5:15 PM - 7:15 PM
[MIS24-P08] The relationship between inundation characteristics and topography in northeastern Saitama Prefecture since Edo period, as reconstructed from historical records.
The northeastern region of Saitama Prefecture (Kita-Saitama and Saikatsu regions) is in a sedimentation zone caused by the Kanto tectonic movement and has suffered so much damage from external flooding that the river had to be repaired many times until the Edo and Meiji periods. However, there has been no external flooding damage from the Tone River since the water disaster caused by Typhoon Kathleen in 1947. In recent years, the number of annual short duration heavy rainfall events (50 mm/h or more) and the number of rivers exceeding the flood level are increasing due to ongoing climate change. Therefore, there is concern about the intensification and frequency of flooding. Clarification of past flood damage would be an effective soft measure to reduce flood damage in the future. Therefore, the purpose of this study was to convert the information on the 1846 and 1890 floods that damaged the Kita-Saitama-Saikatsu region due to a break in the Tone River into geospatial information, examine the relationship between the flooding situations and topography, and identify flooding characteristics in the Kita-Saitama-Saikatsu region.
The research method was to visit local museums to collect historical records related to flooding in the Saikatsu and Kita-Saitama regions of Saitama Prefecture. Then, place names and time information were extracted from the flood damage information obtained from the historical records, and geospatial information was summarized on the behavior of flooding flows and damage over time. In addition, data on the number and height of Mizuka (flood shelter) were processed and summarized into geospatial information. This information was overlaid with topographic information to examine the relationship between the topography and the behavior of flooded flows and the damage situation.
The behavior of flood flows in the 1846 and 1890 floods was estimated based on information from historical records. The main levee break points for the 1846 and 1890 floods were found to be on the attack slope side of the Tone River bend and the left bank of the Arakawa River, and the flood waters from both rivers flowed along the old channels toward Tokyo Bay. It was also found that rising water exceeding the drainage capacity causes the old river channels, such as the Shimakawa River and the Shonai Furukawa River, to back up and break the levees. The flood flow that broke through the cutoff of the Shonai Furukawa River in 1846 was found to have flowed northward against the elevation, which suggests that it flowed along lowlands such as the old channel of the Shonai Furukawa River and several swamp ruins.
The eastern part of Ainokawa River, the former river of the Tone River, where natural levees and riverine dunes developed, was not damaged by the flood of 1890, and there was no damage to the eastern part of the riverine dunes on the left bank of the Furu-Tone River in 1846 and 1890. Therefore, it is considered that natural levees and riverine dunes are effective in blocking the flood flows. In the old map showing the flooded area in 1846, there were also traces of the flood flow from the Shonai Furukawa River cutoff section that had stopped along the natural levee.
The number of Mizuka per large section showed that they are found in large numbers in certain areas. In Hanyu City and the southwestern part of Kuki City, Mizuka were built on the plateau, and the small relative height difference between the plateau and the flood plain due to subsidence caused by the Kanto tectonic movement suggests that the plateau could have been damaged by the flooding flows. In addition, the southwestern part of Kuki City is in the northern part of the Omiya Plateau through which the Moto-Arakawa River flows and is considered an area where flood flows tend to accumulate due to the narrowing of the plateau.
This work was supported by GLEC.
The research method was to visit local museums to collect historical records related to flooding in the Saikatsu and Kita-Saitama regions of Saitama Prefecture. Then, place names and time information were extracted from the flood damage information obtained from the historical records, and geospatial information was summarized on the behavior of flooding flows and damage over time. In addition, data on the number and height of Mizuka (flood shelter) were processed and summarized into geospatial information. This information was overlaid with topographic information to examine the relationship between the topography and the behavior of flooded flows and the damage situation.
The behavior of flood flows in the 1846 and 1890 floods was estimated based on information from historical records. The main levee break points for the 1846 and 1890 floods were found to be on the attack slope side of the Tone River bend and the left bank of the Arakawa River, and the flood waters from both rivers flowed along the old channels toward Tokyo Bay. It was also found that rising water exceeding the drainage capacity causes the old river channels, such as the Shimakawa River and the Shonai Furukawa River, to back up and break the levees. The flood flow that broke through the cutoff of the Shonai Furukawa River in 1846 was found to have flowed northward against the elevation, which suggests that it flowed along lowlands such as the old channel of the Shonai Furukawa River and several swamp ruins.
The eastern part of Ainokawa River, the former river of the Tone River, where natural levees and riverine dunes developed, was not damaged by the flood of 1890, and there was no damage to the eastern part of the riverine dunes on the left bank of the Furu-Tone River in 1846 and 1890. Therefore, it is considered that natural levees and riverine dunes are effective in blocking the flood flows. In the old map showing the flooded area in 1846, there were also traces of the flood flow from the Shonai Furukawa River cutoff section that had stopped along the natural levee.
The number of Mizuka per large section showed that they are found in large numbers in certain areas. In Hanyu City and the southwestern part of Kuki City, Mizuka were built on the plateau, and the small relative height difference between the plateau and the flood plain due to subsidence caused by the Kanto tectonic movement suggests that the plateau could have been damaged by the flooding flows. In addition, the southwestern part of Kuki City is in the northern part of the Omiya Plateau through which the Moto-Arakawa River flows and is considered an area where flood flows tend to accumulate due to the narrowing of the plateau.
This work was supported by GLEC.