• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.541-541
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• 2015

댐 물수지 분석에 있어 매우 중요한 요소는 강수량, 유입 방류량, 토양수분량, 증발산량 등이 있다. 현재 육지에서의 증발산량은 대부분 에디공분산시스템에 의해 관측되고 있으며, 많은 전문가들이 양질의 자료를 산출하고 있다. 하지만 수면에서의 증발량관측은 아직 부족한 상황이다. 우리나라는 기후특성상 여름철에 강우가 집중됨에 따라 효율적인 댐 관리가 매우 중요하다. 댐관리의 주요 인자인 수면증발량은 현재 용담댐에서만 이루어지고 있다. 용담댐의 수면증발량 관측은 2013년부터 수행되고 있고, 수면위에 플랫폼을 설치하고 팬 내부에 수심이 1 m인 대형증발팬을 고정하는 방식을 취하고 있으며, 관측된 수위자료는 호내 수온을 고려하여 수면증발량으로 환산된다. 관측항목으로는 팬 내 외부 및 저수지 표층 수온, 팬 내부 정밀 수위뿐만 아니라 다양한 기상요소들이 있다. 2013년에 생산한 수면증발량은 풍향풍속, 수온, 상대습도, 복사량, 강수량 자료를 통해 정확도를 검증하였으며, Penman(1984)공식을 활용하여 실측 수면증발량과 추정 수면증발량을 비교 분석하였다. 본 연구는 용담호에서 자동 관측되고 있는 수위변동 자료를 활용해 수면에서의 증발량을 분석하였다. 2014년 3월부터 2015년 2월까지의 자료를 활용하였으며, 관측기간 중 최대 일증발량은 9.7 mm/day, 월 최대 일평균증발량은 3.5 mm/month(10월)로 나타났다. 수면에서 가장 많은 증발량이 나타난 시기는 10월 (증발량 : 107.6 mm, 강수량 : 122.9 mm)로 강수량의 약 88 %가 증발되었음을 알 수 있었다. 그 다음으로는 9월과 5월 순이었다. 증발량이 가장 많다고 예상되었던 7월과 8월의 경우는 각각 18일과 21일간 강수가 발생하였으므로 대기 중의 높은 습도로 인해 증발량이 크지 않았다. 결론적으로 수면에서의 증발량이 기상환경에 의존하고 있다는 사실은 명백하다. 그러므로 효율적인 수자원관리를 위해서는 다양한 지점에서의 수면증발 관측 및 기상요소와의 상관 성분석이 시급하다고 판단된다.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.35 no.6
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• pp.518-524
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• 1990

Actual evapotranspiration was measured over rice paddy field by Bowen ratio heat balance method and based on this, investigated was the reliability of actual evapotranpiration estimation from Class-A Pan and small pan evaporation and reference evapotranspiration calculated by modified Penman-Monteith model. Crop coefficients based on Class-A Pan and small pan evaporation and reference evapotranspiration by modified Penman-Monteith model were averaged to be 1.57. 1.10 and 1.49 over the whole rice growing season, respectively. Their respective coefficients of variation were 28.7. 22.7 and 12.8 percent, respectively. Crop coefficient based on modified Penman-Monteith model varied in good agreement with the trend of leaf area development, being greatest around heading stage.

• Magazine of the Korean Society of Agricultural Engineers
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• v.32 no.1
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• pp.55-71
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• 1990

