• 지질공학
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• 제23권2호
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• pp.117-125
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• 2013

강우패턴의 변화에 의한 대하천변 지하수홍수발생은 농 경작지에서 큰 문제로 대두되고 있다. 따라서 대하천변의 지하수홍수 발생 메커니즘을 규명하기 위한 하천의 유량을 결정하는 가장 중요한 요소인 직접유출량과 기저유출량의 정량적인 해석이 필요하다. 이 연구에서는 수변구역에서 WHAT system이라는 Web GIS 기반의 수문분석 방법을 이용하여 산출된 기저유출량과 실제 하천에서 산출된 기저유출량을 정량적으로 비교분석 하였다. 연구지역의 기저유출량은 우기인 2012년 07월 17일에는 0.489 $m^3/s$, 2012년 07월 18일에는 0.260 $m^3/s$, 2012년 07월 19일에는 0.279 $m^3/s$이었고 건기였던 2013년 03월 06일에는 0.006 $m^3/s$, 2013년 03월 30일에는 0.009 $m^3/s$의 기저유출량이 산출되었다. 분석결과 수변구역 충적층 지역에서 강우 발생 시 기저유출량의 증가가 발생하였으며 건기 시 오차가 다소 적게 나타났다.

• 한국수자원학회논문집
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• 제46권8호
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• pp.873-884
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• 2013

우리나라는 몬순기후의 영향으로 여름철 강우가 집중되기 때문에 작은 기후변화에도 심각한 수자원의 문제를 야기시킬 수 있다. 이로 인해 기후변화에 대한 많은 관심이 집중되어 그에 따른 연구도 활발히 진행되고 있다. 본 연구는 남강유역에서의 미래 기후변화에 의한 하천의 흐름과 수질변화를 예측하기 위해 유역-하천모형을 연계하여 하고자 하였다. 인공신경망기법을 이용하여 기후시나리오를 예측한 후 유역수문 모형인 SWAT모형을 구축하였고 모형의 적용성 평가를 위해 환경부자료를 이용하여 검보정한 결과 $R^2$이 0.7 이상으로 적정수준으로 모의되었다. SWAT의 결과와 HEC-ResSIM을 이용한 미래 남강댐 방류량을 QUALKO의 입력 자료로 사용하였다. 그 결과 저수기에는 풍수기와는 달리 연도별 유량에 따라 BOD가 많게는 약 2mg/L의 차이를 보이는 등 변화 폭이 크게 나타났다. 강우와 유역의 유출이 하천의 수질에 큰 영향을 끼치기 때문에 풍수기에 비해 유량이 적은 저수기에 수질 농도가 높은 것을 알 수 있다. 그러므로 남강댐의 저수기의 용수확보를 통해 남강하류 하천의 유지용수를 확보하고 효율적인 관리를 통해 향상된 수질을 관리 할 수 있을 것으로 판단된다.

• 한국수자원학회논문집
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• 제56권9호
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• pp.529-541
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• 2023

기후변화에 따른 가뭄 등 극한 기상을 예측하기 위해, 최근 전 세계적으로 GCMs 모델에 기반하여 향후 7개월까지를 전망하는 계절 기상 전망(Seasonal Forecasts) 기술이 꾸준히 관심을 받고 있다. 그러나 국내에서의 연구 및 적용사례는 많지 않으며, 특히 유역단위에서 그 활용성에 대해서는 검증이 필요하다. 따라서 본 연구에서는 국내 12개 다목적댐 유역에 대해 2011년부터 2020년까지 계절 기상 전망의 정확성을 과거 45년간의 기상 자료(climatology)와 비교하여 평가하였다. 본 연구에서는 ECMWF에서 제공하는 계절 기상 전망의 인자로 향후 수문전망에 활용성이 높은 강수, 기온 그리고 증발산을 선정하였고, 앙상블 전망의 정확성 평가를 위해 Continuous Ranked Probability Skill Score (CRPSS) 기법을 적용하였다. 또한, 계절 기상 전망에 대해 선형 편의 보정기법(Linear scaling)을 적용하여 그 효과를 평가하였다. 연구결과, 계절 기상 전망이 향후 1개월 간은 climatology와 유사한 정확도를 보이나 전망 리드타임이 증가함에 따라 그 정확도가 크게 낮아지는 특성을 나타냈다. Climatology와 비교하여, 계절적으로는 Dry season보다는 Wet season이 더 나은 결과를 보였으며, 특히 건조했던 2015년과 2017년의 Wet season에서는 장기간에 걸친 전망 정확도가 모두 높게 나타났다.

