• Journal of Ecology and Environment
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• v.40 no.1
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• pp.34-44
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• 2016

Background: Little is known about how chemical water quality is associated with ecological stream health in relation to landuse patterns in a watershed. We evaluated spatial characteristics of water quality characteristics and the ecological health of Dongjin-River basin, Korea in relation to regional landuse pattern. The ecological health was assessed by the multi-metric model of Index of Biological Integrity (IBI), and the water chemistry data were compared with values obtained from the health model. Results: Nutrient and organic matter pollution in Dongjin-River basin, Korea was influenced by land use pattern and the major point sources, so nutrients of TN and TP increased abruptly in Site 4 (Jeongeup Stream), which is directly influenced by wastewater treatment plants along with values of electric conductivity (EC), bacterial number, and sestonic chlorophyll-a. Similar results are shown in the downstream (S7) of Dongjin River. The degradation of chemical water quality in the downstream resulted in greater impairment of the ecological health, and these were also closely associated with the landuse pattern. Forest region had low nutrients (N, P), organic matter, and ionic content (as the EC), whereas urban and agricultural regions had opposite in the parameters. Linear regression analysis of the landuse (arable land; $A_L$) on chemicals indicated that values of $A_L$ had positive linear relations with TP ($R^2=0.643$, p < 0.01), TN ($R^2=0.502$, p < 0.05), BOD ($R^2=0.739$, p < 0.01), and suspended solids (SS; ($R^2=0.866$, p < 0.01), and a negative relation with TDN:TDP ratios ($R^2=0.719$, p < 0.01). Conclusions: Chemical factors were closely associated with land use pattern in the watershed, and these factors influenced the ecological health, based on the multimetric fish IBI model. Overall, the impairments of water chemistry and the ecological health in Dongjin-River basin were mainly attributes to point-sources and land-use patterns.

• Journal of the Korean GEO-environmental Society
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• v.14 no.5
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• pp.49-56
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• 2013

The necessity of exploration in deep sea increases to develop the natural resources. The deep marine sediments, which were recovered from the hydrate occurrence regions during the Ulleung Basin Gas Hydrate Expedition 2 (UBGH2), East Sea, Korea in 2010, are explored to obtain the geotechnical characteristics and strength parameters. The index properties of the specimens including the atterberg limits, specific surface, and particle size distribution are measured and compared with the previous studies. X-ray diffraction, scanning electron microscope, and X-ray energy dispersive spectroscopy are conducted to analyze the clay mineralogy, chemical composition, and microstructure of the sediments. Strength parameters and shear wave velocities are measured with the axial strain by using an instrumented triaxial device. The strength parameters estimated by empirical equations are compared with the experimental results.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.5
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• pp.541-550
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• 2008

In this investigative study, the unit mass discharge for the major water quality parameters such as flowrate, SS, BOD, CODmn, CODcr, TN, TP from textile spinning/weaving industry nearby Nakdong river basin was estimated. To represent the respective industries, three companies from hundreds of textile spinning/weaving industries located in Nakdong river basin was carefully selected based on its manufacturing goods, flowrate and location for the estimation of unit mass discharge based on unit operation and process. There was a drastic decrease of unit mass discharge estimation between influents and effluents of water quality parameters, which represents the removal capacity of wastewater treatment plant. With the advent of new regulation on the imposed payment proportional to the total amount of pollutants discharge into the water body, the concept of cleaner production technology should be employed in the unit operation/process in wastewater treatment plant as well as textile manufacturing procedure to minimize the levy on the pollutants discharge. Unit mass discharge estimations of unit process (estimated in this study) in major water quality parameters (SS, BOD, COD, TN and TP) based on land were similar to those of composite process (estimated by National Institute of Environmental Research). But the unit mass discharge estimations of unit process in BOD and CODmn based on total sale were much higher than those of composite one while in SS, TN and TP similar to each other. For the detailed estimation of the imposed payment, unit mass estimation based on unit process should be further emphasized.

