JOURNAL OF JAPAN SOCIETY OF HYDROLOGY AND WATER RESOURCES

[title in Japanese]

[in Japanese]

1997 Volume 10 Issue 2 Pages 121-122
Published: March 05, 1997
Released on J-STAGE: October 22, 2009

DOIhttps://doi.org/10.3178/jjshwr.10.121

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The Seasonal Variation of Heat Balance on a Paddy Field

Sachinobu ISHIDA, Tomomi ISHIDA, Junsei KONDO

1997 Volume 10 Issue 2 Pages 123-132
Published: March 05, 1997
Released on J-STAGE: October 22, 2009

DOIhttps://doi.org/10.3178/jjshwr.10.123

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Micrometeorological observations were carried out on a paddy field, as one of ideal and representative vegetations, for 1 year and 10 months, and the seasonal variation of heat balance was evaluated. The daily average of the temperature difference between the surface and the air was 0 to 3°C for a whole year. The net radiation flux was -20 to 50Wm^-2 in winter, 0 to 200Wm^-2 in summer. The sensible heat flux was about 50 to 200Wm^-2 just before the planting of rice, but in the other season it has a range of ±50Wm^-2. The latent heat flux was less than 50Wm^-2 in winter, 100 to 200Wm^-2 in summer.

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Comparison of the Runoff Component Derived from Water Quality with One Derived from Long-and Short-Term Runoff Model

Akio TADA, Haruhiko HORINO, Toshisuke MARUYAMA, Haruya TANAKAMARU, Tak ...

1997 Volume 10 Issue 2 Pages 133-143
Published: March 05, 1997
Released on J-STAGE: October 22, 2009

DOIhttps://doi.org/10.3178/jjshwr.10.133

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Based on runoff and water quality data at a reclamation farmland catchment at the Gojo Yoshino area in Nara Prefecture, runoff components separated by Multivariate (MV) method were compared to those separated by runoff model (long-and short-term runoff model, LST-II). The former uses water quality information only. Both methods utilize different concept of hydrograph separation. The result showed that both runoff components were almost same by a linear transformation only during the storm event. During the runoff peak, there was a discrepancy which could not be explained by mixing ratio of runoff components derived from LST-II. Comparison of results from long-term runoff analysis by LST-II to those from water quality analysis indicated that long-term variation of water quality could not be explained only by the mixing ratio of LST-II. By using the linear transformation between the mixing ratio derived from LST-II and that derived from MV method, water quality applied to orifice of LST-II could be estimated for each storm. This application showed that water quality of prompt interflow component derived from LST-II were different from that of the flow from underdrain, which drains the prompt outflow through soil layer.

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Estimation of Aerodynamic Roughness Parameter Using Synthetic Aperture Radar Data

Yasuto TACHIKAWA, Michiharu SHIIBA, Shinichi HARAI, Takuma TAKASAO

1997 Volume 10 Issue 2 Pages 144-153
Published: March 05, 1997
Released on J-STAGE: October 22, 2009

DOIhttps://doi.org/10.3178/jjshwr.10.144

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The backscattering coefficients observed by synthetic aperture radar (SAR) are influenced by surface geometric roughness obstacles. By using this attributes, spatial distributions of aerodynamic roughness parameter are estimated from the SAR images obtained by the Japanese Earth Resources Satellite (JERS- 1) and European Remote Sensing Satellite (ERS- 1). These roughness maps are compared with the roughness map derived by the method proposed by Kondo and Yamazawa (1986) which uses the National Land Numerical Information. As a results, it is shown that the roughness map derived from JERS-1 SAR corresponds well to the roughness map derived from the National Land Numerical Information.

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The Effect of Expansion of the Saturated Soil Zone on N0₃^--N Concentration in Streamwater During a Rainfall Event

Eiichi KONOHIRA, Jumpei KUBOTA, Yoshinori TSUKAMOTO

1997 Volume 10 Issue 2 Pages 154-160
Published: March 05, 1997
Released on J-STAGE: October 22, 2009

DOIhttps://doi.org/10.3178/jjshwr.10.154

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The variation of N0₃^--N concentrations in streamwater and in soil solutions on the valley floor was measured during two rainfall events different in total rainfall amount. The 0.52ha catchment located in the Hakyuuchi in Hachiouji City, Tokyo is covered by a broad-leaved forest. By the 109mm rainfall, saturated soil zone expanded to surface soil layer and the N0₃^--N concentration in streamwater increased remarkably. On the other hand, the 44.5mm rainfall kept surface soil layer unsaturated and didn't vary the N0₃^--N concentration in streamwater. These results show that the increase of N0₃^--N concentration in streamwater was caused by saturation of surface soil layer, which was rich in N0₃^--N and had high hydraulic conductivity. Subsuface flow in the surface soil layer was the dominant source of streamwater when it was saturated. Subsuface flow also brings the variation of N0₃^--N concentration in soil solution. This variation occurs by the congruence of concentrations of soil solutions in the direction of subsurface flow.

