• Journal of the Korean Society of Hazard Mitigation
• /
• v.9 no.4
• /
• pp.71-80
• /
• 2009

Although desire for living without hazardous damages grows these days, threats from natural disasters which we are currently exposed to are quiet different from what we have experienced. To cope with this changing situation, it is necessary to assess the characteristics of the natural disasters. Therefore, the main purpose of this research is to suggest a methodology to estimate the potential property loss and assess the flood risk using a regional regression analysis. Since the flood damage mainly consists of loss of lives and property damages, it is reasonable to express the results of a flood risk assessment with the loss of lives and the property damages that are vulnerable to flood. The regional regression analysis has been commonly used to find relationships between regional characteristics of a watershed and parameters of rainfall-runoff models or probability distribution models. In our research, however, this model is applied to estimate the potential flood damage as follows; 1) a nonlinear model between the flood damage and the hourly rainfall is found in gauged regions which have sufficient damage and rainfall data, and 2) a regression model is developed from the relationship between the coefficients of the nonlinear models and socio-economic indicators in the gauged regions. This method enables us to quantitatively analyze the impact of the regional indicators on the flood damage and to estimate the damage through the application of the regional regression model to ungauged regions which do not have sufficient data. Moreover the flood risk map is developed by Flood Vulnerability Index (FVI) which is equal to the ratio of the estimated flood damage to the total regional property. Comparing the results of this research with Potential Flood Damage (PFD) reported in the Long-term Korea National Water Resources Plan, the exports' mistaken opinions could affect the weighting procedure of PFD, but the proposed approach based on the regional regression would overcome the drawback of PFD. It was found that FVI is highly correlated with the past damage, while PFD does not reflect the regional vulnerabilities.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.29 no.4
• /
• pp.297-306
• /
• 2023

Saemangeum Lake is the largest artificial lake in Korea. The continuous deterioration of lake water quality necessitates the introduction of novel water quality management strategies. Therefore, this study aims to identify the spatiotemporal water quality characteristics of Saemangeum Lake using data from the National Water Quality Measurement Network and provide basic information for water quality management. In the water quality parameters of Saemangeum Lake, water temperature and total phosphorous content were correlated, and salt, total nitrogen content, pH, and chemical oxygen demand were significantly correlated. Other parameters showed a low correlation. The spatial principal component analysis of Saemangeum Lake showed the characteristics of its four zones. The mid-to-downstream section of the river affected by freshwater inflow showed a high nutrient salt concentration, and the deep-water section of the drainage gate and the lake affected by seawater showed a high salt concentration. Two types of water qualities were observed in the intermediate water area where river water and outer sea water were mixed: waters with relatively low salt and high chemical oxygen demand, and waters with relatively low salt and high pH concentration. In the principal component analysis by time, the water quality was divided into four groups based on the observation month. Group I occurred during May and June in late spring and early summer, Group II was in early spring (March-April) and late autumn (November-December), Group III was in winter (January-February), and Group IV was in summer (July-October) during high temperatures. The water quality characteristics of Saemangeum Lake were found to be affected by the inflow of the upper Mangyeong and Dongjin rivers, and the seawater through the Garuk and Shinshi gates installed in the Saemangeum Embankment. In order to achieve the target water quality of Saemangeum Lake, it is necessary to establish water quality management measures for Saemangeum Lake along with pollution source management measures in the upper basin.

• Economic and Environmental Geology
• /
• v.53 no.5
• /
• pp.619-629
• /
• 2020

The National Groundwater Monitoring Network (NGMN) in South Korea has been implemented in alluvial/ bedrock aquifers for efficient management of groundwater resources. In this study, aquifer types were reclassified with unconfined and confined aquifers based on water-level fluctuation and water quality characteristics. Principal component analysis (PCA) of water-level data from paired monitoring wells of alluvial/bedrock aquifers results in the principal components of both aquifers showing similar water-level fluctuation pattern. There was no significant difference in the rate of water-level rises responding to precipitations and in the NO₃-N concentrations between the alluvial and bedrock aquifers. In contrast, in the results classified with the hydrogeological type, the principal components of water level were different between unconfined and confined conditions. The water-level rises to precipitation events were estimated to be 4.6 (R²=0.8) in the unconfined and 2.1 (R²=0.4) in the confined aquifers, respectively, indicating less impact of precipitation recharge to the confined aquifer. The confined aquifers have the average NO₃-N concentration below 3 mg/L, implying the natural background level protected from the sources at surface. In summary, reclassification of aquifers into hydrogeological types clearly shows the differences between unconfined and confined aquifers in the water-level fluctuation pattern and NO₃-N concentrations. The hydrogeologic condition of aquifer could improve groundwater resource management by providing critical information on groundwater quantity through recharge estimation and quality for protection from potential contamination sources.

