岡山大学環境理工学部Acta Medica Okayama134190992612021散水によるアスファルト上の暑熱環境緩和効果710ENToshitsuguMOROIZUMINaoyaITOTakeshiMIURAIn this study, water was sprinkled on the asphalt surface during the hottest hours of the day using a sprinkler, and the effect was experimentally verified. An air temperature, a humidity, a ground surface temperature, and a globe temperature which is radiant heat from the ground were measured, and using these measurements, WBGT (Wet-Bulb Globe Temperature), which is an index of thermal stress on the human body, was calculated. In this way, we investigated not only the climate mitigation effect but also the mitigation effect of the thermal environment felt by the human body.</br>
As a result, the following points were clarified in this study: 1) During sprinkling, the air temperature, the black globe temperature, and the WBGT were lower in the sprinkled area than in the controlled area, and the wet-bulb temperature hardly changed. 2) Focusing on the amount of change after watering compared to before watering, the air temperature, the globe temperature, and the WBGT decreased, and the wet-bulb temperature hardly changed. 3) In the sprinkled area, when the WBGT value just before watering is higher than that of the strict caution (WBGT is 28°C or higher), it drops to a level one rank lower, and when the WBGT value just before watering is warning (WBGT value is 25°C or higher), it was almost no change. No potential conflict of interest relevant to this article was reported.岡山大学環境理工学部Acta Medica Okayama134190992612021岡山県3河川流域における実蒸発散量の推定 : Morton 法と修正 Brutsaert and Stricker 法の比較15ENToshitsuguMOROIZUMITakeshiMIURA In the study, the actual evaporation was estimated in the Asahi River, the Takahashi River, and the Yoshii River basins in Okayama prefecture for four years from January 1999 to December 2002. The Morton method and the modified Brutsaert and Stricker (B & S) method were applied to the three river basins to estimate the actual evapotranspiration and compare the two methods.</br>
As a result, the actual evapotranspiration by the Morton method was all almost equal to that by the Penman’s potential evapotranspiration, and the evapotranspiration was overestimated rather than the actual evapotranspiration. The actual evapotranspiration by the modified B & S method was below the Penman’s potential evapotranspiration throughout the year, and the total annual amount was about 80% of the potential evapotranspiration. In addition, the modified B & S method showed the general tendency that the actual evapotranspiration was lower in urban area than in the hilly and mountainous areas. No potential conflict of interest relevant to this article was reported.岡山大学環境理工学部Acta Medica Okayama2187-69402212017岡山地方気象台観測露場移転による気温低下量の推定6164ENTakeshiMiuraGraduate School of Environmental and life Science, Okayama UniversityYuUedaGraduate School of Environmental and life Science, Okayama UniversityHidenoriMoritaGraduate School of Environmental and life Science, Okayama UniversityHidetakaChikamoriGraduate School of Environmental and life Science, Okayama UniversityMasahiroKurokawaYoshitakaNakashimaGraduate School of Environmental and life Science, Okayama UniversityYokoOkiGraduate School of Environmental and life Science, Okayama University10.18926/fest/54863Statistical change in official temperature records at Okayama City caused by relocation of meteorological observation field of Meteorological Agency was evaluated. The observation field of Okayama local meteorological observatory was moved to the Tsushima Campus of