• KSCE Journal of Civil and Environmental Engineering Research
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• v.26 no.4B
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• pp.345-354
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• 2006

Drought brings on long term damage in contrast to flood, on economic loss in the region, and on ecologic and environmental disruptions. Drought is one of major natural disasters and gives a painful hardship to human beings. So we have tried to quantify the droughts for reducing drought damage and developed the drought indices for drought monitoring and management. The Palmer's drought severity index (PDSI) is widely used for the drought monitoring but it has the disadvanges and limitations in that the PDSI is estimated by considering just climate conditions as pointed out by many researchers. Thus this study uses the SWAT model which can consider soil conditions like soil type and land use in addition to climate conditions. We estimate soil water (SW) and soil moisture index (SMI) by SWAT which is a long term runoff simulation model. We apply the SWAT model to Soyang dam watershed for SMI estimation and compare SMI with PDSI for drought analysis. Say, we calibrate and validate the SWAT model by daily inflows of Soyang dam site and we estimate long term daily soil water. The estimated soil water is used for the computation of SMI based on the soil moisture deficit and we compare SMI with PDSI. As the results, we obtained the determination coefficient of 0.651 which means the SWAT model is applicable for drought monitoring and we can monitor drought in more high resolution by using GIS. So, we suggest that SMI based on the soil moisture deficit can be used for the drought monitoring and management.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.16 no.1
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• pp.83-97
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• 2013

This study was carried out to suggest an experimental base in selecting the drought resistance of plants. Adopting the natural drought method, this paper studies the drought resistance of 12 kinds of ground cover plants. focusing on analyzing the changes of relative water content on leaf, relative electric conductivity and chlorophyll content in 12 kinds of plants, and and the relation between soil water content under drought stress. The drought resistance of the plants were subject to laboratory and rooftop drought resistance treatments. The Logistic model of nonlinear regression analysis was used to evaluate the lethal time that were predicted with the range of 10.4~30.1d on roof top, and 19.5~39.0d on hothouse. The result shows that with the increase of stress time, relative water content and chlorophyll content on leaf were in a downward trend; the relative electric conductivity was upward tendency. Among 12 species of ground cover plants, exclude Pulsatilla koreana, Ainsliaea acerifolia were selected for rooftop plants because they showed resist drought strongly and took adaptive ability.

• Journal of Korea Water Resources Association
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• v.51 no.3
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• pp.195-205
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• 2018

Drought is a complex phenomenon caused by various factors which can be classified into natural and anthropogenic causes. In Korea, the natural drought typically occurs when the high pressure of the Pacific Ocean develops rapidly or becomes stronger than usual in summer, resulting in a short-lived monsoon season. Drought also can be classified into meteorological, agricultural, hydrological, and socioeconomic drought depending on the development process and consequences. Each type of droughts can influence the other drought types directly or indirectly. Drought propagation refers a phenomenon that changes from meteorological drought to agricultural or hydrological drought. In this study, the occurrence and patterns of drought propagation are evaluated. The relationship between meteorological and agricultural droughts was assessed using hydrometeorological data. We classified the types of drought into five categories to evaluate the occurrence and characteristics of drought propagation. As results, we found drought propagation did not occur or delayed until three months, depending on the type of drought. The further generalized relationship of drought propagation is expected to be used for predicting agricultural drought from the preceding meteorological drought.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.141-141
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• 2022

