環境

The area for the survey was in the middle of the right bank of Tamagawa(Tama-river). Tamagawa is fed by a few tributaries such as Yajikawa, Asakawa, Oukurikawa, Misawakawa. The headstream of Asakawa consists of Kawaguchikawa, Kitaasakawa, Minamiasakawa, Yudonokawa. As the area was only one hour train ride away from downtown Tokyo, it had rapidly developed since 1970s and the water words had been laid. However, the water quality there was bad. As the sewage system was not yet ready.

Thereafter the water quality improved gradually but not in some areas, which ware still without sewage, and had domestic wastewater released in to the river.

The checks on water quality ware performed twice in summer and winter at 107 locations. The soil at the mountains consist mainly at Mesozoic Kobotoke-group and Early Quaternaly Kazusa-group as the zone is located in the area from the east Kantou Mountains to the west Kantou Plain.

The floor of the hill has a few layers of the diluvial upland, the alluvial plane exists between hilly terrain and the diluvial upland.

In this report, I drew up the Geological map, Geomorphological map and Drain-ago map in the survey area by 1:25,000(scale).And reported each stream catchment area, relative relief and stream profile. Water-quality were surveyed in August 2019 and January 2020.

After this time, I wish this report will utilized on Environmental Protection or diminution of Natural disaster.

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