• Title/Summary/Keyword: Observed Rainfall

검색결과 987건 처리시간 0.026초

WMS HEC-1 모형을 이용한 경안천 유역의 경년 수문변화 분석 (Assessment of Hydrological Impact by Long-Term Land Cover Change using WMS HEC-1 Model in Gyeongan-cheon Watershed)

  • 이준우;권형중;신사철;김성준
    • 한국지리정보학회지
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    • 제6권1호
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    • pp.107-118
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    • 2003
  • 본 연구는 경안천 유역($558.2km^2$)을 대상으로 WMS의 HEC-1 모형을 이용하여 1980년~2000년 동안 토지피복변화에 따른 수문변화 분석을 수행하였다. 토지피복변화를 분석하기 위하여 다시기의 Landsat MSS(1980/2/15) 및 TM 위성영상(1986/4/15, 1990/4/26, 1996/4/26, 2000/5/17)을 이용하여 최대우도법을 실시하였다. 총 유역면적에 대하여 도시지역의 면적은 약 5.6% 증가하였으나, 산림지역은 6.1% 감소하였으며 SCS CN은 9.8 증가하였다. 모형의 매개변수 결정을 위하여 5개의 홍수사상(1998/5/2, 1998/8/23, 1998/9/30, 1999/5/3, 2000/7/29)을 대상으로 검 보정을 실시하였는바, 유출고에 있어 9~36%의 상대오차를 보였다. 30년 빈도의 일 최대강우 254mm를 적용하여 경년 수문변화를 분석한 결과 1986년~2000년 동안 첨두유출시간은 약 4시간 감소하였으며, 첨두유량은 $455m^3/sec$가 증가하였다.

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건물의 영향을 고려한 이중배수체계기반 침수해석 (Analysis of Urban Inundation Considering Building Footprints Based on Dual-Drainage Scheme)

  • 이정영;진기호;하성룡
    • 한국지리정보학회지
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    • 제17권4호
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    • pp.40-51
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    • 2014
  • 본 연구의 목적은 건물의 유무에 따른 도시지역의 침수특성을 이중배수체계기반의 2차원 침수 해석모형을 이용하여 각각 해석하고 해석 결과의 차이를 비교하는데 있다. 이를 위해 LiDAR 측량 기반 $1m{\times}1m$ 해상도의 표고모델과 표고모델 위에 건물의 외벽을 따라 지표수 유입을 억제하는 격자를 생성한 표고모델의 2가지 지형자료를 구축하였고, 2가지 지형조건을 2차원 침수해석모형의 입력 자료로 활용하기 위해 $10m{\times}10m$ 해상도로 re-sampling 하였다. 분석 결과, CCTV 영상에 의한 실측 침수심 자료와 모의값을 비교한 결과, 건물을 고려하지 않은 지형자료를 사용한 경우 침수심이 과소 산출되었으나, 건물을 고려한 경우에는 실측값과 근사하게 모의되었다. 침수심의 차이는 침수 가능 면적의 변화에 따라 침수체적이 변하게 되므로, 지표면으로 유출되는 수문량이 절대량으로 고정된다면 침수 가능영역이 큰 지형자료를 사용한 경우 침수심이 낮아지기 때문인 것으로 판단된다. 한편 침수흔적도와 비교한 침수면적은 두 지형자료 모두 큰 차이를 보이지 않았으나 근사하게 건물을 고려한 경우의 일치도가 높은 것으로 나타났다. 따라서 침수면적과 침수심의 두 가지를 종합적으로 고려한다면, 이중배수체계기반의 2차원 침수해석모형을 활용하여 도시유역의 침수해석을 수행하는 경우, 건물을 고려한 지형자료를 사용하는 것이 바람직하다고 판단된다.

