• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.179-179
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• 2023

This study suggests a new approach of water level forecasting for extended lead times using original data preprocessing with variational mode decomposition (VMD). Here, two machine learning algorithms including light gradient boosting machine (LGBM) and random forest (RF) were considered to incorporate extended lead times (i.e., 5, 10, 15, 20, 25, 30, 40, and 50 days) forecasting of water levels. At first, the original data at two water level stations (i.e., SW173 and SW269 in Bangladesh) and their decomposed data from VMD were prepared on antecedent lag times to analyze in the datasets of different lead times. Mean absolute error (MAE), root mean squared error (RMSE), and mean squared error (MSE) were used to evaluate the performance of the machine learning models in water level forecasting. As results, it represents that the errors were minimized when the decomposed datasets were considered to predict water levels, rather than the use of original data standalone. It was also noted that LGBM produced lower MAE, RMSE, and MSE values than RF, indicating better performance. For instance, at the SW173 station, LGBM outperformed RF in both decomposed and original data with MAE values of 0.511 and 1.566, compared to RF's MAE values of 0.719 and 1.644, respectively, in a 30-day lead time. The models' performance decreased with increasing lead time, as per the study findings. In summary, preprocessing original data and utilizing machine learning models with decomposed techniques have shown promising results for water level forecasting in higher lead times. It is expected that the approach of this study can assist water management authorities in taking precautionary measures based on forecasted water levels, which is crucial for sustainable water resource utilization.

• Economic and Environmental Geology
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• v.57 no.2
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• pp.161-175
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• 2024

Aggregate typically refers to sand and gravel formed by the transportation of rocks in rivers or artificially crushed, constituting a core resource in the construction industry. Gyeongsangbuk-do, the largest administrative area in South Korea, produces various sources of gravel, including forest, land (excluding other sources), river, and crushed stone. As of 2022, it has extracted approximately 6.96 million cubic meters of aggregate, with permitted production totaling around 4.07 million cubic meters and reported production of about 2.88 million cubic meters. The aggregate demand in Gyeongsangbuk-do is estimated to be 12.39 million cubic meters according to the estimation method in Ready-Mix Concrete. From the supply perspective, about 120 extraction sites are operational, with most municipalities maintaining an appropriate balance between aggregate demand and supply. However, in some areas, there is inbound and outbound transportation of aggregate to neighboring regions. Regions with significant inbound and outbound aggregate transportation in Gyeongsangbuk-do are areas connected to Daegu Metropolitan City and Pohang City along the Gyeongbu rail line, showing a high correlation with population distribution. Gyeongsangbuk-do faces challenges such as population decline, aging rural areas, and insufficient balanced regional development. Analysis using GIS reveals these trends in gravel demand and supply. Currently in this study, Gyeongsangbuk-do meets its demand for aggregate through the supply of various aggregate sources, maintaining stable aggregate procurement. River and terrestrial aggregates may be sustained as short-term supply strategies due to the difficulty of longterm development. Considering the reliance on raw material supply for selective crushing, it suggests the need for raw material management to maintain stability. Gyeongsangbuk-do highlights quarries in the forest as an important resource for sustainable aggregate supply, advocating for the development of large-scale aggregate quarries as a long-term alternative. These research findings are expected to provide valuable insights for formulating strategies for sustainable management and stable utilization of aggregate resources.

• Korean Journal of Agricultural and Forest Meteorology
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• v.4 no.2
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• pp.95-102
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• 2002

Spatial interpolation has become a common procedure in converting temperature forecasts and observations at irregular points for use in regional scale ecosystem modeling and the model based decision support systems for resource management. Neglection of terrain effects in most spatial interpolations for short term temperatures may cause erroneous results in mountainous regions, where the observation network hardly covers full features of the complicated terrain. A spatial interpolation model for daytime hourly temperature was formulated based on error analysis of unsampled site with respect to the site topography. The model has a solar irradiance correction scheme in addition to the common backbone of the lapse rate - corrected inverse distance weighting. The solar irradiance scheme calculates the direct, diffuse and reflected components of shortwave radiation over any surfaces based on the sun-slope geometry and compares the sum with that over a reference surface. The deviation from the reference radiation is used to calculate the temperature correction term by an empirical conversion formula between the solar energy and the air temperature on any sloped surfaces at an hourly time scale, which can be prepared seasonally for each land cover type. When this model was applied to a 14 km by 22 km mountainous region at a 10 m horizontal resolution, the estimated hourly temperature surfaces showed a better agreement with the observed distribution than those by a conventional method.

