Kanagawa Prefecture normally does not have draught during summer. Our water supply from Sagami River System 相模川水系 and Sakawa River System 酒匂川水系 has quite adequate reservefor our use. In contrast, Tokyo often has July-August headlines like “Because of water shortage, Tokyo Metropolitan Government has started water intake restriction.” Granted, they have much larger population than Kanagawa. But, unlike Kanagawa where 100% of our water has its source within our prefecture, Tokyo relies heavily on water coming from the other prefectures. They can collect only 20% of water of their use within its border, i.e. from Tama River System 多摩川水系. The remaining 80% comes from Tone River 利根川水系, via long aqueducts coming from the north of Kanto Region 関東地方. For one thing, it would be because the land, Musashino Plateau 武蔵野台地, is flatter in Tokyo than in mountainous Kanagawa so that having large dams near the population center is not plausible. Another, Tokyo’s water problem may be due to a mischief of history which produced the largest Yokohama’s (Citizen) Forest in the late 19th century … I’ll return to it in my later posts. Anyway! I’ve found a chronological table in the museum of Samukawa Water Intake Facility 神奈川県水道記念館 reporting in 1926 Tokyo began to ask Kanagawa and tried several times since to accommodate them with water. So far, none successful. Oh, yeah, we are very prudent, or stingy; take your side, please.
 |
| Here. A chronological Table at the museum. |
Then, one day, I’ve heard a story from my seniors of the Lovers of Niiharu Citizen Forest 新治市民の森愛護会. Dr. Toshiko Kitagawa 北川淑子 of Yokohama Botanical Association 横浜植物会 lamented a possible decline in the Niiharu’s forest of ferns. “Well, the city cut the trees stood on the ridgeway separating the residential area and the forest, which has made easy for dry winds coming into the forest. It’s not at all good for ferns!” The seniors of Niiharu Lovers had a different theory. “Hey, do you remember Mr. H tried to create a biotope in the lower valley just next to the forest of ferns?” “Yeah, but he could not manage it. He expected water would seep into his pond, but it did not occur.” “Then, we noticed small natural ponds that were there at the end of the fern forest started to dry up.” “Yes, yes. That was a way before the City thinned the trees surrounding the forest of ferns.” “I suspect the 1980s’ housing development of Kirigaoka 霧が丘 in the other side of the ridge caused the fundamental problem.” “Meaning?” “They replaced a forest with the row of houses that made the ability of water retention diminished for the entire mountain.” “Ah-ha.” “So the level of underground water beneath the forest of ferns went down. It made the ponds at the end of the forest dry, and the newly created biotope of Mr. H could not collect water.” “Yeah, thinning by the City would not have much impact for the flow of winds … the houses are acting almost as the thinned trees for that matter, aren’t they?” So, you’d ask “So What? How does this theory connect with the relationship between Tokyo and Kanagawa?” That’s the thing I noticed recently when I’ve visited Mt. Takao 高尾山. This week and the next are about my adventure in the hiking road from Mt. Takao to Lake Sagami 相模湖.
