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No.28 (1981/11) >

Title :畑地帯小流域における流出解析について(農業工学科)
Title alternative :On the runoff analysis in small dry field basins (Department of Agricultural Eegineering)
Authors :吉永, 安俊
翁長, 謙良
Authors alternative :Yoshinaga, Anshun
Onaga, Kenryo
Issue Date :30-Nov-1981
Abstract :本研究は, 畑地帯の小流域2ケ所を対象に流出解析を行ったものである。対象流域は, 国頭マージ地帯の金武町屋嘉のパイナップル畑(約4000m^2)とジャーガル地帯の本学附属農場のサトウキビ畑(約10,000m^2)である。以下解析結果を述べる。1.1雨降雨の継続時間 屋嘉流域においては, ハイドログラフの流量減衰状態から判断して, 1時間半から2時間程度の降雨中断があると別降雨とみなせる。千原流域においては, 流域面積のちがいや, うね間タン水の存在があるため, 2&acd;3時間程度の降雨中断があると別降雨とみなせる。2.流出率 降雨量と流出率は図-8(屋嘉)と図-9(千原)に示される関係にあり, それぞれ次式で示される。f=1.0-1.347/R^<0.390> (屋嘉) f=1.0-3.162/R^<0.593> (千原) 3.有効雨量 屋嘉流域における総降雨量と有効雨量は図-9に示される関係になる。両者の関係は次式で示される。r_e=R-1.347R^<0.610> 4.損失雨量 屋嘉流域における降雨量と損失雨量は図-11に示される関係になり, 次式で表わされる。r_l=1.347R^<0.610> 5.ピーク流量 屋嘉流域におけるピーク流量は, 10分間降雨量に最も影響を受ける。したがって, 10分間降雨量の最大の所にピーク流量が現われる。10分間降雨量からピーク流量は次式で求められる。Q_p=0.979R_<10>
The purpose of this study is to investigate the properties of runoff on an unit field. Two experimental fields have been selected for a runoff research. One is located at Yaka, Kincho which excel Kunigami Maaji soil and the other is located at Senbaru, Nishihara-cho which excel Jaagaru soil. The crops cultivated in the two fields are pineapple in Yaka field and sugar cane in Senbaru field. The watershed area of the two fields are about 4000m^2 and 10000m^2 respectively. The results of the investigation are as follows. 1. If a rain storm comes to a half for 1 to 2 hours in case of Yaka field and for 2 to 3 hours in case of Senbaru field, the following rain storm may be regarded as separated one for the runoff analysis. 2. The relationships between rainfall and runoff coefficient of the two fields are illustrated in Figs. 8 (Yaka field) and 9 (Senbaru field) and are also expressed by the following equations. f=1.0-1.347R^<-0.390> (Yaka field) f=1.0-3.162R^<-0.593> (Senbaru field) where f is runoff coefficient and R is rainfall in millimeters. 3. Runoff factors obtained in this investigation at Yaka field are effective rainfall, water losses and peak runoff as well as rainfall itself. The relationships between rainfall and effective rainfall, water losses and peak runoff are expressed by the following equation. The relationships between rainfall and effective rainfall and water losses are also illustrated in Figs 10 and 12,respectively. r_e=R-1.347R^<0.610> r_l=1.347R^<0.610> Q_p=0.979R_<10> where r_e is effective rainfall in mm., r_l is water losses in mm., Q_p is peak runoff in cubic meter per 5min., R_<10> is max. 10min. rainfall intensity and is rainfall in mm..
Type Local :紀要論文
ISSN :0370-4246
Publisher :琉球大学農学部
URI :http://hdl.handle.net/20.500.12000/4057
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.28 p.139 -150
Appears in Collections:No.28 (1981/11)

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