11:45 AM - 12:00 PM
[AHW28-11] Hydrological processes and disaster mitigation measures related to natural disasters in Japan
★Invited Papers
Keywords:hydrological processes, disaster mitigation, disaster prevention, natural disaster
Japan is located in the Asian monsoon region, so there are large seasonal variations in rainfall. In addition, Japan is an island arc formed by the subduction of the Pacific Plate and the Philippine Sea Plate, and a volcanic front has formed in the central part of the islands. Therefore, the distance from the recharge area at the mountainside to the discharge area at the seaside is short, so the flow velocity of rivers and groundwater is faster than in continental areas. In addition, while the sedimentary layers are thin in the steep mountainous areas, unconsolidated sediments are thickly deposited in the coastal plains, and there are also multiple aquifers within these sediments, which is another characteristic of Japan's hydrogeological features.
In recent years, Japan has experienced a large number of natural disasters, including earthquakes and tsunamis, in addition to large-scale slope disasters and flood damage caused by snow and mudflows due to short-term high rainfall associated with climate change and typhoons. In particular, disaster prevention measures have long been taken in Japan to protect against flooding, and in the Edo period, a large-scale project was undertaken to divert the course of the Tone River, which flows through the Kanto Plain, to the east in order to protect the city of Edo from flood damage.
In 1959, a large-scale flood caused by Typhoon Vera, also called Isewan-Typhoon, hit the coastal areas of the Nobi Plain, which is located in the center of Japan, and approximately 5,000 people died. This huge disaster led to the enactment of the Basic Act on Disaster Management in Japan, and various measures against disaster prevention were considered by the national and local governments. On the other hand, since it is impossible to control natural phenomena such as heavy rain and earthquakes that cause huge disasters, in recent years, the concept of “disaster mitigation” has become mainstream, which aims to reduce damage by understanding the occurrence process and taking measures based on this understanding. While there are disasters that cause damage in a short period of time, such as landslide caused by heavy rain, and debris flows caused by snow melting, there are also disasters that cause damage over a long period of time, such as the salination of groundwater due to tsunamis and the groundwater pollution due to the leaching of heavy metals from tsunami deposits.
Understanding the hydrological process is very important on considering disaster mitigation measures against various natural disasters.
Invited lectures from five science societies related to water cycle, will be presented in this session. In this presentation, I will introduce some examples of disasters related to hydrological processes in Japan and the disaster mitigation measures against them.
In recent years, Japan has experienced a large number of natural disasters, including earthquakes and tsunamis, in addition to large-scale slope disasters and flood damage caused by snow and mudflows due to short-term high rainfall associated with climate change and typhoons. In particular, disaster prevention measures have long been taken in Japan to protect against flooding, and in the Edo period, a large-scale project was undertaken to divert the course of the Tone River, which flows through the Kanto Plain, to the east in order to protect the city of Edo from flood damage.
In 1959, a large-scale flood caused by Typhoon Vera, also called Isewan-Typhoon, hit the coastal areas of the Nobi Plain, which is located in the center of Japan, and approximately 5,000 people died. This huge disaster led to the enactment of the Basic Act on Disaster Management in Japan, and various measures against disaster prevention were considered by the national and local governments. On the other hand, since it is impossible to control natural phenomena such as heavy rain and earthquakes that cause huge disasters, in recent years, the concept of “disaster mitigation” has become mainstream, which aims to reduce damage by understanding the occurrence process and taking measures based on this understanding. While there are disasters that cause damage in a short period of time, such as landslide caused by heavy rain, and debris flows caused by snow melting, there are also disasters that cause damage over a long period of time, such as the salination of groundwater due to tsunamis and the groundwater pollution due to the leaching of heavy metals from tsunami deposits.
Understanding the hydrological process is very important on considering disaster mitigation measures against various natural disasters.
Invited lectures from five science societies related to water cycle, will be presented in this session. In this presentation, I will introduce some examples of disasters related to hydrological processes in Japan and the disaster mitigation measures against them.