• KCID journal
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• v.3 no.1
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• pp.20-31
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• 1996

Several drought indices, which indicate the severity of drought in a reservoir or an irrigated area, have been suggested in home and overseas. However, the indices have not been adopted because those were extremely difficult to be understood by the genera

• Journal of Korea Water Resources Association
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• v.46 no.12
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• pp.1249-1263
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• 2013

In order to minimize the damages caused by long-term drought, appropriate drought management plans of the basin should be established with the drought forecasting technology. Further, in order to build reasonable adaptive measurement for future drought, the duration and severity of drought must be predicted quantitatively in advance. Thus, this study, attempts to forecast drought in Korea by using an Artificial Neural Network Model, and drought index, which are the representative statistical approach most frequently used for hydrological time series forecasting. SPI (Standardized Precipitation Index) for major weather stations in Korea, estimated using observed historical precipitation, was used as input variables to the MLP (Multi Layer Perceptron) Neural Network model. Data set from 1976 to 2000 was selected as the training period for the parameter calibration and data from 2001 to 2010 was set as the validation period for the drought forecast. The optimal model for drought forecast determined by training process was applied to drought forecast using SPI (3), SPI (6) and SPI (12) over different forecasting lead time (1 to 6 months). Drought forecast with SPI (3) shows good result only in case of 1 month forecast lead time, SPI (6) shows good accordance with observed data for 1-3 months forecast lead time and SPI (12) shows relatively good results in case of up to 1~5 months forecast lead time. The analysis of this study shows that SPI (3) can be used for only 1-month short-term drought forecast. SPI (6) and SPI (12) have advantage over long-term drought forecast for 3~5 months lead time.

• Journal of The Korean Society of Agricultural Engineers
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• v.53 no.6
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• pp.165-170
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• 2011

Recently natural disasters such as the frequency and intensity of drought have been increasing as a result of climate change. This study suggests a drought index, WADI (Water Availability Drought Index), that considers water availability using 6 components (water intake, groundwater level, agricultural reservoir water level, dam inflow, streamflow, and precipitation) using the Z score and data monitoring on a nationwide level. SPI (Standardized Precipitation Index) was applied in coastal area. For the severe droughts of 2001 spring and 2008 autumn, the index was evaluated by comparison with reported damage areas. suggested to combine The spatial concordance rate of WADI in 2001 and 2008 for estimation of the degree of drought severity was 50 % and 24 % compared to the actual recorded data respectively.

• Journal of Korea Water Resources Association
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• v.45 no.1
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• pp.75-89
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• 2012

This study attempted to analyze statistical characteristics of historical drought of Korea through trend, periodicity and drought spell analysis by using the drought indices. Standard Precipitation Index (SPI) and Palmer Drought Severity Index (PDSI) were calculated using weather data of 59 weather stations under Korea Meteorological Administration (KMA). As a result of analysis, SP13 and SP16 showed trend of drier spring, drier winter and wetter summer in all basin of Korea. However, SPI12 and PDSI showed different trends with shorter duration drought indices. In case of wavelet transform analysis for drought periodicities, in a band of 1~2 years or below 6 years showed significant spectrum. SP13 showed strongest power spectrum near the band of 1~2 year variance, and SPI12 and PDSI showed 6 years periodicities. The results from drought spell showed that Nakdong River Basin, Geum River Basin and Youngsan River Basin were appeared as severe drought vulnerable area of Korea.

• Journal of Korea Water Resources Association
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• v.39 no.9 s.170
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• pp.801-812
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• 2006

In this study, Combined Drought Index which can monitor the drought severity and intensity has been developed using PDSI, SPI and MSWSI. To verify the accuracy and applicability of combined drought index, Drought map of Korea using the combined drought index has compared with past drought event. Drought map using the combined drought index shows good accordance with past drought event and accurate quantitative drought monitoring results. Also the drought outlook technique has been developed using the weather forecast data of Korea Meteorological Administration (KMA). Drought outlook technique of this study can be used effectively as a primitive stage tool for real time drought forecast. As a result of this study, Integrated drought monitoring system has been developed which has capabilities of producing and generating the drought monitoring map and drought outlook map as well as various kinds of drought related information.

• Journal of The Korean Society of Agricultural Engineers
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• v.61 no.1
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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.

