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[in Japanese]
1994 Volume 7 Issue 6 Pages
493-494
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
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Keiji TAKASE, Koichi SATO
1994 Volume 7 Issue 6 Pages
495-502
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
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Evapotranspiration is an important component for water balance as well as it has great influences on runoff and other processes in hydrologic cycle in a catchment. Therefore, it is essential to understand the changes in the properies of evapotranspiration due to changes in land use. In this paper, water balance method was applied to the catchments of reclaimed upland field and forest and properties of evapotranspiration were compared between them. The results revealed that annual amount of evapotranspiration depends on the total rainfall and the ratio of evapotranspiration to potential evaporation decreases when the amount of rainfall is less than about 1, 800 mm/year. The dependence was emphasized in the catchment of upland field. Evapotranspiration in the upland field catchment was highly restrained in summer than winter season, while it was not so in the forest catchment.
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Koichiro FUJIWARA, Fuyuki SATOH, Kaichiro SASA
1994 Volume 7 Issue 6 Pages
503-511
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
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Continuous observations for the winter discharge were carried out at 7 small basins in the mountain of cold and snowy area, such as northern Hokkaido. The discharge of the basin was measured by covering gauging weir with falling snow to avoid freezing. Although the air temperature around the weir dropped to about -30°C, the data for the discharge were obtained succesively without the trouble caused by freezing. Succesive discharge was observed from the basin throughout winter season from mid-December to mid-March (70-100 days). The diurnal change of the discharge by evapotranspiration was obscure in the recession curve of winter discharge. The discharge became near constant in the latter half of the observation period. The value of the constant discharge and the duration to reach such discharge cleary depended on the surface geology of the basin (0.8-1.2mm/day and 10 days for the basin of serpentine rocks, and 0.3-0.8mm/day and 30-40 days for that of tertiary rocks, respectively). Therefore, it can be said that the winter discharge in the snowy and cold area directly reflect on the hydrological character of the basin.
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Daiji KOBAYASHI, Yoshiyuki ISHII, Mutsumi NOMURA
1994 Volume 7 Issue 6 Pages
512-519
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
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The temperatures of streams under thick snow cover in the volcanic basin of Neogene period in northern Hokkaido Island, Japan, were found to rise to 3° or 4°C during the snowmelt runoff. Because these were considerably higher than the temperature of snowmelt (0°C), and the streams were perfectly insulated from heat sources from above by snow cover, it was reasoned that soil heat was furnishing most of the heat in runoff. The stream temperatures during the rainstorm runoff in August and September decreased gradually after peak runoff, attaining a nearly constant temperature 9∼11°C on the contrary to that during snowmelt runoff. These stream temperatures attained in the falling limb of each stormflow are comparable to those of soil at about 1.8m below land surface in each period in this basin. The hydrographs in each stormflow were separated assuming the stream tempratures depending on the mixing of direct discharge of meltwater or rain with indirect discharge of subsurface water having 1.8 m soil temperatures. The separated subsurface flow occupied 80∼90% of the total flow in each flood. The hydrograhs were also separated by electric conductance following the stream temperature method.
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Wataru SHINTANI, Kuniyoshi TAKEUCHI, Vanchai SIVAARTHITKUL
1994 Volume 7 Issue 6 Pages
520-528
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
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There are two large reservoirs in the Chao Phraya River Basin, namely, the Bhumibol and the Sirikit. The Storage volume is 13.5 and 9.5 [×109m3], respectively. Up to 1980, the priority was given to hydro-power generation and nowadays to paddy field irrigation of the Chao Phraya Delta. Water crisis in the Chao Phraya River Basin have been occurring continuously in 1990's and water storage levels of both reservoirs are low. The main reasons are the decrease of inflows and the increase of consumption disobeying the planned operation rule. To solve the problem, we introduce, apart from the measures that Thai Government is taking, the rule that restricts irrigation area according to reservoir storage available at the beginning of cropping season.
