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구자웅 한국농공학회 1977 한국농공학회논문집 Vol.19 No.3
In order to estimate furture consumtive use, some statistical characteristics of 22-year pan evaporation data at four selected stations were calculated in this study. Districal distribution, trend analysis and time-series, statistical and periodic analysis for annual, monethly and ten-day values were performed in the statistical analysis. The stations are Seoul, Taeku, Jeonju and Mokpo for monthly data, and Suweon data are compared to the reported Penman values. The results are as followed: 1. Annual evaporation ranged to 990-1,375mm varying with the locations of the stations. The Districal distribution of evaporation in the Republic is shown in Fig. 1. 2. The trend analysis for annual evaporation resulted in detail in Table 2 and Fig. 2, through simple moving average methods. The results show relatively short-period data of about 10 years would be acceptable for field use. 3. The means and dispersions of monthly evaporation at four stations are detailed in Table 3. 4. The monthly evaporation approached to the trend of normal distribution Fig. 3 showed the examples of normal distribution for each typical monthly data. 5. The correlograms detailed in Fig. 4, shows the time-series characteristics of monthly evaporation, whose periodic term should be twelve months. 6. The periodic analysis for monthly evapolation results in Table 4. Fig. 5 shows the comparison of estimated values to actual and the trend approaches Shuster's periodic trend. 7. A periodic description of days after March 1 for irrigation periods was developed to predict ten-day evaporation in Fig. 6. The ten-day etraporation is different in the distribution form and occurence period of maximum values from the reported Penman's man's evapotranspiration.
구자웅,은종호 한국농공학회 1988 한국농공학회논문집 Vol.30 No.4
This laboratory study was carried out in order to produce fundamental data for analyzing salt movement and desalinization effects, using samples of silt loam soil collected in Gyehwado and Daeho reclaimed tidelans, and samples of silty clay loam soil collected in Kimie tideland. Desalinization experiments with gypsum treatment were performed to analyze changes of the hydraulicc conductivity with changes of the soil property and the salt concentration during the desalinization of reclaimed tideland soils by leaching through the subsufface drainage, and correlations between factors infl uencing the reclamation of salt affected soils were analyzed by the statistical method. The results were summarized as follows: 1. The reclaimed tideland soils used in this study were saline-sodic soils with the high exchangeable sodium percentage and the high electrical conductivity. 2. Changes of the hydraulic conductivity with the amount of leaching water and the leaching time elapsed were affected by the amount of gypsum except exchangeable sodium and clay contents. The regression equation between the depth of water leached per unit depth of soil (Dw / Ds : X) or the square root of the leaching time elapsed (T $^1$ $^2$ : X) and the relative hydraulic conductivity (HCr:Y) could be expressed in Y=a . bx. 3. The more exchangeable sodium and clay contents regardless of the amount of gypsum, the more the leaching time was required until a given volume of water was leached through the soil profile. The regression analysis showed that the relationship between the depth of water leached per unit depth of soil(Dw /Ds:X) and the square root of the leaching time elapsed(T$^1$$^2$ :Y) could be described by Y=a . Xb. 4. The hydraulic conductivity was influenced to a major degree by the salt concentration provided that the electrical conductivity was below 10 mmhos / cm during the desalinization of reclaimed tideland soils. The regression equation between the relative electrical conductivity ( ECr : X) and the relative hydraulic conductivity (HCr:Y) could be expressed in Y=a + b . X-$^1$. 5. In conclusion, the hydraulic conductivity, leaching requirements and the leaching time elapsed can be estimated when the salt concentration decreases to a certain level during the desalinization of reclaimed tidelands, and the results may be applied to the analysis of salt movement and desalinization effects.
간척지토양의 제염과정중 전기전도도와 치환성 나트륨 백분율 및 pH 사이의 관계
구자웅,은종호 한국농공학회 1988 한국농공학회논문집 Vol.30 No.4
This study was performed to obtain the basic data analyzing salt movement and desalinization effects, and two different desalinization experiments through leaching and rinsing were carried out, using samples of silt loam soil and silty clay loam soil collected in reclaimed tidelands. The relationships between the electrical conductivity of saturation extract and the electrical conductivity at various dilutions, and the correlations between electrical conductivity, total salt concentration, exchangeable sodium percentage and pH during the desalinization of reclaimed tidelands, were analyzed by the statistical method. The results obtained from this study were summarized as follows: 1.The sample soils used in this study were saline-sodic soils in accordance with the USDA classi- fication system of salt affected soils. 2.The electrical conductivity of saturation extract could be estimated conveniently, using the electrical conductivity of extract from various different soil-water suspensions. 3.The total salt concentration could be expressed in the electrical conductivity, but there was a little difference by soil textures. 4.The regression analysis showed that the relationship between the electrical conductivity of saturation extract and the exchangeable sodium percentage during the desalinization of reclaimed lands could be described by a linear regression equation. 5.The value of pH showed a tendency to increase according as the exchangeable sodium percentage decreased during the desalinization of reclaimed tidelands.