• Magazine of the Korean Society of Agricultural Engineers
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• v.31 no.1
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• pp.71-81
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• 1989

Soil erosion was investigated to find out difference in amount of soil eroded from slope land at early stage of young grasses and at later stage with sufficient cover with different slopes. The six experimental plots were formed on 8$^{\circ}$, 10$^{\circ}$, 15$^{\circ}$, 20$^{\circ}$, and 25$^{\circ}$, with 2m width and 20m length located at the Hwak Kok Ri, Chun Sung Gun, Kang Weon Do. The amount of soil eroded and run-off were collected from 1. May 1987. to 30. October 1988, growing with grasses sowed 2. September 1987. The results were as follows : 1. The amount of soil eroded from the plots except 8$^{\circ}$ plot exceeded the allowable soil erosion with 14 ton/ha during the land formuing before establishment of sufficient surface cover with grasses. Therefore, proper soil conservation practice should be recommeneed. 2. The amount of soil eroded increased exponentially with increased slope as 1.24 times for 15$^{\circ}$1.65 times for 20*, and 2.94 times for 25$^{\circ}$, m comparing with standared 10$^{\circ}$ polt. 3. The erosion occurred mainly by high density of rainfall exceeding lOOmm as consecutive precipitation during the raining peried or accompanied by typhoon passing. 4. The significant soil erosion, when the land covering ratio was over 95% after seeding of grass, was recorded only by the single continuous storms over lOOmm of concentrated precpitation, of which amounts were 1/73~/250 of the allowable soil erosion. 5. The amount of soil erosion from the plots with sufficient surface cover with grasses increased as the slope increased however the amounts were small enough to be neglected. 6. Desolation by soil erosion would be minor problem up to the slope of 20$^{\circ}$ when the mountainous area developed to the grassland with sufficient cover. But it could be concerned on the turn to the hare land by the treading of livestocks with the land slope over 25$^{\circ}$. 7. The run-off of rainfall increased by the increament of slope but it was not exponentially increased. 8. The run-off of rainfall after seeding of grass reduced by 20% in comparison with the run-off of rainfall before seeding, which might be due to infiltration of rainfall promoted by the grass roots.

• Journal of Korea Water Resources Association
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• v.38 no.8 s.157
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• pp.605-616
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• 2005

In this paper, runoff curve numbers (CN's) for a small forested mountainous catchment are estimated using rainfall-runoff data measured at Sulma experimental catchment every 10 minutes and a new guideline for applying the antecedent rainfall conditions (ARC's) for small mountainous watersheds in Korea is proposed. Sulma experimental catchment is a typical natural mountainous basin with $97\%$ of forested land cover and CN's are estimated to be in the range between 51 and 89 with median value of 72. The test hypothesis stating as 1-day ARC is better than 5-day ARC in determining CN's for a small mountainous watershed is shown to be acceptable. Also, linear regression equations for the estimation of CN's for small mountainous catchments are proposed. As there is no significant investigations available on CN's for small mountainous catchments, the newly proposed relationships between CN's and ARC may be used as a preliminary guideline to assign CN's for the estimation of floods from rainfall data on mountainous regions.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2004.04a
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• pp.459-462
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• 2004

This study assesses groundwater vulnerability to contaminants in 12 administrative districts of the city of Changwon, using DRASTIC technique. DRASTIC was originally applied to situations in which the contamination sources are at the ground surface, and the contaminants flow into the groundwater with infiltration of rainfall. However, groundwater contamination in urban areas can also be related to excessive pumping resulting in a lowering of the water level. The correlation coefficient between minimum DRASTIC indices and the degree of poor water quality for 10 districts is low as 0.40. The correlation coefficients between minimum DRASTIC indices and the groundwater discharge rate, and between minimum DRASTIC indices and well density per unit area are 0.70 and 0.87, respectively. Thus, to evaluate the potential of groundwater contamination in urban areas, it is necessary to consider other factors such as groundwater withdrawal rate and well density per unit area with ratings and weights as well as the existing six DRASTIC factors.

• Journal of Korean Society of Water and Wastewater
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• v.10 no.1
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• pp.69-77
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• 1996

To evaluate the change of the groundwater flow and the water table response resulting from urbanization, two cases of the transient three-dimensional numerical simulations were performed. Variations of the groundwater flow system caused by withdrawals were analyzed. Two cases of infiltration rates were applied in this study to verify the water table changes. One is the rate under the circumstance during 1994 and the other is the revised rate. The numerical results from this study indicated that groundwater flow was influenced by human impacts. Groundwater flow has been concentrated to Taegu Textile Complex area where had large amount of pumping. Water table so far decreased -2.76m a year due to withdrawals. Water tables of many points were increased more than 30cm when the surface was reformed by infiltrating the rainfall. It was appeared that the improvement of surface to recharge the precipitation was very important to preserve and manage for the groundwater.

