• Title/Summary/Keyword: flooding depths

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Ecophysiology of Seed Germination in Chinese Milk Vetch (Astragalus sinicus L.)

  • Shim, Sang-In;Kang, Byeung-Hoa
    • KOREAN JOURNAL OF CROP SCIENCE
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    • v.49 no.1
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    • pp.19-24
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    • 2004
  • Germination and emergence habits of Chinese milk vetch (CMV) were examined to obtain the basic information for the effect of environmental conditions and cultural practices on the seedling density. Seed germination tests with different water potentials, temperatures, and soil and water depths showed the environmental effects on the characters related to seed germination in CMV. Imbibition under different temperatures reflects that initial velocity was rapid at higher temperature, however, the times to full imbibition were not different between 15 and $25^{\circ}$. The optimal germination temperature for CMV germination was ranged from 15 to 20 and the germination was highly affected by water potential of media at relatively high temperature above $20^{\circ}$. When the seeds were sown in flooded condition the germination was not proportionally affected by water depth. In addition, there was no correlation between water depth and oxygen concentration. The germination of seeds flooded by 2cm water depth were poorly germinated compared to other depths. Results indicated that the germination of submerged seeds was more highly influenced by flooding depth than the temperature, it was also affected more strongly at 10 than $20^{\circ}$. Emergence of CMV depending on the thickness of covered soil was poor when the soil layer was greater than 5cm. In the experiment with seeds collected between 22 days after flowering (OAF) and 52 DAF, the highest germination ability of CMV seeds was observed at 39 DAF and germinability was decreased subsequently as seeds became mature. The lower germinability may be due to the enhanced seed dormancy.

Efficient crosswell EM tomography for monitoring geological sequestration of $CO_2$

  • Lee, Ki-Ha;Kim, Hee-Joon;Song, Yoon-Ho
    • 한국지구물리탐사학회:학술대회논문집
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    • 2003.11a
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    • pp.321-327
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    • 2003
  • [ $CO_2$ ] sequestration in oil reservoirs can be one of the most effective strategies for long-term removal of greenhouse gas from atmosphere. This paper presents an advantage of the localized nonlinear approximation of integral equation solutions for inverting crosswell electromagnetic data, which are observed as a part of pilot project of $CO_2$ flooding at the Lost Hills oil field in central California, U.S.A. To monitor the migration of $CO_2$, we have used 2-D cylindrically symmetric and 2.5-D tomographic inversion methods. These two schemes produce nearly the same images if the borehole separation is large compared with the skin depth. However, since the borehole separation is much less than five skin depths in this $CO_2$ injection experiment, the 2.5-D model seems to be more reliable than the 2-D model. In fact, the pre-injection 2.5-D image is more successfully compared with induction logs observed in the two wells than the 2-D model. From the time-lapse crosswell imaging, we can confirm the replacement of brine with $CO_2$ makes a decrease of conductivity.

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Impacts of Flooding Depths on Weed Occurrence and Yield in No-tillage Paddy Field Covered with Chinese Milk Vetch (무경운 자운영 피복 논에서 담수 깊이가 잡초발생과 수량에 미치는 영향)

  • Hong, Kwang-Pyo;Lee, Young-Han
    • Korean Journal of Soil Science and Fertilizer
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    • v.44 no.2
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    • pp.176-180
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    • 2011
  • Rice production depended on the weed control. The purpose of this study was conducted to evaluate the influence of tillage with chemical amendments + 5 cm flooded, no-tillage without Chinese milk vetch + 5 cm flooded (NTNT 5 cm), no-tillage amended with Chinese milk vetch + 5 cm flooded (NTCM 5 cm), and no-tillage amended with Chinese milk vetch + 10 cm flooded (NTCM 10 cm) on weed occurrence and yield of rice in paddy. Triplicate experimental plots were laid out in a randomized complete block design and compared by employing least significant difference. The dry weights of weeds in NTCM 5 cm and NTCM 10 cm were 11% and 4% level of NTNT 5 cm (p<0.05) and were 3.2 times and 1.2 times more than in conventional tillage system. In addition, the Aneilema keisak and Ludwigia prostrata were significantly increased in NTNT 5 cm (p<0.05). The yield of rice grain in NTCM 10 cm was 2.6 times more than in NTNT 5 cm and was 89% level of conventional tillage system. Our findings suggest that NTCM 10 cm should be enhance of weed control as well as improving of yield of rice in paddy.