Drought is a global phenomenon that affects almost all landscapes and causes major damages. Due to non-linear nature of contributing factors, drought occurrence and its severity is characterized as stochastic in nature. Early warning of impending drought can aid in the development of drought mitigation strategies and measures. Thus, drought forecasting is crucial in the planning and management of water resource systems. The primary objective of this study is to make improvement is existing drought forecasting techniques. Therefore, we proposed an improved version of Seasonal Autoregressive Integrated Moving Average (SARIMA) model (MD-SARIMA) for reliable drought forecasting with three years lead time. In this study, we selected four watersheds of Han River basin in South Korea to validate the performance of MD-SARIMA model. The meteorological data from 8 rain gauge stations were collected for the period 1973-2016 and converted into watershed scale using Thiessen's polygon method. The Standardized Precipitation Index (SPI) was employed to represent the meteorological drought at seasonal (3-month) time scale. The performance of MD-SARIMA model was compared with existing models such as Seasonal Naive Bayes (SNB) model, Exponential Smoothing (ES) model, Trigonometric seasonality, Box-Cox transformation, ARMA errors, Trend and Seasonal components (TBATS) model, and SARIMA model. The results showed that all the models were able to forecast drought, but the performance of MD-SARIMA was robust then other statistical models with Wilmott Index (WI) = 0.86, Mean Absolute Error (MAE) = 0.66, and Root mean square error (RMSE) = 0.80 for 36 months lead time forecast. The outcomes of this study indicated that the MD-SARIMA model can be utilized for drought forecasting.

• Journal of Korea Water Resources Association
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• v.56 no.12
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• pp.929-937
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• 2023

This study aims to develop rules for the Determination of Drought Stages at the Local Level based on the drought cases in Gwangju and Jeollanam-do in 2022-2023. Among the eight drought indicators provided, six indicators (Agricultural drought stage (for paddy), Residential & industrial drought stage, SPI-12, Relative agricultural water storage, Residential water consumption change (for domestic use), Residential water consumption change (for non-domestic use) were confirmed to have statistical correlations with the perceptions of local government officials and experts. Additionally, this drought indicator was applied to a decision tree algorithm to develop rules for determining the severity of drought. Although it presented results similar to those of the existing method presented in previous studies, it showed a significant comparative advantage in explaining the temporal and spatial patterns of drought in the Gwangju and Jeollanam-do.

• Atmosphere
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• v.23 no.4
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• pp.539-547
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• 2013

The objective of this study is to standardize the calculation method of Palmer Drought Severity Index (PDSI) for the three Drought Management Agencies (DMA) in south Korea, and to evaluate the PDSI applicability. For comparison and review of the method, the code and input data of PDSI are collected from each DMA. The calculation method is the same, but the used input data (number of meteorological stations, normal year period, Available Water Capacity (AWC) of the soil) are different. Through discussions with drought experts and literature review, the standardized method is determined. 61 stations which have the data period more than 30 years are selected. Also the normal year is fixed for 30 years and updated every 10 years. The observed AWC is utilized using GIS data. Empirical equation of PDSI is re-estimated according to domestic climate characteristics. For evaluating the standardized PDSI, past drought events are investigated and drought indices including the existing SPI and PDSI are used for comparative analysis. As results, although the accuracy of standardized PDSI through ROC analysis is lower than SPI, the newly standardized PDSI is better than existing PDSI from DMA, Also it reasonably explain the spatial drought situation through the spatial analysis.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.197-197
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• 2016

Forecasting future drought events in a region plays a major role in water management and risk assessment of drought occurrences. The creeping characteristics of drought make it possible to mitigate drought's effects with accurate forecasting models. Drought forecasts are inevitably plagued by uncertainties, making it necessary to derive forecasts in a probabilistic framework. In this study, a new probabilistic scheme is proposed to forecast droughts, in which a discrete-time finite state-space hidden Markov model (HMM) is used aggregated with the Representative Concentration Pathway 8.5 (RCP) precipitation projection (HMM-RCP). The 3-month standardized precipitation index (SPI) is employed to assess the drought severity over the selected five stations in South Kore. A reversible jump Markov chain Monte Carlo algorithm is used for inference on the model parameters which includes several hidden states and the state specific parameters. We perform an RCP precipitation projection transformed SPI (RCP-SPI) weight-corrected post-processing for the HMM-based drought forecasting to derive a probabilistic forecast that considers uncertainties. Results showed that the HMM-RCP forecast mean values, as measured by forecasting skill scores, are much more accurate than those from conventional models and a climatology reference model at various lead times over the study sites. In addition, the probabilistic forecast verification technique, which includes the ranked probability skill score and the relative operating characteristic, is performed on the proposed model to check the performance. It is found that the HMM-RCP provides a probabilistic forecast with satisfactory evaluation for different drought severity categories, even with a long lead time. The overall results indicate that the proposed HMM-RCP shows a powerful skill for probabilistic drought forecasting.

