• Journal of Wetlands Research
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• v.20 no.4
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• pp.353-362
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• 2018

The purpose of this study is to suggest a structure plan for improving the utilization of inactive storage in the dam for overcoming the drought. Inactive storage in the dam is composed of the emergency storage and dead storage. The emergency storage can be used for the case of emergency such as drought. But, in general, the dead storage for sedimentation is not used even for the emergency. Therefore, this study considers the part of dead storage that the sedimentation is not progressed yet can be used during the severe drought period and is called "drought storage in a dam". The accurate Sediment Level(SL) analysis for the computation of the drought storage should be performed and so the present and future SL in the dam reservoir is estimated using SED-2D linked with RMA-2 model of SMS. After the consideration of additionally available storage capacity based on the estimated SL, the drought storage is finally determined. Present data based on historical data, future predicted future climate factors by Representative Concentrarion Pathways(RCP) 8.5 scenario. Then, using the TANK model, dam inflows were determined, and future period such as SL and drought storage were suggested. As the results, we have found that the available drought storage will be reduced in the future when we compare the present drought storage with the future one. This is due to a increase variability of climate change. Therefore, we should take the necessary study for the increase of available drought storage in the future.

• Korean Journal of Agricultural and Forest Meteorology
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• v.21 no.3
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• pp.121-134
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• 2019

This study was conducted to review the trends of forest meteorological studies based on the publications for last 20 years in Korean Journal of Agricultural and Forest Meteorology (KJAFM), and to provide insight for future prospect for researches in the field of forest meteorology. A total of 220 papers related to forest meteorology were published in KJAFM for the last 20 years. That corresponds to 33.5% out of all the papers including agricultural meteorology papers. To review the trends of forest meteorology studies, the 220 published papers were classified into seven categories. They are forest meteorology and forest fire, forest meteorology and tree physiology, forest meteorology and forest protection, micrometeorology in mountain area, climate and forest growth, climate and forest vegetation distribution, and climate change and forest ecosystem. Even if there were differences in paper numbers among the seven categories, it was found that various and very specific studies were conducted in the field of forest meteorology for the last 20 years. It was also expected that the accumulation and utilization of various and accurate forest meteorological information would bring remarkable progress of forest meteorological studies in the near future.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.67 no.2
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• pp.95-110
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• 2022

This study was conducted to determine the extent to which climate change is expanding areas in which barley can be successfully cultivated. In 2019 and 2020, we collected data on areas that had requested certified seeds from the Korea Seed and Variety Service to determine potential cultivation areas. In addition, we surveyed the growth and yield of different types of barley in fields. Certified seeds of hulled and dehulled barley were requested by farmers across Korea from the Korea Seed and Variety Service in both years. Areas that were provided with certified seeds were considered potential barley cultivation areas. The varieties and use rates of certified seeds varied based on the barley type and region. For example, certified seeds of dehulled barley in 2019 and 2020 were not used in some areas, whereas in others, these seeds constituted 100% of the seeds sown for barley crops. In 2019 and 2020, the average sowing days in Korea were from October 17 to November 9 for dehulled barley, October 26 to November 13 for hulled barley, October 19 to November 5 for malting barley, and October 3 to November 1 for naked oats. Thus, the sowing days of the barley types varied depending on the area and year they were used. For example, in the case of hulled barley in Jeonnam, some farmers sowed until December 12. The yield per 10 a of barley cultivation was typically higher in the main production areas than in the cultivation limit areas. In extreme cases, harvest was impossible in some cultivation limited areas, such as Gangwon-do. Based on the current 20-year January minimum average temperature (JMAT) in Korea (2002-2021), climate change scenarios suggest that barley cultivation is feasible, provided that the minimum temperature in January is no lower than -10℃, -8℃, and -4℃ for hulled barley, dehulled barley, and for malting barley and naked oats, respectively. Additionally, cultivation of barley across South Korea seems feasible based on data on certified barley seeds by area. Although both JMAT and certified seed data suggest that barley cultivation across Korea is feasible, our survey results of barley growth and yield showed that harvest was impossible in certain cultivation areas, such as Gangwon-do. Therefore, climate change scenarios related to the cultivation limits of different barley types need to be re-estimated by factoring in survey data on the growth and yield of crops within those cultivation areas.

