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An oscillatory S-curve causes unexpected fluctuations in a unit hydrograph (UH) of desired duration or an instantaneous UH (IUH) that may affect the constraints for hydrologic stability. On the other hand, the Savitzky–Golay smoothing and differentiation filter (SG filter) is a digital filter known to smooth data without distorting the signal tendency. The present study proposes a method based on the SG filter to cope with oscillatory S-curves. Compared to previous conventional methods, the application of the SG filter to an S-curve was shown to drastically reduce the oscillation problems on the UH and IUH. In this method, the SG filter parameters are selected to give the minimum influence on smoothing and differentiation. Based on runoff reproduction results and performance criteria, it appears that the SG filter performed both smoothing and differentiation without the remarkable variation of hydrograph properties such as peak or time-to peak. The IUH, UH, and S-curve were estimated using storm data from two watersheds. The reproduced runoffs showed high levels of model performance criteria. In addition, the analyses of two other watersheds revealed that small watershed areas may experience scale problems. The proposed method is believed to be valuable when error-prone data are involved in analyzing the linear rainfall–runoff relationship.
Kee-Won Seong; Jang Sung. Derivation of S-Curve from Oscillatory Hydrograph Using Digital Filter. Water 2021, 13, 1456 .
AMA StyleKee-Won Seong, Jang Sung. Derivation of S-Curve from Oscillatory Hydrograph Using Digital Filter. Water. 2021; 13 (11):1456.
Chicago/Turabian StyleKee-Won Seong; Jang Sung. 2021. "Derivation of S-Curve from Oscillatory Hydrograph Using Digital Filter." Water 13, no. 11: 1456.
The relationships between a variety of hydro-meteorological variables and irrigation water use rates (WUR) were investigated in this study. Standardized Precipitation Index (SPI), Potential Evapotranspiration (PET), and Normalized Difference Vegetation Index (NDVI) were explored to identify the relationship with the WUR. The Yeongsan river basin, the agricultural land of which is mostly occupied by well-irrigated paddy, was used for the pilot study. Four different temporal scales of SPI-3, 6, 9, and 12 were tested, and PET was calculated using the Thornthwaite method. To calculate NDVI, the surface spectral reflectance data, which was acquired by Moderate Resolution Imaging Spectroradiometer (MODIS) equipped on the Terra satellite, were used. As a result, there was a statistically significant relationship between SPI9 and the WUR during drought periods in which negative values of SPI9 were obtained. The WUR was strongly correlated with both PET and NDVI. Compared with SPI, the variability of WUR in this study area was more sensitively affected by PET and NDVI, which can cause a potential lack of agricultural water supply. The finding of this study implies that SPI9, PET, and NDVI are the critical factors for predicting water withdrawal during drought conditions so that they can be used for irrigational water use management. Although a part of the findings of this study has been discussed by a few previous studies, this study is novel in that it quantifies the relationship between these factors using actual field observations of streamflow withdrawal for irrigation.
Jang Sung; Donghae Baek; Young Ryu; Seung Seo; Kee-Won Seong. Effects of Hydro-Meteorological Factors on Streamflow Withdrawal for Irrigation in Yeongsan River Basin. Sustainability 2021, 13, 4969 .
AMA StyleJang Sung, Donghae Baek, Young Ryu, Seung Seo, Kee-Won Seong. Effects of Hydro-Meteorological Factors on Streamflow Withdrawal for Irrigation in Yeongsan River Basin. Sustainability. 2021; 13 (9):4969.
Chicago/Turabian StyleJang Sung; Donghae Baek; Young Ryu; Seung Seo; Kee-Won Seong. 2021. "Effects of Hydro-Meteorological Factors on Streamflow Withdrawal for Irrigation in Yeongsan River Basin." Sustainability 13, no. 9: 4969.