• Korean Journal of Environment and Ecology
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• v.26 no.2
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• pp.186-191
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• 2012

The Chinese Sparrowhawk($Accipiter$ $soloensis$) is the most common breeding raptor in Korea, but its spatial use in the breeding season has been poorly documented. Therefore, to estimate the territory and home range sizes of breeding sparrowhawks, six territorial males(four in 2005 and two in 2006) were observed from June to July in Gyeonggi Province, the Republic of Korea. Main perches, which were used repeatedly(more than three times) or where apparent territorial behaviors were observed, were identified and the locations were analyzed by GIS software. According to the 100% Minimum Convex Polygons which were identified from $25.2{\pm}5.3$ perches, Chinese Sparrowhawks occupied $4.62{\pm}0.90$ ha for breeding territories and used $22.57{\pm}5.12$ ha for their home ranges. These estimates showed larger spatially occupied areas than those in one previous report, but this study suggests that Chinese Sparrowhawks intensively use small areas throughout the breeding season. This result also implies that the sparrowhawks have the potential to be significantly affected by any habitat changes and resource exploitation in the small areas(particularly in small rice paddies of 0.6-2.0 ha) which they largely rely on for food. Although this study was based on observations solely for territory size estimations, this study may be worthwhile as preliminary pilot research for Chinese Sparrowhawk conservation, management, and further studies.

• Korean Journal of Environment and Ecology
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• v.27 no.5
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• pp.614-624
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• 2013

The purpose of this study is to offer the raw data for establishing the plan of disaster prevention and the continuous conservation of soil ecosystem by grasping the potential soil loss and the danger of erosion using RUSLE method on whole districts in Gyeongju National Park, Korea. In the results of the average amount of soil erosion for the year, the average of all districts was 5.7 ton/ha in annual, and Namsan district was the highest in 7.6 ton/ha in annual and Seoak district was the lowest in 2.1 ton/ha in annual. The dangerous district due to the soil erosion was analyzed as under 1%, and Gumisan and Hwarange district was not serious. But Namsan district was higher than others, especially, there was intensive in all over Geumohbong. Therefore, to protect the all over Geumohbong, we will establish the valid of restoration and management. The types of land cover in Gyeongju National Park mostly showed forest, and as the average amount of soil erosion in forest was 3.7 ton/ha in annual, there was good condition. In the results of the amount of soil erosion due to landform, the deep canyon showed as 7.3 ton/ha in annual per unit area, secondly, the U-shaped valley was analyzed as 6.1 ton/ha in annual. The plain and high ridge were predicted that there occurred the small amount of soil erosion. In future, if we will analyze the amount of soil erosion in Korean National Parks, we will offer the help to establishing the plan of conservation and restoration on soil ecosystem in whole National Parks.

• Korean Journal of Agricultural and Forest Meteorology
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• v.6 no.2
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• pp.107-117
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• 2004

If doubtlessly contributes much to agriculture and rural development. The roles can be summarized as; 1. to activate rural areas and to provide more comfortable and safe rural life with equivalent services to those in urban areas, facilitating distance education, tole-medicine, remote public services, remote entertainment etc. 2. To initiate new agricultural and rural business such as e-commerce, real estate business for satellite officies, rural tourism and virtual corporation of small-scale farms. 3. To support policy-making and evaluation on optimal farm production, disaster management, effective agro-environmental resource management etc., providing tools such as GIS. 4. To improve farm management and farming technologies by efficient farm management, risk management, effective information or knowledge transfer etc., realizing competitive and sustainable farming with safe products. 5. To provide systems and tools to secure food traceability and reliability that has been an emerging issue concerning farm products since serious contamination such as BSE and chicken flu was detected. 6. To take an important and key role for industrialization of farming or lam business enterprise, combining the above roles.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.7 no.5
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• pp.12-25
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• 2004

Integration system of conservation ecology, ecosystem management and land planing in landscape scale is major principle strategy for national management system of environmental resource and biodiversity. Current conservation strategy is concerned with not only population and habitat level but also ecosystem and landscape level. In especially, ecological networking to link core areas or major habitat patches is most eminent and emerging issue in European Union (EU) and North America. Moreover, the promotion of national ecological network system in EU is focused on national cooperation to construct ecological corridor for key habitat that distributed in many countries. Integrating landscape ecology into conservation ecology and restoration have important role to stimulate the network system in regional and national level. In this review paper, comprehensive and necessary considerations arisen from the view of landscape ecology were discussed for the present situations of wildlife conservation and management in Korea compared with other countries. Especially, the conservation strategy and policy of biodiversity were addressed in broad sense including habitat protection, legal approaches, and ecological network programs. Finally, a national ecological network system was suggested for environmental policy in Korea in global consideration after the Korean Unification.