Development of a New Flood Index for Local Flood Severity Predictions (국지홍수 심도예측을 위한 새로운 홍수지수의 개발)

  • Jo, Deok Jun;Son, In Ook;Choi, Hyun Il
    • Journal of Korea Water Resources Association
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    • v.46 no.1
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    • pp.47-58
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    • 2013
  • Recently, an increase in the occurrence of sudden local flooding of great volume and short duration due to global climate changes has occasioned the significant danger and loss of life and property in Korea as well as most parts of the world. Such a local flood that usually occurs as the result of intense rainfall over small regions rises quite quickly with little or no advance warning time to prevent flood damage. To prevent the local flood damage, it is important to quickly predict the flood severity for flood events exceeding a threshold discharge that may cause the flood damage for inland areas. The aim of this study is to develop the NFI (New Flood Index) measuring the severity of floods in small ungauged catchments for use in local flood predictions by the regression analysis between the NFI and rainfall patterns. Flood runoff hydrographs are generated from a rainfall-runoff model using the annual maximum rainfall series of long-term observations for the two study catchments. The flood events above a threshold assumed as the 2-year return period discharge are targeted to estimate the NFI obtained by the geometric mean of the three relative severity factors, such as the flood magnitude ratio, the rising curve gradient, and the flooding duration time. The regression results show that the 3-hour maximum rainfall depths have the highest relationships with the NFI. It is expected that the best-fit regression equation between the NFI and rainfall characteristics can provide the basic database of the preliminary information for predicting the local flood severity in small ungauged catchments.

Flood Inundation Analysis from Levee Failure in Nakdong River (낙동강 제방 붕괴에 따른 범람홍수 해석)

  • Jeon, Min-Woo;Han, Kun-Yeun;Choi, Kyu-Hyun
    • Journal of Korea Water Resources Association
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    • v.38 no.4 s.153
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    • pp.259-269
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    • 2005
  • One- and two-dimensional coupling model has been developed to analyze the flood inundation aspect of protected lowland. One-dimensional model solves the Saint-Venant equations by the Preissmann method, and two-dimensional model solves the shallow water equation by the integrated finite difference method. The coupling model approximates unsteady supercritical and subcritical flow, backwater flooding effects, and escaping and returning flow from two-dimensional flow model to channel system. The model has been applied to the levee failure in the Nakdong river during September 13 through 15, 2000. Velocity distributions and inundated depths were presented to demonstrate model simulation results.

Inundation Analysis on Coastal Zone around Masan Bay by Typhoon Maemi (No. 0314) (태풍 매미(0314호)에 의한 마산만 주변연안역에서의 범람해석)

  • Chun, Jae-Young;Lee, Kwang-Ho;Kim, Ji-Min;Kim, Do-Sam
    • Journal of Ocean Engineering and Technology
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    • v.22 no.3
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    • pp.8-17
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    • 2008
  • Wrenching climatic changes due to ecocide and global wanning are producing a natural disaster. Coastal zones have been damaged by typhoons and accompanying storm surges. Severe waves, and destruction of the environment are adding to the severity of coastal disasters. There has been an increased interest in these coastal zone problems, and associated social confusion, after the loss of life and terrible property damage caused by typhoon Maemi. Especially if storm surges coincide with high ticks, the loss of life and property damage due to high waters are even worse. Therefore, it is desirable to accurately forecast not only the timing of storm surges but also the amount water level increase. Such forecasts are very important from the view point of coastal defense. In this study, using a numerical model, storm surge was simulated to examine its fluctuation characteristics for the coastal area behind Masan Bay, Korea. In the numerical model, a moving boundary condition was incorporated to explain wave run-up. Numerically predicted inundation regimes and depths were compared with measurements from a field survey. Comparisons of the numerical results and measured data show a very good correlation. The numerical model adapted in this study is expected to be a useful tool for analysis of storm surges, and for predicting inundation regimes due to coastal flooding by severe water waves.