Due to the recent appearance of shares socioeconomic pathway (SSP) scenarios, there have been many studies that compare the results between Coupled Model Intercomparison Project (CMIP)5 and CMIP6 general circulation models (GCMs). This study attempted to project future drought characteristics in the Cheongmicheon watershed using SSP2-4.5 of Australian Community Climate and Earth System Simulator-coupled model (ACCESS-CM2) in addition to Representative Concentration Pathway (RCP) 4.5 of ACCESS 1-3 of the same institute. The historical precipitation and temperature data of ACCESS-CM2 were generated better than those of ACCESS 1-3. Two meteorological drought indices, namely, Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) were used to project meteorological drought while a hydrological drought index, Standardized Streamflow Index (SDI), was used to project the hydrological drought characteristics. The metrological data of GCMs were bias-corrected using quantile mapping method and the streamflow was obtained using Soil and Water Assessment Tool (SWAT) and bias-corrected meteorological data. As a result, there were large differences of drought occurrences and severities between RCP4.5 and SSP2-4.5 for the values of SPI, SPEI, and SDI. The differences in the minimum values of drought index between near (2021–2060) and far futures (2061–2100) were very small in SSP2-4.5, while those in RCP4.5 were very large. In addition, the longest drought period from SDI was the largest because the variation in precipitation usually affects the streamflow with a lag. Therefore, it was concluded that it is important to consider both CMIP5 and CMIP6 GCMs in establishing the drought countermeasures for the future period.
Jin Hyuck Kim; Jang Hyun Sung; Eun-Sung Chung; Sang Ug Kim; Minwoo Son; Mohammed Sanusi Shiru. Comparison of Projection in Meteorological and Hydrological Droughts in the Cheongmicheon Watershed for RCP4.5 and SSP2-4.5. Sustainability 2021, 13, 2066 .
AMA StyleJin Hyuck Kim, Jang Hyun Sung, Eun-Sung Chung, Sang Ug Kim, Minwoo Son, Mohammed Sanusi Shiru. Comparison of Projection in Meteorological and Hydrological Droughts in the Cheongmicheon Watershed for RCP4.5 and SSP2-4.5. Sustainability. 2021; 13 (4):2066.
Chicago/Turabian StyleJin Hyuck Kim; Jang Hyun Sung; Eun-Sung Chung; Sang Ug Kim; Minwoo Son; Mohammed Sanusi Shiru. 2021. "Comparison of Projection in Meteorological and Hydrological Droughts in the Cheongmicheon Watershed for RCP4.5 and SSP2-4.5." Sustainability 13, no. 4: 2066.
This study proposed a deep learning-based model to estimate stream water-use rate (WUR) using precipitation (P) and potential evapotranspiration (PET). Correlations were explored to identify relationships among accumulated meteorological variables for various time durations (three-, four-, five-, and six-month cumulative) and WUR, which revealed that three-month cumulative meteorological variables and WUR were highly correlated. A deep belief network (DBN) based on iterating parameter tuning was developed to estimate WUR using P, PET, and antecedent stream water-use rate (DWUR). The training and validation periods were 2011–2016, and 2017–2019, respectively. The results showed that the PET-DWUR based model provided better performances in Nash–Sutcliff efficiency (NSE), root mean square error (RMSE), and determination coefficient (R2) than the P-PET-DWUR and P-DWUR models. The framework in this study can provide a forecast model for deficiencies of stream water use coupled with a weather forecast model.
Jang Hyun Sung; Young Ryu; Eun-Sung Chung. Estimation of Water-Use Rates Based on Hydro-Meteorological Variables Using Deep Belief Network. Water 2020, 12, 2700 .
AMA StyleJang Hyun Sung, Young Ryu, Eun-Sung Chung. Estimation of Water-Use Rates Based on Hydro-Meteorological Variables Using Deep Belief Network. Water. 2020; 12 (10):2700.
Chicago/Turabian StyleJang Hyun Sung; Young Ryu; Eun-Sung Chung. 2020. "Estimation of Water-Use Rates Based on Hydro-Meteorological Variables Using Deep Belief Network." Water 12, no. 10: 2700.