• Water for future
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• v.12 no.1
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• pp.56-59
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• 1979

A prompt subsurface runoff producing mechanism whih creaters a depletion curve of direct runoff hydrograph is simulated by a dead zone dispersion model technique. Runoff processes are carried out by routing of the outflow resulted from previous linear channel and effective rainfall from its corresponding subwatershed through a series of conceptual linear channels representing subwatersheds of a catchment. Working rules are explained for evaluation the model parameters such as translatory velocity, diffusive factor, and parameters concerning the infiltration and relative magnitude of the prompt subsurface flow region.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 1998.10a
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• pp.237-242
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• 1998

Salt accumulation is frequently experienced in soils under protected cultivation. Since protected cultivation does not have rainfall and resulting infiltration, salt accumulation in the soils is inevitable. In this study, analyzed were chemical charecteristics of soils under protected cultivation to investigate the factors which may contribute the salt accumulation. Soil samples were collected from 99 protected cultivation facilities around An-sung Gun, Gyungki-Do and analyzed for electrical conductivity, pH, organic matter con-tents. The results showed that there was no significant trend of changes in electrical conductivity and pH along cultivation years. the only factor influencing salt accumulation was irrigation type. Soils in facilities using drip irrigation showed higher electrical conductivity than those using diversion-hose type irrigation.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2002.10a
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• pp.477-480
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• 2002

The purpose of this study Was to investigate the effects of ponding depth treatment on water balance in paddy fields. Three ponding depth treatment, shallow, traditional, and deep were used. Daily values of rainfall amount, ponding depth, irrigation water, drainage water, evapotranspiration, and infiltration were measureed in the field. The results showed that irrigation water depths were 198mm, 195mm, and 355mm in shallow, traditional, and deep ponding, respectively. The three treatments did not show any statistical difference in growth and yields. Shallow depth treatment showed the largest yield.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2003.10a
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• pp.263-266
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• 2003

The purpose of this study is to investigate the effects of ponding depth treatment on water balance in paddy fields. The ponding depth treatments were very shallow, shallow and deep. Daily values of rainfall amount, ponding depth, irrigation water, drainage water, evapotranspiration, and infiltration were measured in the field. The medium ponded plots saved irrigation water about 16% to 53.4% without any statistical difference in rice growth and yields. Hence, the medium ponded depth treatment is better than the traditional deep ponded depth to save water in the transplanted rice culture.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1408-1411
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• 2005

The purposes of daily cover are to control odor and volatile organic compound emissions, to control litters, to mitigate rainfall infiltration. Under usual operation of landfill, the soil layer of 15cm thick is used for daily cover, but about $20{\sim}$25% of landfill capacity is consumed by daily cover volume. Considering our limited land and difficulty in getting landfill site, developing an alternative daily cover material which usually occupies much less volume than soil will be very significant. Also, if we can use waste material for alternative daily cover, we can get additional benefit of recycling waste.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.387-391
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• 2011

국내에서 사면 붕괴의 직접적인 원인은 강우에 의한 것으로 볼 수 있으며, 강우침투에 따른 지하수위 상승과 간극수압 증가, 강우강도 크기에 직접적으로 영향을 받는 지표면 유출로 인한 사면의 표면토사 유출 및 얕은 사면붕괴로 나타난다. 본 연구에서는 강우로 인한 지반내 침투로 불포화토가 포화토로 변화는 과정에서 침투능을 산정하고자 기존의 침투공식을 검토하고 TDR 센서를 이용한 실내실험을 통한 침투능 산정공식을 제시하였다. 제시한 침투능 산정공식을 검증하기 위한 침투실험을 수행하여 결과를 비교 분석하였으며, 이론적 해석 및 실내실험에 의한 결과는 다음과 같다. 첫째, 포화도 변화에 따른 TDR데이터 변화는 일정했으며 이를 회귀분석을 통하여 함수화하였고, 이 함수를 이용하여 지반의 포화도 및 함수비를 파악할 수 있었다. 둘째, 흡인수두항과 중력수두항이 결합된 연속적인 침투능 산정공식을 새로이 유도하였으며, 이를 이용한 결과와 TDR 센서를 이용한 실험결과와 거의 유사함을 알 수 있었다.