• Journal of Korean Society of Disaster and Security
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• v.14 no.4
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• pp.47-60
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• 2021

Recently, as the occurrence frequency of sudden floods due to climate variability increased, the damage of aging chuteway slabs of spillway are on the rise. Accordingly, a wide array of field survey, hydraulic experiment and numerical simulation have been conducted to find the cause of damage on chuteway slabs. However, these studies generally reviewed the flow characteristics and distribution of pressure on chuteway slabs. Therefore the derivation of damage on chuteway slabs was relatively insufficient in the literature. In this study, the cavitation erosion and hydraulic jacking were assumed to be the causes of damage on chuteway slabs, and the phenomena were reproduced using 3D numerical models, FLOW-3D and COMSOL Multiphysics. In addition, the cavitation index was calculated and the von Mises stress by uplift pressure distribution was compared with tensile and bending strength of concrete to evaluate the possibility of cavitation erosion and hydraulic jacking. As a result of numerical simulation on cavitation erosion and hydraulic jacking under various flow conditions with complete opening gate, the cavitation index in the downstream of spillway was less than 0.3, and the von Mises stress on concrete was 4.6 to 5.0 MPa. When von Mises stress was compared with tensile and bending strength of concrete, the fatigue failure caused by continuous pressure fluctuation occurred on chuteway slabs. Therefore, the cavitation erosion and hydraulic jacking caused by high speed flow were one of the main causes of damage to the chuteway slabs in spillway. However, this study has limitations in that the various shape conditions of damage(cavity and crack) and flow conditions were not considered and Fluid-Structure Interaction (FSI) was not simulated. If these limitations are supplemented and reviewed, it is expected to derive more efficient utilization of the maintenance plan on spillway in the future.

• Journal of Korea Water Resources Association
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• v.56 no.3
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• pp.195-210
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• 2023

Additional deposition and erosion in large rivers in South Korea have continued to occur toward morphological stabilization after massive dredging through the four major river restoration project, subsequently requiring precise bathymetry monitoring. Hyperspectral bathymetry method has increasingly been highlighted as an alternative way to estimate bathymetry with high spatial resolution in shallow depth for replacing classical intrusive direct measurement techniques. This study introduced the conventional Optimal Band Ratio Analysis (OBRA) of hyperspectral bathymetry method, and evaluated the performance in a domestic large river in normal turbid and flow condition. Maximum measurable depth was estimated by applying correlation coefficient and root mean square error (RMSE) produced during OBRA with cascadedly applying cut-off depth, where the consequent hyperspectral bathymetry map excluded the region over the derived maximum measurable depth. Also non-linearity was considered in building relation between optimal band and depth. We applied the method to the Nakdong and Hwang River confluence as a large river case and obtained the following features. First, the hyperspectal method showed acceptable performance in morphological mapping for shallow regions, where the maximum measurable depth was 2.5 m and 1.25 m in the Nakdong and Hwang river, respectively. Second, RMSE was more feasible to derive the maximum measurable depth rather than the conventional correlation coefficient whereby considering various scenario of excluding range of in situ depths for OBRA. Third, highly turbid region in Hwang River did not allow hyperspectral bathymetry mapping compared with the case of adjacent Nakdong River, where maximum measurable depth was down to half in Hwang River.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.30 no.2B
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• pp.121-135
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• 2010

