|Thailand Monsoon Project – Field work diary January 2010|
This is our last week in Thailand. Hywel, our moviemaker, left us in the evening of January 20th to fly back to the UK. It felt a bit strange to suddenly be out of focus and surveillance! Hywel will visit us in March or April in Stockholm to film the laboratory part of the project, i.e. sampling and analyzing the sediments and also wants to see us in a more “normal working environment”. The finished film will be accessible on this homepage.
Instead of a strong boat motor which runs on petrol and makes a lot of noise, we use a solar powered battery run motor. This motor has not so much power, but enough to move us and the equipment silently forward over the lakes. We core from a specially constructed coring platform which is adapted to the size of the boat and to the PVC chimney. The platform can be folded and easily carried. To stabilize the boat during coring and as anchors we use bamboo sticks.
Ludvig and Pare are ready to leave. The coring platform is in place and the bamboo anchors have been cut.
For coring we only use modified Russian corers (manufactured by a small workshop in a village outside of Lund in southern Sweden; see www.geol.lu.se) made of strong steel. They have a chamber length of 1 meter and diameters of 5, 7.5 and 10 cm. Depending on the stiffness of the sediments we used either the 7.5 or 5 cm diameter corer. Generally we core from the sediment-water interface in 1 m overlapping segments (two close-by holes) by adding steel rods of 1.5 cm length to the corer. Once we reach the sediment depth we want to core we close the core chamber with a handle fixed to the uppermost rod and pull the corer out again.
The last fieldwork days in northeastern Thailand were dedicated to also obtain a longer record from Lake Kumphawapi where we cored last year. Now we wanted sediments older than 8000 years and these can only be found, according to investigations by Dan Penny, in the southern part of the lake. This part of the lake is however not very accessible for our zodiac because of the dense vegetation and can only be navigated with narrow canoes. Luckily we got help from the local fishermen who promised to take us out in their canoes and to find a “dry” spot from which we could core. This meant making a new bamboo platform to stand on so that we would not sink deep into the soft mud.
This time Pare, Nut and Koy were in charge of the whole coring operation so that they would be able to do fieldwork on their own in the future.
Happy with this year’s fieldwork we drove back to Bangkok where all our cores were today shipped to Sweden. We forgot to make a group pictures – too bad – but we have many, many pictures otherwise.
Next week we (Ludvig and Barbara) will move on to Taiwan where more lakes are waiting for us to be cored. Nut is getting ready to join us in Sweden in two weeks and Pare and Koy will arrive in April in Stockholm and spend 6 months at Stockholm University.
Hywel George from Plasticbuddha has arrived and will be with us for the coming ten days. Hywel will make a short science movie about our field work and our quest for the monsoon (or for the reconstruction of monsoon variability).
One more lake has proven to be unsuitable since all sediments had been removed by dredging, as in many of the other lakes we visited earlier. But almost coinciding with Hywel’s arrival, we found a perfect spot: remnants of an undisturbed wetland between two (dredged) lake basins! The narrow channels in the wetland could however not be navigated with our zodiacs, but fortunately we could borrow canoes from the local fishermen and were so able to explore the wetland in greater detail. Handling the canoes was not an easy task and demanded quite a lot of balance.
Keeping a good balance in the wiggling canoes with all the heavy coring equipment was a struggle, but coring in the small channels proved to be an even greater struggle - we sank knee-deep into the soft mud and lost our balance. We therefore quickly abandoned this procedure and decided instead to construct a simple bamboo platform which could be laid out in a more stable area and which could provide some stable ground from which we could core more easily.
The result of our efforts were two sites with beautiful, 2.50 m long cores which contained alternating layers of calcareous clay and peaty gyttja/peat. Let’s hope that these are a signal for water level changes.
After these first successful sediments we deserved a nice treat – sightseeing in one of the National Parks and a visit to the old temples in Sukothai.
From northern Thailand we headed eastwards to our former fieldwork area because we wanted to get more and deeper sediments in both of our “old” sites, Lakes Pa Kho and Kumphawapi.
Pa Kho was luckily still the same lake as we had left it last year! Last year we could retrieve here an 8 m long sequence which has a bottom age of 42,000 years. Now we wanted to try to get even deeper and to complement the existing cores so that we would have more material for all the planned analyses. And – we managed to get deeper! Now we have 10.15 m of sediment. It will be exciting to see how old the deepest part of the sediments will be!
Next week we will sample Lake Kumphawapi and after this it will be time for us to pack our things together and drive back to Bangkok. Three more weeks of fieldwork are ahead of us in Taiwan.
On January 4th we all met in Chiang Mai in Northern Thailand for this year’s fieldwork. Our targets for this season are several lakes in the northern part of Thailand, some of them we had checked out earlier, others we had only identified on maps.
From Chiang Mai we first visited Doi Inthanon, Thailand’s highest mountain 2565 m above sea level. Originally we had planned to sample a small peat bog close to the mountain top, but our application to the National Park Authorities came in too late to be approved in time. Therefore we only checked the site and discussed how we could best core next year without disturbing the fragile ecosystem.
This year our group consists of Pare, Koy and Nut from Chulalongkorn University in Bangkok, Sheri from the University of Nebraska in Lincoln, Gung and Luped, our two drivers from Bangkok, and Ludvig and Barbara from Stockholm University. Pare and Koy are MSc students and Nut will soon start his PhD education at Stockholm University.
Our next stop was the small town of Chiang Saen, which is situated along the Mekong River, just opposite of Laos. Here we planned to survey a number of lakes which had looked promising, at least based on the topographic map. Specifically we wanted to measure the water depth, the pH, conductivity, and the sediment depth. And of course we wanted to get a sediment core full of nice and interesting lake sediments!
Our new zodiac, with a specially made coring chimney works very well and is much better than the boat we had last year. Moreover we now have a small engine which is driven by solar power. No noise and no petrol fumes, just gliding silently over the lakes’ surface makes our explorations really pleasant.
The lakes around Chiang Saen proved to be very shallow and did not contain any soft sediment. Therefore we moved on to Chiang Rai, some 200 km south of Chiang Saen, an area which used to have several wetlands and lakes. But even here we were not lucky and only found that the wetlands had been drained and that the former lakes had been greatly modified.
Lakes are rather frequent in Thailand, but most of these are dams or reservoirs, while real natural lakes are very rare. Wetlands and natural lakes that had existed on topographic maps some 10-30 years ago have in the mean time been drained and converted to agricultural land, or the sediments have been removed completely to create small and not very productive water bodies for fishing. However there is also the chance to find former wetlands which have recently been flooded and where sediment sequences are still preserved.
After a full week of bad luck we finally found a promising site, some 20 km north of the small town of Phayao. Although much of the former large wetland has also been converted into farm land and fishing ponds, our survey showed that areas with soft sediments exist in the lake. Moreover parts of the wetland have been preserved and the old trees in this marshland show that it is largely undisturbed.
Today Hywel George, a science movie maker from Bristol joined us to document our search for lakes and the lake sediment coring. Now we really need to find a good sequence!!