GIS Based Flood Inundation Analysis in Protected Lowland Considering the Affection of Structure (구조물의 영향을 고려한 GIS기반의 제내지 홍수범람해석)

  • Choi, Seung-Yong;Han, Kun-Yeun;Cho, Wan-Hee
    • Journal of the Korean Association of Geographic Information Studies
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    • v.12 no.4
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    • pp.1-17
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    • 2009
  • In recent years, most of flood damage is associated with the levee failure. The objective of this study is to predict flow depths, flood area, flooding time and flood damage through flood inundation analysis considering the overflow of levee and the characteristics of levee failure. The hydrological parameters were extracted from GIS data such as DEM, land cover and soil map to estimate levee failure discharge. In addition, the characteristics of flood wave propagation could be accurately predicted as flood inundation analysis was accomplished considering the affection of structure within protected lowland and hourly prediction of flooded areas and estimation of flood strength will be utilized as basic data for the flood defence and establishment of measure to reduce flood damage.

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General Inundation Modeling of Paddy Field Districts Considering Drainage Delay (배수지연을 고려한 논 지구의 범용 침수 모의 기법 개발)

  • Jun, Sang Min;Lee, Hyun Ji;Hwang, Soon Ho;Song, Jung-Hun;Choi, Soon-Kun;Kang, Moon Seong
    • Journal of The Korean Society of Agricultural Engineers
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    • v.61 no.4
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    • pp.87-96
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    • 2019
  • The objective of this study was to develop a general inundation modeling technique considering the effect of drainage delay in the paddy field districts. In most studies, farmland inundation simulations have been conducted using previously developed watershed models. However, the water cycle in the paddy fields has a different structure from that of the general watershed, and the effect of the drainage delay should be considered. In this study, the drainage delay algorithm was developed using water balance equation, and the inundation modeling was performed for inundation-prone paddy fields located near Doowol stream. As a result, the depth of inundation was 43.1 cm and 45.2 cm, respectively, due to the 100-year and 200-year frequency rainfall. With the operation of drainage pump ($0.1m^3/s$), inundation depths decreased by 5.8 cm and 6.0 cm, respectively, and inundation time reduced by 20 hours and 21 hours, respectively for the 100-year and 200-year frequency rainfall. The result showed that the general inundation modeling technique developed in this study could reflect the effect of drainage delay due to the rise of external water level and the flooding reduction effect by operation of drainage pump. The results of this study are expected to be useful to establish measures for damage caused by farmland inundation.

Studies on Wet Paddy Field Underdrainage Improvement in the Gum-Ho Area (I) (금호지구 저습답의 암거배수효과에 관한 연구(I))