• 대한지리학회지
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• 제44권2호
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• pp.105-121
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• 2009

지형 굴곡이 심한 하와이 화산섬의 경우, 측후소 분포가 매우 제한적이어서 공식적인 기온 분포도가 작성되지 못하고 있는 실정이다. 본 연구에서는 이러한 기온 지도화의 문제점을 해결하는 방법으로 위성기반의 지표온도 자료로부터 기온추정치를 추출하여 내삽법에 필요한 입력자료로 사용하였다. 추출된 온도값을 표본값으로하여 거리 역비례 가중치법(IDW)과 공동크리깅 (cokriging)을 적용하여 기온추정치를 지도화하였다. 기온과 고도값을 함께 이용한 cokriging이 IDW에 비해 크게 향상된 추정 오차값을 나타내었다. Cokriging은 주 변수와 고도와 같은 추가 변수 간의 상관관계가 유의하게 나타날 때 효과적으로 사용되는 내삽법이지만, 내삽 정확도는 계절적인 기상조건에 민감하게 영향받는 것으로 조사되었다. 강수량이 크게 증가하는 우기에는 건기에 비해 공간적인 기온변화가 크며, 이에 따라 기온 추정 오차값도 우기에 높게 나타났다.

• 한국환경과학회지
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• 제21권12호
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• pp.1511-1521
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• 2012

An attempt is made to analyse characteristic features of heavy rainfalls which occur at the metropolitan area of the Korean peninsular the on- and off- Changma season. For this, two representative heavy rainfall episodes are selected; one is the on-Changma season wherein a torrential rain episode happened at Goyang city on 12 July 2006, and the other is the off-Changma season, a heavy rainfall event in Seoul on 21 September 2006. Both recorded considerable amounts of precipitation, over 250mm in a half-day, which greatly exceeded the amount expected by numerical prediction models at those times, and caused great damage to property and life in the affected area. Similarities in the characteristics of both episodes were shown by; the location of upper-level jet streak and divergence fields of the upper wind over heavy rainfall areas, significantly high equivalent potential temperatures in the low atmospheric layer due to the entrainment of hot and humid air by the low-level jet, and the existence of very dry air and cold air pool in the middle layer of the atmosphere at the peak time of the rainfall events. Among them, differences in dynamic features of the low-level jet and the position of rainfall area along the low-level jet are remarkable.

• Environmental Engineering Research
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• 제21권1호
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• pp.84-90
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• 2016

Regionally the lowest average concentration of TOC was observed with 0.66 mg/L in Nakdong river, while the highest concentration of TOC was observed with 0.91 mg/L in Yeongsan river. The average concentration of TOC for national water quality monitoring site showed that the lowest average concentration of TOC was 1.58 mg/L in Han river, while the highest concentration of TOC was 3.37 mg/L in Yeongsan river. Seasonally, the average concentration of TOC at six upstream sites showed 0.77 mg/L and 0.56 mg/L, 0.69 mg/L and 0.63 mg/L, 0.80 mg/L and 0.73 mg/L, and 1.21 mg/L and 0.68 mg/L between wet season and dry season in Han river, Nakdong river, Gem river and Yeongsan river, respectively. For the national water quality site, the average concentration of TOC between wet season and dry season was 1.70 mg/L and 1.45 mg/L in Han river, 2.01 mg/L and 1.75 mg/L in Nakdong river, 2.01 mg/L and 1.60 mg/L in Gem river, and 3.75 mg/L and 3.00 mg/L in Yeongsan river. The distribution of TOC in upstream and national water quality monitoring sites on four major rivers have been influenced by seasonal and regional characteristics in Korea.

