An integrated hydrological-hydraulic model employing the 2-D local inertial equation as the core is established for effective numerical simulation of surface water flows in a great lake and its floodplain. The model is a cascade of validated hydrological and hydraulic sub-models. The model was applied to simulating the surface water flows of the Tonle Sap Lake and its floodplain in Cambodia using the roughness coefficient value calibrated comparing with a remote-sensing data set. The resulting model reasonably handles backwater flows during the rainy season and simulates the propagations of wet and dry interfaces without numerical instability, owing to a proper setting of time step supported by a novel numerical stability analysis. Sensitivity analysis of the surface water dynamics focusing on the setting of roughness coefficient and the backwater effect was also carried out. Overall, utilizing the 2-D local inertial equation in the assessment of lake water dynamics is a new modelling approach, which turns out to be an efficient simulation tool.

This study proposes a generalized framework for the assessment of flood risk and potential strategies to mitigate flood under various vulnerability and adaptation scenarios. The possible causes of hazard, exposure and vulnerability in flood disaster were clearly identified by using a climate risk template. Then, levels of exposure and vulnerability with adaptive capacity and sensitivity were further defined by a quantification approach, and the climate risk maps were consequently provided. The potential possible climate adaptation strategies were investigated through the comparison of climate risk maps with diverse adaptation options. The framework was demonstrated in the Kyoto City in Japan with residents as a target population to reduce the flood risk. The results indicate that the government should pay attention to reducing the population in flood-prone areas and adopt diverse adaptation strategies to reduce the flood risk to the residents. Rainwater storage and green roofs as adaptation strategies as short-term planning options are recommended. The construction of detention ponds has been suggested to prevent flood risks in future as a part of the long-term planning process. In conclusion, the proposed framework is expected to be a suitable tool for supporting climate risk analysis in the context of flood disasters.

Rice is a major agricultural crop in Thailand, while paddy fields near river lines are exposed to high flood risk. This study assesses rice exposure and economic flood risk under future climate in the Lower Chao Phraya River Basin, Thailand. To encompass various flood events, this study estimates the frequency of rice economic damage by employing a large ensemble climate projection dataset based on database for Policy Decision making for Future climate change (d4PDF). Results show that, in the 4‐K warmer climate, the 100‐year exposed cultivation area and duration will increase approximately by 1.2–1.4 and 1.1–1.2 times, respectively. Decreased rice production is evaluated as monetary damage through several fragility curves. The economic damage by the 2011 flooding is estimated as 11.25 billion Thai Baht, while the estimation varies from the fragility curves employed. In the 4 K warmer climate, regardless of the fragility curves, 100‐year rice damage is projected to increase by 1.2–1.4 times. The 2011 flooding is larger than all 3000‐year simulations in the past climate, whereas extreme events in the 4 K warmer climate showed higher damage than the 2011 flooding, indicating that agricultural damage corresponding to the 2011 flooding may occur more frequently in the future climate.

Integrated flood risk management based on urban policies remains challenging compared with infrastructure due to the unclear risk‐reduction effects over time. To consider heterogeneity in social responses to urban planning measures, a previous study developed an agent‐based household relocation model under flood risk (AHR‐FLOOD) by combining flood‐inundation and agent‐based relocation models. However, accurate modelling of relocation incentives remains challenging. This study aimed to improve AHR‐FLOOD by introducing spatial amenities based on transportation convenience and reflecting their impact on the decision‐making processes of agents to analyze the development of different flood risk areas. AHR‐FLOOD considering access to public transportation reproduced the spatial characteristics of the actual population and housing prices. The development of low‐risk areas reduced flood exposure and resulting flood damage. However, this effect was less clear for low‐income individuals, but the development of low‐amenity areas had the potential to induce low‐income population to move to safe areas. Chain migration was observed as a long‐term effect of the spatial amenity policy. This study presents insights into the effect of transportation policies on flood safety for long‐term spatial distance management in an agent‐based approach with the rigorous modelling and validation of local amenity impact on household relocation choices.