Enter the Sundarbans mangroves and return
M/V Bawali, our home next week.
In the evening we headed to the ghat (pier) around 8pm. Busy as usual, with many people coming and going from ferries and private boats, stalls selling food, and lots of vehicles honking their horns. Boat owner Bachchu took us to the right spot on the hillside. M/V Bawali’s wooden country boat, our home next week, arrived and helped previous travelers leave. The crew then quickly helped load all our gear and luggage onto the wooden boat. Once we were settled, they crossed the channel to where Bavali was waiting for us.
Pinky and Masood were on a country boat with our two armed rangers. Dipu turned back with Sanju and Nasir on the right.
Bawali, which means lumberjack, is a 60-foot Sundarban tourist boat with 6 cabins, one for each of us. We were supposed to join her in the morning. To make up for the delay, she cruised through the night so we could reach our first stop in the morning. We got on the boat, settled down, had dinner, and enjoyed the many delicious buffets as usual. Still, it took us a few hours to get moving. It will be an easier but slower way to travel after the last few days of long drives. We spent the evening chatting and exchanging stories before handing over the house. We are still heading south in the Psul River to the largest mangrove forest in the world.
Masud measures altitude, while Ira (Eera) records the measurements.
When we woke up the next morning, we were already deep in the forest and arrived at our destination after breakfast. Katka is a popular tourist attraction in the Sundarbans and we saw many other boats. However, we are going to an RSET site in the forest. I don’t have a GNSS site here, so this is my chance to see the RSET survey done. As usual, we were accompanied by two armed guards to keep the tigers at bay, occasionally shouting to scare them away.
Sanju and Ira measure the thickness of sediment accumulated on tiles.
With Pinky and Masud in charge, with Ira, Sanju and two boatmen assisting, things went relatively quickly. Masud and Ira added a survey arm to the monument and took 72 measurements of the elevation around it. Meanwhile, Pinky and Sanju found the sediment tiles and measured the thickness of the sediment. The difference between elevation change and subsidence will produce shallow subsidence above the bottom of the pole. Both sites were completed at 11:30 am.
Littlefinger is laying new sediment floor tiles that are flush with the forest floor.
As the weather turned rainy and we missed out on walks and beaches, we started our journey to our next destination. The boat sailed out of the river into the Bay of Bengal and into the next channel, heading west towards Hiron Point. At sunset we passed what is known as Kokilmoni and sailed near Tinkona Island.
Sunset on Tincona Island in the mangroves of the Sundarbans.
We waited until the next morning to cross the 10km wide strait to Hiron Point. The Bavali waited outside the channel as we entered by country boat. The walkway to the tide gauge has been broken since our last visit, so we won’t be visiting it this time.
The walkway to the Hiron Point tide gauge has broken down since our last visit.
Instead, we went to the ranger station and started working on our GNSS. As usual the batteries died and we replaced them. They continued until the end of October, when they started to fail. We also brought a modem as Hiron Point has a phone service and it was successfully online for the first time since the 2012 installation. When we were done, two wild boars wandered around the grounds.
Downloading a year’s worth of data from Hiron Point GNSS onto my laptop. No one has been here for a long time.
When we were done, we crossed the river in a country boat to the RSET team, who were finishing touches. Then we all took the elevated forest walkway to the observation tower about a kilometer in the forest. The wooden slats were not in good shape and many were broken. We all walked carefully through the concrete frame, and the nail heads were easy to find. It was a beautiful forest walk with several deer along the way.
A wild boar roams near the ranger station.
Back in the country boat, I was surprised to find that we were going upstream. As we continued onward, I learned that we were going through a maze of passages to the next main passage north. 1.5-2 hours along our way. On the boat ride we saw a lot of deer, a few monkeys and a crocodile. Towards the end, we harvested the fruit of a galpata tree (nipa palm) and split it with a machete, we got to try its fruit. We got back to Bavali just in time for our usual 2:30 lunch before heading to the next location.
Pinky and the others are on the elevated walkway through the forest, where there are many broken planks.
The first part of the ride was through a narrow passage that allowed us to see a lot of deer in the woods. After a few hours, we entered a large river one kilometer wide and headed north to our next destination. We stayed for one night and arrived in Qiao Xing in the morning. Pinky, Masud and Ira went to RSET, Chris went to shoot vegetation, Sanju and I took GNSS to school. When finished, the RSET team headed to their second location outside the polder. Sanju and I went to find Chris and then took a speedboat to RSET in the mangroves.
One of the many deer we spotted from sidewalks and boats.
Once that’s done, we start the transfer to the last site. During the trip, we spotted monkeys in the Sundarbans and freshwater dolphins in the Great Shibsa River. We first headed to the GNSS station at the northwest corner of Polder 32, then to the RSET on the south side. Our last GNSS service for this trip was also at an elementary school. We walked ½ mile to the site and got to work, checking out the GNSS site with Pinky and Ira. The last stop went well too, and after tea with the principal, we returned to Bavali feeling satisfied.
An egret took off early in the morning as we sailed through the Sundarbans.
We have now visited all of our southern coastal sites and measured delta subsidence. All were online and transmitting data back to the US, although one had trouble locking onto the satellite. I may have to visit it on my next trip in March. The RSET team still has 8 locations to visit in Sorbhatkhali on the south side of Polder 32 over the next two days. Four in the Sundarbans and four in the polders.
While sailing in the Sundarbans, we saw a lot of evidence of changing course.Here the land is growing and new little trees are settling in this fresh land
However, Chris and I are going home. First we will meet the smaller M/V Mowali (Sundarbans Honey Collector) to take us back to Khulna. Then the next day, we returned to Dhaka and, after completing the required COVID tests, finally got on a flight back to New York.
The RSET team works in the rice fields. Dense, small fields are being transplanted to larger flooded fields.
My GNSS network got to work again, collecting data to better determine the tectonics of the subduction zone in northeastern Bangladesh and the subsidence of the southeastern delta. Together, they will improve our estimates of a potential large earthquake in eastern Bangladesh and the hazards of sea level rise and climate change in southwestern Bangladesh. Meetings between my two service runs in Dhaka will help build new projects to continue our research here. It’s been a successful trip and I’m ready to go home.
Sanju and I met Chris while walking back after surveying the vegetation in the area to validate his remote sensing analysis.