This study projected future changes in potential evapotranspiration (PET) over North Korea, which has been exposed to climate change risks. For this purpose, climate change scenarios downscaled at station scale were produced under RCP8.5, which downscale method preserves the long-term trend driven by climate models. Based on the ability to replicate observation, representative climate change scenarios (RCCS) were selected using performance indicators and TOPSIS method. The GCMs having higher spatial resolution were selected as RCCS, and projected that PET would increase in the future. It is found that the inter-model variability of PET in the summer was gradually increased over North Korea and annual mean evapotranspiration would be expected to increase by 1.4 times (F1, 2011–2040), 2.0 times (F2, 2041–2070) and 2.6 times (F3, 2071–2100). In preparation for the deficit of available water due to the increase in evapotranspiration, securing alternative water resources and construction of multi-purpose dams are required.
Young Ryu; Eun-Sung Chung; Seung Beom Seo; Jang Hyun Sung. Projection of Potential Evapotranspiration for North Korea Based on Selected GCMs by TOPSIS. KSCE Journal of Civil Engineering 2020, 24, 2849 -2859.
AMA StyleYoung Ryu, Eun-Sung Chung, Seung Beom Seo, Jang Hyun Sung. Projection of Potential Evapotranspiration for North Korea Based on Selected GCMs by TOPSIS. KSCE Journal of Civil Engineering. 2020; 24 (9):2849-2859.
Chicago/Turabian StyleYoung Ryu; Eun-Sung Chung; Seung Beom Seo; Jang Hyun Sung. 2020. "Projection of Potential Evapotranspiration for North Korea Based on Selected GCMs by TOPSIS." KSCE Journal of Civil Engineering 24, no. 9: 2849-2859.
Accurate streamflow forecasts enable the appropriate management of water resources. Although there is a general consensus that climate information can enhance hydrological predictability, this might not be the case if the accuracy of the given climate information is unreliable. Hence, this study has developed a modeling framework to estimate the role of climate information in forecasting accurate streamflow. Ensemble streamflow prediction (ESP) technology was adopted as a dynamic hydrologic forecast method to 35 watersheds in South Korea. The probabilistic precipitation forecast (PPF), issued by the Korea Meteorological Administration, was used as climate information for updating the probabilities of climate scenarios. First, we found that the current PPF is not accurate enough for significantly enhancing the streamflow forecasting accuracy. Subsequently, multiple sets of PPF were synthetically generated to evaluate the role of climate information. Given the perfect categorical climate forecasts, we found that there is much potential for the enhancement of streamflow forecast skill especially in the seasons that exhibit greater streamflow variability. However, there is less potential for increasing the streamflow forecasting skill under below-normal conditions. The proposed modeling framework is capable of quantifying the magnitude of potential improvement in hydrological predictability under the assumption that better climate information will be available in the future. We expect that this modeling framework can be effectively applied to other regions across a wide range of climate regimes.
Seung Beom Seo; Jang Hyun Sung. The role of probabilistic precipitation forecasts in hydrologic predictability. Theoretical and Applied Climatology 2020, 141, 1203 -1218.
AMA StyleSeung Beom Seo, Jang Hyun Sung. The role of probabilistic precipitation forecasts in hydrologic predictability. Theoretical and Applied Climatology. 2020; 141 (3-4):1203-1218.
Chicago/Turabian StyleSeung Beom Seo; Jang Hyun Sung. 2020. "The role of probabilistic precipitation forecasts in hydrologic predictability." Theoretical and Applied Climatology 141, no. 3-4: 1203-1218.
In order to enhance the streamflow forecast skill, seasonal/sub-seasonal streamflow forecasts can be post-processed by incorporating new information, such as climate signals. This study proposed a simple yet efficient approach, the “Bivar_update” model that utilizes bivariate climate forecast to update individual probabilities of the ensemble streamflow prediction. The Bayesian updating scheme is used to update the joint probability mass function derived from historic precipitation and temperature data sets. Thirty-five dam basins were used for the case study, and the modified Tank model was embedded into the ensemble streamflow prediction framework. The performance of the proposed approach was evaluated through a comparison with a reference streamflow forecast model, the “Univar_update” model, that reflects only precipitation forecast, in terms of deterministic and categorical streamflow forecast accuracy. For this purpose, multiple cases of probabilistic precipitation and temperature forecasts were synthetically generated. As a result, the Bivar_update model was able to decrease the errors in forecast under below-normal conditions. The improvements in forecasting skills were found for both measures; deterministic and categorical streamflow forecasts. Since the proposed Bivar_update model reflects both precipitation and temperature information, it can compensate low predictability especially under dry conditions in which the streamflow’s dependency on temperature increases.
