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日本林野厅计划从1981年开始,用4年时间,在群马县的利根川,岐阜县的木曾川,广岛县的太田川,福冈县的筑后川上游町村分别建立1000公顷‘人工林绿色水库’。初步计划投资12亿日元。根据林野厅的调查,有树木覆盖的青山,仅有25％的雨水形成地表迳流,其余全部渗入地下。而在无树木覆盖的秃山,仅有5％的降雨渗入地下,其余95％则蒸发或流失掉。另外在有树木覆盖的13
Japan’s Forestry, Forestry and Fisheries Department plans to establish 1000 hectares of plantation green reservoirs in 1981 respectively in Tone River in Gunma Prefecture, Kiso River in Gifu Prefecture, Ota River in Hiroshima Prefecture, and Chikugo River upstream area in Fukuoka Prefecture ’. Initial plan to invest 1.2 billion yen. According to the survey conducted by the Forestry Department, only 25% of the green hills covered by trees form the surface flow, and the rest all penetrate into the ground. In the bald mountain covered by trees, only 5% of the rainfall infiltrated the ground and the remaining 95% evaporated or lost. In addition there is tree cover 13