  • 김조웅;김시원
    • Magazine of the Korean Society of Agricultural Engineers
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    • v.22 no.4
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    • pp.82-95
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    • 1980
  • This paper complies the results of the studies so far made on the subsoil improvement of subsurface drainage systems for wet paddy fields (those were located in the Gum-Ho area in Kyung Buk province) which had poor permeability and a high water table. In general, a drainage problem is an excess of water on the ground surface which can effect the productivity and bearing capacity of the soil. With drain pipe systems, (According to their depths and spacing) it may be possible to correct that problem. The experimentation consisted of three test plots, two of which included drain pipe systems with varing depths and width spacing of the pipes. The third plot (C) was an ordinary plot being exempt of a drain pipe system. In detail, the depth of plot A was 80 cm, and the width spacings began at 2. Om and increased by 2. Om up to 10. 0m. The depth of plot B was 60cm and the width spacing was the same as plot A. These tests were performed to research specific details; such as crop yeild, bearing capacity of the soil, the amount of underdrainage, surface cracks, root distribution, the water table level, the consumptive water depth and the soil moisture content. The test period lasted three years, from 1977 thru 1979. The results obtained were as follows: 1. During the test period, the weather conditions for the area tested were in accordance with the annual average for that area. Furthermore the precipitation factor during the spring cultivation season, the intermediate drainage period and the harvest drainage period was of optimum conditions for controling surface cracks, because of less precipitation than evaporation. 2. The difference in the level of the ground water table in plots A and B was hardly noticable, but the difference in the test plots and the ord. plot was greatly noticable. The test plots (A, B) were 30 to 40cm lower than the ordinary plot. On the whole, the ground water table of the ord. plot always stayed at a level of 15-20cm beneath the surface of the soil, the ground water table of the test plot A showed The difference in the depth of the pipe lower than the test plot B, while the test plots showed a remarkable descending effect. 3. The soil temperature in plot A was slightly core than in plot B with a difference of 0. 47$^{\circ}$C, but plot A was 1. 6$^{\circ}$C higher than the ord. plot during the flooding period, but after drainage the temperature difference climed to 2. 0$^{\circ}$C. 4. During the 3rd test year, the values of the cracks were recorded with the values of 59cm in plot A, 42cm in plot B and 15cm in the ordinary plot. Plots A and B had increased 2.5 times the value of the first year while the ordinary plot had remained the same. 5. The root weight of the rice was measured at a value of 77.2 gr. for plot A, 73.5 gr. for plot B and 65.3 gr. for the ord. plot. Therefore, the root growths in plots A and B were much more energetic than in the ord. plot. 6. The consumptive water depth measured during the 3rd year resulted in the values of 26. 0mm per day for plot A, and 24.9 mm per day for plot B, respectively. Therefore, both plot A and plot B maintained the optimum consumptive water depths, but the ordinary plot only obtained the value of 12.3 mm per day, which clearly showed less than the optimum consumptive water depth which is 20 to 30 mm/day. 7. The soil moisture content is in direct relationship to the ground water level. During drainage, test plot A decreased in its ground water level much more rapidly than the other two plots. Therefore, plot A had a much less soil moisture content. But this decreased water level could be directly effected by the weather conditions. 8. The relationship between the bearing capacity and the soil moisture content were directly inversely proportional. It can be assumed that the occurence of soil creaks is limited by the soil moisture content. Therefore, the greater the progress of the surface creaks resulted in a greater bearing capacity. So, tast plot A with a greater amount of surface cracks than the other test plots resulted in a greater bearing capacity. But, the bearing capacity at the harvest season could be effected by the drainage during the intermediate drainage period and by the weather conditions. 9. Comparing the production of the test plots to the ord. plot; there was an increased value of 840kg for plot A, 755kg for plot B and 695kg for the ord. plot in the rough rice. Therefore, plot A had an increase of 20% over the ordinary plot. The possibility of producing double crops was investigated. The effects on barley production in the test plots showed a value of 367kg per 10 acres, which substantiated the possibility of double crops because that value showed an increased value over the average yearly yield for those uplands. 10. So as a result, it can be recommended that by including a drain pipe system with the optimum conditions of an (80cm centimeter) depth and a (l0m) spacing will have a definite positive effect on the over all production capacity and quality of wetpaddy fields.

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Analysis of Hydraulic Effect by River Dredging in a Meandering Channel (하도준설이 사행하천에 미치는 수리학적 영향 분석)

  • KIM, Tae-Hyeong;KIM, Byung-Hyun;HAN, Kun-Yeun
    • Journal of the Korean Association of Geographic Information Studies
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    • v.18 no.4
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    • pp.14-30
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    • 2015
  • This paper attempted to analyze the hydraulic effects that the dredging can take as an alternative to reduce possible damages of flooding due to the overflow of river levee in meandering rivers, where riverbed aggradation, seepage and erosion may occur. In order to make a hydraulic analysis in a section of meandering rivers, a two-dimensional hydraulic analysis model, RMA-2, was selected. The GIS was applied to construct two-dimensional finite element grids to consider the hydraulic conditions before and after dredging. The water surface elevations, depths, velocities, and tractive forces were compared before and after the dredging. The difference of water surface elevation between the inside and outside of river was turned out to be the maximum value of 0.58m under the design flood condition. It could be evaluated that the tractive force at the bank decreased about 42 to 67% on average for all the sections. These results could give valuable information that the dredging of the stream channel at the meandering sections decreased the risk of overflow, seepage and erosion of the banks. The methodologies given in this study will contribute to mitigating the flood damages in the surrounding farmlands.