• Journal of Ecology and Environment
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• v.33 no.1
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• pp.47-57
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• 2010

To understand day-to-day fluctuations in soil moisture content in Seoul, I simulated daily soil moisture content from 1908 to 2009 using long-term climatic precipitation and temperature data collected at the Surface Synoptic Meteorological Station in Seoul for the last 98 years with a hydrological simulation model, BROOK. The output data set from the BROOK model allowed me to examine day-to-day fluctuations and the severity and duration of droughts in the Seoul area. Although the soil moisture content is highly dependent on the occurrence of precipitation, the pattern of changes in daily soil moisture content was clearly quite different from that of precipitation. Generally, there were several phases in the dynamics of daily soil moisture content. The period from mid-May to late June can be categorized as the initial period of decreasing soil moisture content. With the initiation of the monsoon season in late June, soil moisture content sharply increases until mid-July. From the termination of the rainy season in mid-July, daily soil moisture content decreases again. Highly stochastic events of typhoons from late June to October bring large amount of rain to the Korean peninsula, culminating in late August, and increase the soil moisture content again from late August to early September. From early September until early October, another sharp decrease in soil moisture content was observed. The period from early October to mid-May of the next year can be categorized as a recharging period when soil moisture content shows an increasing trend. It is interesting to note that no statistically significant increase in mean annual soil moisture content in Seoul, Korea was observed over the last 98 years. By simulating daily soil moisture content, I was also able to reconstruct drought phenomena to understand the severity and duration of droughts in Seoul area. During the period from 1908 to 2009, droughts in the years 1913, 1979, 1939, and 2006 were categorized as 'severe' and those in 1988 and 1982 were categorized as 'extreme'. This information provides ecologists with further potential to interpret natural phenomenon, including tree growth and the decline of tree species in Korea.

• Journal of The Korean Society of Agricultural Engineers
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• v.57 no.4
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• pp.1-9
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• 2015

The development of drought index that provides detailed-spatial-resolution drought information is essential for improving drought planning and preparedness. The objective of this study was to develop the concept of using satellite-based hybrid drought index called the Vegetation Drought Response Index in South Korea (VegDRI-SKorea) that could improve spatial resolution for monitoring local and regional drought. The VegDRI-SKorea was developed using the Classification And Regression Trees (CART) algorithm based on remote sensing data such as Normalized Difference Vegetation Index (NDVI) from MODIS satellite images, climate drought indices such as Self Calibrating Palmer Drought Severity Index (SC-PDSI) and Standardized Precipitation Index (SPI), and the biophysical data such as land cover, eco region, and soil available water capacity. A case study has been done for the 2012 drought to evaluate the VegDRI-SKorea model for South Korea. The VegDRI-SKorea represented the drought areas from the end of May and to the severe drought at the end of June. Results show that the integration of satellite imageries and various associated data allows us to get improved both spatially and temporally drought information using a data mining technique and get better understanding of drought condition. In addition, VegDRI-SKorea is expected to contribute to monitor the current drought condition for evaluating local and regional drought risk assessment and assisting drought-related decision making.

• Journal of The Korean Society of Agricultural Engineers
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• v.59 no.5
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• pp.127-136
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• 2017

The object of this study was to assess availability of meteorological drought index for agricultural dorught estimation in ungauged area of agricultural drought parameters which are reservoir water level and soil moisture. The IADI (Integrated Agricultural Drought Index) and the SPI (Standard Precipitation Index), which are the criteria for determining agricultural drought and meteorological drought, were calculated and compared. For this purpose, the droughts that occurred in the Baeksan reservoir in Gimje and the Edong reservoir in Suwon were evaluated by using the IADI and SPI drought indecies. In addition, we compared and analyzed the depth of drought based on the two drought indices. Evaluations derived form the IADI and SPI showed that the standard precipitation index tended to indicate the occurrence of drought earlier than the integrated agricultural drought index. However, the integrated agricultural drought index was better than the standard precipitation index at evaluating the severity of drought during the period of irrigation. The relationship between these two drought indices seems to be useful for decision making in the case of drought, and it is considered that more studies are needed to examine the applicability of these drought indexes.

• Journal of Korea Water Resources Association
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• v.39 no.7 s.168
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• pp.617-626
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• 2006

In this study 3-month SPI data from 59 stations over the Korean peninsula are analyzed by deriving and spatially characterizing the EOFs. Also, the coefficient time series of EOF are applied to the multi-variate time series model to generate the time series of 10,000 years, to average them to estimate the areal average, and to decide the maximum drought severity for given return periods. Finally, the drought prevention ability is evaluated by considering the effective storage of dam within the basin and the size of agricultural area. Especially for the return period of 30 years, only the Han river basin has the potential to overcome the drought. Other river basins like the Youngsan river basin, which has a large portion of agricultural area but less water storage, are found to be very vulnerable to the rainfall-sensitive agricultural drought.