This study is to assess the effect of potential future climate change on the inflow of agricultural reservoir and its impact to downstream streamflow by reservoir operation for paddy irrigation water supply using the SLURP. Before the future analysis, the SLURP model was calibrated using the 6 years daily streamflow records (1998-200398 and validated using 3 years streamflow data (2004-200698 for a 366.5 $km^2$ watershed including two agricultural reservoirs (Geumgwang8 and Gosam98located in Anseongcheon watershed. The calibration and validation results showed that the model was able to simulate the daily streamflow well considering the reservoir operation for paddy irrigation and flood discharge, with a coefficient of determination and Nash-Sutcliffe efficiency ranging from s 7 to s 9 and 0.5 to s 8 respectively. Then, the future potential climate change impact was assessed using the future wthe fu data was downscaled by nge impFactor method throuih bias-correction, the future land uses wtre predicted by modified CA-Markov technique, and the future ve potentiacovfu information was predicted and considered by the linear regression bpowten mecthly NDVI from NOAA AVHRR ima ps and mecthly mean temperature. The future (2020s, 2050s and 2e 0s) reservoir inflow, the temporal changes of reservoir storaimpand its impact to downstream streamflow watershed wtre analyzed for the A2 and B2 climate change scenarios based on a base year (2005). At an annual temporal scale, the reservoir inflow and storaimpchange oue, anagricultural reservoir wtre projected to big decrease innautumnnunder all possiblmpcombinations of conditions. The future streamflow, soossmoosture and grounwater recharge decreased slightly, whtre as the evapotransporation was projected to increase largely for all possiblmpcombinations of the conditions. At last, this study was analysed contribution of weather, vegetation and land use change to assess which factor biggest impact on agricultural reservoir and stream watershed. As a result, weather change biggest impact on agricultural reservoir inflow, storage, streamflow, evapotranspiration, soil moisture and groundwater recharge.

• Journal of Wetlands Research
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• v.25 no.4
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• pp.335-344
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• 2023

Brachydiplax chalybea flavovittata, a climate-sensitive biological indicator species, was first observed and recorded at Jeju Island in Korea in 2010. Overwintering was recently confirmed in the Yeongsan River area. This study was aimed to predict the potential distribution patterns for the larvae of B. chalybea flavovittata and to understand its ecological characteristics as well as changes of population under global climate change circumstances. Data was collected both from the Global Biodiversity Information Facility (GBIF) and by field surveys from May 2019 to May 2023. We used for the distribution model among downloaded 19 variables from the WorldClim database. MaxEnt model was adopted for the prediction of potential and future distribution for B. chalybea flavovittata. Larval distribution ranged within a region delimited by northern latitude from Jeju-si, Jeju Special Self-Governing Province (33.318096°) to Yeoju-si, Gyeonggi-do (37.366734°) and eastern longitude from Jindo-gun, Jeollanam-do (126.054925°) to Yangsan-si, Gyeongsangnam-do (129.016472°). M type (permanent rivers, streams and creeks) wetlands were the most common habitat based on the Ramsar's wetland classification system, followed by Tp type (permanent freshwater marshes and pools) (45.8%) and F type (estuarine waters) (4.2%). MaxEnt model presented that potential distribution with high inhabiting probability included Ulsan and Daegu Metropolitan City in addition to the currently discovered habitats. Applying to the future scenarios by Intergovernmental Panel on Climate Change (IPCC), it was predicted that the possible distribution area would expand in the 2050s and 2090s, covering the southern and western coastal regions, the southern Daegu metropolitan area and the eastern coastal regions in the near future. This study suggests that B. chalybea flavovittata can be used as an effective indicator species for climate changes with a monitoring of their distribution ranges. Our findings will also help to provide basic information on the conservation and management of co-existing native species.

• Korean Journal of Agricultural and Forest Meteorology
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• v.25 no.4
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• pp.346-358
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• 2023