Jang Hyun Sung; Young Ryu; Seung Beom Seo. Utilizing Bivariate Climate Forecasts to Update the Probabilities of Ensemble Streamflow Prediction. Sustainability 2020, 12, 2905 .
AMA StyleJang Hyun Sung, Young Ryu, Seung Beom Seo. Utilizing Bivariate Climate Forecasts to Update the Probabilities of Ensemble Streamflow Prediction. Sustainability. 2020; 12 (7):2905.
Chicago/Turabian StyleJang Hyun Sung; Young Ryu; Seung Beom Seo. 2020. "Utilizing Bivariate Climate Forecasts to Update the Probabilities of Ensemble Streamflow Prediction." Sustainability 12, no. 7: 2905.
The numerous choices between climate change scenarios makes decision-making difficult for the assessment of climate change impacts. Previous studies have used climate models to compare performance in terms of simulating observed climates or preserving model variability among scenarios. In this study, the Katsavounidis-Kuo-Zhang algorithm was applied to select representative climate change scenarios (RCCS) that preserve the variability among all climate change scenarios (CCS). The performance of multi-model ensemble of RCCS was evaluated for reference and future climates. It was found that RCCS was well suited for observations and multi model ensemble of all CCS. Using the RCCS under RCP (Representative Concentration Pathway) 8.5, the future extreme precipitation was projected. As a result, the magnitude and frequency of extreme precipitation increased towards the farther future. Especially, extreme precipitation (daily maximum precipitation of 20-year return-period) during 2070-2099, was projected to occur once every 8.3-year. The RCCS employed in this study is able to successfully represent the performance of all CCS, therefore, this approach can give opportunities managing water resources efficiently for assessment of climate change impacts.
Jang Hyun Sung; Minsung Kwon; Jong-June Jeon; Seung Beom Seo. A Projection of Extreme Precipitation Based on a Selection of CMIP5 GCMs over North Korea. Sustainability 2019, 11, 1976 .
AMA StyleJang Hyun Sung, Minsung Kwon, Jong-June Jeon, Seung Beom Seo. A Projection of Extreme Precipitation Based on a Selection of CMIP5 GCMs over North Korea. Sustainability. 2019; 11 (7):1976.
Chicago/Turabian StyleJang Hyun Sung; Minsung Kwon; Jong-June Jeon; Seung Beom Seo. 2019. "A Projection of Extreme Precipitation Based on a Selection of CMIP5 GCMs over North Korea." Sustainability 11, no. 7: 1976.
The standardized precipitation index (SPI)—a meteorological drought index—uses various reference precipitation periods. Generally, drought projections using future climate change scenarios compare reference SPIs between baseline and future climates. Here, future drought was projected based on reference precipitation under the baseline climate to quantitatively compare changes in the frequency and severity of future drought. High-resolution climate change scenarios were produced using HadGEM2-AO General Circulation Model (GCM) scenarios for Korean weather stations. Baseline and future 3-month cumulative precipitation data were fitted to gamma distribution; results showed that precipitation of future climate is more than the precipitation of the baseline climate. When future precipitation was set as that of the baseline climate instead of the future climate, results indicated that drought intensity and frequency will decrease because the non-exceedance probability for the same precipitation is larger in the baseline climate than in future climate. However, due to increases in regional precipitation variability over time, some regions with opposite trends were also identified. Therefore, it is necessary to understand baseline and future climates in a region to better design resilience strategies and mechanisms that can help cope with future drought.
Minsung Kwon; Jang Hyun Sung. Changes in Future Drought with HadGEM2-AO Projections. Water 2019, 11, 312 .
AMA StyleMinsung Kwon, Jang Hyun Sung. Changes in Future Drought with HadGEM2-AO Projections. Water. 2019; 11 (2):312.
Chicago/Turabian StyleMinsung Kwon; Jang Hyun Sung. 2019. "Changes in Future Drought with HadGEM2-AO Projections." Water 11, no. 2: 312.