Okayama University from the downtown area of Okayama City in March, 2015. Comparison between the air temperature records measured at meteorological agency station and the records at Tanjo Pond in Tsushima Campus, showed 0.56 ℃ drop in annual average before and after relocation. Moreover, comparison between the records of Okayama local meteorological observatory and that at the surrounding meteorological observing 9 stations showed 0.55 ℃ drop in annual average. Those results suggest that the relocation dropped annual average of air temperature by about 0.6 ℃.No potential conflict of interest relevant to this article was reported.岡山大学環境理工学部Acta Medica Okayama2187-69402212017現地気象観測データを用いた最低気温予測方法とその精度―インターネットを利用した最低気温予報システムの改良―5559ENYuUedaGraduate School of Environmental and life Science, Okayama UniversityTakuyaMishimaTakeshiMiuraGraduate School of Environmental and life Science, Okayama UniversityToshitsuguMoroizumiGraduate School of Environmental and life Science, Okayama University10.18926/fest/54862We have developed a minimum air temperature forecasting system using local meteorological
observation data in order to prevent or mitigate the frost damage. In this paper, the correlation between the meteorological factors and the decrease in air temperature during the night was shown. Then minimum air temperature was predicted by the multiple regression equation that uses air temperature and humidity at 18:00 as explanatory variables. As the result, the root mean square error (RMSE) was 2.8°C. When the difference of air temperature between 17:00 and 18:00 was used for the prediction instead of humidity, the RMSE was 3.5°C. Next, the prediction was carried out only in clear nights, then the equation that use air temperature and humidity at 18:00 showed that the RMSE was 1.3°C. Although the predictive accuracy of the equations for clear nights is low on cloudy or rainy nights, we can forecast safely on frosty nights by using those equations in combination with the equations for all nights.No potential conflict of interest relevant to this article was reported.岡山大学環境理工学部Acta Medica Okayama2187-69402012015インターネットを利用した最低気温予報システムの構築 ―予報ウェブページの設計―3540ENTakuyaMishimaTakeshiMiuraToshitsuguMoroizumi10.18926/fest/53219 The purpose of this study is to build a forecast system for predicting at minimum air
temperature in the next morning from the meteorological data, such as air temperature,
humidity, and the amount of solar radiation, in a field in the evening on the previous day. The
meteorological data are sent to a relay server, and then, transferred to a PC in our laboratory
of Okayama University by executing the computer program to import the data which are used
to calculate the predicted values of minimum air temperature. The predicted minimum air
temperatures are released for the farmers on the website in the server of Okayama University.
The website is also created by our laboratory. As a result, the predicted minimum air
temperatures agreed with the measured ones.No potential conflict of interest relevant to this article was reported.