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Myanmar’s tsunami and cyclone record – Surveying coastal geoarchives for sedimentary evidence of extreme wave events

Substantiated by historical observations and model predictions, it has been accepted that coasts, in particular densely populated delta areas, currently face an unprecedented acceleration of global sea level rise (SLR). In combination with subsidence in large deltas, SLR will furthermore exacerbate the negative effects of delta flooding due to combinations of tropical cyclone-induced river floods and storm surges.

The regional focus of the project is the Ayeyarwady Delta which will be strongly affected by the entire spectrum of SLR-related hazards. Its high vulnerability was exemplified by Cyclone Nargis in 2008, which triggered a 5-m storm-surge with extensive flooding, leaving 138,400 dead and missing. Storm-induced river floods also affect higher delta parts; for example during cyclonic storm Komen in Aug 2015 >3 M people in Myanmar were affected, particularly along the Ayeyarwady River. Both Nargis and Komen were disasters unprecedented in history.

The uniqueness of the project lies in its research area and in its design which links the sedimentary and historical records of past SLR and delta flooding events (DFE) with the socio-economic development of the region. The interactions between SLR, DFE, and societal impacts shall be exemplified for six sites within the Ayeyarwady Delta, with the four most promising sites studied in-depth over different timescales. Using a combination and mutual interpretation of data from physical and human geographical research, natural and human drivers for SLR and DFE and their consequences shall be identified.

In Part 1 (1988 to present, i.e. the period of marked-oriented economy) and Part 2 (1860–1988, i.e. the period since the beginning of delta colonization), high-resolution records of SLR and DFE shall be studied. Sea level reconstruction will be based on tide and river gauge data, which for the first time ever will be made available internationally. For the reconstruction of historical to modern DFEs, a combination of high-resolution sedimentary records and historical archive data shall be used. By combining SLR and DFE frequencies with data on land-use, landscape changes, population density and socio-economic developments in the delta area derived from historical archives and expert and household interviews, the human response to SLR and DFEs shall be investigated. In Part 3 (i.e. the period prior to delta colonization in 1860), long-term SLR and DFE frequency-magnitude patterns during the last few millennia will be investigated based on sedimentary records.

The synergetic analysis of these data will ultimately help to understand how and to which extent SLR and DFE affected the socio-economic development in the Ayeyarwady Delta and vice versa. Since Myanmar has nearly been a terra incognita for many decades, we assume that these findings are highly relevant for improving present hazard assessment, and for developing future strategies of mitigation and risk governance.