Although the magnitude and frequency of extreme events on the global scale are expected to change because of changes in the hydrological cycle under climate change, little quantitative assessment of future extreme precipitation in North Korea has been attempted. Therefore, this study projected the changes in extreme precipitation in North Korea by applying downscaling to GCMs forced by Representative Concentration Pathway (RCP) Scenarios 4.5 and 8.5, preserving the long-term trend of climate change projection. Employing climate change scenario ensembles of RCP8.5, the precipitation level of the 20-year return period in the reference period of 1980–2005 increased to 21.1 years for the future period 2011–2040, decreased to 16.2 years for 2041–2070, and decreased to 8.8 years for 2071–2100. Extreme precipitation was expected to occur often in the future. In addition, an increase in extreme precipitation at the border of North and South Korea is expected, and it is concluded that a joint response for the Imjin River, a river shared by North and South Korea, is needed.
Minsung Kwon; Jang Hyun Sung; Jaehyun Ahn. Change in Extreme Precipitation over North Korea Using Multiple Climate Change Scenarios. Water 2019, 11, 270 .
AMA StyleMinsung Kwon, Jang Hyun Sung, Jaehyun Ahn. Change in Extreme Precipitation over North Korea Using Multiple Climate Change Scenarios. Water. 2019; 11 (2):270.
Chicago/Turabian StyleMinsung Kwon; Jang Hyun Sung; Jaehyun Ahn. 2019. "Change in Extreme Precipitation over North Korea Using Multiple Climate Change Scenarios." Water 11, no. 2: 270.
This study developed a methodological framework to update the rainfall intensity-duration-frequency (IDF) curves under climate change scenarios. A model output statistics (MOS) method is used to downscale the daily rainfall of general circulation models (GCMs), and an artificial neural network (ANN) is employed for the disaggregation of projected daily rainfall to hourly maximum rainfall, which is then used for the development of IDF curves. Finally, the 1st quartiles, medians, and 3rd quartiles of projected rainfall intensities are estimated for developing IDF curves with uncertainty level. Eight GCM simulations under two radiative concentration pathways (RCP) scenarios, namely, RCP 4.5 and RCP 8.5, are used in the proposed framework for the projection of IDF curves with related uncertainties for peninsular Malaysia. The projection of rainfall revealed an increase in the annual average rainfall throughout the present century. The comparison of the projected IDF curves for the period 2006–2099 with that obtained using GCM hindcasts for the based period (1971–2005) revealed an increase in rainfall intensity for shorter durations and a decrease for longer durations. The uncertainty in rainfall intensity for different return periods for shorter duration is found to be 2 to 6 times more compared to longer duration rainfall, which indicates that a large increase in rainfall intensity for short durations projected by GCMs is highly uncertain for peninsular Malaysia. The IDF curves developed in this study can be used for the planning of climate resilient urban water storm water management infrastructure in Peninsular Malaysia.
Muhammad Noor; Tarmizi Ismail; Eun-Sung Chung; Shamsuddin Shahid; Jang Hyun Sung. Uncertainty in Rainfall Intensity Duration Frequency Curves of Peninsular Malaysia under Changing Climate Scenarios. Water 2018, 10, 1750 .
AMA StyleMuhammad Noor, Tarmizi Ismail, Eun-Sung Chung, Shamsuddin Shahid, Jang Hyun Sung. Uncertainty in Rainfall Intensity Duration Frequency Curves of Peninsular Malaysia under Changing Climate Scenarios. Water. 2018; 10 (12):1750.
Chicago/Turabian StyleMuhammad Noor; Tarmizi Ismail; Eun-Sung Chung; Shamsuddin Shahid; Jang Hyun Sung. 2018. "Uncertainty in Rainfall Intensity Duration Frequency Curves of Peninsular Malaysia under Changing Climate Scenarios." Water 10, no. 12: 1750.
