Mangrove-mud coasts across the world erode because of uninformed management, conversion of mangrove forests into aquaculture ponds, development of infrastructure and urbanization, and/or extraction of groundwater inducing land subsidence. The accompanied loss of ecosystem values, amongst which safety against flooding, has far reaching consequences for coastal communities, exacerbated by sea-level rise. To halt erosion various nature-based solutions have been implemented as an alternative to hard infrastructure sea defenses, including mangrove planting and erection of low-tech structures such as bamboo fences, permeable brushwood dams, etc. These structures have been designed on the basis of best-engineering practice, lacking sufficient scientific background. This paper investigates the use and success of permeable dams over a period of about 15 years, describing their application in Guyana, Indonesia, Suriname, Thailand and Vietnam, summarizing the lessons-learned, and analyzing their functioning in relation to the physical-biological coastal system. Also an overview of relevant costs is given. The basic philosophy behind the construction of permeable dams is the rehabilitation of mangrove habitat through re-establishment of the (fine) sediment dynamics – we refer to Building with Nature as the overarching principle of this approach. Our main conclusions are that a successful functioning of permeable dams requires (1) a thorough understanding of the physical-biological system and analysis of the relevant processes, (2) patience and persistence, including maintenance, as the natural time scales to rehabilitate mangrove green belts take years to decades, and (3) intensive stakeholder involvement. We give a list of conditions under which permeable dams may be successful, but in qualitative terms, as local site conditions largely govern their success or failure.@en

The world is encountering climate change and severe natural disasters. Floods have been one of the most disruptive disasters these decades. The 2011 flood in Thailand affected 13.6 million people and caused damage of USD 46.5 billion, while the 2013 flood in Jakarta, despite its short period, affected more than 45,000 people. This study intends to examine the changes of disaster information preference before and during each disaster. Questionnaire surveys were conducted in July 2013 in Thailand and Indonesia. The results found that the preferences for information increased once the disaster approached, except for preparedness plans and warnings in both cases and waste disposal in the Indonesian case. While most of the information preferences show no significant difference in mean between the two disasters, the results found significant differences in preferences for traffic/transportation infrastructure both before and during the arrival of disasters, availability of food and water, waste disposal before disaster impact, and overall damage information during the impact. The findings are crucial in terms of information gathering and dissemination to maintain the lives and livelihoods of human being during disasters. This study can contribute to both research and practice in terms of disaster information analysis and better preliminary examination of the preference for information needs from similar disasters with different scales and geographies.

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