• Journal of Korea Water Resources Association
• /
• v.52 no.1
• /
• pp.51-60
• /
• 2019

The major purpose of this study is to construct an in-situ soil moisture verification network employing Frequency Domain Reflectometry (FDR) sensors for Cosmic-ray soil moisture observation system operation as well as long-term field-scale soil moisture monitoring. The test bed of Cosmic-ray and FDR verification network system was established at the Sulma Catchment, in connection with the existing instrumentations for integrated data provision of various hydrologic variables. This test bed includes one Cosmic-ray Neutron Probe (CRNP) and ten FDR stations with four different measurement depths (10 cm, 20 cm, 30 cm, and 40 cm) at each station, and has been operating since July 2018. Furthermore, to assess the reliability of the in-situ verification network, the volumetric water content data measured by FDR sensors were compared to those calculated through the core sampling method. The evaluation results of FDR sensors- measured soil moisture against sampling method during the study period indicated a reasonable agreement, with average values of $bias=-0.03m^3/m^3$ and RMSE $0.03m^3/m^3$, revealing that this FDR network is adequate to provide long-term reliable field-scale soil moisture monitoring at Sulmacheon basin. In addition, soil moisture time series observed at all FDR stations during the study period generally respond well to the rainfall events; and at some locations, the characteristics of rainfall water intercepted by canopy were also identified. The Temporal Stability Analysis (TSA) was performed for all FDR stations located within the CRNP footprint at each measurement depth to determine the representative locations for field-average soil moisture at different soil profiles of the verification network. The TSA results showed that superior performances were obtained at FDR 5 for 10 cm depth, FDR 8 for 20 cm depth, FDR2 for 30 cm depth, and FDR1 for 40 cm depth, respectively; demonstrating that those aforementioned stations can be regarded as temporal stable locations to represent field mean soil moisture measurements at their corresponding measurement depths. Although the limit on study duration has been presented, the analysis results of this study can provide useful knowledge on soil moisture variability and stability at the test bed, as well as supporting the utilization of the Cosmic-ray observation system for long-term field-scale soil moisture monitoring.

• Journal of the Korean Geographical Society
• /
• v.42 no.3 s.120
• /
• pp.368-387
• /
• 2007

In order to explain geomorphological characteristics of the Korean Peninsula, it is necessary to understand the spatial distribution of tectonic movements and its causes. Even though geomorphological elements which might have been formed by tectonic movements(e.g. tilted overall landform, erosion surface, river terrace, marine terraces, etc.) have long been considered as main geomorphological research topics in Korea, the knowledge on the spatial distribution of tectonic movement is still limited. This research aims to identify the spatial distributions of tectonic movement via sequential analyses of Digital Elevation Model(DEM). This paper first developed a set of terrain analysis techniques derived from theoretical interrelationships between tectonic uplifts and landsurface denudation processes. The terrain analyses used in this research assume that elevations along major drainage basin divides might preserve original landsurfaces(psuedo-landsuface) that were formed by tectonic movement with relatively little influence by denudation processes. Psuedo-landsurfaces derived from a DEM show clear spatial distribution patterns with distinct directional alignments. Lines connecting psuedo-landsufaces in a certain direction are defined as psuedo-landsurface axes, which are again categorized into two groups: the first is uplift psuedo-landsurface axes that indicate the axis of landmass uplift; and the second is denudational psuedo-landsurface axes that cross step-shaped pusedo-landsurfaces formed via surface denudation. In total, 13 axes of pusedo-landsurface are identified in the Korean Peninsula, which show distinct direction, length, and relative uplift rate. Judging from the distribution of psudo-landsurfaces and their axes, it is concluded that the Korean Peninsula ran be divided into four tectonic regions, which are named as the Northern Tectonic Region, Center Tectonic Region, Southern Tectonic Region, and East Sea Tectonic Region, respectively. The Northern Tectonic Region had experienced a regional uplift centered at the Kaema plateau, and the rate of uplift gradually decreased toward southern, western and eastern directions. The Center Tectonic Region shows an arch-shaped uplift. Its uplift rate is the highest along the East Sea and the rate decreases towards the Yellow sea. The Southern Tectonic Region shows an asymmetric uplift centered a line connecting Dukyu and Jiri Mountains in the middle of the region. The eastern side of the Southern Regions shows higher uplift rate than that of the western side. The East Sea Tectonic Region includes south-eastern coastal area of the peninsula and Gilju-Myeongchun Jigudae, which shows relatively recent tectonic movements in Korea. Since this research visualizes the spatial heterogeneity of long-term tenonic movement in the Korean peninsula, this would provide valuable basic information on long-term and regional differences of geomorphological evolutionary processes and regional geomorphological differences of the Korean Peninsula.