• Water for future
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• v.19 no.4
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• pp.347-354
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• 1986

To predict flood runoff from rainfall and watershed Characteristics, Nash's parameters of N, K are needed to be determined. Also parameters of IUH N and K are derived by the moment method. Nash's model whose parameters are derived from rainfall characteristics is applied to the Wi-stream basin, which is a tributary located in the Nakdong river. For the derivation of IUH by applying linear conceptual model, the storage constant, K, with the rainfall characteristics was adopted as K=1.327 $$.$$$.$$$.$$$.$$$.$$ having a highly significant correlation coefficient, 0.970. Gamma function argumetn, N, derived with such rainfall characteristics was found to be N=0.032$$.$$$.$$$.$$$.$$$.$$ having a highly significant correlation coefficient, 0.970. From the tested results it is proved that Nash's IUH and consequently flood runoff can be predicted from rainfall characteristics.

• Geophysics and Geophysical Exploration
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• v.15 no.2
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• pp.92-101
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• 2012

Three-dimensional finite-difference simulation in a small-scale half-sphere basin with planar free-surface is performed for an arbitrary shear-dislocation point source. A new scheme to deal with free-surface boundary condition is presented. Then basin parameters are examined to understand main characteristics on ground-motion response in the basin. To analyze the frequency content of ground motion in the basin, spectral amplitudes are compared with each other for four sites inside and outside the basin. Also particle motions for those sites are examined to find which kind of wave plays a dominant role in ground-motion response. The results show that seismic energy is concentrated on a marginal area of the basin far from the source. This focusing effect is mainly due to constructive interference of the direct Swave with basin-edge induced surface waves. Also, ground-motion amplification over the deepest part of the basin is relatively lower than that above shallow basin edge. In the small-scale basin with relatively simple bedrock interface, therefore, the ground-motion amplification may be more related to the source azimuth or direction of the incident waves into the basin rather than depth of it.

• Magazine of the Korean Society of Agricultural Engineers
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• v.24 no.2
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• pp.76-88
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• 1982

The stream morphological characteristics of a basin have important influence upon the analysis of runoff. In this study, the laws of stream morphology-the law of average stream fall and the law of least rate of potential energy expenditure-which were derived based on the analogy of entropy in thermodynamics are introduced and their validity is analysised with the data taken from the topographic maps covering the whole Geum River system. The first law is the Law of Average Stream Fall which states that under the dynamic equilibrium condition the ratio of average fall between any two different order stream in the same river basin in unity. The second law is the law of least rate of energy expenditure which states that all natural streams are intended to choose their own course of flow such that the rate of potential energy loss per unit mass of water this course is a minimum. The parameters representing the morphological characteristics of 13 tributaries in the Geum River system such as stream bifurcation ratio and stream concavity were Computed from the Horton-Strahler's laws and are used to check the law of average stream fall. The result showed that the law of average stream fall agrees reasonably well with law of Horton-Strahler. Concavity of a river basin is shown to be the determinative factor to the formation of a stream system. Concavity of a river basin is shown to be the determinative factor to the formation of a stream system. Based on Horton's Law and the law of average stream fall, longitudinal stream profiles can be calculated.

• Journal of Korean Society for Geospatial Information Science
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• v.11 no.1 s.24
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• pp.3-12
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• 2003

The main objective of this study is to extract the hydro-Parameter of the Tamjin River basin. A CIS is capable of extracting various hydrological factors from DEM. One of important tasks for hydrological analysis is the division of watershed. In this study, watershed itself and other geometric factors of watershed are extracted from DEM by using a CIS technique. The data of topographical map with scale of 1:25,000 and 1:250,000 in the Tamjin River basin is used for this study and it is converted to DEM date. Various forms of representation of spatial data are handled in main modules and a CRID module of ArcView. A GRID module is used on a stream in order to define watershed boundary. Based on the spatial analysis using those GIS technique, it would be possible to obtain the reasonable results of watershed characteristics. Also, the results show not only that GIS can aid watershed management, research and surveillance, but also that the geometric characteristics as parameters of watershed can be quantified more accurately and easily than conventional graphic methods. From the equations($Y=14632.87{\cdot}X^{-0.542444},\;Y=37014.1{\cdot}X^{-1.058808}$), it can be concluded that the optimal count of flow accumulation is 468 and cell size is 42m for spatial analysis by using GIS technique in Tamjin River basin.

