Thailand visit: Wednesday 12 until Sunday 16 December 2007.
Visitors: Joel Smethurst (Southampton), Stephanie Glendinning (Newcastle), David Hughes (QuB), Paul Hughes (Newcastle), Neil Dixon (Loughborough), Tom Dijkstra (Loughborough)
Purpose: To attend a seminar on the ‘Impact of Climate Change on Slope stability’held at Kasetsart University Bangkok on Thursday 13 December 2007, providing an opportunity to meet and network with academics and to carry out field investigations with Dr Apiniti Jotisankasa from Kasetsart University in the Thai uplands focusing on the possible causes and mechanisms of recent cases of slope instability.
13 December 2007: The first day in Thailand involved a seminar on ‘Impact of Climate Change on Slope stability’ (9.30 until 12.30). The seminar, was held in the Engineering Department of Kasetsart University in Bangkok. It was attended by 35 people, including the following speakers; Dr Warakorn Mairiang (Kasetsart University), Dr Suttisak Soralump (Kasetsart University), Dr Auckpath Sawangsuriya (Royal Dept. of Highway), Dr Apiniti Jotisankasa (Kasetsart University), Dr Joel Smethurst (University of Southampton), Dr Stephanie Glendinning (University of Newcastle), Dr Paul Hughes (University of Newcastle), Dr David Hughes (Queen’s University Belfast), Prof. Neil Dixon (Loughborough University) and Dr Tom Dijkstra (Loughborough University). Additional participants included staff, researchers and international graduates based at Kasetsart University.
Dr Warakorn Mairiang welcomed all to the symposium and opened proceedings with a general overview of landslide studies in Thailand. He clearly illustrated that the impact of landslide hazards can significantly delay (or even set back) effective development, and that, without a better understanding of processes, it would be difficult to generate appropriate risk mitigation and adaptation strategies. His group is therefore actively engaging in gaining a better understanding of the processes contributing to instability in Thailand’s upland regions. This includes looking at detailed studies of saturated and partially saturated soil behaviour, the influence of root zone development on soil strength and rainfall thresholds that influence slope stability. In this context the long-term temporal variations of rainfall, as it may be driven by climate change, forms an important variable that needs to be better understood. Dr Suttisak Soralump illustrated the approaches taken to arrive at a landslide hazard map for regions at risk in Thailand. A clear increase in the number of incidents of slope instability has been reported. However, it is not clear how many of those can be attributed to climate change and how many to elements of land use mismanagement. Dr Soralump indicated that some 90% of cases could be associated with construction (?) and only 10% could be considered to have been caused by ‘natural processes’. Dr Sawangsuriya provided a further illustration of rainfall induced landslides problems related to highways in Thailand and discussed slope failures associated with steep cutslopes, surface erosion processes, stream undercutting and problematic soils. The first session was concluded with a presentation by Dr Jotisankasa on issues with unsaturated soil behaviour and geotechnical problems occurring in collapsible (loess) soils and lateritic soils. Following a short break, the PICNIC team contributed to the seminar with a series of presentations similar to those presented earlier in Hong Kong.
The afternoon involved a 7-hour transfer from Bangkok to Uttaradit in the Northern Foothills of Thailand.
Friday 14 December: In the upland area around Utteradit two regions were visited to investigate the possible climate change signal in the recent increases in landslide activity. The first region visited was affected by large scale landsliding following extreme intensity rainfall the previous year. The disintegration of the landslide masses and the incorporation of the debris into the streamflow led to very mobile high density flows that covered infrastructure and buildings many kilometres downstream. In certain places downstream, the ground level had been elevated by at least 1m, affecting buildings and infrastructure. What remains unclear is whether the observed increased impact of these type of landslides in this region is a consequence of a change in climate. Anecdotal evidence of changes in upland forest management, with a likely enhanced sensitivity of hill slopes to rain-induced failure, perhaps provides a stronger argument.
Saturday 15 December: The Saturday was taken up by the return journey to Bangkok, with an interlude at the ancient capital of the Kingdom of Sukhotai (1219 – 1463).
Outcome: An important outcome of the seminar was an expression of interest from the participants to engage in a network similar to that of the UK-based CLIFFS network. This forms a repeat of the interest shown during the earlier visit to Hong Kong. The delegates were invited to send an expression of interest to the cliffs email address and additional pages under an international umbrella will be created to provide a portal to relevant activities outside the UK.
Outputs: All contributions to the seminar are available on the SEA CLIFFS website (cliffs.lboro.ac.uk).
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