• 한국수자원학회:학술대회논문집
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• 한국수자원학회 2008년도 학술발표회 논문집
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• pp.67-74
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• 2008

The regional-scale transient groundwater-river interaction model is developed to gain a better understanding of the regional-scale relationships and interactions between groundwater and river system and quantify the residual river flow after groundwater abstraction from the aquifers with climate variability in the Waimea Plains, New Zealand. The effect of groundwater abstraction and climate variability on river flows is evaluated by calculating river flows at the downstream area for three different drought years (a 1 in 10 drought year, 1 in 20 drought year, and 1 in 24 drought year) and an average year with metered water abstraction data. The effect of future water demand (50 year projection) on river flows is also evaluated. A significant increase in the occurrence of zero flow, or very low flow of 100 L/sec at the downstream area is predicted due to large groundwater abstraction increase with climate variability. Modeling results shows the necessity of establishing dynamic cutback scenarios of water usage to users over the period of drought conditions considering different climate variability from current allocation limit to reduce the occurrence of low flow conditions at the downstream area.

• 한국수자원학회논문집
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• 제43권8호
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• pp.709-720
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• 2010

본 연구에서는 개념적인 토양수분 모형을 이용하여 가뭄에 대한 기후변화의 영향을 모형화하고, 모형으로부터의 결과를 분석하고 있다. 미래 기후자료로서 A2 온실가스 배출 시나리오에 따라 CCCma CGCM3-T63에 의해 도출된 자료가 이용되며, 일별 강수분포 및 월별 강수량 및 잠재증발산량의 변화를 고려하기 위하여 일별 스케일링 기법이 적용된다. 모형으로부터 도출된 주요결과로부터 미래에는 우리나라에 보다 잦은 가뭄이 있을 수 있음을 살펴볼 수 있다.

• 한국기후변화학회지
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• 제9권1호
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• pp.31-45
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• 2018

This study implemented the prediction of drought properties (number of drought events, intensity, duration) using the user-oriented systematical procedures of downscaling climate change scenarios based the multiple global climate models (GCMs), AIMS (APCC Integrated Modeling Solution) program. The drought properties were defined and estimated with Effective Drought Index (EDI). The optimal 10 models among 29 GCMs were selected, by the estimation of the spatial and temporal reproducibility about the five climate change indices related with precipitation. In addition, Simple Quantile Mapping (SQM) as the downscaling technique is much better in describing the observed precipitation events than Spatial Disaggregation Quantile Delta Mapping (SDQDM). Even though the procedure was systematically applied, there are still limitations in describing the observed spatial precipitation properties well due to the offset of spatial variability in multi-model ensemble (MME) analysis. As a result, the farther into the future, the duration and the number of drought generation will be decreased, while the intensity of drought will be increased. Regionally, the drought at the central regions of the Korean Peninsula is expected to be mitigated, while that at the southern regions are expected to be severe.

• 한국농공학회논문집
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• 제61권1호
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• pp.31-44
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• 2019

The main objective of this research is to develop a hydroclimate drought index (HCDI) using the gridded climate data inputs in a Variable Infiltration Capacity (VIC) modeling platform. Typical drought indices, including, Standardized Precipitation Index (SPI), Standardized Precipitation Evapotranspiration Index (SPEI), and Self-calibrated Palmer Drought Severity Index (SC-PDSI) in South Korea are also used and compared. Inverse Distance Weighting (IDW) method is applied to create the gridded climate data from 56 ground weather stations using topographic information between weather stations and the respective grid cell ($12km{\times}12km$). R statistical software packages are used to visualize HCDI in Google Earth. Skill score (SS) are computed to evaluate the drought predictability based on water information derived from the observed reservoir storage and the ground weather stations. The study indicates that the proposed HCDI with the gridded climate data input is promising in the sense that it can help us to predict potential drought extents and to mitigate its impacts in a changing climate. The longer term drought prediction (e.g., 9 and 12 month) capability, in particular, shows higher SS so that it can be used for climate-driven future droughts.

• 한국수자원학회논문집
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• 제50권11호
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• pp.745-758
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• 2017

Copula 함수 기반의 모형들은 가뭄빈도해석 및 수문시계열분석 등 수문학적 모델링을 위해 다각적으로 활용되고 있다. 그러나 기존 연구에서는 Copula 함수 및 주변확률분포 매개변수에 대한 불확실성을 정량적으로 평가할 수 있는 모형의 개발 사례는 국내외적으로 미진한 실정이다. 이러한 점에서 본 연구에서는 기존 Copula 모형에 Bayesian 기법을 도입하여 매개변수의 불확실성을 평가할 수 있는 이변량 가뭄빈도해석 기법을 개발하였다. 본 연구에서는 우선적으로 모의자료를 대상으로 모형의 적합성을 평가하였으며, 모형 적용결과 가정한 매개변수를 정확하게 재추정하는 것을 확인할 수 있다. 최종적으로 기 개발된 Bayesian Copula 함수 기반의 이변량 가뭄빈도해석 모형을 한강유역에 적용하여 최근 2013~2015년에 가뭄 사상을 평가하였다. 서울, 경기 및 강원 지역에서 특히 가뭄이 심한 것으로 나타났으며, 대부분의 지역에서 결합재현기간이 100년을 상회하는 것으로 평가되었다. 본 연구를 통해 제안된 모형의 검증과정과 도출된 결과를 기준으로 판단해보면 가뭄자료의 분포특성 및 자료간의 상관성을 효과적으로 재현하는데 유리할 뿐만 아니라 매개변수의 불확실성을 평가할 수 있는 장점을 확인할 수 있었다.