• Journal of Wetlands Research
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• v.21 no.spc
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• pp.39-50
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• 2019

This study aims to assess the influence of climate change on the hydrological cycle at a basin level in North Korea. The selected model for this study is MRI-CGCM 3, the one used for the Coupled Model Intercomparison Project Phase 5 (CMIP5). Moreover, this study adopted the Spatial Disaggregation-Quantile Delta Mapping (SDQDM), which is one of the stochastic downscaling techniques, to conduct the bias correction for climate change scenarios. The comparison between the preapplication and postapplication of the SDQDM supported the study's review on the technique's validity. In addition, as this study determined the influence of climate change on the hydrological cycle, it also observed the runoff in North Korea. In predicting such influence, parameters of a runoff model used for the analysis should be optimized. However, North Korea is classified as an ungauged region for its political characteristics, and it was difficult to collect the country's runoff observation data. Hence, the study selected 16 basins with secured high-quality runoff data, and the M-RAT model's optimized parameters were calculated. The study also analyzed the correlation among variables for basin characteristics to consider multicollinearity. Then, based on a phased regression analysis, the study developed an equation to calculate parameters for ungauged basin areas. To verify the equation, the study assumed the Osipcheon River, Namdaecheon Stream, Yongdang Reservoir, and Yonggang Stream as ungauged basin areas and conducted cross-validation. As a result, for all the four basin areas, high efficiency was confirmed with the efficiency coefficients of 0.8 or higher. The study used climate change scenarios and parameters of the estimated runoff model to assess the changes in hydrological cycle processes at a basin level from climate change in the Amnokgang River of North Korea. The results showed that climate change would lead to an increase in precipitation, and the corresponding rise in temperature is predicted to cause elevating evapotranspiration. However, it was found that the storage capacity in the basin decreased. The result of the analysis on flow duration indicated a decrease in flow on the 95th day; an increase in the drought flow during the periods of Future 1 and Future 2; and an increase in both flows for the period of Future 3.

• Journal of Korea Water Resources Association
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• v.40 no.2 s.175
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• pp.171-182
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• 2007

In this study, as a method for decreasing the confidence interval of the estimates of Clark hydrograph's concentration time and storage coefficient, regression equations of these parameters with respect to those of rainfall, meteorology, and basin characteristics are derived and analyzed using the Monte Carlo simulation technique. The results are also reviewed by comparing them with those derived by applying the Bootstrap technique and empirical equations. Results derived from this research are summarized as follows. (1) Even in case of limited rainfall events are available, it is possible to estimate the mean runoff characteristics by considering the affecting factors to runoff characteristics. (2) It is also possible to use the Monte Carlo simulation technique for estimating and evaluating the confidence intervals for concentration time and storage coefficient. The confidence intervals estimated in this study were found much narrower than those of Yoo et al. (2006). (3) A supporting result could also be derived using the Bootstrap technique. However, at least 20 independent rainfall events are necessary to get a rather significant result for concentration time and storage coefficient. (4) No empirical equations are found to be properly applicable for the study basin. However, empirical equations like the Kraven(I) and Kraven(II) are found valid for the estimation of concentration time, on the other hand the Linsley is found valid for the storage coefficient In this study basin. But users of these empirical formula should be careful as these also provide a wide range of possible values.

• Journal of Korean Society on Water Environment
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• v.29 no.5
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• pp.630-640
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• 2013

It is one of the most critical steps identifying impaired waterbodies exactly in the selection of target water quality indicators for the management of Total Maximum Daily Loads (TMDLs). Excess ratio and excess level were applied and analyzed by the stream zone basis in order to evaluate water impairment for Nakdong, Geum, Youngsan and Seomjin rivers. Each river basin was divided into stream zones in the light of its watershed and waterbody characteristics. Selected water quality parameters discussed in this study were pH, DO, BOD, COD, SS, T-P, T-Coli and F-Coli. The excess ratios of the water quality parameters were used to discriminate water bodies that did not meet water quality standards. The excess levels were used to classify the degradation of water quality. The excess ratios and the excess levels to the water quality criteria of the medium influence areas were used for each stream zone. The results indicate that the excess ratios and the excess levels are varied on the stream zone in each river basin. Three parameters, pH, DO and SS, met water quality standards in all stream zones. The other five parameters indicated very high excess ratios in most waterbodies, and especially T-P and T-Coli revealed to be very high excess levels in some waterbodies. These parameters could be considered as major target indicators for the management of TMDLs.