강민구 Kang Min Goo

DOI: JKWST Vol.56(No.2) 1-9, 2014

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A modeling system is constructed by integrating an one-dimensional unsteady flow simulation model and a hydrologic model to simulate flood flows in drainage channel networks of paddy field districts. The modeling system's applicability is validated by simulating flood discharges from a paddy field district, which consists of nine paddy fields and one drainage channel. The simulation results are in good agreement with the observed. Particularly, in the verification stage, the relative errors of peak flows and peak depths between the observed and simulated hydrographs range 8.96 to 10.26 % and －10.26 to 2.97 %, respectively. The modeling system's capability is compared with that of a water balance equation-based model; it is revealed that the modeling system's accuracy is superior to the other model. In addition, the simulations of flood discharges from large-sized paddy fields through drainage channels show that the flood discharge patterns are affected by drainage outlet management for paddy fields and physical characteristics of the drainage channels. Finally, it is concluded that to efficiently design drainage channel networks, it is necessary to analyze the results from simulating flood discharges of the drainage channel networks according to their physical characteristics and connectivities.

남원호 Nam Won-ho , 홍은미 Hong Eun-mi , 최진용 Choi Jin-yong

DOI: JKWST Vol.56(No.2) 11-23, 2014

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The impact and adaption on agricultural water resources considering climate change is significant for reservoirs. The change in rainfall patterns and hydrologic factors due to climate change increases the uncertainty of agricultural water supply and demand. The quantitative evaluation method of uncertainty based on agricultural water resource management under future climate conditions is a major concern. Therefore, it is necessary to improve the vulnerability management technique for agricultural water supply based on a probabilistic and stochastic risk evaluation theory. The objective of this study was to analyse the uncertainty of water resources under future climate change using probability distribution function of water supply in agricultural reservoir and demand in irrigation district. The uncertainty of future water resources in agricultural reservoirs was estimated using the time-specific analysis of histograms and probability distributions parameter, for example the location and the scale parameter. According to the uncertainty analysis, the future agricultural water supply and demand in reservoir tends to increase the uncertainty by the low consistency of the results. Thus, it is recommended to prepare a resonable decision making on water supply strategies in terms of using climate change scenarios that reflect different future development conditions.

임성윤 Lim Seong-yoon

DOI: JKWST Vol.56(No.2) 25-35, 2014

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New technology and construction methods in civil engineering area have been noticeably improved associated with the industrial development. However, thicknesses of a lift is strictly specified for subgrade and roadbed embankment as 20 cm and 30 cm in the specification of Korea Highway. Since there has been a problem to get enough amount of soils to be used for compaction, the rocks have been replaced for those. However, there is no guideline for the quality control of rock while changing compaction efficiency of equipment and physical properties of reck while changing compaction method such as thicknesses of a lift, number of compaction and etc. The main objective of this research is to establish the specification for the rock compaction method of embankment which including thickness of lift and quality control method in Korea Expressway.

홍은미 Hong Eun Mi , 최진용 Choi Jin-yong , 남원호 Nam Won Ho , 강문성 Kang Moon-seong , 장정렬 Jang Jeong-ryel

DOI: JKWST Vol.56(No.2) 37-46, 2014

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Water for crop growth were supplied by irrigation in protected cultivation and these are accumulated in the soil and utilized for crop evapotranspiration. The study for analyzing soil moisture characteristics is necessary for adequate irrigation water and soil water management in protected cultivation. Soil moisture content, irrigation water quantity and meteorological data were monitored to analyze soil moisture increment and extraction characteristics in terms of soil layers and cucumber crop growth stages. In first cropping period, the total amount of irrigation water was 5.07 mm/day, soil moisture increment was 4.82 mm/day and soil moisture extraction was 5.56 mm/day. In second cropping period, the total amount of irrigation water was 4.82 mm/day, soil moisture increment was 4.65 mm/day and soil moisture extraction was 4.73 mm/day. Soil moisture extraction rate from 0 to 75 cm is 90.3 % in first cropping period and 79.1 % in second cropping period. The majority irrigation water were consumed in root zone, however, about 15 % of soil moisture were losses by infiltration in lower soil layer. Soil moisture extraction and extraction pattern of cucumber crop calculated in this study can be utilized as a basic data for irrigation water management in protected cultivation.

신민환 Shin Min Hwan , 장정렬 Jang Jeong Ryeol , 원철희 Won Chul Hee , 금동혁 Kum Dong Hyuk , 정영훈 Jung Young Hun , 이수인 Lee Su In , 임경재 Lim Kyoung Jae , 최중대 Choi Joong Dae

DOI: JKWST Vol.56(No.2) 47-57, 2014

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This study was conducted to predict greenhouse gas (GHG) emission from paddy by future climate change scenario in Korea. Chuncheon city in Kangwon province were selected as study area. A1B Special Report on Emission Scenario (SRES) of the IPCC (Intergovernmental panel on climate change) was used to assess the future potential climate change. The rainfall and temperature was projected to increase by 8.4 % and 1.9 % (2040s), 35.9 % and 27.0 % (2060s), 19.2 % and 30.8 % (2090s), respectively, compare to the 2010s value. Under the climate change, Denitrification-Decomposition (DNDC) predicted an increase in N₂O, CO₂ and CH₄ emissions from paddy. The simulations resulted in annual net emissions of 0.4～2.4, 500.5～734.5 and 29.4～160.4 kg/ha/year of N₂O-N, CH₄-C and CO₂-C, respectively, with a cumulated global warming potential (GWP) of 14.5～21.7 t · CO₂/ha/year were affected by rainfall, temperature, manure amendment and fertilizer amount. The simulation results suggested that implementation of manure amendment or reduction of water consumption instead of increased fertilizer application rates would more efficiently mitigate GHG emissions.

이달원 Lee Dal Won , 노재진 Noh Jae Jin

DOI: JKWST Vol.56(No.2) 59-64, 2014

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In this study, the large scale test was performed to investigate the behavior of failure for the embankment and spillway transitional zone by overtopping. The pore water pressure, earth pressure, settlement and failure pattern of covering embankment with geotextile were compared and analyzed. The pore water pressure showed a small change in the spillway transition zone and core, indicating that the geotextile efficiently reinforced the embankment. The earth pressure decreased the infiltration of the pore water only in inclined cores type to secure local stability. The behavior of failure started from the bottom and gradually progressed upwards. After the intermediate overtopping period (100 min), width and depth of the seepage erosion were very small due to the effect of geotextile which delayed failure. Therefore, the reinforced method by geotxtile was a very effective method to respond to the emergency due to overtopping.