Disturbance: Typhoon Hagibis for Yadoriki Water Source Forest

Yadoriki Water Source Forest やどりき水源林 also had substantial disturbance by Typhoon Hagibis. At this moment, the Forest is off limit for visitors, and the gate for the forestry roads to Yadoriki Forest is locked. As of November 1st, after Hagibis, the area had two more long torrential rains, and numerous mini squalls. Yadoriki Forest’s recovery from the Hagibis is unpredictable at best.  We Kanagawa Forest Instructors have not received information from the Prefectural Office when the gate is open ... This week, I report you scars I’ve found in Yadoriki two weeks after the visit of Hagibis. I hope you could have some idea about the situation.

The way Nakatsugawa River 中津川 / Yadoriki Stream 寄沢 flows has changed. Above photo was taken at the point before Hadano Forestry Road begins. The river goes around nearer to the banks so that many points have collapsed by strong rains from Hagibis and others. (Oh, yes, Nakatsugawa River and Yadoriki Stream are the same flow. It changes name at Yadoriki Bridge 寄大橋.)

Mini landslides are here and there along the community road from Yadoriki community 寄 to the gate of Yadoriki Water Source Forest. It would take a couple or so of dry months before the soil stabilizes. As we have to think the effect of frost and frozen ground during winter in this part of our prefecture, it may be difficult to expect the situation improves quicker. If you plan to drive to red Yadoriki Bridge, please be very careful.

Red Yadoriki Bridge over there.
 Could you see a large log was caught by the weir?

Inside the gate for Yadoriki Water Source Forest, the road condition is worse. Its forestry road which was passable for a city car before is now for off-road types only.

It seems to me
 animals are taking the advantage of
 human-less environment in Yadoriki now.

Yadoriki stream inside the Yadoriki Water Source Forest has changed its shape drastically after the rains. It destroyed trekking roads along the stream from the gate and eroded the open space. It seems to me substantial amount of large rocks and logs were carried by the flood to the downstream.

Destruction

It’s a matter of time before these picnic benches are gone.

Forestry road in the Water Source Forest collapsed in the middle. So, beyond this point it is strictly closed for the unauthorized visitors. The soil was washed away below the asphalt.

Here and there, Yodoriki’s utility forestry roads are covered by landslides like this. Though, these points could be cleared soon as the season of logging is approaching.

And cones of conifers promptly utilize the chance
of sunshine for sprouting thanks to the land collapses.
 Mini-forest. Cute.
 (And they will be gone quickly by the next slide …)

It seems to me Hadano Forestry Road 秦野林道 also has large disturbances due to these rains by typhoons and others. The streams along the road certainly experienced large flows and landslides. This is Teshiro Stream 手代沢. Before we could not see the waterfall from the forestry road. Now both sides of the valley collapsed and trees that concealed the vista were broken or washed away. Yeah, the view from Teshiro Bridge 手代橋 is nicer now, but can the bridge last when the next big storm comes?

Map of Hadano Forestry Road

Above is a stream that is filled with soil avalanches. This is a naturally made dam creating a pond whose surface was just few inches below the paved forestry road. I will not be surprised if Hadano Forestry Road collapses here when the next large rain comes.

Majority of Yadoriki Forest is owned by the Prefectural Government so that how to deal with the situation is, in the end, totally up to the budgetary condition of Kanagawa Prefecture 神奈川県. Geologically Tanzawa mountains are very fragile. (More to this soon.) Scars in the forest by 2019 storms can easily expand. They may turn into debris-avalanche that would swallow human settlements downstream … I don’t know. I’ve heard all the people in Yadoriki Community inherited a warning from their ancestors, saying “When the water of Nakatsugawa River turns white, run!” Fingers crossed.

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/