• The Journal of Fisheries Business Administration
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• v.51 no.3
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• pp.1-15
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• 2020

The Korean government has been carrying out the marine ranch development project since 1998 with the purpose of responding to the decrease in coastal fishery resources and fishery income, preparing a systematic management system for the sustainable use of fishery resources and realizing advanced fisheries power by expanding and upgrading fisheries resource development projects. In addition, the government established the Korea Fisheries Resources Agency and promoted projects for the protection and management of fishery resources by increasing basic productivity by artificially creating marine forests in areas where whitening events occur. Since the project of building marine ranches and marine forests requires immense government financial support, it is important to estimate the economic value and thoroughly evaluate the feasibility of the project. In this paper, the project of non-market economic value of the development of marine ranches and the development of marine forests was estimated. CVM (Contingent Valuation Method) was applied as a methodology for benefits estimation. Prior to the analysis, a one-on-one interview survey was conducted with participation of 512 residents and 514 residents respectively for the project of creating a marine ranch and developing a marine forest. A DBDC (Double-Bounded Dichotumous Choice) model was applied in the WTP (Willingness To Pay) analysis model and the socioeconomic variables of the surveyor, such as sex, age, education and income, were reflected in the model. The economic benefits from the two projects, namely, building of marine ranches and developing marine forests were estimated to be equal to 4,608 won and 7,772 won per household per year, respectively. According to the results of the survey, it seems that respondents think that marine forests are more valuable than marine ranches. This is as a result of ordinary citizens' thought that the marine ranches are more cost-effective than the marine forests. The benefits estimated through this study can be used for analysis of economic feasibility prior to carrying out the project of building marine ranches and developing marine forests, and are considered to be the valuable for policy-making purposes and finding social and economic consensus.

• Korean Journal of Ecology and Environment
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• v.45 no.4
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• pp.392-402
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• 2012

In this study, to analyze the stream health using fish assemblage and make effective management, we conducted fish monitoring in the Hoeya River basin and neighboring streams. A total of 33 species classified into 12 families were collected from 29 sites in 2007. Dominant species was Zacco platypus (Relative abundance, RA: 24.8%), and subdominant species was Rhynchocypris oxycephalus (RA: 16.2%). Eight Korean endemic species and 4 exotic species were identified. Moreover, two species (Opsariichthys uncirostris amurensis and Hemiculter eigenmanni) were translocated from other basin. To evaluate stream health of the study sites, Index of Biological Integrity (IBI) was applied, based on fish assemblages. Overall, IBI values were "C (Fair)" or "D (Poor)" condition, according to the grade except two sites which recorded "B (Good)". The correlation between land use pattern of surrounding watershed and IBI was analyzed to verify impact of development on stream health using fish assemblage. As a result, when percentage of the developmental groups increased, IBI values were decreased (Pearson correlation, r=-0.425, p=0.022). In contrast, increment of percent forest and grass land was positively correlated with IBI (r=0.556, p=0.002). The agricultural group and IBI did not significantly correlate with each other (r=-0.231, p=0.333). In this study, we identified a relationship between land use of surrounding watershed and stream health using fish data (i.e. IBI). These results could be provided useful fundamental information to establish management and restoration plan in the Hoeya River basin and other rivers distributed in Korea.

• Journal of Ecology and Environment
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• v.44 no.3
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• pp.196-206
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• 2020

Background: The Himalayan forests are of great importance to sustain the nature and community resource demands. These forests are facing pressures both from anthropogenic activities and ongoing global climatic changes. Poor natural regeneration has been considered a major problem in mountainous forests. To understand the population structure and regeneration status of Larix (Larix griffithiana and Larix himalaica), we conducted systematic vegetation surveys in three high-altitude valleys namely Ghunsa (Kanchenjunga Conservation Area, KCA), Langtang (Langtang National Park, LNP), and Tsum (Manaslu Conservation Area, MCA) in Nepal Himalaya. The average values of diameter at breast height (DBH), height, and sapling height were compared for three sites and two species using Kruskal-Wallis test. Population structure was assessed in terms of proportion of seedlings, saplings, and trees. Regeneration was analyzed using graphical representation of frequencies of seedlings, saplings, and trees in histograms. Results: The results showed that the population structure of Larix in terms of the proportion of seedling, sapling, and tree varied greatly in the three study areas. KCA had the highest record of seedling, sapling, and tree compared to other two sites. Seedlings were the least among three forms and many plots were without seedlings. We found no seedling in MCA study plots. The plot level average DBH variation among sites was significant (Kruskal-Wallis χ² = 7.813, df = 2, p = 0.02) as was between species (Kruskal-Wallis χ² = 5.9829, df = 1, p = 0.014). Similarly, the variation in average tree height was significant (Kruskal-Wallis χ² = 134.23, df = 2, p < 0.001) among sites as well as between species (Kruskal-Wallis χ² = 128.01, df = 1, p < 0.001). All the sites showed reverse J-shaped curve but more pronounced for KCA and MCA. In comparing the two species, Larix griffithiana has clear reverse J-shaped diameter distribution but not Larix himalaica. Conclusion: The varied responses of Larix manifested through regeneration status from spatially distinct areas show that regeneration limitations might be more pronounced in the future. In all the three studied valleys, regeneration of Larix is found to be problematic and specifically for Larix griffithiana in MCA and Larix himalaica in LNP. To address the issues of disturbances, especially serious in LNP, management interventions are recommended to sustain the unique Himalayan endemic conifer.