岡山大学環境理工学部Acta Medica Okayama2185-33471612011補完関係式を用いた実蒸発散量推定式の改良3539ENTakeshiNakamichiToshitsuguMoroizumiTakeshiMiura10.18926/fest/44792Advection-Aridity(AA) model can calculate actual evapotranspiration by using only meteorological data. However, comparing the model with Penman equation showed that AA model doesn’t properly evaluate evapotranspiration from urban moisture area. In urban area, Actual evaporation from water calculated by AA model(E) are much less than that by Penman equation(Epo). Multiple regression analysis using estimation results indicates that the difference between the models is due to the difference of the sensitivity to vapor pressure deficit between the models. To improve this problem, modification coefficient k, defined as k=a･albedo+b, is suggested. Regression coefficients a, b are determined as satisfying k=Epo/E for water and k=1 for urban surface. By using this coefficient k, evaporation from water is nearly equal to value estimated by Penman equation, while evaporation from urban surface is changeless.No potential conflict of interest relevant to this article was reported.岡山大学環境管理センターActa Medica Okayama0917-1533312009TDR法を用いた土壌中の水分と電気伝導度の同時測定に関する予備的検討3237ENToshitsuguMoroizumiTomoyoKusuyamaTakeshiMiuraIt is very important to measure the water content and electric conductivity in soil for monitoring the environment of agricultural land continuously. TDR (Time Domain Reflectometry)method plays a key role on the
measurement of water content and electric conductivity in soils recently. Some calibrations are needed to measure them accurately. The objective of this study was to investigate preliminaly the corrections of TDR probe, the probe constant for electric conductivity, and the dependence of water pemittivity on temperature as TDR calibrations. The results showed the importance for the corrections of TDR probe and the reasonable value of probe constant.The TDR system used in this study could measure the dependence of water pemittivity on temperature.No potential conflict of interest relevant to this article was reported.Department of Mathematics, Faculty of Science, Okayama UniversityActa Medica Okayama0030-15664612004A Note on Commutative Gelfand Theory for Real Banach Algebras121130ENSin-EiTakahashiTakeshiMiuraOsamuHatori10.18926/mjou/33926<p>Pfaffenberger and Phillips [2] consider a real and unital case of the classical commutative Gelfand theorem and obtain two representation theorems. One is to represent a unital real commutative Banach algebra A as an algebra of continuous functions on the unital homomorphism space ΦA. The other is to represent A as an algebra of continuous sections on the maximal ideal space MA. In this note, we point out that similar theorems for non-unital case hold and show that two representation theorems are essentially identical.</p>
No potential conflict of interest relevant to this article was reported.Department of Mathematics, Faculty of Science, Okayama UniversityActa Medica Okayama0030-15664412002A Representation of Ring Homomorphisms on Unital Regular Commutative Banach Algebras143154ENTakeshiMiura10.18926/mjou/33119<p>We give a complete representation of a ring homomorphism from a unital semisimple regular commutative Banach algebra into a unital semisimple commutative Banach algebra, which need not be regular. As a corollary we give a sufficient condition in order that a ring homomorphism is automatically linear or conjugate linear.</p>
No potential conflict of interest relevant to this article was reported.