Hiroaki Shimada

Assessment of Safety on Evacuating Route During Underground Flooding

Heavy rainfalls over 50 mm/hr have been observed frequently in the last decade in Japan. If a sewage system in urban area could not drain such rains, flood water would be flooding and flowing into underground spaces such as subway or basement of building. As the area of underground space is limited, flood water fills up the area in a short time. It is very dangerous situation and people should evacuate from there as soon as possible in order to save their life. To draw up an evacuation plan, it is important to assess the safety of evacuating route. In this paper, the method of safety assessment on the evacuating route is discussed on the basis of experimental results and flood simulation data in an underground space. In order to assess the safety on an evacuating route, the value of the specific force per unit width, M=0.125m2, is used in this study, of which value has been obtained in the previous work. Using the relation between M values and evacuating speed, the assessment of safety on evacuating routes during underground flooding has been carried out well and the data for preparing an evacuation plan have been shown. The data are very useful for the people to evacuate from when and through which route.

NUMERICAL STUDY OF STORM SURGES IN THE SETO INLAND SEA BY MULTI PHYSICS MODEL

This study proposes a multi physics model which consists of atmosphere, tide, surge and wave physics. It was applied to storm surge prediction in the Seto Inland Sea with complex topography and large tidal fluctuation. The storm surges generated by Typhoon Chaba and Songda were hind casted well by the numerical model of SuWAT using the mesoscale weather model output under fluctuating tide condition since the pressure and wind field is well estimated by the weather model. The hind casted water level variation by an empirical typhoon model under high water sea level is underestimated in comparison with the measurements.

Estimation of Acceptable Tsunami Magnitude Determined from Sheltering Capacities

の発生を受けて,南海トラフの地震についても想定の見 直しが行われている(中央防災会議, 2012).このよう に,今世紀前半に起こる確率が高いと推定されている南 海トラフの巨大地震に対し,早急に備える必要がある. 東北地方太平洋沖地震のように,従来想定を超える巨 大津波によって沿岸部の避難所が浸水すると,被災後の 利用が困難になり,想定していた対応ができず,そこに 避難するはずであった住民は他の避難所に避難しなくて はならなくなる.被災する避難所が少なければ,他の避 難所への振り分け等の市町村レベルでの災害対応は容易 であるが,広範囲に多くの避難所や収容人数の多い避難 所が被災してしまうと,避難者収容可能人数が著しく喪 失され,他の避難所への振り分けは困難になり,県レベ ルの災害対応への転換が必要となる可能性が出てくる. 本研究では,特に長期間避難生活をする場としての2次 避難所に着目し,災害対応の転換が必要となる津波規模 を,避難所生活者の収容可能人数の喪失割合という観点 から推定する.具体的には,南海トラフに対する2003年 想定の震源域で規模を変えたモデルおよび2012年想定の 南海トラフの巨大地震モデルを用いて,和歌山県を対象 に津波シミュレーションを実施し,避難所の喪失数およ び喪失収容可能人数を調べる.津波高と喪失収容人数を 比較し,その変化度合いが急変する津波高を,自治体の 災害対応転換が生じる限界津波高として推定する.

EVALUATION METHOD OF FISHERY ENVIRONMENT WITH WATER QUALITY AND SESSILE ORGANISM IN INTERTIDAL ZONE

To preserve the fishery resources, some maintenance works have been done in Japan. However, it is not easy to assess the effect of these projects because of increasing research cost on the relation between fisheries and environment. In this paper, a simple method of environmental assessment, has been proposed by using Habitat Evaluation Procedure Method (HEP). A model of HSI(Habitat Suitable Index) with two indexes is used to estimate the quality of biotope in an intertidal zone. These two indexes are water quality and number of attached organism there. From the results, it is found that HSI value is closely related to fish catches based on statistical data. This means that the method is available for assessing the effect of environmental change on the resources of fisheries in the intertidal zone.

Characteristics of Wave Overtopping on Vertical Type Seawall Covered with Wave-dissipating Blocks

In recent years, seawalls coated with wave-dissipating blocks heve been set in front of upright seawalls. However, wave overtopping on this type of seawall is not fully investigated. Therefore, in this paper, characteristics of wave overtopping on upright seawall covered with wave-dissipating blocks was examined experimentally. From the results, it is found that this type of seawall is effective to reduce the wave overtopping rate. The crest height of the seawall is less than the height in upright seawall case to get the same wave overtopping rate. In addition, an easy method to estimate the runup height on the seawall has been suggested.

CONSTRUCTION TECHNIQUE OF MAN-MADE TIDE POOL WITH THE BEST HABITABLE CONDITIONS FOR MARINE ORGANISMS

The purpose of this study is to establish the construction technique of man-made tide pool with the best habitable conditions for marine organisms. From this view point, field observations on marine organisms were carried out in eight man-made tide pools at Tannowa-Hakotsukuri man-made rocky coast.As a result, the number of species of marine organisms increases with decrease of the distance from shoreline to tide pool, and increase of the rate of seawater flow due to wave and current. The diversity index on marine organisms depends on the size of gravel filled in the man-made tide pool.

FIELD OBSERVATIONS ON MARINE ORGANISMS AND SEDIMENTS IN GRAVEL BEACH

The purpose of this study is to disclose the relationship between marine organisms and sediments in gravel beach. From this viewpoint, the field observations on marine organisms are carried out in a man-made gravel beach and natural one. It is found that the diversity index of marine organisms in gravel beach depends on the time of exposure from sea water and the volume of gravel. For this reason, the the diversity index on marine organism in natural gravel beach is larger than those in man-made one and natural rocky coast.

Wave Overtopping over a Gentle Slope and Roughened Seawall

The purpose of this study is to improve the effect of gentle slope-type seawall on prevention of wave overtopping. With this in view, the experiments on irregular wave overtopping are carried out for a gentle slope and roughened seawall. In these experiments, artificial wave furrows are used as a roughness. Consequently, the effective arrangement and shape of artificial wave furrows are clarified to prevent wave overtopping. In addition, the Weibull distribution can be applied to approximately the frequency distribution of wave overtopping rate over a gentle slope and roughened seawall.