가을철 대기환경 중 수용성 이온성분의 침적특성 (Deposition Characteristics of Water-soluble Inorganic Ions in the Iksan Ambient Air during Fall, 2004)

  • 강공언;김남송;전선복
    • 한국환경보건학회지
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    • 제32권4호
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    • pp.359-372
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    • 2006
  • In order to investigate the daily deposition characteristics of water-soluble inorganic components in airborne deposit on the Iksan, deposition samples were collected using a deposition gauge from October 16 to November 1, 2004. Deposition samples were collected using two different sampling gauges, a dry gauge and a wet gauge, respectively. To get wet the bottom of wet gauge during the sampling period, the volume of $30{\sim}50ml$ distilled ionized water was added in a wet gauge before the beginning of each deposition sampling. Deposition samples were collected twice a day and analyzed for inorganic water-soluble anions ($Cl^-,\;{NO_3}^-,\;{SO_4}^{2-}$) and cations (${NH_4}^+,\;Na^+,\;K^+,\;Mg^{2+},\;Ca^{2+}$) using ion chromatography. Qualify control and quality assurance of analytical data were checked by the data obtained from reinjection of standard solution, Dionex cross check standard solutions, and random several deposition samples, and measured data was estimated to be reliable. Considering the deposition sample volume, the sampling time, the surface area of sampling container, and the ion concentration measured, the daily deposition amounts for measured ions were calculated in $mg/m^2$. The total daily deposition amounts of all measured ions for dry and wet gauge were $7.5{\pm}2.8$ and $17.7{\pm}4.2mg/m^2$, respectively. A significant increase in deposition amount during rainfall days was observed for both wet gauge and dry gauge, having no difference of deposition amount between in wet gauge and in dry gauge. The mean deposition of all ions measured in this study were higher in wet gauge than in dry gauge because of the surface difference of the sampling container, especially for ${NH_4}^+\;and\;{SO_4}^{2-}$. The mean deposition amounts of ${NH_4}^+\;and\;{SO_4}^{2-}$ in wet gauge were found to be about 10 times and 3 times higher than those in dry gauge, while the rest of the chemical species were equal or a little higher in wet gauge than in dry gauge. Dominant species in dry gauge were ${NO_3}^-\;and\;Ca^{2+}$, accounting for 21% and 28% of the total ion deposition, whereas those in wet gauge were ${SO_4}^{2-}\;and\;{NH_4}^+$, accounting for 19% and 41% of the total ion deposition, respectively.

지반특성을 고려한 토사재해 예측 기법별 위험지 분석 (Analysis of Hazard Areas by Sediment Disaster Prediction Techniques Based on Ground Characteristics)

  • 최원일;최은화;백승철
    • 한국지반환경공학회 논문집
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    • 제18권12호
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    • pp.47-57
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    • 2017
  • 본 연구에서는 도심지 토사재해 예비중점관리 대상지역 중 총 6개 연구지역(춘천, 성남, 세종, 대전, 미량, 부산)을 선정하여 토사재해 위험지 예측 분석을 실시하였다. 분석에 사용된 모델은 현재 토사재해 위험지 예측에 보편적으로 사용되고 있는 기존 모델(SINMAP, TRIGRS)과 본 연구를 통해 개발된 프로그램(LSMAP)을 활용하였으며, 결과 비교분석을 통해 개발모델의 적용성을 검토하였다. 토사재해 위험지 예측에 사용되는 매개변수는 크게 지형특성, 토질특성, 임상특성, 강우특성으로 분류하였으며, 각 모델에 따른 토사재해 위험지 예측 분석 결과 LSMAP 및 TRIGRS에 비해 SINMAP을 이용한 분석은 대체로 위험지를 광범위하게 예측하였다. 이러한 결과는 모델별 적용되는 분석 매개변수의 차이에 의한 것으로 판단된다. 또한 임상특성을 고려한 LSMAP은 TRIGRS 결과와 비교하였을 때 예측 위험지 기준 -0.04~2.72%의 범위 내로 유사한 경향을 보이는 것으로 분석되었다. 이는 산지에 분포하는 임상 정보가 비탈면 안정에 다양한 영향을 미치는 것이라 할 수 있으며, 토사재해 위험지 예측에 중요한 매개변수임을 알 수 있다.

조선 중기 이후 서울의 장마철 강수 평균과 극한강수현상의 변화 (Changes in Means and Extreme Events of Changma-Period Precipitation Since mid-Joseon Dynasty in Seoul, Korea)