岡山大学環境管理センターActa Medica Okayama0917-1533302008Amplitude Domain Reflectometry法による不飽和砂地盤中のNAPL含有量と誘電率に関する基礎的研究2732ENToshitsuguMoroizumiYumiSasakiTakeshiMiuraSubsurface contamination by non-aqueous phase liquid (NAPL) has become a serious environmental issue. Therefore, it is necessary to estimate the NAPL content (θNAPL) in unsaturated soil to detect and monitor the NAPL contaminations in soil and groundwater. The objective of this study was to investigate the relationship between θNAPL and permittivity (K) in unsaturated sandy soil as a fundamental study to estimate the θNAPL. An ADR (Amplitude Domain Reflectometry) method was used to measure the K in the soil including the NAPL which was a castor oil as light NAPL or a HFE-7100 as dense NAPL. The experimental study indicated the linear relation between θNAPL and K in unsaturated soil with soil-NAPL-air. Using this relationship, we can estimate the θNAPL. On the other hand, although we obtained the relationship between θNAPL, θw and (root) K in unsaturated soil with soil-NAPL-water-air, it was not possible to estimate the θNAPL using this relationship.No potential conflict of interest relevant to this article was reported.岡山大学農学部附属山陽圏フィールド科学センターActa Medica Okayama0910-8742262004水田と畑の放射収支の特徴と放射収支計の機種の違いによる測定値の差異2627ENTakeshiMiuraToshitsuguMoroizumiNo potential conflict of interest relevant to this article was reported.岡山大学農学部附属山陽圏フィールド科学センターActa Medica Okayama0910-8742262004二酸化炭素のフラックスと勾配の関係1419ENTooruIwataTakeshiMiuraNo potential conflict of interest relevant to this article was reported.岡山大学農学部附属山陽圏フィールド科学センターActa Medica Okayama0910-8742262004二酸化炭素と水蒸気濃度変動に関するモニン･オブコフ相似則2025ENTooruIwataTakeshiMiuraNo potential conflict of interest relevant to this article was reported.岡山大学環境理工学部Acta Medica Okayama1341-9099111996Crop Water Use From Shallow Groundwater -Simulation Using Field Measured Soil and Climatic Parameters-169179ENTakeshiMiura10.18926/fest/11635The SWAP93 model was used to predict how much capillary rise would occur in cropped fields. The experimental fields were located in a humid climate and it was thought that contribution from groundwater sources to total water use could be significant. In one field planted with soybean, the model predicted an average daily uptake of 1.3 mm; in another field planted with pumpkin, there was average daily uptake of 0.3 mm; and yet in a third field located in a vinyl house there was average daily uptake of 0.03 mm. These predictions represent about 38,7 and 1% contribution to total water use respectively. Even though there were no measured data to compare with, the results lie within the range of other works reported in the literature.No potential conflict of interest relevant to this article was reported.岡山大学環境理工学部Acta Medica Okayama1341-9099111996岡山市の気温・降水量の経年変化163168ENTakeshiMiura10.18926/fest/11628In this paper, secular changes of air temperature and the amount of precipitation in Okayama city are discussed using observed values at Okayama meteorologiccal station. Special reference is made to 1993 and 1994 in which peculiar changes occurred. The results obtained are summarized as follows: (1) The increasing rate of the annual mean air temperature at Okayama city is 0.85℃/100y. This value is nearly equal to the average of Japan; 0.87℃/100y. (2) The increasing rate indicates seasonal changes, and the rate is high especially in April and May. (3) The rapid increase of the air temperature in the 1980s is due to removal of Okayama meteorological station from the edge of town to the center. (4) The annual mean air temperature in 1994 is 16.9℃, and the monthly mean temperature for July and August are 29.8 and 29.6℃ respectively. These values are new records at the Okayama station. (5) The air temperature in July and August, 1993 are higher than in 1980 when it was much colder in the summer. (6) The amount of precipitation does not show any secular changes.No potential conflict of interest relevant to this article was reported.