The purpose of this study is to find out the basic data for irrigation plans of red pepper and radish during the growing period, such as total amount of evapotranspiration, coefficent of evapotranspiration at each growth stage, the peak stage of evapotranspiration, the maximum ten day evapotranspiration , optimum irrigation point, total readily available moisture and intervals of irrigation date. The plots of experiment were arranged with split plot design which were composed of two factors, irrigation point for main plot and soil texture for split plot, and three levels ; irrigation point with pH1.7-2.0, pF2.1-2.4 and pF2.5-2.8, at soil texture of sandy soil, sandy loam and silty clay for both red pepper and radish, with two replications. The results obtained are summarized as follows. 1.1/10 exceedance probability values of maximum total pan evaporation during growing period for red peppr and radish were shown as 663.6 mm and 251.8 mm. respectively, and those of maximum ten day pan evaporation for red pepper and radish, 67.1 mm and 46.9 mm, respectively. 2.The time that annual maximum of ten day pan evaporation can he occurred, exists at any stage between the middle of May and the late of August for red pepper, and at any stage between the late of August and the late September for radish. 3.The magnitude of evapotranspiration and its coefficient for red pepper was occurred large in order of pF1.7-2.0 pF2.1-2.4 and pF2.5~2.8 in aspect of irrigation point and the difference in the magnitude of evapotranspiration and of its coefficient between levels of irrigation point was difficult to be found out due to the relative increase in water consumption resulted from large flourishing growth at the irrigation point in lower water content for radish. In aspect of soil texture they were appeared large in order of sandy loam, silty clay and sandy soil for both red pepper and radish. 4.The magnitude of leaf area index was shown large in order of pF2.1-2.4, pF2.5-2.8, and pFl.7-2.0, for red pepper and of pF2.5-2.8, pF2.1-2.4, pFl.7-2.0 for radish in aspect of irrigation point, and large in order of sandy loam, silty clay, sandy soil for both red pepper and radish in aspect of soil texture 5.1/10 exceedance probability value of evapotranspiration and its coefficient during the growing period for red pepper were shown as 683.5 mm and 1.03, respectively, while those of radish, 250.3 mm and 0, 99. respectively. 6.The time that the maximum evapotranspiration of red pepper can be occurred is in the middle of August around the date of ninetieth to hundredth after transplanting, and the time for radish is presumed to be in the late of September, around the date of thirtieth to fourtieth after sowing. At that time, 1/10 exceedance probability value of ten day evapotranspiration and its coefficient for red pepper is assumed to be 81.8 mm and 1.22, respectively, while those of radish, 49, 7 mm and 1, 06, respectively. 7.Optimum irrigation point for red pepper on the basis of the yield of raw matter is assumed to be pFl.7-2.0 for sandy soil, pF2.5-2.8 for sandy loam, and pF2.1-2.4 for silty clay. while that for radish is appeared to be pF2.5-2.8 in any soil texture used. 8.The soil moisture extraction patterns of red pepper and radish have shown that maximum extraction rates exist at 7 cm deep layer at the beginning stage of growth in any soil texture and that extraction rates of 21 cm to 35 cm deep layer are increased as getting closer to the late stage of growth. And especially the extraction rates have shown tendency to be greatest at 21cm deep layer from the most flourishing stage of growth for red pepper and at the last stage of growth for radish. 9.The total readily available moisture on the basic of the optimum irrigation point become 3.77-8.66 mm for sandy soil, 28.39-34.67 mm for sandy loam and 18.40-25.70 mm for silty clay for red pepper of each soil texture used but that of radish that has shown the optimum irrigation point of pF2.5-2.8 in any soil texture used. 12.49-15.27 mm for sandy soil, 23.03-28.13 mm for sandy loam, and 22.56~27.57 mm for silty clay. 10.On the basis of each optimum irrigation point. the intervals of irrigation date at the growth stage of maximum consumptive use of red pepper become l.4 days for sandy soil, 3.8 days for sandy loam and 2.6 days for silty clay, while those of radish, about 7.2 days.

• Magazine of the Korean Society of Agricultural Engineers
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• v.11 no.4
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• pp.1775-1782
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• 1969

