• Journal of The Korean Society of Agricultural Engineers
• /
• v.51 no.4
• /
• pp.43-47
• /
• 2009

Soil aggregation is an important part of influencing the soil behaviors in reducing rainfall-runoff and soil erosion, aeration, infiltration, and root penetration. Some inorganic materials such as clay minerals, Fe and Al oxides/hydroxides, and calcium carbonate can act as cementing agents within macroaggregates. The objective of this study was to determine the effects of different cementing agents (Fe, Mn, and Al) on soil aggregate formation in reclaimed tidelands. Water stable aggregate ratio and MWD (mean weight diameter) were higher in iron dioxides treatment than two other treatments. This result indicates significant correlation between soil aggregate formation and iron dioxides.

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.14 no.5
• /
• pp.69-79
• /
• 2011

This study assessed the subsurface runoff and peak flow reduction in rain gardens. The results showed that the highest water retention was found in rain garden mesocosms in which Rhododendron lateritium and Zoysia japonica were planted, followed by mesocosms in which either R. lateritium or Z. japonica was planted, and the lowest water retention rate was found in non-vegetated control treatment mesocosms(${\alpha}$ < 0.05). Although higher rainfall intensity caused a decrease of peak flow reduction in both vegetated and non-vegetated treatments, peak flow reduction was the greatest in mesocosms with mixed plants. A rain garden can be an effective tool for environment-friendly stormwater management and improving ecological functions in urban areas. Depending on the purpose such as delaying runoff or increasing infiltration, various plant types should be considered for rain garden designing.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2009.03a
• /
• pp.299-307
• /
• 2009

New lake dike in Saemanguem area is 125km length and require a great amount of fill materials, but it's difficult to get the amount of materials and develop a quarry because of environment conservation. Therefore, the solution is to use the dredged soil in project area as the fill materials not to develop quarry. However, characteristic of dredged soil as a silty fined sand is very weak at seepage, sliding, erosion of dike due to infiltration of rainfall, wind etc. So, lake dike using dredged soil must be constructed safely against the unstable problem of dredged sand. The objective of research is to make safe lake dike using dereged soil on construction of Saemangeum new lake dike. So, we analyzed the characteristic of dredged soil and suggested a standard section of lake dike.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.40 no.1
• /
• pp.88-95
• /
• 1998

Salt accumulation is frequently experienced in soils under protected cultivation. Since protected cultivation does not bave rainfall and resulting infiltration, salt accumulation in the soils is inevitable. In this study, analyzed were chemical characteristics 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 Ansung-Gun, Gyungki-Do and analyzed for electrical conductivity, PH, organic matter contents. The results showed that there was no significant trend of changes in electrical conductivity and pH along cultivation years. The only factor influencing salt acculmuation was irrigation type. Soils in facilities using drip irrigation showed higher electrical conductivity than these using diversion-hose type irrigation.

• Journal of the Korean Geotechnical Society
• /
• v.16 no.5
• /
• pp.107-116
• /
• 2000

강우에 의한 얕은 사면파괴는 우리 나라에서 흔히 볼수 있는 사면파괴의 형태이다. 본 연구에서는 재현기간에 따른 강우강도와 지속시간을 고려한 한계평형법에 의하여 이러한 얕은 사면파괴의 가능성을 평가하기 위함 방법에 대하여 논의하였다. 이를 위해 일차원 침투모델인 Green-Ampt 모델에 바탕을 둔 두 방법을 고려하였다. 즉 침투능에 따른 침투깊이를 산정하는 Pradel과 Raad의 방법과 일정한(uniform) 강우강도가 작용할 경우 폰딩(ponding)에 대해 해를 주는 Mein과 Larson의 방법을 고려하여 함수특성이 알려진 화강풍화토사면에 적용하였다. 연구결과에 의하며 Pradel과 Raad 방법은 실제 적용된 강우강도가 아닌 침투능을 바탕으로 침투깊이를 산정하므로 Mein과 Larson 방법에 비해 보수적인 사면안정 해석결과를 예측한다.

• Journal of Korea Water Resources Association
• /
• v.37 no.3
• /
• pp.249-255
• /
• 2004

To investigate the return flow ratio of irrigation water, lots of observations were made during the irrigation periods in 2003 crop year. This Area is a portion of Dae-Am pumping station basin which is located in Changryung-gun, Gyeongnam province. A water balance analysis was performed for a paddy field in Dae-Am pumping station in the Nakdong river basin, which is constructed for irrigation water supply. Daily rainfall data in the this area were collected and irrigation water flow rate, drainage water flow rate, infiltration and evaportranspiration were measured in field area. Irrigation water flow rate and drainage water flow rate were continuously observed by water level logger(GTDL-L10) during the growing season. The infiltration and evaportranspiration were measured by cylindrical 300mm depletion meter and cylindrical 200mm infiltrometer, respectively. Total irrigation and drainage flows were 654.7mm and 281.2mm in 2003. Total infiltration and evaportranspiration were 36.0mm and 160.0mm respectively. The mean of the daily evaportranspiration rate was 4.3mmm/d. The prompt return flow and retard return flow ratio were 43.0％ and 5.5％, respectively. Total return flow ratio was 48.5％. Therefore, it can be concluded that the amount of irrigation water was much higher than design standard or reference in this study. It means that this was caused by the inadequate water management practice in the area where water was oversupplied on farmers' request rather than following sound water management principles, and design standard should be changed in the future.