• Journal of Forest and Environmental Science
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• v.28 no.2
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• pp.97-105
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• 2012

A Gangwon region consisting of over 80% of forest area has industries that have been developed by utilizing its clean region image. However, the recent climate change has increased the forest disease & insect pest as well as the forest fire and the major cause is known to be the increase in the frequency of a drought occurrence. From the aspect of climate change, it can be said that drought and forest are important in every aspect of the adaptation and mitigation of climate change measure as they increase forest disease & insect pest that leads to desolation of usable forest resource. In addition, the increase of forest fire reduces resources that can absorb greenhouse gas, which leads to increase in green house emission. The purpose of this study is to provide a motive for concentrating administrative power for protecting forest in a Gangwon region by selecting a drought management needed local government through a drought forecast according to the climate change scenario of a Gangwon region.

• Magazine of the Korean Society of Agricultural Engineers
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• v.37 no.6
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• pp.103-111
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• 1995

Drought index calculation based on the principal hydrological parameters, such as rainfall and reservoir storage, can estimate the duration and intensity of drought in irrigation reservoirs. It is difficult to build up a drought criteria since the conditions change variously by the reliability of rainfall. Because of the increasing water demands, it is urgent to prepare a generalized positive countermeasure to overcome drought. Water demands can at calculated but the estimation of drought characteristics, and the effective water management method can be established. The purpose of this study is to obtain a drought index and build up a data-base on the reservoir basins for establishing the fundamental hydrological data-base. This Index can observe the behavior of the WSI(Water Supply Index) and the component indices. The results summarized through this study are as follows. 1. WSI value of zero does not correspond to 100% in average due to the skewness in the probability distributions. 2. WSI is not a linear index; that is, given change in terms of water volume or percentage of average does not result in a proportional change on the WSI scale. 3. WSI is not always between the reservoir and the rainfall index in magnitude. This is only true if the component indices are of opposite sign. If they are of the same sign, the SWSI will often have a mangitude greater than either of the component indices. This is easily understood, because the concurrence of extreme values of the same sign for the two components is rarer than the occurrence of extreme values for either of the two components individually.

• Journal of Wetlands Research
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• v.18 no.4
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• pp.432-447
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• 2016

The increased frequency of drought and flood due to climate change was a global problem. In particular, drought was recognized as a serious environmental, ecological, social, and economic disaster. Therefore, it is necessary to study the measures to prevent it. In this study, we will estimate the meteorological drought index in the Han River Basin and analyze the impact of climate change on drought. The change of the meteorological drought occurrence due to climate change in the Han River separated by the common drought and severe drought was analyzed using the Representative Concentration Pathways (RCPs) scenarios provided by the Intergovernmental Panel on Climate Change (IPCC). The years 1973 - 2010 were selected for analysis in the current period. Using the scenario, we separated the future period (Target I: 2011 - 2039, Target II: 2040 - 2069, Target III : 2070 - 2099). The number of occurrences of less than -1.0 and -1.5 standard precipitation index were analyzed by SPI 3, 6, 12. Looking at the results, trends in rainfall in the Han River was expected to increase from the current figures, the occurrence of drought is predicted to decline in the future. However, the number of drought occurrence was analyzed to increase toward long-term drought. The number of severe drought occurrences was usually larger than the common drought estimated. Additional studies may be considered in addition to the agricultural drought, hydrological drought, socio-economic drought. This will be done by using efficient water management. The results can be used as a basis for future drought analysis of the Han River.