South Korea endured extreme drought through 2015 and 2016. This hydrological drought led to a socio-economic drought which is a restriction on stream water use. Previous studies have explored streamflow drought using a threshold level based on flow duration curves, but streamflow drought does not necessarily lead to stream water deficit, which is related to water demand. Therefore, this study introduced a threshold for stream water deficit in South Korea, which is termed as river management flow, and was applied to Geum River Basin where a severe drought recently occurred. The stream water coordination council has restricted the use of stream water to cope with the stream water deficit. The deficit characteristics for the upstream and downstream river management flow should be similar in order to ensure the feasibility of stream water restrictions. Thus, upstream and downstream river management flows, which reproduced similar deficit characteristics to those of the reference site, were estimated. The deficit characteristics of Bugang and Gyuam were estimated from their river management flows for the 2015 drought and were comparable to those of Gongju. We expect this study to minimize the conflict between upstream and downstream water users in future.
Jang Hyun Sung; Seung Beom Seo. Estimation of River Management Flow Considering Stream Water Deficit Characteristics. Water 2018, 10, 1521 .
AMA StyleJang Hyun Sung, Seung Beom Seo. Estimation of River Management Flow Considering Stream Water Deficit Characteristics. Water. 2018; 10 (11):1521.
Chicago/Turabian StyleJang Hyun Sung; Seung Beom Seo. 2018. "Estimation of River Management Flow Considering Stream Water Deficit Characteristics." Water 10, no. 11: 1521.
Climate change may accelerate the water cycle at a global scale, resulting in more frequent extreme climate events. This study analyzed changes in extreme precipitation events employing climate projections statistically downscaled at a station-space scale in South Korea. Among the CMIP5 climate projections, based on spatial resolution, this study selected 26 climate projections that provide daily precipitation under the representative concentration pathway (RCP) 4.5. The results show that a 20-year return period of precipitation event during a reference period (1980∼2005) corresponds to a 16.6 yr for 2011 to 2040, 14.1 yr for 2041 to 2070, and 12.8 yr for 2071 to 2100, indicating more frequent extreme maximum daily precipitation may occur in the future. In addition, we found that the probability density functions of the future periods are located out of the 10% confidence interval of the PDF for the reference period. The result indicates that the design standard under the reference climate is not managed to cope with climate change, and accordingly the revision of the design standard is required to improve sustainability in infrastructures.
Jang Hyun Sung; Hyung-Il Eum; Junehyeong Park; JaePil Cho. Assessment of Climate Change Impacts on Extreme Precipitation Events: Applications of CMIP5 Climate Projections Statistically Downscaled over South Korea. Advances in Meteorology 2018, 2018, 1 -12.
AMA StyleJang Hyun Sung, Hyung-Il Eum, Junehyeong Park, JaePil Cho. Assessment of Climate Change Impacts on Extreme Precipitation Events: Applications of CMIP5 Climate Projections Statistically Downscaled over South Korea. Advances in Meteorology. 2018; 2018 ():1-12.
Chicago/Turabian StyleJang Hyun Sung; Hyung-Il Eum; Junehyeong Park; JaePil Cho. 2018. "Assessment of Climate Change Impacts on Extreme Precipitation Events: Applications of CMIP5 Climate Projections Statistically Downscaled over South Korea." Advances in Meteorology 2018, no. : 1-12.
This study developed a Reliability–Resiliency–Vulnerability (R–R–V) approach that aggregates the frequency, duration, and severity of droughts estimated using the Standardized Precipitation Evapotranspiration Index (SPEI). This approach was used to analyze the characteristics of droughts for the current (1976–2005) and the future (2010–2099) climates. The future climate data obtained from 28 general circulation models (GCMs) of Coupled Model Intercomparison Project Phase 5 (CMIP5) was divided into three general periods: Future 1: 2010–2039, Future 2: 2040–2069; and Future 3: 2070–2099. As a result, aggregation R–R–V representing water availability would increase during Future 1, and then gradually decrease until the end of the century. The frequencies of future drought events for Future 2 and Future 3 were similar to the current frequency, while the durations will be longer and the severity will be higher at most locations during Future 3. Thus, the mean of R–R–V over South Korea is expected to decrease, except for Future 1, and the spatial variability of R–R–V is expected to increase. In the end, the changes in the mean and variance of rainfall and temperature would lead to a decrease in the mean and increase in the spatial variation of sustainability in South Korea. This approach and its results can be used to establish a long-term drought strategy for regions where the risk of future drought is expected to increase.