  • 최광용
    • 대한지리학회지
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    • 제51권1호
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    • pp.23-40
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    • 2016
  • 본 연구에서는 조선시대 측우기(1777~1907년)와 현대적 기상장비(1908~2015년)로 측정한 강우량 자료를 종합 분석하여 서울의 장마철 강수량과 극한강수현상에 나타난 장기간 변화 양상을 밝히고자 하였다. 또한 이와 관련된 동아시아 영역의 종관 기후장에 나타난 변화 특징을 밝히고자 하였다. 약 239년 동안의 서울의 강수자료 시계열을 분석한 결과, 20세기 후반으로 올수록 장마철(6월 하순~9월 초순) 강수량이 증가하고, 경년변동성도 더 커짐을 알 수 있다. 특히 1990년대 초반부터는 장마철 중에서도 여름장마기(6월 하순~7월 중순)와 장마 휴지기(7월 하순~8월 초순)에 극한강수현상 중심의 강수량이 뚜렷하게 증가하면서 장마기의 구분이 모호해지고 있음을 알 수 있다. 이와 관련하여 변화가 뚜렷한 1990년 전후의 상층 종관기후장을 비교해 보면, 최근에는 북서태평양 주변의 해수면 온도가 상승하고 북태평양 아열대 고기압 강도가 강화되어 해양성 기단이 한반도 방향으로 더 확장하고, 유라시아 대륙 내부 몽골 지역을 중심으로 강한 고기압 편차핵이 형성되면서 고위도로부터 기류가 더 활발하게 유입되고 있음을 알 수 있다. 즉, 서로 다른 성질의 기류들이 강해지면서 이들 기류들이 만나는 북서태평양 연안 지역에 상승 기류 흐름이 활발해지면서 최근에는 서울의 장마철 강수평균 및 극한강수현상이 증가하였다고 할 수 있다.

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다양한 첨단 유량 계측기기를 활용한 제주도 하천 유출 비교 분석 (Analysis and Comparison of Stream Discharge Measurements in Jeju Island Using Various Recent Monitoring Techniques)

  • 양성기;김동수;정우열;류권규
    • 한국환경과학회지
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    • 제20권6호
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    • pp.783-788
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    • 2011
  • Different from the main land of South Korea, Jeju Island has been in difficulties for measuring discharge. Due to high infiltration rate, most of streams in Jeju Island are usually in the dried state except six streams with the steady base flow, and the unique geological characteristics such as steep slope and short traveling distance of runoff have forced rainfall runoff usually to occur during very short period of time like one or two days. While discharge observations in Jeju Island have been conducted only for 16 sites with fixed electromagnetic surface velocimetry, effective analysis and validation of observed discharge data and operation of the monitoring sites still have been limited due to very few professions to maintain such jobs. This research is sponsored by Ministry of Land, Transport and Maritime Affairs to build water cycle monitoring and management system of Jeju Island. Specifically, the research focuses on optimizing discharge measurement techniques adjusted for Jeju Island, expanding the monitoring sites, and validating the existing discharge data. First of all, we attempted to conduct discharge measurements in streams with steady base flow, by utilizing various recent discharge monitoring techniques, such as ADCP, LSPIV, Magnetic Velocimetry, and Electromagnetic Wave Surface Velocimetry. ADCP has been known to be the most accurate in terms of discharge measurement compared with other techniques, thus that the discharge measurement taken by ADCP could be used as a benchmark data for validation of others. However, there are still concerns of using ADCP in flood seasons; thereby LSPIV would be able to be applied for replacing ADCP in such flooded situation in the stream. In addition, sort of practical approaches such as Magnetic Velocimetry, and Electromagnetic Wave Surface Velocimetry would also be validated, which usually measure velocity in the designated parts of stream and assume the measured velocity to be representative for whole cross-section or profile at any specified location. The result of the comparison and analysis will be used for correcting existing discharge measurement by Electromagnetic Wave Surface Velocimetry and finding the most optimized discharge techniques in the future.

실외 실험적 온난화 및 강수 처리에 따른 소나무와 낙엽송 유묘의 초기 생장 특성 (The Early Growth Performances of Pinus densiflora and Larix kaempferi Seedlings Under Open-field Experimental Warming and Precipitation Manipulation)