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Catchment Evapotranspiration Estimates by the Short-time Water-budget Method
Hiroshi TAKIMOTO, Haruhiko HORINO, Tsugihiro WATANABE, Toshisuke MARUY ...
1994 Volume 7 Issue 6 Pages
529-535
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
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The investigation of changes in evapotranspiration properties due to land reclamation is an important subject in irrigation and water resources plannings. Rainfall and outflow records for a period of 12 years, from 1980 to 1991, have been investigated for two adjacent catchment areas, namely A (a reclaimed farmland) and B (a natural forest), at Gojo Yoshino area of the Nara Prefecture. Using these data, seasonal evapotranspirations have been estimated by the short-time water-budget method. The results obtained showed that Catchment B shows a higher evapotranspiration than catchment A and evapotranspira-tions increase from spring to summer and decrease from autumn to winter. Ratios of evapotranspiration to potential evapotranspiration vary from 0.4 to 0.7 for catchment A and from 0.6 to 1.1 for catchment B periodically depending on the amount of rainfall pattern. Evapotranspiration for catchment A is suppressed when potential evapotranspiration is more than about 3.0mm/d; but evapotranspiration for catchment B increases progressively when potential evapotranspiration is up to about 4.0mm/d.
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Toshiharu KOJIRI, U.S. PANU, Kunio TOMOSUGI
1994 Volume 7 Issue 6 Pages
536-543
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
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There are many observation lacks in hydrological data because of non-working of monitoring equipment, rapid change of monitoring condition and etc. However, the hydrograph is generated on the basis of it's own characteristics which are classified into several representative patterns. In this paper, we will classify the observed hydrographs with pattern classification method and represent the occurrence characteristics through IF-THEN form. Then the similarities of considered hydrograph against patterns are evaluated according to the lack situation for observed parts and the whole shape of hydrograph is inferred with fuzzy theory.
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Yasuyuki SHIMIZU, Mutsuhiro FUJITA
1994 Volume 7 Issue 6 Pages
544-551
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
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Various kinds of flood control projects, such as retarding basins, diversion channels, dams, embankments and expansion of the width of channels, are planned in instances when the design flood discharge exceeds the capacity of the present river channel. The selection of one or a combination of these counter measures are decided by considering the physical, social and economic characteristics of the river. Among these options, channel expansion is often considered to be superior from the economic and social viewpoint. However, this artificial improvement may change the hydraulic characteristics of the river itself. The channel expansion may reduce the bed shear stress, thus reducing the sediment transport capacity of the river, and hence resulting in the deposition of sediment. Therefore, channel expansion is not always an effective method to increase the flood capacity from a long-term perspective. In this paper, the long-term effect of the artificial expansion of the width of channels is studied using a mathematical model which predicts the channel bed deformation due to suspended and bed load. As a test, the model is applied to the Ishikari River, and the effects of the channel expansion are discussed.
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[in Japanese]
1994 Volume 7 Issue 6 Pages
552-561
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
JOURNAL
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[in Japanese]
1994 Volume 7 Issue 6 Pages
562-565
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
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[in Japanese]
1994 Volume 7 Issue 6 Pages
566-569
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
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[in Japanese]
1994 Volume 7 Issue 6 Pages
570-575
Published: November 05, 1994
Released on J-STAGE: February 10, 2010
JOURNAL
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[in Japanese]
1994 Volume 7 Issue 6 Pages
576-582
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
JOURNAL
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[in Japanese]
1994 Volume 7 Issue 6 Pages
583-586
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
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[in Japanese]
1994 Volume 7 Issue 6 Pages
594-596_1
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
JOURNAL
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1994 Volume 7 Issue 6 Pages
597-600
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
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[in Japanese], [in Japanese], [in Japanese]
1994 Volume 7 Issue 6 Pages
601
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
JOURNAL
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[in Japanese]
1994 Volume 7 Issue 6 Pages
602
Published: November 05, 1994
Released on J-STAGE: October 22, 2009
JOURNAL
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