岡山大学環境理工学部Acta Medica Okayama1341-9099311998スイカ・ビニールハウス内外での微気象環境の比較121126ENNoboruMoritaTakeshiMiura10.18926/fest/11572The use of glass and plastic greenhouses have rapidly increased in recent years. Meteorological and soil moisture environments inside a greenhouse are significantly different from those in the open field. These differences should be understandable to establish accurate predictions of water consumption and evapotranspiraton inside a greenhouse which play impotrant roles in the design of any irrigation system. This study aims to estimate the micrometeorological conditions inside a watermelon plastic greenhouse which can be used for evapotranspiration calculations. Therefore, micrometeorological data were measured inside and outside the greenhouse for the comparison purposes. The results of this study may be summarized as : (1) Solar radiation inside the greenhouse was about 70% of that of outside it. (2) Net radiation during the daytime inside the greenhouse was almost the same as the absorbed total short-wave radiation. (3) The difference of air temperature inside and outside the greenhouse was very large during the daytime whereas not much difference was observed during the nighttime. (4) Both relative humidity and saturation deficit inside the greenhouse were higher than outside in case of highly vegetative land. (5) Wind speed inside the greenhouse was almost zero, while outside the average value was 1.8m/s.No potential conflict of interest relevant to this article was reported.岡山大学環境理工学部Acta Medica Okayama1341-9099612001青森市における気候変動傾向8184ENToshitsuguMoroizumiYuichiSatoKoichiSatoTakeshiMiura10.18926/fest/11537Characteristics of long-term change for air temperature, precipitation and snowfall-depth at Aomori city were analyzed with data during the 111 years, from 1886 to 1996. The typical results were as follows: (1) The increasing rate of the annual mean air temperature was 1.07℃/111 year. (2) The increasing rate of the monthly minimum air temperature was larger than that of the monthly maximum air temperature. (3) The increasing rate of the monthly air temperature was large from winter to spring, however, was not so from summer to autumn. (4) The decreasing rate of annual precipitation was 0.187 mm/year. (5) The 5-year moving average of annual snowfall-depth might indicate the existence of about 10-year period.No potential conflict of interest relevant to this article was reported.岡山大学環境理工学部Acta Medica Okayama1341-9099712002岡山大学津高牧場における降雨変動特性107111ENToshitsuguMoroizumiAtsushiYomotaTakeshiMiura10.18926/fest/11536Characteristics of long-term change in rainfall at Tsudaka Farm of Okayama University were analyzed with data during the 20 years, from 1979 to 1998. The typical results were as follows: (1) The average of annual rainfall was 1203 mm at average, 1726 mm at maximum, and 666 mm at minimum. (2) The decreasing rate of the annual rainfall was 5.37 mm/year. (3) Trend of rainfall intensity in each rainfall duration showed an increase of which rate were 0.005~0.256 mm/h/year, contrary to the annual trend. (4) Rainfall intensities in n-years probability were estimated using the maximum rainfall intensity for each rainfall duration.No potential conflict of interest relevant to this article was reported.