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Estimating Transmission Losses in the Main Channel of River Tana, Kenya

Maurice O. NYADAWA, Shigeki KOBATAKE, Kazuhiro EZAKI

1997 Volume 10 Issue 2 Pages 161-173
Published: March 05, 1997
Released on J-STAGE: October 22, 2009

DOIhttps://doi.org/10.3178/jjshwr.10.161

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This study has presented correlation equations thought to define channel loss in River Tana in Kenya. Modified Tank Model is used to transfer runoff information from gaged basins to ungaged ones in the study area. The study has revealed that channel loss has two step functions corresponding to flow rates below 800m³/s and larger values.

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On an Integrated Operation Planning of Multiple Reservoirs for Agriculture on the Kino River System

Hirofumi KAKUDO, Yutaro SENGA, Yoichiro KOJIMA, Michiko NISHITA

1997 Volume 10 Issue 2 Pages 174-180
Published: March 05, 1997
Released on J-STAGE: October 22, 2009

DOIhttps://doi.org/10.3178/jjshwr.10.174

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An effective methodology is needed for the operation of a multiple reservoir water supply system. In addition to meeting the release requirements to the command area, the system must also contain drought countermeasures to avoid critical reservoir water levels such as empty storage. In this study, a method of operation was developed based upon the “Method of Required Storage for Drought Curve” theory. The site for this study was the Kinokawa River region, where two major reservoirs need to meet agriculture water use demands. The new method balances the release of water to the command area against the actual reservoir water levels, the probability of storage recovery, and the target level of recovery. This methodology was verified by computer simulation using historical data as input. The simulation results showed that the new method had advantages over the current method of operation. During the drought year of 1994, the new method's drought countermeasures gave a lower ratio of restrictive release. In addition, this new methodology reduced amount of ineffective releases of water from the reservoirs for most of the years that were simulated.

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Simple but Reliable Method to Extract Soil Water for Stable Isotope Analysis

Tsutomu YAMANAKA, Jun SHIMADA

1997 Volume 10 Issue 2 Pages 181-184
Published: March 05, 1997
Released on J-STAGE: October 22, 2009

DOIhttps://doi.org/10.3178/jjshwr.10.181

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As a method to extract soil water for stable isotope analysis, a simple distillation technique without heating under ordinary pressure (ordinary temperature distillation method) was suggested, and compared the results with that by the centrifuge method. As a result, it was shown that the isotope ratio of the water extracted by the ordinary temperature distillation method had a tendency to be underestimated due to the isotopic fractionation effect during the extraction process. However, this fractionation effect can be corrected theoretically. By using this correction method, root mean square errors from reference value reduced from 9.49 to 2.5‰ forδD and from 1.9 to 0.47‰ for δ¹⁸O, respectively.

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[title in Japanese]

[in Japanese]

1997 Volume 10 Issue 2 Pages 186
Published: March 05, 1997
Released on J-STAGE: October 22, 2009

DOIhttps://doi.org/10.3178/jjshwr.10.186

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Open IGBP/BAHC-LUCC Joint Inter-Core Projects Symposium on Interactions Between the Hydrological Cycle and Land Use/Cover

[in Japanese], [in Japanese], [in Japanese], [in Japanese]

1997 Volume 10 Issue 2 Pages 187-192
Published: March 05, 1997
Released on J-STAGE: October 22, 2009

DOIhttps://doi.org/10.3178/jjshwr.10.187

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[title in Japanese]

[in Japanese]

1997 Volume 10 Issue 2 Pages 193
Published: March 05, 1997
Released on J-STAGE: October 22, 2009

DOIhttps://doi.org/10.3178/jjshwr.10.193

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[title in Japanese]

[in Japanese]

1997 Volume 10 Issue 2 Pages 194
Published: March 05, 1997
Released on J-STAGE: October 22, 2009

DOIhttps://doi.org/10.3178/jjshwr.10.194

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