A SIMULATION OF DRAINAGE OF INFLUENT WATER CAUSED BY TSUNAMI AT TOKUSHIMA

本論文では徳島市沖洲地区を対象として，南海地震による津波の堤内地への流入，その後の排水過程をシミュレーションした．堤外の計算は浅水理論によって行い，堤内の計算は地表面，排水路，下水路の三つのレイヤーに分けて，それぞれのレイヤー間で水のやり取りを行いつつ，水の流れを計算する．最終的に，排水ポンプによって堤外へ排出される．安政南海地震を対象として，排水ポンプすべてが健全とした計算では，津波で流入した海水の大部分の排水に約16時間を要した．排水ポンプのうち排水機能が高い上位３つを停止させると，流入した水の大部分の排水完了まで約72時間かった．また，内閣府想定のケース３を対象とした場合，地殻変動による沈降が大きいため，一部境界より朔望平均満潮位のほうが高くなり，津波襲来後もそこから海水が流入し続けた．This paper simulates drainage of infuluent water caused by tsunami of the Nankai earthquakes. The target area is Okinosu, Tokushima. To simulate inlands water flow, we attempted 3 layers model, which is composed of ground, channel, and sewer. These 3 layers exchange water each other. Finally, water is drain to foreland by drainage pumps. In a simulation using the Ansei Nankai earthquake source model as input, if all drainage pumps works, the drainage finish about 16 hours after the earthquake. But, some water is not drained because of sunken place. If pumps that are top 3 of the drainage capacity don't work, the drainage finish about 72 hours after the earthquake. In this case, water which is not drained is increased. In a simulation using case 3 of Cabinet Office earthquake source models as input, because of big displacement in this area, certain boundary area becomes lower than sea level. So, water comes inland always