Jang Sung; Eun-Sung Chung; Shamsuddin Shahid. Reliability–Resiliency–Vulnerability Approach for Drought Analysis in South Korea Using 28 GCMs. Sustainability 2018, 10, 3043 .
AMA StyleJang Sung, Eun-Sung Chung, Shamsuddin Shahid. Reliability–Resiliency–Vulnerability Approach for Drought Analysis in South Korea Using 28 GCMs. Sustainability. 2018; 10 (9):3043.
Chicago/Turabian StyleJang Sung; Eun-Sung Chung; Shamsuddin Shahid. 2018. "Reliability–Resiliency–Vulnerability Approach for Drought Analysis in South Korea Using 28 GCMs." Sustainability 10, no. 9: 3043.
The widely used meteorological drought index, the Standardized Precipitation Index (SPI), basically assumes stationarity, but recent changes in the climate have led to a need to review this hypothesis. In this study, a new non-stationary SPI that considers not only the modified probability distribution parameter but also the return period under the non-stationary process was proposed. The results were evaluated for two severe drought cases during the last 10 years in South Korea. As a result, SPIs considered that the non-stationary hypothesis underestimated the drought severity than the stationary SPI despite that these past two droughts were recognized as significantly severe droughts. It may be caused by that the variances of summer and autumn precipitation become larger over time then it can make the probability distribution wider than before. This implies that drought expressions by statistical index such as SPI can be distorted by stationary assumption and cautious approach is needed when deciding drought level considering climate changes.
Junehyeong Park; Jang Hyun Sung; Yoon-Jin Lim; Hyun-Suk Kang. Introduction and application of non-stationary standardized precipitation index considering probability distribution function and return period. Theoretical and Applied Climatology 2018, 136, 529 -542.
AMA StyleJunehyeong Park, Jang Hyun Sung, Yoon-Jin Lim, Hyun-Suk Kang. Introduction and application of non-stationary standardized precipitation index considering probability distribution function and return period. Theoretical and Applied Climatology. 2018; 136 (1-2):529-542.
Chicago/Turabian StyleJunehyeong Park; Jang Hyun Sung; Yoon-Jin Lim; Hyun-Suk Kang. 2018. "Introduction and application of non-stationary standardized precipitation index considering probability distribution function and return period." Theoretical and Applied Climatology 136, no. 1-2: 529-542.
Junehyeong Park; Yoon-Jin Lim; Baek-Jo Kim; Jang Hyun Sung. Erratum to: Appraisal of Drought Characteristics of Representative Drought Indices using Meteorological Variables. KSCE Journal of Civil Engineering 2017, 22, 2650 -2650.
AMA StyleJunehyeong Park, Yoon-Jin Lim, Baek-Jo Kim, Jang Hyun Sung. Erratum to: Appraisal of Drought Characteristics of Representative Drought Indices using Meteorological Variables. KSCE Journal of Civil Engineering. 2017; 22 (7):2650-2650.
Chicago/Turabian StyleJunehyeong Park; Yoon-Jin Lim; Baek-Jo Kim; Jang Hyun Sung. 2017. "Erratum to: Appraisal of Drought Characteristics of Representative Drought Indices using Meteorological Variables." KSCE Journal of Civil Engineering 22, no. 7: 2650-2650.
In order to efficiently utilize meteorological drought indices, meteorological variables were compared with drought characteristics from the widely known Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI). The results of this study indicate that SPI overestimated drought severity and SPEI overestimated drought frequency and length under the same weather conditions. For droughts of high severity and short duration, the shortage of precipitation was the dominant cause for the occurrence of drought. For investigation on drought duration, it was revealed that precipitation was the dominant variable influencing droughts at short durations. The effect of precipitation on drought decreased at long durations, with the effect of Potential Evapotranspiration (PET) on drought became important. For investigation on drought severity, it was revealed that drought severity was proportional to precipitation in both SPI and SPEI, but other meteorological variables did not have a significant relationship with drought severity. These results mean that the magnitudes of the two drought indices changes in different meteorological regimes and it is possible to contribute to the quantitative decision and the combination of drought indices for meteorological drought.