• Journal of the Korean Institute of Landscape Architecture
• /
• v.38 no.5
• /
• pp.80-92
• /
• 2010

The purpose of this study was to analyze drainage facilities in mountainous urban neigbborhood parks--Baebongsan Park and Ogeum Park--in Seoul. Based on an analysis of existing drainage facilities, the volume of storm water runoff (VSW), the runoff rate of open channels(ROC), and the detention capacity of open charmels(DCOC) by each drainage watershed, the coefficient of runoff rate(CROC) as evaluated to be relevant between VSW and ROC and the coefficient of the detention capacity of open channe1s(CDCOC) as evaluated with DCOC compared to VSW were estimated and analyzed by parks and by watersheds. The results are as follows: 1. The total drainage area of Baebongsan Park was 34.13ha including surface runoff area(15.05ha; 44.09%), open channel area(l4.60ha; 42.78%), and natural waterway area(4.48ha; 13.13%). The total drainage area of Ogeum Park was 20.39ha including open channel area (10.14ha; 49.73%), ridge-side gutter area(7.17ha; 35.16%), surface runoff area (2.52ha; 12.36%), and natural waterway area (0.56ha; 2.75%). In Baebongsan Park, the portion of surface runoff was comparatively higher while the portion of artificial drainage area was higber in Ogeum Park. 2. In Baebongsan Park drainage districts were largely divided: VSW was $7.28m^3/s$ in total(average $0.23m^3/s$). Comparatively, tbe VSW in Ogeum Park, including smaller drainage districts, was $4.37m^3/s$ in total(average $0.12m^3/s$). 3. The ROC of Baebmgsan Park was $11.58m^3/s$ in total(average $0.77m^3/s$) and the CROC was 5.26, while in Ogeum Park, the ROC was $15.40m^3/s$(average $0.34m^3/s$) and tbe CROC was 8.87 higher than that of Baebongsan Because the size and slope of the open channel in Baebongsan Park was higher, the average ROC was larger, while tbe CROC of Ogeum Park was higher than that of Baebongsan Park, for the VSW in Ogeum Park was comparatively lower. 4. The DCOC in Baebongsan Park was $554.54m^3$ and the average of CDCOC was 179.83. That of Ogeum Park was $717.74m^3$ and the average of the CDCOC was 339.69, meaning that the DCOC of Ogeum Park was so much higber that drainage facilities in Ogeum Park were built intensively. This study was focused m the capacity of the drainage facilities in mountainous urban neighborhood parks by using the CROC to evaluate relevance between VSW and ROC and the CDCOC to evaluate the DCOC as compared with VSW. The devised methodology and coefficient for evaluating drainage facilities in mountainous urban neighborhood parks may he universally applicable through additional study. Further study m sustainable urban drainage systems for retaining rainwater in a reservoir and for enhancing ecological value is required in the near future.

• Journal of Korea Water Resources Association
• /
• v.42 no.12
• /
• pp.1029-1038
• /
• 2009

Recently, it is expected that small hydropower (SHP) could potentially provide sufficient amounts of alternative energy in Korea where there is an abundance of potential sites and where social efforts are being made to reduce the emissions of green house gases. In the past, the resources survey for SHP development has been carried out using onsite surveys and paper maps, which incurred a great deal of time and cost. Furthermore, the tools for decision making such as determining development priorities or evaluating feasibility have been considered only economic aspect and focused on the performance characteristics of power generation. However, as the concept of sustainable development has been being advanced in recent years, especially focused on human-social, environmental and ecological in addition to economical sector; the consideration of these multiple criteria has become essential for sustainable SHP development. This study aims to propose the spatial multi-criteria decision making (MCDM) methodology for determining priorities among a number of locations on the planning stage of SHP development using AHP and GIS. The proposed methodology is applied for determining development priorities among the SHP locations in Cho River basin and this study presents the detailed spatial information data and the results of development priorities. As a fundamental work, this study will be beneficial to the future activation of SHP development and will help the decision making in evaluating the feasibility of SHP development.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
• /
• v.31 no.1
• /
• pp.29-40
• /
• 2013

