• 한국농공학회논문집
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• 제59권2호
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• pp.19-27
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• 2017

Recently, the hydrological model Soil Water Assessment Tool (SWAT) has been applied in many watersheds in South Korea. This study estimated parameters in SWAT for calibrating streamflow in long-term drought periods. Therefore, we focused on the continuous severe drought periods 2014~2015, and understand the model calibrated parameters. The SWAT was applied to a $366.5km^2$ Gongdo watershed by using 14 years (2002~2015) daily observed streamflow (Q) including two years extreme drought period of 2014~2015. The 9 parameters of CN2, CANMX, ESCO, SOL_K, SLSOIL, LAT_TIME, GW_DELAY, GWQMN, ALPHA_BF were selected for model calibration. The SWAT result by focusing on 5 normal years (2002~2006) calibration showed the 14 years average Nash-Sutcliffe model efficiency (NSE) for Q and 1/Q with 0.78 and 0.58 respectively. On the other hand, the 14 years average NSEs of Q and 1/Q by focusing on 2 drought years (2014~2015) calibration were 0.86 and 0.76 respectively. Thus, we could infer that the SWAT calibration trial by focusing on drought periods data can be a good approach to calibrate both high flow and low flow by controlling the 9 drought affected parameters.

• 한국농공학회논문집
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• 제60권1호
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• pp.11-20
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• 2018

This study is to calibrate the SWAT (Soil and Water Assessment Tool) water quality of SS (Suspended Solid), T-P (Total Phosphorus), and T-N (Total Nitrogen) by focusing on 2014~2015 drought periods and identify the important parameters. For Gongdo watershed ($366.5km^2$), the SWAT was calibrated for 2 cases of 2002~2006 normal year focusing calibration and 2014~2015 drought focusing calibration respectively. The parameters of N_UPDIS (Nitrogen uptake distribution parameter) and CMN (Rate factor for humus mineralization of active organic nutrients) played important roles for T-N calibration during drought periods. The SWAT SS, T-N, and T-P average $R^2$ (Coefficient of determination) results by focusing on 2014~2015 drought periods calibration showed 0.71, 0.65 and 0.62 while 2002~2006 normal year focusing calibration showed 0.63, 0.58 and 0.50 respectively. Also SWAT SS, T-N, and T-P model efficiency NSE (Nash-Sutcliffe efficiency) results by focusing on drought period (2014~2015) calibrated showed 0.76, 0.77, 0.87 respectively. Even though the SS, T-P parameters were unchanged during the calibration, the SS and T-P results were improved by the hydrological parameters (SCS-CN, SOL_K, SLSOIL) during the drought periods. The SWAT water quality calibration needs to be considered for the movement of SS and nutrients transport especially focusing on the drought characteristics.

• 한국수자원학회논문집
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• 제34권5호
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• pp.533-542
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• 2001

가뭄에 대한 대책을 수립하기 위해서는 각 가뭄상태별로 가뭄의 지속기간을 산정하는 것이 선행되어야 한다. 이러한 가뭄의 지속기간 분석에 사용할 수 있는 방법에는 비선형 물수지모형과 Palmer 가뭄심도지수방법이 있다. 비선형 물수지모형은 지표면과 대기의 수분이동을 고려한 물수지방법을 추계학적 변동에 의해 야기되는 건기와 습윤기 사이의 변환기간을 모의할 수가 있다. Palmer 가뭄심도지수는 강우량과 잠재증발산량을 바탕으로 기상학적으로 필요한 강우량과 실제강우량을 비교하여 가뭄의 정도를 나타내는 물수지방법이다. 본 연구에서는 한강유역에 대해 비선형 물수지모형과 Palmer 가뭄심도지수를 이용하여 가뭄의 지속기간을 산정하였다. 비선형 물수지모형을 사용하여 산정된 토양함수비에 따른 가뭄의 지속기관과 Palmer 가뭄심도지수를 이용하여 산정된 지수별 가뭄의 지속기간이 유사하게 나타났다. 연구 결과 한강유역에서의 극심한 가뭄상태에서 습윤기로 변환되는 지속기간이 약 3년으로 산정되었다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권1호
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• pp.76-87
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• 2021