Junehyeong Park; Yoon-Jin Lim; Baek-Jo Kim; Jang Hyun Sung. Appraisal of Drought Characteristics of Representative Drought Indices using Meteorological Variables. KSCE Journal of Civil Engineering 2017, 22, 2002 -2009.
AMA StyleJunehyeong Park, Yoon-Jin Lim, Baek-Jo Kim, Jang Hyun Sung. Appraisal of Drought Characteristics of Representative Drought Indices using Meteorological Variables. KSCE Journal of Civil Engineering. 2017; 22 (5):2002-2009.
Chicago/Turabian StyleJunehyeong Park; Yoon-Jin Lim; Baek-Jo Kim; Jang Hyun Sung. 2017. "Appraisal of Drought Characteristics of Representative Drought Indices using Meteorological Variables." KSCE Journal of Civil Engineering 22, no. 5: 2002-2009.
Kwang Jai Won; Eun-Sung Chung; Bo-Ram Lee; Jang Hyun Sung. Characteristics of the Han River Basin drought using SPEI and RDI. Journal of Korea Water Resources Association 2016, 49, 187 -196.
AMA StyleKwang Jai Won, Eun-Sung Chung, Bo-Ram Lee, Jang Hyun Sung. Characteristics of the Han River Basin drought using SPEI and RDI. Journal of Korea Water Resources Association. 2016; 49 (3):187-196.
Chicago/Turabian StyleKwang Jai Won; Eun-Sung Chung; Bo-Ram Lee; Jang Hyun Sung. 2016. "Characteristics of the Han River Basin drought using SPEI and RDI." Journal of Korea Water Resources Association 49, no. 3: 187-196.
The Standardized Precipitation Evapotranspiration Index (SPEI) analysis was conducted using monthly precipitation data and temperature data on a 12.5 km × 12.5 km resolution based on a Representative Concentration Pathways (RCP) 8.5 climate change scenario, and the characteristics of drought were identified by the threshold. In addition, the changes in drought severity and intensity were projected using the threshold based on the run-length concept and frequency analysis. As a result of the analysis, the probability density function of the total drought and maximum drought intensity moved the upper tail for the upcoming years, and the average drought intensity was also projected to become stronger in the future than in the present to the right side. Through this, it could be projected that the drought scale and frequency and the drought intensity will become severer over South Korea because of future climate change.
Byung Sik Kim; In Gi Chang; Jang Hyun Sung; Hae Jin Han. Projection in Future Drought Hazard of South Korea Based on RCP Climate Change Scenario 8.5 Using SPEI. Advances in Meteorology 2016, 2016, 1 -23.
AMA StyleByung Sik Kim, In Gi Chang, Jang Hyun Sung, Hae Jin Han. Projection in Future Drought Hazard of South Korea Based on RCP Climate Change Scenario 8.5 Using SPEI. Advances in Meteorology. 2016; 2016 ():1-23.
Chicago/Turabian StyleByung Sik Kim; In Gi Chang; Jang Hyun Sung; Hae Jin Han. 2016. "Projection in Future Drought Hazard of South Korea Based on RCP Climate Change Scenario 8.5 Using SPEI." Advances in Meteorology 2016, no. : 1-23.
Bo-Ram Lee; Jang Hyun Sung; Eun-Sung Chung. Comparison of Meteorological Drought and Hydrological Drought Index. Journal of Korea Water Resources Association 2015, 48, 69 -78.
AMA StyleBo-Ram Lee, Jang Hyun Sung, Eun-Sung Chung. Comparison of Meteorological Drought and Hydrological Drought Index. Journal of Korea Water Resources Association. 2015; 48 (1):69-78.
Chicago/Turabian StyleBo-Ram Lee; Jang Hyun Sung; Eun-Sung Chung. 2015. "Comparison of Meteorological Drought and Hydrological Drought Index." Journal of Korea Water Resources Association 48, no. 1: 69-78.