Plastic, including microplastic, is a common product in the society today and is starting to be more common in oceans where it can stay for a long time. Microplastic is defined usually in the size range five millimeter and smaller and together with the important Chao Phraya river in Bangkok, Thailand, the main subject of this paper is described. More clearly, the aim of this paper is to provide a first-hand quantification of microplastics flowing into the Chao Phraya River. Samples were taken at upstream, middle and downstream locations in the river with a pump-system and were then analyzed in a lab. The result showed an increasing load of microplastic entering the river from Bangkok, for example the result for size range five to one millimeter showed a six times increase of microplastic between the upstream and downstream point. / Plast, däribland mikroplaster, är en vanlig förekommande produkt i samhället idag och börjar bli allt vanligare i hav där det också kan stanna ett långt tag efter att det hamnat där. Mikroplaster definieras oftast med storleks intervallet fem millimeter och mindre och tillsammans med den viktiga floden Chao Phraya i Bangkok, Thailand, är huvudämnet för denna studie beskriven. Mer tydligt, målet för denna studie är att förse en första kvantifiering av mikroplaster som flödar in till Chao Phraya floden. Prover togs på platser som var uppströms, i mitten och nedströms på floden och sedan analyserades dessa prover i ett laboratorium. Resultatet som framkom visade på ökande belastning av mikroplaster i floden från Bangkok, exempelvis visade resultatet för storleks intervallet fem till en millimeter på en sex gånger ökning av mikroplaster mellan uppströms platsen och nedströms platsen. Ökningen som troligen kommer från innerstaden kan bero på olika faktorer såsom väder, stadens avfallshantering och användningen av engångsprodukter som är av plastmaterial. Således påvisar detta vikten av, bland annat, en fungerande avfallshantering.

京都大学 / 新制・課程博士 / 博士(工学) / 甲第23165号 / 工博第4809号 / 新制||工||1752(附属図書館) / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 立川 康人, 准教授 市川 温, 教授 田中 茂信 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第18555号 / 工博第3916号 / 新制||工||1602(附属図書館) / 31455 / 京都大学大学院工学研究科社会基盤工学専攻 / (主査)教授 立川 康人, 教授 戸田 圭一, 准教授 KIM Sunmin / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第22760号 / 工博第4759号 / 新制||工||1744(附属図書館) / 京都大学大学院工学研究科都市環境工学専攻 / (主査)教授 清水 芳久, 教授 田中 宏明, 教授 米田 稔 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

Thailand has been often affected by severe flood events over the past century. The 2011’s Thailand Flood Catastrophe was the costliest in country’s history, and it was ranked to be the second most damaging natural hazard in the world in terms of economic losses. The Chao Phraya River Basin was noted to be the most vulnerable area prone to flooding in Thailand. The dynamics of flood risk in the river basin have changed drastically over the past fifty years. In particular, flood exposure increased due to rapid urbanization and population growth. Since 2012, integrated flood risk management has been addressed to be the major framework of water-related disasters with the goal of losses and damage reductions. However, there is currently little research in Thailand on how to quantify flood risks and mitigate flood inundation damage on the relation between the occurrence of flood events and their consequential socio-economic implications. In this study, a tradition method in flood risk assessment is implemented by integrating 2D hydrodynamic modelling and the assessment of socio-economic impact of floods into the Chao Phraya River Basin. More specifically, the fully 2D version of the LISFLOOD-FP model code was used to model flood inundation processes. The output of the model was then used to map inundation depth and assess the levels of physical/environmental risk associated to flood hazards on multiple receptors/elements at risk. The European Flood Directive and the KULTURisk methodology were applied to quantify flood risks in monetary terms for residential, industrial, and agricultural sectors. The 2011 flood event was used for model calibration, while a hypothetical flood event with a return period of 100 years was simulated to identify the potential flood losses. Depth-damage functions comprising of JRC-ASIA, the Flemish, and JICA models were used to estimate potential damage for residential and industrial structures. The results showed that LISFLOOD-FP could satisfactorily reproduce the flood inundation extent obtained from satellite imagery in 2011. The model performance (Critical Success Index or F1) was of 56%, with a Bias of 112%. The latter meant the total inundated area was 12% larger than flood extent’s observation. Moreover, the model could simulate flood levels with overall Root Mean Square Error (RMSE) and Mean Absolute Error (MAE) of 2.03 m a.s.l. and 1.78 m a.s.l., respectively. For the estimation of flood damage and losses, the Flemish model showed the strongest agreement with the reported flood damage in the residential sector, while JICA-ASIA model underestimated flood damage for industrial sector by just 1%. The KULTURisk methodology also well-estimated crop losses in the 2011 event which an overestimation about 21% from the reported value. Apart from that, fully 2D numerical method could not perfectly represent 1-in-100 year flood inundation due to non-consideration of important features such as the precise river channel topography, hydraulic infrastructures, and flood protection schemes in the river basin. Lack of such features results in an overestimation of flood damage and losses for 1-in-100 year flood comparing to the national flood hazard map and damage assessment which are simulated and estimated by JICA’s study. Such features can be better handled by using a coupled 1D/2D numerical method in order to simulate flood inundation extent more realistically and estimate flood losses. This could help the Thai government to better prepare a budget for flood risk prevention. In addition, even if the Flemish model indicates a good representation of relative flood damage to housing structures, the government should establish depth-damage curves specific for Thailand.

Rapid economic development and urban expansion of the Bangkok Metropolitan Region (BMR) places pressure on biomes and communities alike. In a world suffering from the increasing effects of climate change, unchecked urbanisation comes at the expense of carbon sequestrating environments. The modernisation, concretisation and gentrification of this low-lying, deltaic, monsoonal metropolis has seen its traditional, water-based urban morphology replaced with a solid state of perception, parallel to a loss of flood mitigating infrastructure. As the metropolis’ boundaries expand into its hinterlands, agriculturally productive land is being converted to residential, commercial and industrial development and the fate of low-income urban populations and farmers lies in the hands of speculators hoping to capitalise on increasing land values. Combatting this backdrop of neoliberal urbanisation is legislative framework intended to prevent speculation, yet it results in additional ecological damage as landowners clear natural-growth forests and mangroves to meet tax-reducing criterium. The purpose of this thesis is to examine the reasons behind and consequences of under-regulated urbanisation and gentrification and the effects this has had on the vulnerable ecology and communities of the BMR. It provides lessons on how previous short sighted and poor development regulations will have enduring social and environmental consequences long into the future and how adoption of traditional morphological ways-of-life and legislative amendments can limit further damage. The legacy of neoliberal urban development resulting in gentrification and underpinned by conflicting local planning laws are analysed and supported by various theoretical materials, field studies and interviews.