Groundwater is considered to be the best water resource to solve water shortage problems during drought periods. Even though excessive pumping (overdraft) during short-period may give an unprofitable effect on groundwater hydrology, it has a primary role to solve a lack of water resources and to maintain incomes of farmers. This study evaluated maximum irrigation amounts of groundwater to each local-government and province during drought periods. Maximum irrigation amounts of groundwater were evaluated using cumulative groundwater usage data of each local-government during normal and drought years. Maximum irrigation amounts of groundwater during drought periods would be roughly identified as approximately 1.3 times more than the exploitable amounts of groundwater resources for each local-government. Drawdown-limitation depth on groundwater levels at each monitoring well was determined by transforming the maximum irrigating amounts into degree of change on levels. Universal limitation depth of drawdown on groundwater levels was evaluated to be approximately three times of annual fluctuating range on groundwater levels for each monitoring well. Systematic response on groundwater demands with abiding by drawdown-limitation depth can attain an optimal irrigation of groundwater resources during short-term drought.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2012년도 학술발표회
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• pp.458-458
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• 2012

Climate extreme variability is a major cause of disaster such as flood and drought types occurred in Korea and its effects is also more severe damage in last decades which can be danger mature events in the future. The main aim of this study was to assess the effectives of climate change on drought for an agriculture as Nakdong basin in Korea using climate change data in the future from data of General Circulation Models (GCM) of ECHO-G, with the developing countries like Korea, the developed climate scenario of medium-high greenhouse gas emission was proposed of the SRES A2. The Standardized Precipitation Index (SPI) was applied for drought evaluation. The drought index (SPI) applied for sites in catchment and it is evaluated accordingly by current and future precipitation data, specific as determined for data from nine precipitation stations with data covering the period 1980-2009 for current and three periods 2010-2039, 2040-2069 and 2070-2099 for future; time scales of 3month were used for evaluating. The results determined drought duration, magnitude and spatial extent. The drought in catchment act intensively occurred in March, April, May and November and months of drought extreme often appeared annual in May and November; drought frequent is a non-uniform cyclic pattern in an irregular repetitive manner, but results showed drought intensity increasing in future periods. The results indicated also spatial point of view, the SPI analysis showed two of drought extents; local drought acting on one or more one of sites and entire drought as cover all of site in catchment. In addition, the meteorology drought simulation maps of spatial drought representation were carried out with GIS software to generate for some drought extreme years in study area. The method applied in this study are expected to be appropriately applicable to the evaluation of the effects of extreme hydrologic events, the results also provide useful for the drought warning and sustainable water resources management strategies and policy in agriculture basins.

• 한국수자원학회:학술대회논문집
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• 한국수자원학회 1992년도 수공학연구발표회논문집
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• pp.411-418
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• 1992

The purpose of this study is to develop dynamic-stochastic models that can forecast the inflow into reservoir during low/drought periods and flood periods. For the formulation of the models, the discrete transfer function is utilized to construct the deterministic characteristics, and the ARIMA model is utilized to construct the stochastic characteristics of residuals. The stochastic variations and structures of time series on hydrological data are examined by employing the auto/cross covariance function and auto/cross correlation function. Also, general modeling processes and forecasting method are used the model building methods of Box and Jenkins. For the verifications and applications of the developed models, the Chungju multi-purpose reservoir which is located in the South Han river systems is selected. Input data required are the current and past reservoir inflow and Yungchun water levels. In order to transform the water level at Yungchon into streamflows, the water level-streamflows rating curves at low/drought periods and flood periods are estimated. The models are calibrated with the flood periods of 1988 and 1989 and hourly data for 1990 flood are analyzed. Also, for the low/drought periods, daily data of 1988 and 1989 are calibrated, and daily data for 1989 are analyzed.

• 한국수자원학회논문집
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• 제47권9호
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• pp.813-824
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• 2014