The object of this research is to elicit the ecological wetland's creating and maintaining conditions through GIS and AHP(Analytic Hierarchy Process) on common characteristics of wetland, by exploring the function of the long-standing and naturally created wetlands in South Han-river basin. Geomorphological, geologic, hydraulic & hydrological, pedological, environmental & ecological approaches of five categorizations were made based on the documents and precedent studies in order to perform the research object. Elicitation of the common creating and maintaining conditions on the objected wetlands through analysis of satisfactory conditions was conducted by performing an overlay analysis from the gathered information in each category and linking its result to each wetland. Also, elicitation of highly believable qualified analysis result was made by calculating the each factor's weight through application of AHP analysis method on each factor. The research result is expected to be applied effectively in suitability selection for creation of an artificial wetland and restoration and maintenance for naturally created wetlands when introducing the No Net Loss of Wetlands. In addition, with a new understanding on wetland and beyond the value of its conservativeness, this research result can be considered as a solution for Eco-Wetland's maintainable development.

• Korean Journal of Environment and Ecology
• /
• v.34 no.3
• /
• pp.235-248
• /
• 2020

The purpose of this study was to quantitatively analyze and investigate changes in the structural characteristics of the warm-temperate evergreen broad-leaved forest community in Mt. Cheomchalsan on Jindo Island. The Mt. Cheomchalsan has high conservation value because the representative warm temperate species such as Quercus acuta and Castanopsis sieboldii are distributed there. The community classification with TWINSPAN and DCA identified 4 communities: C. sieboldii community (I), C. sieboldii-Q. Salicina community (II), Q. acuta-C.sieboldii community (III), and deciduous broad-leaved trees-evergreen broad-leaved trees community (IV). According to the results of the mean importance percentage (MIP) analysis, C. sieboldii, Q. salicina, and Q. acuta were dominant species in the canopy layer, Camellia japonica, Ligustrum japonicum, and Cinnamomum yabunikkei were dominant in the understory layer, and Trachelospermum asiaticum, C. japonica, and C. sieboldii were dominant in the shrub layer. The comparison of the results of the diameter of breast height (DBH) analysis with the past data showed that the ratio of large-sized trees in the C. sieboldii and Q. acuta, which dominated the canopy layer, increased. However, there was no difference in the distribution of C. japonica and L. japonicum in the understory layer. In the future, it is necessary to generate a precision inhabiting vegetation map around the Natural Reserve to understand the actual habitation of evergreen broad-leaved trees and rezone the protective districts of evergreen broad-leaved trees forest with the watershed concept to preserve the evergreen broad-leaved forests of Mt. Cheomchalsan in Jindo.

• Journal of Wetlands Research
• /
• v.13 no.3
• /
• pp.377-384
• /
• 2011

The objective of this research is to observe and to analyze how the precipitation change can affect urban area and coastal area to groundwater recharge. The variation in the precipitation data of the regional groundwater basin, which includes Busan Metropolitan City Suyeong Gu area, was to estimate the change in the groundwater recharge and to analyze the characteristic changes. Research result reflects that as the precipitation varied, there was some difference in the groundwater recharge. However, differences in the precipitation ratio and the groundwater recharge ratio were consistent. Variation in the precipitation had less impact on the groundwater recharge ratio, and the groundwater recharge ratio decreased as timeline increased. When the precipitation increased by 10 %, groundwater recharge changed by 2.23 %. Accordingly, when it decreased by 10 %, groundwater recharge changed by 2.20 %. When it increased by 20 %, groundwater recharge changed by 4.39 %, and when it decreased by 20 %, groundwater recharge changed by 4.36 %. Despite the dramatic changes in the precipitation, the changes in the groundwater recharge were minimal. From the research, we can observe that the precipitation change had a significant impact on the ratio, but it doesn't really affect the groundwater recharge. Therefore, in urban area, the changes in groundwater recharge don't conform to the changes in the precipitation, and the effect of direct runoff can increase the possible occurrence of urban flooding.