• Journal of Soil and Groundwater Environment
• /
• v.17 no.2
• /
• pp.37-46
• /
• 2012

This study was conducted to identify groundwater recharge and discharge amounts of a representative urban-rural composite area located in Yongin city, Kyounggi-do, Korea. Groundwater recharge would be affected by mainly two processes in the study area: rainfall and leakage from public water pipelines including water-supply and sewage system. Groundwater recharge rate was estimated to be 13.5% by applying annual groundwater level data from two National Groundwater Monitoring Stations to the master regression curve method. Subsequently, the recharge amounts were determined to be $13,253{\times}10^3m^3/yr$. Leakage amounts from water-supply and sewage system were estimated to be $3,218{\times}10^3$ and $5,696{\times}10^3m^3/yr$, respectively. On the whole, a total of the recharge amounts was $22,167{\times}10^3m^3/yr$, of which 60% covers rainfall recharge and 40% pipeline leakage. Groundwater discharge occurred through three processes in the composite area: baseflow, well pumping, and discharge from urban infrastructure including groundwater infiltration into sewage pipeline and artificial extraction of groundwater to protect underground facilities from submergence. Discharge amounts by baseflow flowing to the Kiheung agricultural reservoir and well pumping were estimated to be $382{\times}10^3$ and $1,323{\times}10^3m^3/yr$, respectively. Occurrence of groundwater infiltration into sewage pipeline was rarely identified. Groundwater extraction amounts from the Bundang subway line as an underground facility were identified as $714{\times}10^3m^3/yr$. Overall, a total of the discharge amounts was determined to be $2,419{\times}10^3m^3/yr$, which was contributed by 29% of artificial discharge. Even though groundwater budget of the composite area was identified to be a surplus, it should be managed for a sound groundwater environment by changing deteriorated pipelines and controlling artificial discharge amounts.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.2
• /
• pp.404-411
• /
• 2019

In this study, the HEC-HMS was applied to determine rainfall-runoff processes for the Gokgyuchun basin. Several sub-basins have large-scale reservoirs for agricultural needs and they store large amounts of initial runoff. Three infiltration methods were implemented to reflect the effect of initial loss by reservoirs: 'SCS-CN'(Scheme I), 'SCS-CN' with simple surface method(Scheme II), and 'Initial and Constant rate'(Scheme III). Modeling processes include incorporating three different methods for loss due to infiltration, Clark's UH model for transformation, exponential recession model for baseflow, and Muskingum model for channel routing. The parameters were calibrated using an optimization technique with trial and error method. Performance measures, such as NSE, RAR, and PBIAS, were adopted to aid in the calibration processes. The model performance for those methods was evaluated at Gangcheong station, which is the outlet of study site. Good accuracy in predicting runoff volume and peak flow, and peak time was obtained using the Scheme II and III, considering the initial loss, whereas Scheme I showed low reliability for storms. Scheme III did not show good matches between observed and simulated values for storms with multi peaks. Conclusively, Scheme II provided better results for both single and multi-peak storms. The results of this study can provide a useful tool for decision makers to determine master plans for regional flood control management.

• Journal of Korea Water Resources Association
• /
• v.52 no.3
• /
• pp.219-226
• /
• 2019

Recently, research about Low-Impact Development (LID) techniques has been expanded due to problems with the effects of climate change and urbanization that have been increasing. LID technology is used to control flood damage environmentally to reduce runoff and is reduce runoff on city also restore into previous water circulation system from present developed city. However, studies about quantitative data of LID techniques are insufficient. Therefore in this study, the Curve Number (CN) was calculated with the Planter Box, which is storage type LID technology to conduct the water circulation (infiltration, runoff, overflow) analysis. Rainfall intensity scenario (60.4 mm/hr, 83.1 mm/hr, 97.4 mm/hr, 108.2 mm/hr) about water circulation analysis of Planter Box is selected on the basis of probable rainfall intensity table. According to the experimental results, the storage rate of rainwater in Building Planter Box and Street Planter Box was 43.5% to 52.9% and 33.4% to 39%, respectively. In addition, CN value is estimated to 83 at the Planter box and the runoff reduction effect by applying Horton's infiltration capacity curve showed on 51% to 98%.

• Journal of the Korean Geotechnical Society
• /
• v.35 no.5
• /
• pp.31-41
• /
• 2019

This paper demonstrates safety factor for effective planning at initial stage by utilizing results on changes of safety factor according to various conditions of slop and examines impacts of factors that affect slope safety factors as well. Firstly, it describes shear strength which satisfies minimum allowable safety factor: 1.20 depending on height and slope. As the height increases by 5.0 m, the safety factors decrease by 0.04 while it tends to consistently reduce by approximately 20%, 30% and 40% after height goes to 10.0 m. As slope reduces by about 0.3, the safety factors increases by 0.4, which shows the rate of safety factors on slope grows by about 10%, 20% and 30% on lowering slope. When cohesion goes up by 10.0 kPa the safety factors increases by around 40% respectably while the angle of internal friction grows by $5^{\circ}$, it increases by about 8%. The rate of safety factors is identified as $Fs=3.86H^{-0.59}$, Fs = 0.43 s, Fs = 0.04 c, $Fs=0.02{\phi}$ depending on height, slope and shear strength. The safety factor with rainfall infiltration tends to increase by 18% compared to the condition of saturated surface on earth.