 |
| Can this forest of ferns in Niiharu survive in the future? |
Both Mt. Takao 高尾山 and Lake Sagami 相模湖 are well-known weekend destinations, within one-hour train ride from JR Tokyo Station 東京駅. Overlooking Lake Sagami, there is an amusement park, Pleasure Forest プレジャー・フォレスト, where we can enjoy German-style forest athletic facilities and winter-illumination for roller coaster, et al. The area has lots of camping sites, boating facilities, and fishing spots. The surrounding mountains, though less than ASL 1000m, are popular as a day-hike destination from Tokyo. One of these mountains is Mt. Takao that is the smallest Quasi-national Park in Japan, called Meiji Forest Takao Quasi-national Park 明治の森高尾国定公園. The place was awarded 3 stars by Michelin Green Guide thanks to a very-Japanese tourist trash controlling system and well-constructed hiking roads. Well, the area now is as such, but before the place was a thriving agricultural community along Koshu Highway 甲州街道 (the current National Route 20) connecting Nihonbashi 日本橋 (the place now Bank of Japan stands) and Lake Suwa 諏訪湖 in Nagano Prefecture 長野県. During the 1930s when Japan took expansionary policy for everything like a frog of Aesop’s Fables, the needs for more water and electricity grew rapidly to sustain heavy industries for armament and labors arriving for the factories in Yokohama-Kawasaki 京浜工業地帯. In 1938, the Prefectural Council of Kanagawa decided to secure large water reservoir along Sagami River 相模川 near the border with Yamanashi Prefecture 山梨県. They started the construction of a multi-purpose dam in 1940. Amazingly, despite of devastating continuation of World War II, people continued their work, and Sagami Dam 相模ダム was completed in 1947. Lake Sagami was the first man-made water reservoir in Japan, awarded a name “Lake.” Those communities along the Sagami River were massively relocated to higher grounds especially along Koshu Highway, which are now the tourism towns surrounding the Lake. After these 70 years, Sagami Dam is still a working multipurpose dam providing electricity to the neighborhood and sending water to all over Kanagawa Prefecture, including Yokohama.
 |
| Sagami dam with a working power plant |
 |
| Lake Sagami |
 |
| Along
the lake shore, there are lots of monuments commemorating the flooded village structures. This boulder was once situated on a riverside and worshipped as a holy spot. People saved it from the submersion. |
Hmmmmm, so, Lake Sagami is collecting water from the surrounding mountains. It could be a contentious issue whether Mt. Takao, whose address is “Takao-cho, Hachioji City, Tokyo, 193-8686,” plays any part as a water source forest for Kanagawa. Between the border with Kanagawa and the peak of Mt. Takao, there are three water-running valleys, which means Mt. Takao is obviously not a watershed for Kanagawa Prefecture. Even though, Mt. Takao has recorded 1300 species of vegetation in 7.7 km2 (FYI, the entire UK has max 1600 kinds of plants), sitting on a famously affluent underground water system. If it’s gone for, say, housing development like the north-slope for Niiharu’s forest of ferns, could we in Yokohama still enjoy abundant water supply from Lake Sagami? For these 10 years, the construction of Takao-san Tunnel 高尾山トンネル for Kenoh-do Highway 圏央道 and Michelin Awards accelerated development of both underground and surface of Mt. Takao. Some civil society organizations, such as Japan Civil Network for the UN Decades on Biodiversity 国連生物多様性の10年市民ネットワーク, sound alarm for possible deterioration of the area as the water source. If Niiharu can be any guide, we may have to wait for at least 30 years before the results of these construction activities appear in Mt. Takao or to Lake Sagami ... One thing was certain for me: when I’ve visited Mt. Takao and came down to Lake Sagami recently, the continuation of nature did not matter if the water stored by the forests would pour, or not, in Lake Sagami. While the torrents we overlooked from the trekking roads in my itinerary were always amazingly transparent, local Tokyonites are noticing some of these water spots are getting thinner, or disappearing altogether … What could happen for the plants in the forests in the future, then? Let me tell you next week my actual adventure in the border line water source forests from Mt. Takao to Lake Sagami.
 |
| The stream near Myo-on Bashi Bridge 妙音橋 on the eastern slope of Mt. Takao |
The
contact address for the office in charge of Meiji Forest Takao Quasi-national
Park 明治の森高尾国定公園 is
Bureau
of Environment, Tokyo Metropolitan Government 東京都環境局
2-8-1
Nishi-Shinjuku, Shinjuku-ku, Tokyo, 163-8001
Phone: 03-5388-3539, FAX: 03-5388-1379
S0000618@section.metro.tokyo.jp
The
contact address for the office in charge of Sagami Dam is
Enterprise
Bureau, Kanagawa Prefectural Government 神奈川県企業局
1045
Nihon-Odori, Naka-ku, Yokohama 231-8588
Phone: 210-1111
https://shinsei.e-kanagawa.lg.jp/kanagawa/uketsuke/dform.do?acs=SF3204
No comments:
Post a Comment