Development of simulation model of tsunami flow coupling water channel network flow and overland inundation

In coastal industrial areas, seawalls and dykes are usually constructed to protect the industrial facilities from tsunami inundation. However, even when these protective structures work properly, tsunami inundation due to overflow from underground water channels such as intakes, outfalls and water drainage channels could occur. Since this tsunami overflow inundation may damage electrical facilities, lose evacuation routes and be an obstacle to safety measures, it is important to evaluate the risks of the inundation and consider countermeasures from the perspective of BCP. In this study, an integrated numerical simulation model for tsunami overflow inundation was developed. The developed simulation model consists of two simulation models; an 1-D overflow simulation model to simulate overflow volume from pits of water channel networks and a 2-D inundation model to simulate inundation flow on the ground. The 1-D overflow simulation model proposed in this paper is derived by improving an 1-D pipe network flow model, generally used for a surging analysis. The feature of the 1-D overflow simulation model is to consider local pressure differences occurring at the connection between a pit and pipes, which are neglected in a general 1-D pipe network flow model. Hydraulic physical model tests considering different water channels were conducted for the validation of the developed simulation model. The results obtained from the experiments and the developed simulation model show good agreements and therefore the model was validated. Since the developed model has advantages of requiring less computational efforts compared with a 3-D numerical simulation model, it is helpful for estimating the risks of tsunami overflow inundation and for contriving a suitable BCP. (author)