  • 권보람;조민석;양아람;장한나;안지애;손요환
    • 한국산림과학회지
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    • 제109권1호
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    • pp.31-40
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    • 2020
  • 본 연구는 기후변화와 관련하여 양묘과정에서 온도와 강수 변화에 따른 주요 침엽수의 생존 및 생장 특성 변화를 알아보고자 수행하였다. 소나무와 낙엽송 노지묘(1-0)를 대상으로 대조구 기준 3℃의 온도를 상승시키거나 ±40%의 강수를 조절한 6처리 생육환경[온도 2처리(대조: TC, 증가: TW) × 강수 3처리(대조: PC, 감소: PD, 증가: PI)] 실외 실험구를 조성하였으며, 생존율, 근원경, 묘고, 물질생산량 및 묘목품질지수 변화를 조사하여 이원분산분석을 수행하였다. 소나무는 온도와 강수 처리에 따른 생존율 차이가 없었지만, 강수가 증가할수록 묘목품질지수가 낮아지는 경향을 보였다. 낙엽송은 온도 상승과 강수 감소에 따라 고사율이 증가하였으며, 묘목품질지수는 두 요인 간 상호작용을 보이면서 온도대조-강수증가 처리구에서 가장 낮게 나타났다. 따라서 양묘과정에서 소나무는 강수 증가, 낙엽송은 온도 증가 또는 강수 감소에서 낮은 묘목 생산량과 품질이 예상되며, 기후변화에 따른 두 수종의 특이적 민감도를 확인할 수 있었다. 향후 지구온난화와 가뭄·폭우 등의 강수 변화에 의해 수종별 묘목 생존과 품질의 변화가 예상되기 때문에 각 수종의 생육 반응 특성에 따른 적합한 양묘시업 대응 전략이 필요할 것으로 판단된다.

CMIP5 Historical 시나리오에 근거한 WRF를 이용한 한반도 중심의 동북아시아 상세기후 (Present-Day Climate of the Korean Peninsula Centered Northern East Asia Based on CMIP5 Historical Scenario Using Fine-Resolution WRF)

  • 안중배;홍자영;서명석
    • 대기
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    • 제23권4호
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    • pp.527-538
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    • 2013
  • In this study, climate over Korea based on the Historical scenario induced by HadGEM2-AO is simulated by WRF. For this purpose, a system that can be used be for numerical integration over the Far East Asian area of the center of the Korean Peninsula with 12.5 km-horizontal resolution was set-up at "Haebit", the early portion of KMA Supercomputer Unit-3. Using the system, the downscaling experiments were conducted for the period 1979-2010. The simulated results of HadGEM2-AO and WRF are presented in terms of 2 m-temperature and precipitation during boreal summer and winter of Historical for the period 1981~2005, compared with observation. As for the mean 2 m-temperature, the general patterns of HadGEM2-AO and WRF are similar with observation although WRF showed lower values than observation due to the systematic bias. WRF reproduced a feature of the terrain-following characteristics reasonably well owing to the increased horizontal resolution. Both of the models simulated the observed precipitation pattern for DJF than JJA reasonably, while the rainfall over the Korean Peninsula in JJA is less than observation. HadGEM2-AO in DJF 2 m-temperature and JJA precipitation has warm and dry biases over the Korean Peninsula, respectively. WRF showed cold bias over JJA 2 m-temperature and wet bias over DJF precipitation. The larger bias in WRF was attributed to the addition of HadGEM2-AO's bias to WRF's systematic bias. Spatial correlation analysis revealed that HadGEM2-AO and WRF had above 0.8 correlation coefficients except for JJA precipitation. In the EOF analysis, both models results explained basically same phase changes and variation as observation. Despite the difference in mean and bias fields for both models, the variabilities of the two models were almost similar with observation in many respects, implying that the downscaled results can be effectively used for the study of regional climate around the Korean Peninsula.

Growth and yield responses of rice varieties to various soil water deficit conditions under different soil types