• 한국농공학회논문집
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• 제58권5호
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• pp.1-10
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• 2016

Drought is a slow-varying natural hazard that is characterized by various factors such that reliable drought forecasting along with uncertainties estimation has been a major issue. In this study, we proposed a stochastic simulation technique based scheme for providing a set of drought scenarios. More specifically, this study utilized a nonstationary Hidden markov model that allows us to include predictors such as climate state variables and global climate model's outputs. The simulated rainfall scenarios were then used to generate the well-known meteorological drought indices such as SPI, PDSI and PN for the three dam watersheds in South Korea. It was found that the proposed modeling scheme showed a capability of effectively reproducing key statistics of the observed rainfall. In addition, the simulated drought indices were generally well correlated with that of the observed.

• 환경위생공학
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• 제17권4호
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• pp.1-9
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• 2002

In order to define about concern with discharge and water-quality, it is calculated drought flow, low flow, normal flow and wet flow in Chungju watershed from flow duration analysis. Water quality modeling study is performed for forecasting at upstream of Chungju lake. It is devided method of modeling into before and after the equipment of environmental treatment institution. And it is estimated the change of water quality. Before the equipment of environmental treatment, BOD concentration is increased from 23000 to 2006 years at all site and decrease on 2012 years. The rate of increasing BOD concentration is showed height between 2000 years and 2003 years most of all site. And after the equipment of environmental treatment, it is showed first grade of BOD water quality in most of sample site beside Jucheon river. The result of water quality modeling using drought flow showed that a lot of pollution occurred. And water quality using wet flow is good, so much discharge make more improve water quality than little discharge.

• 대한토목학회논문집
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• 제41권2호
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• pp.113-121
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• 2021

폭염의 발생 메커니즘은 대부분 종관 규모적 관점에서 연구가 이루어지고 있으나, 폭염발생 이전의 또 다른 자연재해로 인한 연쇄적인 영향을 해석하기 위한 연구도 중요하다. 본 연구에서는 폭염 발생 이전에 나타나는 가뭄과의 인과관계 및 영향을 평가하기 위해 부분최소제곱 구조방정식 모형(PLS-SEM)을 이용하였다. 1974년부터 약 46년간 발생한 여름철 폭염에 미치는 계절별 가뭄의 영향정도는, 겨울철 서울(경기)지역은 37%, 강원지역은 21 %, 충청지역은 17 %이며, 봄철 서울(경기)지역은 29 %, 강원지역은 18 %, 충청지역은 8 %이며, 여름철 서울(경기)지역은 22 %, 강원지역은 29 %, 충청지역 38 %로 확인되었다. 이는 지역별로 나타나는 폭염과 계절별 가뭄이 미치는 영향의 정도가 다르기 때문에 따라 나타나는 결과로 해석된다. 여름철 가뭄-폭염 간의 영향이 크게 나타난 강원, 충청 지역은 서울(경기)지역에 비해 가뭄-폭염으로 인한 피해양상이 복합적으로 나타날 가능성이 있다.

• Journal of the Korean Statistical Society
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• 제36권1호
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• pp.93-109
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• 2007

Gamma distributions are some of the most popular models for hydrological processes. In this paper, a very flexible family which contains the gamma distribution as a particular case is introduced. Evidence of flexibility is shown by examining the shape of its pdf and the associated hazard rate function. A comprehensive treatment of the mathematical properties is provided by deriving expressions for the nth moment, moment generating function, characteristic function, Renyi entropy and the asymptotic distribution of the extreme order statistics. Estimation and simulation issues are also considered. Finally, a detailed application to drought data from the State of Nebraska is illustrated.

• Korean Journal of Hydrosciences
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• 제8권
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• pp.125-136
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• 1997

The simulation techniques of hydrologic data series have develped for the purposes of the design of water resources system, the optimization of reservoir operation, and the design of flood control of reservoir, etc. While the stochastic models are usually used in most analysis of water resources fields for the generation of data sequences, the indexed sequential modeling (ISM) method based on generation of a series of overlapping short-term flow sequences directly from the historical record has been used for the data generation in the western USA since the early of 1980s. It was reported that the reliable results by ISM were obtained in practical applications. In this study, we generate annual inflow series at a location of Hong Cheon Dam site by using ISM method and autoregressive, order-1 model (AR(1)), and estimate the drought characteristics for the comparison aim between ISM and AR(1).