Survival Game: Lives and the Lingering Effects of Flood Threats from Rivers in Kanagawa Prefecture

Last fall, we live in Metropolitan Tokyo area were hit twice by Super Typhoons, Faxai and Hagibis. In Kanagawa Prefecture, several were killed by landslides and flood. Tama River, marking the border between Tokyo and Kanagawa, flooded to kill a person in Kawasaki. Very fortunately, though, the banks of large rivers flowing in Kanagawa Prefecture did not collapse. It kept the damage from the typhoons somehow lesser in our towns compared with the other places like in Chiba or Nagano. In any case, it was a terrible experience. (For the photos about the disaster by Hagibis in Kanagawa, you can find them here, the site by Kanagawa Shinbun Newspaper Co.) 

A scenery showing how close it was for Sakawa River.

One of my seniors of Kanagawa Forest Instructors lives in Hiratsuka City 平塚市 along Sagami River 相模川. The bank of the river has been for her relaxed strolling. Then on 12^th of October, the city issued an evacuation order to her neighborhood because of the torrential rain, and the warnings from 4 dams, Doshi Dam 道志ダム, Miyagase Dam 宮ケ瀬ダム, Sagami Dam 相模ダム, and Shiroyama Dam 城山ダム, for imminent release of water to Sagami River. “You see, our 50-inch TV was brand-new, and it was on the first floor. So my husband and I brought it first to the second floor. Then, my son came home. We all three frantically moved our furniture to the second floor. Gosh, how heavy our microwave was! Finally, only the refrige remained. We discussed if we can carry it to the second floor. It was impossible. We decided to let go the machine and the food if the flood comes …” Then, they got into the car with few items of their belongings and headed for the designated shelter that was a nearby elementary school. “We found the place was damned full. No room was left for our family. In any case, the school was also near the river so that we moved on to another school that was in higher elevation. It was full again. We drove around for some time to find a safer place, and ended up in a school not in a walking distance from our home, but on a hill safely away from the river.” Her family stayed in the gymnasium of that elementary for the night of October 12th. They were distributed 2 blankets per person to sleep on a hard wood floor. “You see? I don’t know why but I grabbed my yoga mat when we evacuated our home. It turned out to be a jackpot-move. At least I could lay on the floor more easily. It was hard to sleep at that night. Many kids started to cry, and lots of elderly people had hard time to get up to go to toilet …” Thank God. Sagami River held up even with the discharge from four dams.

A goal post for soccer turned into a jumble of scraps
 thanks to the inundation from Sagami River last fall.

One of my pals as Forest Instructor is an officer working for Kanagawa Water Supply Authority 神奈川県内広域水道企業団. They are in charge of Doshi Dam, Sagami Dam, Shiroyama Dam, Miho Dam and water intake weirs in Sagami and Sakai Rivers. On that night they were on an emergency night shift. “You see? We did not want to discharge water but the speed of rising water level was abnormal. In the end, the gate of Shiroyama Dam was opened 5 minutes before the final warning was issued by the Prefecture. It was a close call. Thank God, Sagami River did not overflow … That was a super night.” Well, even though, the water of rivers in Kanagawa, Sagami, Sakawa, Tsurumi, et al rose quite close to the limit. My instructor senior went to the river bank several days later. “You see? Only the top 10cm of tall reeds kept its green, and the rest was covered by mud. In addition, quite many of them were completely beaten down to the same direction. The power of flood water was horrible …”

Could you see in this photo at least
 the water reached to that level from Sagami River?

The phot was taken on the bank of Sagami River early January.
 The vegetation was recovering to green,
 but those flatten muddy reeds tell the power of water.

It could be indeed miraculous the only death by flood of rivers in Kanagawa Prefecture was on the border with Tokyo. I’ve heard several communities received substantial damage in their rice paddies and tangerine orchards in the west of the Prefecture. Water of the rivers kept muddy for more than a month after Hagibis. Humans are still struggling to recover from the weather incidents. Having said that, to some extent, it would be an evidence the Prefecture does well to control rivers in the territory. Yeah, on October 13^th, a Rugby World Cup match between Scotland and Japan was held in Nissan Stadium even though the flood basin of Tsurumi River inundated the sports park surrounding the Stadium. It was thanks to a very good civil engineering design for flood control. Still, the power of Tsurumi River from 12^th of October was shocking. It extirpated many forests that existed along the Tsurumi River before Hagibis.

Sakawa River in the middle of November 2019.
 The water was still raging.

This photo of Tsurumi River was taken last August
 before super typhoons came.

This is for the same place as above
 after the typhoons in November.
 Frankly, I was shocked.

Then, what happened for wildlife along the river? In January, the waters of rivers have finally returned non-muddy. But the effect is still lingering. I knew there was a large Japanese walnut tree on a bank of Tsurumi River that was a home for lots of pacific reef herons. Then, the flood uprooted the tree, and these days I cannot find black herons there … The birds have received the damage too. Still, the place near Sagami-Ozeki Weir 相模大堰 on Sagami River has welcomed many migratory water birds as usual this winter. In the area, we have found accumulation of poops by Japanese raccoon dog family, and feces of wild Japanese hare. A peregrine falcon perched high-up on the power transmission tower near railroad bridge for Odakyu Line. Aster kantoensis, which is an endangered species (CR+EN in Kanagawa) were survived … Whatever happens by super typhoons, they are resilient at least for now. Is there anything we can do to ride on this strange series of weather with them together in 2020?

102140: This is also the photo of last August
in the bank of Tsurumi River where
 pacific reef herons returned before sunset.

Immediately after the typhoons,
 the tree itself stood with herons.
 But could you figure out
 the back of their nest is in a mess with uprooted trees
 and garbage from the river?

The city cleared the space for further riparian maintenance.
 No tree in January 2020. No herons.
 But could you see a Eurasian coot in the middle?
 Life goes on after the storm …

Poops of Japanese raccoon dogs
 on the dusty bank of Sagmi River this month.

Humans are busy to restore the bank for Sagami River.

I was a sort of impressed with these
 as hare was so resilient to leave their dropping here
 on the riverbed after the flood.

Sagami-Ozeki Weir in early January 2020.
 It withstood with the flood water
 which left such muddy vegetation and sandbags around.

But goose came to the Weir as usual this winter.

A nice couple of Eurasian teal,
 regulars for winter at Sagami-Ozeki Weir.

Somewhere in this photo,
 there must be a peregrine falcon …

If you find environmental issues in Kanagawa Prefecture, please make a contact with Kanagawa Natural Environment Conservation Center 神奈川県自然環境保全センター

657 Nanasawa, Atsugi City, 243-0121

〒243－0121　厚木市七沢657
Phone: 046-248-0323

You can send an enquiry to them by clicking the bottom line of their homepage at http://www.pref.kanagawa.jp/div/1644/