  • Kikuta, Mayumi;Samejima, Hiroaki;Magoti, Rahab;Kimani, John M.;Yamauchi, Akira;Makihara, Daigo
    • 한국작물학회:학술대회논문집
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    • 한국작물학회 2017년도 9th Asian Crop Science Association conference
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    • pp.322-322
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    • 2017
  • To avoid drought stress under rainfed upland conditions, it is important for rice to efficiently utilize water at shallow soil layers supplied by rainfall, and access to water retained in deer soil layers. The root developmental characteristics of rice, which play important role in the adaptability to drought conditions, vary depending on the variety. Moreover, water availability for plant differs depending on the soil types that have different physical properties such as water holding capacity, permeability, capillary force, penetration resistance, etc. In this study, we evaluated growth and yield responses of rice varieties to various soil water deficit conditions under three different soil types. The experiment was conducted in a plastic greenhouse at the Kenya Agricultural and Livestock Research Organization-Mwea from October 2016 to January 2017. Two upland varieties (NERICA 1 and 4) and one lowland variety (Komboka) were grown in handmade PVC pots (15.2 cm diameter and 85.0 cm height) filled with three different types of soil collected from major rice-growing areas of the country, namely black cotton (BC), red clay (RC), and sandy clay (SC). Three watering methods, 1) supplying water only from the soil surface (W1), 2) supplying water only from the bottom of the pots (W2), and 3) supplying water both from the soil surface and the bottom of pots (W3), were imposed from 40 days after sowing to maturity. Soil water content (SWC) at 20, 40, and 60 cm depths was measured regularly. At the harvesting stage, aboveground and root samples were collected to determine total dry weight (TDW), grain yield, and root length at 0-20, 20-40, 40-60, and 60-80 cm soil layers. Irrespective of the watering methods, the greatest root development was obtained in RC, while that in BC was less than other two soils. In BC, the degree of yield reduction under W1 was less than that in RC and SC, which could be attributed to the higher water holding capacity of BC. In RC, the growth and yield reduction observed in all varieties under W1 was attributed to the severe drought stress. On the other hand, under W2, SWC at the shallow soil depth in RC was maintained because of its higher capillary force compared with BC and SC. As the result, growths and yields in RC were not suppressed under W2. In SC, deep root development was not promoted by W2 irrespective of the varieties, which resulted in significant yield losses. Under W1, the rice growth and yield in SC was decreased although shallow root development was enhanced, and the stomatal conductance was maintained higher than RC. It was suspected that W1 caused nutrients leaching in SC because of its higher permeability. Under rainfed conditions, growth and yield of rice can be strongly affected by soil types because dynamics of soil water conditions change according to soil physical properties.

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Hydrogeochemical study of a watershed in Pocheon area: controls of water chemistry

  • Kim, Kyoung-Ho;Yun, Seong-Taek;Chae, Soo-Ho;Jean, Jong-Wook;Lee, Jeong-Ho;Kweon, Hae-Woo
    • 한국지하수토양환경학회:학술대회논문집
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    • 한국지하수토양환경학회 2004년도 임시총회 및 추계학술발표회
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    • pp.121-121
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    • 2004
  • The groundwater in the Pocheon area occurs from both a fractured bedrock aquifer in igneous and metamorphic rocks and an alluvial aquifer with a thickness of <50 m, and forms a major source of domestic and agricultural water supply. In this study, we performed a hydrogeochemical study in order to identify the control of geochemical processes on groundwater quality. For this study, groundwater level and physicochemical parameters (EC, Eh, pH, alkalinity) were monitored once a month from a total of 150 groundwater wells between June 2003 to August 2004. A total of 153 water samples (13 surface water, 66 alluvial groundwater, 74 bedrock groundwater) were also collected and analyzed in February 2004. Groundwater chemistry in the study area is very complex, depending on a number of major factors such as geology, degree of chemical weathering, and quality of recharge water. Hydrochemical reactions such as the leaching of surficial and near-solace soil salts, dissolution of calcite, cation exchange, and weathering of silicate minerals are proposed to explain the chemistry of natural groundwater. Alluvial groundwaters locally have very high TDS concentrations, which are characterized by their chloride(nitrate)-sulfate-bicabonate facies and low Na/Cl ratio. Their grondwater levels are highly fluctuated according to rainfall event. We suggest that high nitrate content and salinity in such alluvial groundwaters originates from the local recharge of sewage effluents and/or fertilizers. Likewise, high concentrations of nitrate were also locally observed in some bedrock groundwaters, suggesting their effect of anthropogenic contamination. This is possibly due to the bypass flow taking place through macropores. Tile degree of the weathering of silicate minerals seems to be a major control of the distribution of major cations (sodium, calcium, magnesium, potassium) in bedrock groundwaters, which show a general increase with increasing depth of wells. Thermodynamic interpretation of groundwater chemistry shows that the groundwater in the study area is in chemical equilibrium with kaolinite and Na-montmorillonite, which indicates that weathering of plagioclase to those minerals is a major control of hydrochemistry of bedrock groundwater. The interpretation of the molar ratios among major ions, as well as the mass balance calculation, also indicates the role of both dissolution/precipitation of calcite and Ca-Na cationic exchange as bedrock groundwaters evolves progressively.

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