bengal almost to Bangladesh’s northern border with India, a trip of over 350 miles. Along the way we stopped at Humayun’s childhood home, had several flats and picked up a student of Humayun’s from the town where we installed it. After getting the GPS set up at the site he selected, we concluded with a feast at his home, driving by signs of the upcoming Hindu and Muslim festivals, and our own final celebration.
We traveled by boat to the south part of the Sundarbans near the Indian Ocean to install a GPS at Hiron Point, this isolated facility also hosts a tide gauge recording long-term water level changes due to rising sea level and land subsidence. Our GPS will help distinguish how much of each there is in the midst of the world’s largest mangrove forest.
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