No abstract

Physically-based distributed hydrological modelling, Rainfall-Runoff-Inundation (RRI) model is used to evaluate runoff accuracy by using six satellite based rainfall products such as GPM, GSMaP, TRMM 3B42V7, CMORPH, and PERSIANN. These products input to drive the model on the Nan River basin, Thailand that is the watershed of 13,000 km 2 . The performance of the precipitation products, rainfall depth and runoff, was evaluated from storm event on 2014 by using statistical approach, Volume bias, Peak bias, RMSE, Correlation, and Mean bias, to compare with observation data. Overall of the satellite based products, the CMORPH and GPM performed the best that was provided by the statistical values, comparing with average observed rainfall data. For the runoff estimated from GPM closed to the observed data and was better than other five products, satellite and rain gauge, to provide the high correlation and small RMSE value. This study presents the uncertainty of satellites that have a potential for runoff estimation to apply for water resources management.

Abstract. Tsunami fragility functions describe the probability of structural damage due to tsunami flow characteristics. Fragility functions developed from past tsunami events (e.g., the 2004 Indian Ocean tsunami) are often applied directly, without modification, to other areas at risk of tsunami for the purpose of damage and loss estimations. Consequentially, estimates carry uncertainty due to disparities in construction standards and coastal morphology between the specific region for which the fragility functions were originally derived and the region where they are being used. The main objective of this study is to provide an alternative approach to assessing tsunami damage, especially for buildings in regions where previously developed fragility functions do not exist. A damage assessment model is proposed in this study, where load-resistance analysis is performed for each building by evaluating hydrodynamic forces, buoyancies and debris impacts and comparing them to the resistance forces of each building. Numerical simulation was performed in this study to reproduce the 2011 Great East Japan tsunami in Ishinomaki, which is chosen as a study site. Flow depths and velocities were calculated for approximately 20 000 wooden buildings in Ishinomaki. Similarly, resistance forces (lateral and vertical) are estimated for each of these buildings. The buildings are then evaluated for their potential of collapsing. Results from this study reflect a higher accuracy in predicting building collapse when using the proposed load-resistance analysis, as compared to previously developed fragility functions in the same study area. Damage is also observed to have likely occurred before flow depth and velocity reach maximum values. With the above considerations, the proposed damage model might well be an alternative for building damage assessments in areas that have yet to be affected by modern tsunami events.

Abstract:The aim of this study is to assess the performances of different infrastructures as structural tsunami countermeasures in Sendai City, based on the lessons from the 11 March 2011, Great East Japan Tsunami, which is an example of a worst-case scenario. The tsunami source model Ver. 1.2 proposed by Tohoku University uses 10 subfaults, determined based on the tsunami height and the run-up heights measured for all tsunami affected areas. The TUNAMI-N2 model is used to simulate 24 cases of tsunami defense in Sendai City based on a combination of 5 scenarios of structural measures, namely, a seawall (existing and new seawall), a greenbelt, an elevated road and a highway. The results of a 2D tsunami numerical analysis show a significant difference in the tsunami inundations in the areas protected by several combinations of structures. The elevated road provides the highest performance of the single schemes, whereas the highest performance of the 2-layer schemes is the combination of an existing seawall and an elevated road. For the 3-layer scenarios, the highest performance is achieved by the grouping of an existing seawall, a new seawall, and an elevated road. The combination of an existing seawall, a new seawall, a greenbelt and an elevated road is the highest performing 4-layer scenario. The Sendai City plan, with a 5-layer scenario, reduces the tsunami inundation area by 20 sq. km with existing structural conditions. We found that the combination of an existing seawall, a greenbelt, an elevated road and a highway (a 4-layer scheme) is the optimum case to protect the city against a tsunami similar to the 2011 Great East Japan Tsunami. The proposed approach can be a guideline for future tsunami protection and the evaluation of countermeasure schemes.

Thailand was hit by a great flood in 2011 resulting from irregular rainfall during the typhoon season that was estimated at 140% more than average. The flood began in the north and slowly moved to the central region, where it remained for more than 4 months. The flood caused great damage to the economy because it adversely affected industrial estates and agricultural areas. In the north, there are four main rivers in the region that combine into a river called Chao Phraya in the central region. The Yom River is one of the northern rivers where no large-scale dam has been constructed, resulting in frequent flood and drought. Sukhothai Province is located in the Yom Basin, where flood and drought occur on a regular basis, and the province was also severely damaged in the 2011 flood. In order to estimate flood damage cost in 2011, a simple regression curve is presented first to relate flood areas and damage cost based on past records. The 2011 flood in Sukhothai province was then simulated by using a Rainfall-Runoff-Inundation (RRI) model with satellite based rainfall (TRMM). After simulation results were compared with the observed stream flow water level, discharge and inundation extent, this study estimates damage cost for the 2011 flood based on the simulated flood area. The proposed approach could be a useful guideline in damage cost computation.