본 연구에서는 가뭄지수를 이용하여 북한지역의 가뭄분석을 수행하였다. 분석 대상지점으로는 평양 등 27개 지점을 선정하였으며, 월 강수량 및 평균기온 자료를 수집하여 분석에 이용하였다. 가뭄분석을 위한 가뭄지수로는 SC-PDSI를 이용하였으며, 27개 지점별로 1984~2013년(30년)의 월 단위 가뭄지수를 산정하였다. 가뭄지수를 이용하여 과거 가뭄에 대해 검토한 결과, 대부분의 지점에서 2000년대 초반과 중반에 심각한 가뭄이 발생하였음을 확인할 수 있었다. 북한의 과거 가뭄사상에 대한 정량적 평가를 위해 6개 지점(평양, 함흥, 청진, 원산, 해주, 신의주)을 대상으로 지속기간별 최대 가뭄심도 자료계열을 구성하였으며, 빈도분석을 통해 지점별 가뭄심도-지속기간-재현기간(Severity-Duration-Frequency, SDF) 곡선을 유도하였다. 6개 지점의 과거 주요 가뭄사상을 추출한 후 SDF 곡선을 이용하여 각 사상별 재현기간을 추정한 결과, 2000년대 초반과 중반에 발생했던 가뭄은 최대 20~50년의 재현기간을 갖는 가뭄사상인 것으로 나타났다.

• 한국수자원학회논문집
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• 제49권10호
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• pp.823-833
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• 2016

본 연구에서는 최근 발생한 2014~2015 가뭄 사상을 보다 정확하게 분석하기 위해 삼변량 Copula 함수를 도입하여 연구를 진행하였다. 기존 연구에서는 일반적으로 가뭄 분석시 이변량(가뭄 지속시간, 심도)를 활용한 연구가 다수 진행되었다. 그러나 최근 강우자료의 패턴을 살펴보면 두 변량 이외의 가뭄 강도가 중요한 인자로 평가되어 이를 함께 고려한 삼변량 Copula 분석을 수행하였으며, 기상청 관측소 중 서울 관측소를 대상으로 연구를 진행하였다. 기본적으로, 이변량 빈도해석 결과에 비해 삼변량 해석 결과는 동일한 가뭄 사상에 대해서 다소 증가된 재현기간을 나타내는 것으로 파악됐다. 이와 더불어, Gumbel Copula 함수의 경우 Student t Copula 함수보다 가뭄 위험도 평가 시 다소 과대 추정하는 것으로 확인되었다. 즉, 삼변량 빈도해석 시 고려되는 Copula 함수의 선택이 가뭄의 재현기간을 추정하는데 있어 매우 민감한 사항으로 평가되었다.

• 한국농공학회지
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• 제13권1호
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• pp.2177-2190
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• 1971

본 시험은 한발시기를 이앙적기연한발구와 적기이앙직후한발구 그리고 유수형성기한발구별로 처리하고 한천일수를 10일, 20일, 30일간 단수했을 때의 벼 생육과 수량에 미치는 영향을 구명하였다. 가. 기상상항은 평년에 비해 일반적으로 성화에 비가 많았고 일조시간은 적었으며 온도는 비슷한 편으로 벼 작항에는 별차이가 없었다. 나. 관개수질은 중성으로 양호하였다. 다. 본 시험포의 토질은 비옥토가 양호한 편으로 일반 답토양과 비슷한 성질의 것이었다. 라. 분얼기의 생육상항은 하발 유형별로 보면 이앙적기지연한발구가 다른 처리구에 비해 초장은 가장 부량하였으나 분얼수는 가장 많았고 이앙직후한발구에서 분얼수가 가장 적었다. 한천일수별에 있어서는 일반적으로 한천일수가 길수록 초장 분얼수가 현저히 부량하였다. 마. 출수상항은 이앙지연한발구가 다른 처리구에 비해 $1{\sim}2$일정도 늦은 경향이었다. 하천일수별에 있어서는 일정한 경향이 없었다. 바. 성숙기의 생육 및 수량상항에서 한발시기별을 보면 이앙직후 한발구가 다른 처리구에 비해 양호하였고 유수형성기한발구가 가장 부량하였다. 한천일수별에 있어서는 한천일수가 길수록 생육 및 수량이 현저히 감소되었다.

• 한국농공학회:학술대회논문집
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• 한국농공학회 2003년도 학술발표논문집
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• pp.451-454
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• 2003

This study was mainly conducted to derive the design drought rainfall by the consecutive duration using probability weighted moments with rainfall in the regional drought frequency analysis. Selecting the drought rainfall series by the consecutive durations of drought observed for the long period all over the regions in Korea, optimal regionalization of the drought rainfall was classified by the climatologically and geographically homogeneous regions. Using the L-moment ratio and Kolmogorov- Smimov test, resonable frequency distribution for the drought rainfall was selected by the regions and consecutive periods of drought. Design drought rainfalls by the regions and consecutive durations were derived and compared by at-site and regional drought frequency analysis using the method of L-moments.