JPSS SDOC JPSS PGRR - Satellite-based Disaster Outreach Coordinator (SDOC)

As expected, there was some flooding from Hagibis. There were three main regions that had flooding according to media reports (ABC News, Reuters). These were the area around Nagano, the area around Tōkyō (東京), and in the Fukushima Prefecture (福島県) and Miyagi Prefecture (宮城県). This flooding was observed by both Synthetic-aperture radar (SAR) imagery from Sentinel-1B during the storm (Sentinel-1A was used as pre-storm reference), collected by NOAA’s Satellite Oceanography and Climatology Division, specifically the Sea Surface Roughness Group at NOAA/STAR, as well as the  the VIIRS and AHI Flood Products.

The overall flood situation could be seen in the Joint VIIRS/AHI Flood Product, produced by George Mason University, seen here from 13 October 2019, which was the first day there were clear skies over Japan

As can be seen, there were clear skies in the Tōkyō (東京) and the Fukushima Prefecture (福島県), Miyagi Prefecture (宮城県) regions. As it turns out these were also the two regions that Sentinel-1B observed on 12 September, just as the storm was passing.

We will discuss each region separately. Note that for simplisity, this discussion will use UTC time

The primary areas in Tōkyō (東京) that were affected were the areas around Kawagoe-shi (川越市), parts of the Tama River (多摩川), Tone River (利根川). Sentinel-1A passed over the region at ~2043UTC on 6 October 2019 (~5:43am on 7 October 2019 JST), providing an excellent “pre-storm” shot for the ~2043UTC on 12 October 2019. Recall that the VIIRS pass from the previous post was at 1617 UTC on 12 October 2019, so this is only a few hours after Hagibis had departed Japan.

Sentinel-1A/B acquired by ESA/Copernicus, provided by Christopher Jackson, NOAA/STAR/SOCD
Contains modified Copernicus Sentinel data 2019

As can be seen, the major rivers are extremely swollen from the rains that Hagibis dumped into the surrounding mountains. This lead to many areas that are right near the rivers to be saturated or flooded

Sentinel-1A/B acquired by ESA/Copernicus, provided by Christopher Jackson, NOAA/STAR/SOCD
Contains modified Copernicus Sentinel data 2019

These areas continued to be saturated through the day time hours and could be seen by the VIIRS, AHI and Joint VIIRS-AHI flood products, shown below (left to right).

Of particular note is the area near Kawagoe-shi (川越市) near the Arakawa River (荒川). The VIIRS product seems to show large amounts of flooding. This appears to be confirmed by the Sentinel-1B from 12 October 2019, which showed that the Arakawa River (荒川) was swollen significantly from 6 October.

An investigation of imagery from GoogleEarth indicates that most of the potentially flooded or saturated land was farmland that surrounding the region.

Fukushima Prefecture (福島県) and Miyagi Prefecture (宮城県)

The other area that had notable flooding was the area in the Fukushima (福島県) and Miyagi (宮城県) Prefectures. Like the areas around Tōkyō (東京), these areas continued to be saturated through the day time hours and could be seen by the VIIRS, AHI and Joint VIIRS-AHI flood products, shown below (left to right).

Of more are the areas north of Ishinomaki-shi (石巻市), inland towards Ōsaki-shi (大崎市) as well as further south along the coast near Sendai-shi (仙台市). An investigation using the Sentinel-1B from 12 October 2019 showed significant areas of saturated land as well as likely flooding.

One could easily see the flooding of the areas around the Yoshida and Naruse rivers, something confirmed by media reports. In addition, the area just to the north of Ishinomaki-shi (石巻市) also showed possible flooding or saturated ground. It is worth noting that most of the staurated areas appear to be agricultural, primarily the cultivation of rice. Thus it is likely the areas that were affected were mainly rice paddies.

All of these products were provided in response to the International Disasters Charter call to aid in the response to Habigis.