Due to the acceleration of climate change or global warming, it is important to predict rice productivity in the future and investigate physiological changes in rice plants. The research aimed to explore how rice adapts to climate change by examining the response of nitrogen absorption and nitrogen use efficiency in rice under elevated levels of carbon dioxide and temperature, utilizing the SPAR system for analysis. The temperature increased by +4.7 ℃ in comparison to the period from 2001 to 2010, while the carbon dioxide concentration was held steady at 800 ppm, aligning with South Korea's late 21st-century RCP8.5 scenario. Nitrogen was applied as fertilizer at rates of 0, 9, and 18 kg 10a^-1, respectively. Under conditions of climate change, there was an 81% increase in the number of panicles compared to the present situation. However, grain weight decreased by 38% as a result of reduction in the grain filling rate. BNUE, indicative of the nitrogen use efficiency in plant biomass, exhibited a high value under climate change conditions. However, both NUEg and ANUE, associated with grain production, experienced a notable and significant decrease. In comparison to the current conditions, nitrogen uptake in leaves and stems increased by 100% and 151%, respectively. However, there was a 25% decrease in nitrogen uptake in the panicle. Likewise, the nitrogen content and NDFF (Nitrogen Derived from Fertilizer) in the sink organs, namely leaves and roots, were elevated in comparison to current levels. Therefore, it is imperative to ensure resources by mitigating the decrease in ripening rates under climate change conditions. Moreover, there seems to be a requirement for follow-up research to enhance the flow of photosynthetic products under climate change conditions.

• Korean Journal of Environmental Agriculture
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• v.24 no.1
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• pp.56-60
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• 2005

In order to increase the storage stability of watermelon stalk, storage environments such as temperature and other treatments such as vaseline, mixture of soybean oil and wheat flour, and coated paper label were tested separately after harvesting. At different storage temperatures (7, 18 and $30^{\circ}C$) shelf-life of stalk was inversely proportional to temperature. The results showed that during storage at $30^{\circ}C$ they were completely wilted in 7 days, at $18^{\circ}C$ in 15 days and at $7^{\circ}C$ in 19 days. Our data also showed that stability of watermelon stalk depending on temperature was very closely correlated with water content of watermelon stalk; during storage at $30^{\circ}C$ the water content of watermelon stalk was decreased to 21.1 % in 7 days, whereas at $7^{\circ}C$ the water content was decreased gradually to 71.2 % for 19 days of storage. In order to reduce the physiological changes in watermelon stalk at $30^{\circ}C$, following treatments such as vaseline, mixture of soybean oil and wheat flour, and coated paper label were tested. As a result, watermelon stalk without any treatment was completely wilted in 9 days, while stalks treated with vaseline and mixture of soybean oil with wheat flour were wilted in 15 and 12 days, respectively. The wilt delay was noted in the watermelon stalk for $3{\sim}6$ days during both treatments but the outward quality was found detracted, whereas when treated with coated paper label, the wilt of stalk was delayed for 3 days along with the improvement in the outward quality. Therefore this data indicate that the treatment of coated paper label during storage at $30^{\circ}C$ can be considered as a potent method for maintaining the physiology of watermelon stalk.

• Journal of Korean Society of Forest Science
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• v.103 no.2
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• pp.159-164
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• 2014

The objective of this study was to establish an open-field experimental warming treatment and precipitation manipulation system to simulate climate change impact for Pinus densiflora seedlings based on a climate change scenario in Korea. Two-year-old seedlings were planted in a nursery in April, 2013. The air temperature of warmed plots (W) was set to increase by $3.0^{\circ}C$ compared to control plots (C) using infrared lamps from May, 2013. The three precipitation manipulation consisted of precipitation decrease using transparent panel (-30%; $P^-$), precipitation increase using pump and drip-irrigation (+30%; $P^+$) and precipitation control (0%; $P^0$). Initially, the air temperature was $2.2^{\circ}C$ higher in warmed plots than in control plots and later air temperature was maintained close to the target temperature of $3.0^{\circ}C$. The average soil temperature was $3.1^{\circ}C$ higher in warmed plots than in control plots. Also the average soil moisture content after the precipitation manipulation increased by 13.9% in $P^+W$ and decreased by 10.0% in $P^-W$ compared to $P^0W$, and increased by 23.7% in $P^+C$ and decreased by 7.6% in $P^-C$ compared to $P^0C$. It was confirmed that the open-field experimental warming and precipitation manipulation system was properly designed and operating.