岡山大学環境理工学部Acta Medica Okayama1341-9099912004水稲耕作地における熱収支8185ENDongmeiYangToruIwataTakeshiMiuraEijiOhtaki10.18926/fest/11463Experience of flux measurements over tall canopies has revealed that the eddy flux of sensible plus latent heat is about 30% smaller than the available radiant energy flux. A systematic observation was carried out to investigate the imbalance problem on rice field. The rice field represents a complex system consisting of rice plant, irrigated water and soil. Date obtained in this experiment show that appreciable understimations of sensible and latent heat fluxes are not recognized but understimations of 15 to 23% are counted in the soil heat flux.No potential conflict of interest relevant to this article was reported.岡山大学環境理工学部Acta Medica Okayama1341-90991212007白瓜ビニールハウス内外での微気象環境の比較125130ENYujiMorimotoEmiHiranoTakeshiMiura10.18926/fest/11462The use of greenhouses has rapidly increased after 1965, and the area became 11 times of 1965 as of 2001. Meteorological conditions and soil moisture environments inside a greenhouse are significantly different from those in the open field. These differences should be understandable to establish accurate predictions of water consumption and evapotranspiration inside a greenhouse which play important roles in the design of any irrigation system. This study aims to estimate the micrometeorological conditions inside an oriental pickling melon greenhouse which can be used for evapotranspiration calculations. Therefore, micrometeorological data were measured inside and outside the greenhouse for the comparison purposes. The results of this study may be summarized as: (1) Solar radiation inside the greenhouse was decreased about 30% of that of outside it by plastic film and frame. (2) Net radiation during the daytime inside the greenhouse was almost the same as the absorbed total short-wave radiation. (3) The difference of daytime mean air temperature inside and outside the greenhouse was between 3 and 4 degree Celsius in day average. (4) Both relative humidity and saturation deficit inside the greenhouse were higher than outside, and those were affected by ventilation. (5) Wind speed inside the greenhouse was greatly affected by opening rate of the house side.No potential conflict of interest relevant to this article was reported.岡山大学環境理工学部Acta Medica Okayama1341-90991212007白瓜の生育に伴う根系の測定119123ENEmiHiranoYujiMorimotoTakeshiMiura10.18926/fest/11460It is important to clarify how the soil moisture changes by irrigation and how moisture is consumed by absorption of root, to plan irrigation appropriately in upland field. And, it is thought that clarifying the growth of the root can be important information in the water management, because the amount and the pattern of root water uptake change depending on the growth stage. However, there are not too much a lot of researches that measure the root, in addition, the example intended for crops of 'Gourd family (scientific name:Cucurbitaceae)' is not found. Therefore, for oriental pickling melon, it measured how for the root system to grow up as crop grew every three weeks. The results of this study may be summarized as: 1) Root amount increased with the growth of crops, and the majority of the root existed to 20cm in depth. A lot of rootlets with the role of water uptake existed outside of from 10 to 20cm. 2) Root length has grown up in horizontal and vertical direction at a dash at the stage of growing initial. 3) It was able to be confirmed to the growth of the ground part and the root that the length and amount either also had implications. Moreover, root amount and plant caver ratio drew similar curve.No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0910-87422512003八浜農場での熱収支710EN太陽から地表面に与えられた熱エネルギーは、顕熱や潜熱に変換されるが、地表面の種類や状態によってその配分比率が変わり、大気に及ぼす効果は異なる。従来から、いろいろな地表面において熱収支に関する研究が行われており、裸地面ではその収支は釣り合っているとされている（例えば、古藤田、1984；近藤、1995；Seo、1958)。