• Fisheries and Aquatic Sciences
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• 제26권8호
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• pp.482-490
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• 2023

Food and feeding habits of Labeobarbus intermedius were studied from the newly constructed Ribb Reservoir, Ethiopia during the dry (December-March) season and wet season (June-August) of 2021. The objective of the study was to determine the diet composition, seasonal variation, and ontogenetic dietary shift in the diets of the dominant cyprinid fish in Ribb Reservoir. In this study, frequency of occurrence and volumetric analysis methods were used to present the results. From a total of 203 fish samples, 132 (65%) guts contained food items. Macrophytes (29.4%), phytoplankton (27.2%), detritus (14.8%), and insects (13.6%) were the major food items in the diets volumetrically. During the dry season, L. intermedius was mainly dependent on phytoplankton (58.2%), insects (15.2%), and zooplankton (13.7%) volumetrically. Whereas, macrophytes (50.3%) and detritus (23.3%) were the dominant food items in the wet season. The frequency occurrence and volumetric contribution of the diets of L. intermedius varied significantly (χ² test, p < 0.05) between seasons. Schoener's diet overlap index revealed a slight ontogenetic dietary shift in the diets of L. intermedius. While insects, nematodes, and zooplankton were the main diets of small-sized L. intermedius, macrophytes and detritus were ingested by large-sized L. intermedius. Generally, L. intermedius fed both plant and animal-origin food items and is considered an omnivorous feeder in Ribb Reservoir.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2021년도 학술발표회
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• pp.268-268
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• 2021

Groundwater resource is mostly used in Abomey-calavi (southern region of Benin) as main source of water for domestic, industrial, and agricultural activities. Groundwater intake across the region is not perfectly controlled by a network due to the presence of many private boreholes and traditional wells used by the population. After some decades, this important resource is becoming more and more vulnerable and needs more attention. For a better groundwater management in the region of Abomey-calavi, the present study attempts to predict a future probable groundwater drought using Recurrent Neural Network (RNN) for future groundwater level prediction. The RNN model was created in python using jupyter library. Six years monthly groundwater level data was used for the model calibration, two years data for the model test and the model was finaly used to predict two years future groundwater level (years 2020 and 2021). GRI was calculated for 9 wells across the area from 2012 to 2021. The GRI value in dry season (by the end of March) showed groundwater drought for the first time during the study period in 2014 as severe and moderate; from 2015 to 2021 it shows only moderate drought. The rainy season in years 2020 and 2021 is relatively wet and near normal. GRI showed no drought in rainy season during the study period but an important diminution of groundwater level between 2012 and 2021. The Pearson's correlation coefficient calculated between GRI and rainfall from 2005 to 2020 (using only three wells with times series long period data) proved that the groundwater drought mostly observed in dry season is not mainly caused by rainfall scarcity (correlation values between -0.113 and -0.083), but this could be the consequence of an overexploitation of the resource which caused the important spatial and temporal diminution observed from 2012 to 2021.

• Asian-Australasian Journal of Animal Sciences
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• 제9권6호
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• pp.737-741
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• 1996

Dry matter yield of reed canarygrass was investigated in uncultivated rice paddy in Korea, and an attempt was made to estimate the most economic and efficient cutting frequency and rates of nitrogen (N) fertilization, for increased production of reed canarygrass. Total dry matter yields of reed canarygrass per year were 7.4-15.7, 8.5-16.1, and 7.5-13.4 tons/ha in 3, 4, and 5 cutting frequencies, respectively, and over the N treatments of 0-120 kg N/ha/cut. When cut 3 or 5 times annually, the 2nd cut produced the highest proportion of total yield at 38.4 and 33.0%, respectively, when cut 4 times the 3rd cut was highest (38.3%). The ranges of economic N level, limiting N level and efficiency of dry matter production were 243.3-293.0, 387.2, and 14.6 kg DM/kg N, respectively. These indicators were particularly low for the 5 cutting frequency possibly because of the unusually high temperature in the summer season. The best cutting frequency for the dry matter production of reed canarygrass in 1994 was 3 per year because of the higher efficiency of dry matter production.

• 대한원격탐사학회지
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• 제22권3호
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• pp.175-182
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• 2006

Because of the phenological variation of vegetation growth in temperate region, it is often difficult to accurately assess the surface conditions of agricultural croplands, grasslands, and disturbed forests by multi-spectral remote sensor data. In particular, the spectral similarity between soil and dry vegetation has been a primary problem to correctly appraise the surface conditions during the non-growing seasons in temperature region. This study analyzes the spectral characteristics of the mixture of dry vegetation and soil. The reflectance spectra were obtained from laboratory spectroradiometer measurement (GER-2600) and from EO-1 Hyperion image data. The reflectance spectra of several samples having different level of dry vegetation fractions show similar pattern from both lab measurement and hyperspectral image. Red-edge near 700nm and shortwave IR near 2,200nm are more sensitive to the fraction of dry vegetation. The use of hyperspectral data would allow us for better separation between bare soils and other surfaces covered by dry vegetation during the leaf-off season.