The results of the study on the consumptine use of irrigated water in paddy fields during the growing season of rice plants are summarized as follows. 1. Transpiration and evaporation from water surface. 1) Amount of transpiration of rice plant increases gradually after transplantation and suddenly increases in the head swelling period and reaches the peak between the end of the head swelling poriod and early period of heading and flowering. (the sixth period for early maturing variety, the seventh period for medium or late maturing varieties), then it decreases gradually after that, for early, medium and late maturing varieties. 2) In the transpiration of rice plants there is hardly any difference among varieties up to the fifth period, but the early maturing variety is the most vigorous in the sixth period, and the late maturing variety is more vigorous than others continuously after the seventh period. 3) The amount of transpiration of the sixth period for early maturing variety of the seventh period for medium and late maturing variety in which transpiration is the most vigorous, is 15% or 16% of the total amount of transpiration through all periods. 4) Transpiration of rice plants must be determined by using transpiration intensity as the standard coefficient of computation of amount of transpiration, because it originates in the physiological action.(Table 7) 5) Transpiration ratio of rice plants is approximately 450 to 480 6) Equations which are able to compute amount of transpiration of each variety up th the heading-flowering peried, in which the amount of transpiration of rice plants is the maximum in this study are as follows: Early maturing variety ; Y=0.658+1.088X Medium maturing variety ; Y=0.780+1.050X Late maturing variety ; Y=0.646+1.091X Y=amount of transpiration ; X=number of period. 7) As we know from figure 1 and 2, correlation between the amount evaporation from water surface in paddy fields and amount of transpiration shows high negative. 8) It is possible to calculate the amount of evaporation from the water surface in the paddy field for varieties used in this study on the base of ratio of it to amount of evaporation by atmometer(Table 11) and Table 10. Also the amount of evaporation from the water surface in the paddy field is to be computed by the following equations until the period in which it is the minimum quantity the sixth period for early maturing variety and the seventh period for medium or late maturing varieties. Early maturing variety ; Y=4.67-0.58X Medium maturing variety ; Y=4.70-0.59X Late maturing variety ; Y=4.71-0.59X Y=amount of evaporation from water surface in the paddy field X=number of period. 9) Changes in the amount of evapo-transpiration of each growing period have the same tendency as transpiration, and the maximum quantity of early maturing variety is in the sixth period and medium or late maturing varieties are in the seventh period. 10) The amount of evapo-transpiration can be calculated on the base of the evapo-transpiration intensity (Table 14) and Tablet 12, for varieties used in this study. Also, it is possible to compute it according to the following equations with in the period of maximum quantity. Early maturing variety ; Y=5.36+0.503X Medium maturing variety ; Y=5.41+0.456X Late maturing variety ; Y=5.80+0.494X Y=amount of evapo-transpiration. X=number of period. 11) Ratios of the total amount of evapo-transpiration to the total amount of evaporation by atmometer through all growing periods, are 1.23 for early maturing variety, 1.25 for medium maturing variety, 1.27 for late maturing variety, respectively. 12) Only air temperature shows high correlation in relation between amount of evapo-transpiration and climatic conditions from the viewpoint of Korean climatic conditions through all growing periods of rice plants. 2. Amount of percolation 1) The amount of percolation for computation of planning water requirment ought to depend on water holding dates. 3. Available rainfall 1) The available rainfall and its coefficient of each period during the growing season of paddy fields are shown in Table 8. 2) The ratio (available coefficient) of available rainfall to the amount of rainfall during the growing season of paddy fields seems to be from 65% to 75% as the standard in Korea. 3) Available rainfall during the growing season of paddy fields in the common year is estimated to be about 550 millimeters. 4. Effects to be influenced upon percolation by transpiration of rice plants. 1) The stronger absorbtive action is, the more the amount of percolation decreases, because absorbtive action of rice plant roots influence upon percolation(Table 21, Table 22) 2) In case of planting of rice plants, there are several entirely different changes in the amount of percolation in the forenoon, at night and in the afternoon during the growing season, that is, is the morning and at night, the amount of percolation increases gradually after transplantation to the peak in the end of July or the early part of August (wast or soil temperature is the highest), and it decreases gradually after that, neverthless, in the afternoon, it decreases gradually after transplantation to be at the minimum in the middle of August, and it increases gradually after that. 3) In spite of the increasing amount of transpiration, the amount of daytime percolation decreases gadually after transplantation and appears to suddenly decrease about head swelling dates or heading-flowering period, but it begins to increase suddenly at the end of August again. 4) Changs of amount of percolation during all growing periods show some variable phenomena, that is, amount of percolation decreases after the end of July, and it increases in end August again, also it decreases after that once more. This phenomena may be influenced complexly from water or soil temperature(night time and forenoon) as absorbtive action of rice plant roots. 5) Correlation between the amount of daytime percolation and the amount of transpiration shows high negative, amount of night percolation is influenced by water or soil temperature, but there is little no influence by transpiration. It is estimated that the amount of a daily percolation is more influenced by of other causes than transpiration. 6) Correlation between the amount of night percoe, lation and water or soil temp tureshows high positive, but there is not any correlation between the amount of forenoon percolation or afternoon percolation and water of soil temperature. 7) There is high positive correlation which is r=+0.8382 between the amount of daily percolation of planting pot of rice plant and amount and amount of daily percolation of non-planting pot. 8) The total amount of percolation through all growin. periods of rice plants may be influenced more from specific permeability of soil, water of soil temperature, and otheres than transpiration of rice plants.