しかし、森林などの複雑地形状で渦相関法を用いた測定では熱収支が閉じないと指摘されている（Finnigan et al.,2003)。我々の研究目的は、裸地と森林の中間的な粗度面である水稲群落圃場での熱収支を明らかにすることである。特に、圃場の土壌及び灌漑水の貯熱量に注目し解析を行った。No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02547311989笠岡湾干拓地域の風向風速特性5965ENTakeshiMiuraAtushiYomotaAkihiroNagai笠岡湾干拓地域の気象特性のうち,風向風速特性を干拓地隣接の笠岡地域気象観測所(AMeDAS)でのデータから検討した.本来は干拓地内での測定値を基に検討を加える必要があるが種々の制約から測定ができなかった.そこで測定機器のメインテナンスも行き届いて欠測も殆どない地域気象観測所での測定値を用いた.笠岡地域気象観測所は今回の干拓事業で行われた干拓地の東側に隣接する旧干拓地に位置し,距離的にも,環境的にも現干拓地とはかけ離れていないと考えられ,ここで得られた結果を干拓地におけるものとしても大差はないで'あろうと考えられる. 干拓地内での風向風速の測定値が得られれば,風向風速の日変化の様子も分かり,より詳細な風向風速特性を明らかにすることができよう. ここで得られた結果をまとめると次の通りである. (1)笠岡湾干拓地域の主風向は冬季(11～2月)には西～北西,3月以降は東北東～東,5月以降夏季には東方向に加え若干南方向も加わる(Fig.3.). (2)日最大風速時風向は冬季(11～2月)の季節風の時期には西が他を抜きんでており,また同方向の風速も強い.3月になると東方向が増加し,5月以降夏季になると南方向の頻度も多くなる(Fig.5.).日最大風速5m/s以上の強風時の風向はほとんどが西方向である. (3)3年間の日平均風速は1.0m/s,日平均風速が2m/sを越える日数は僅か40日,最大風速は6m/s(4日,いずれも西風),日最大風速が5m/sを越える日数は19日(風向は東西方向のみ)と強風の日数が少ない.笠岡湾干拓地域は風のかなり弱い地域と言えるであろう. 笠岡湾干拓地周辺の地形は,北側の旧海岸線近くまで丘陵地が迫り,また南側には神島が位置している.すなわち干拓地の南北を丘陵地と島により挾まれる形になっており,主風向が東西方向で風が弱い原因の一つとしては,この地形に起因していると考えるのが自然であろう。No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02547011987笠岡湾干拓地域の気象特性2335ENKinzoNagahoriTakeshiMiuraTakaoAmaya本論文では,笠岡湾干拓地及び周辺地域の気象特性を,干拓地内の試験圃場,笠岡地域気象観測所,岡山地方気象台での測定値を基に論じるとともに,他のわが国の代表的干拓地近傍の気象官署である秋田(八郎潟),松江(中海),佐賀(有明湾)の気象資料との対比を通して,笠岡湾干拓地域の気象の特徴をより鮮明にした.その概要は以下の通りである.(1)笠岡湾干拓地のある岡山県南西部は,笠岡地域気象観測所での1980～1986年の7年間平均値で,年平均気温14.9℃,年降水量1,077mm,日照時間2,582時間,年平均風速1.0m/sと温暖で,少雨,年間を通して日照時間の多い典型的な瀬戸内型の気候を示している(Table2).(2)月平均気温から推定した10℃以上の期間は3月29日から11月21日の238日間,その間の積算温度は4,790℃,10℃以上の有効積算温度は2,410℃となった.(3)笠岡地域気象観測所での1980～1986年の月別の最多風向は,11-2月にかけては北西が,3～10月までは東北東ないし東が多い.風災害対策で重要である最大風速時の風向は,10～2月は西を中心として,3～9月には東西方向を中心とした風向は多いことが分った(Table3).(4)笠岡湾干拓地内の試験圃場で熱収支法により蒸発散量を測定し,ペンマン式による蒸発散位,大型蒸発計蒸発量,降水量,日照時間との関係を検討した.その結果,蒸発散量は,降雨の直後は蒸発散位に近い値を示し,晴天が続くと地表面の乾燥のため蒸発散位をはずれて低下した.月間値では,蒸発散量は蒸発散位,大型蒸発計蒸発量と11～3月には同等な値を示したが,4-10月にはかなり小さな値となった(Figs.3～4).(5〉わが国の代表的な干拓地近傍の気象官署(岡山,秋田,松江,佐賀)の30年間の測定値の比較では,岡山は気温は中庸,降水量は少なく,日照時間が年間を通して多いことが分かった(Fig.2,Table1),一年を通して日照時間が多く蒸発散位が大きいこと,降水量が少ないことから判断すれば,他地区と比較して,笠岡湾干拓地の気象特性がヘドロ土壌の乾燥収縮に最も有効に働くと考えられる.笠岡湾干拓地での農業を有利に展開するためには,以上のような気象特性を踏まえて営農にあたられんことを期待する.また,潜在的な乾燥能力が大きいことと土壌の除塩問題との関係は,圃場での水収支・土壌の物理性を踏まえて,今後農地工学的に詳細に検討しなければならない課題であろうと考えられる。No potential conflict of interest relevant to this article was reported.岡山大学農学部Acta Medica Okayama0474-02546011982圃場整備水田における水需要構造5363ENAtsushiYomotaTakeshiMiura水田の他地目への転用(工場・宅地化,畑転など)により水稲作付面積が減少しているが,用水量はそれにみあって減少していない. それは,水田用水量のなかで,消費水量以外の水量,すなわち栽培管理用水量と配水管理用水量の占める割合が大きいためと考えられる. 本研究では,農区レベルでの水需要と上記の管理用水量の実態を明らかにするため,特別な水管理が行われる田植,中子し期と普通期に分けて,用排水量を中心とした現地観測を行った. 以下その結果の概要を述べる. （1)調査対象地区の減水深は小さく,実測値は蒸発計蒸発量より若干大きい程度である(Table2). すなわち,蒸発散主導型の水消費が行われている. （2)代かき時には,140～150 mmの用水量を必要とした. （3)田植時に,稚苗機械植えのための強制落水量73 mm(S56)が観測された. (4)中干し時の強制落水量は70mm,中干し終了直後の取水量は4日間に154 mm(S56)であった. 中干し復元用水量の集中は代かき用水量に匹敵する. （5)中干しにともなう浸透量の増加は総量で120～130 mm(S56)に達することがわかった. 浸透速度は取水開始後の経過時間のベキ乗に比例して減少した(Fig. 5). (6)幹線用水路から小用水路への取水量管理が十分でなく,配水管理用水量(小用水路レベル)はかなり大きな値を示した(Figs. 2,3). 無降雨が続くと,配水管理用水率は減少する. 昭和56年8月中旬～下旬の例では,50%前後から10%程度まで減少した(Fig. 3). (7)取水量優先利用,降雨量優先利用という2つの方法で,水田落水量から栽培管理用水量と無効雨量を求めた. 昭和56年の田植期,中干し期,減水深測定時を除く50日間の総量で,水田取水量＋有効雨量に対する栽培管理用水量の割合(栽培管理用水率)は取水量優先利用の方法で33.4%,降雨量優先利用の方法で37.6%になった. すなわち,利用可能水量の約1/3が掛流しもしくは強制落水量となっていることがわかった(Table 4). 水田作付面積が減して余剰水が生じても,投下労働力の減少により管理用水量が増加して,結果として用水量の減少に結びつかないのではなかろうかと推論される。No potential conflict of interest relevant to this article was reported.岡山大学農学部附属農場Acta Medica Okayama0910-874261984牛床暖房ソーラーシステムの集熱能力について5561ENNo potential conflict of interest relevant to this article was reported.