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No.27 (1980/11) >

 
Title :降雨インテーク・レートの 2・3 の特性について (2) : 降雨による緊密層形成に伴う浸透速度の低下について(農業工学科)
Title alternative :Some characterristics of intake rate of rainfall (2) : On the process of decrease of percolation ratio in the soil, due to crust made on the soil-sureface by raifall (Department of Agricultural Engineering)
Authors :吉永, 安俊
山城, 三郎
Authors alternative :Yoshinaga, Anshun
Yamashiro, Saburo
Issue Date :29-Nov-1980
Abstract :人工降雨を用いて, 土壌の浸透速度の減少過程を降雨開始から経時的に調べた。1.降雨の経過時間に伴う浸透速度の減少過程は図-7で示される逆S字状をなし, タン水深が約10mmに達するまで減少を示し, タン水深が約10mmのとき浸透速度は最小値に達する。その後若干回復するがほぼ平衡状態を保つ。2.浸透速度の減少過程は降雨強度によって異なり, 降雨強度が大きい程, 減少量は小さい。3.それぞれの降雨強度における最小浸透速度の値を降雨未経験試料の値に対する割合で示すと, 117mm/hrで1/4,74mm/hrで1/10,32mm/hrで1/14となる。従って降雨強度の小さな雨をタン水深が約10mmに達するまで経験させると, 浸透速度はかなりの割合で低下するものと考える。
Making use of a rain simulator, an observation was made on the process of decrease in the percolation ratio of the soil. 1. The process of decrease in percolation ratio versus the lapse of time of rainfall forms a reversed S curve as shown in Fig. 7. It shows a decrease of percolation ratio until the depth of flood reaches around 10mm, and the percolation ratio shows it's minimum value at the depth of 10mm. From then on it regains a little, but holds a state close to the equilibrium. 2. The process of decrease of the percolation ratio differs with the intensity of rainfall; the stronger the intensity, the less the decrease. 3. The proportion of minimum percolation ratio at each rainfall intensity to the percolation of the meterial with none rainfall experience, are 1/4 at 117mm/hr, 1/10 at 74mm/hr and 1/14 at 32mm/hr. Therefore, it is infered that if rainfall of a small intensity is experienced until the depth of flood reaches approximately 10mm, the ratio of percolation should decrease remarkably.
Type Local :紀要論文
ISSN :0370-4246
Publisher :琉球大学農学部
URI :http://hdl.handle.net/20.500.12000/4102
Citation :琉球大学農学部学術報告 = The Science Bulletin of the Faculty of Agriculture. University of the Ryukyus no.27 p.223 -229
Appears in Collections:No.27 (1980/11)

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