• Korean Journal of Ecology and Environment
• /
• v.51 no.1
• /
• pp.1-15
• /
• 2018

With land-use (cover) and water quality, the distributional characteristics of epilithic diatom communities were studied with 193 samples from estuaries of Korean peninsula between 2015 and 2016. Of total 394 taxa classified, Nitzschia perminuta (19.6%) and N. inconspicua (14.0%) were the 1st and 2nd dominant species. Using a cluster analysis, the epilithic diatom communities of Korean estuaries were divided into four groups (G1-G4). Ecological characteristics of each group were followed: G1 was located in estuaries of the East Sea, and characterized by high forest land-use and high DO and low nutrients; G2 was the eastern part of the South Sea, and characterized by low turbidity and nutrients; G3 was the western part of the South Sea, and characterized by high agriculture, low electric conductivity and low salinity; G4 was the Yellow Sea, and characterized by high nutrients. The environmental factors having significant correlation with diatom distributions were as follows: TN to G1, turbidity to G2, agriculture to G3, and TP to G4. Moreover, the important factors affecting the occurrence of indicator species were forest land-use for Fragilaria construens var. venter in G1, turbidity for Rhoicosphenia abbreviata in G2, urban land- use and total phosphorus (TP) for Bacillaria paradoxa and Hantzschia amphioxys of G3, and TP and turbidity for N. ovalis and Stephanodiscus invistatus of G4. These results collectively indicate that the distribution of epilithic diatom communities in Korean peninsula was largely effected by water quality and land cover/use.

• Journal of Korea Water Resources Association
• /
• v.40 no.6 s.179
• /
• pp.459-468
• /
• 2007

To estimate the groundwater recharge, the fully distributed parameter based model, MIKE SHE was applied to the Gyeongan-cheon watershed which is one of the tributaries of Han River Basin, and covers approximately $260km^2$ with about 49 km main stream length. To set up the model, spatial data such as topography, land use, soil, and meteorological data were compiled, and grid size of 200m was applied considering computer ability and reliability of the results. The model was calibrated and validated using a split sample procedure against 4-year daily stream flows at the outlet of the watershed. Statistical criteria for the calibration and validation results indicated a good agreement between the simulated and observed stream flows. The annual recharges calculated from the model were compared with the values from the conventional groundwater recession curve method, and the simulated groundwater levels were compared with the observed values. As a result, it was concluded that the model could reasonably simulate the groundwater level and recharge, and could be a useful tool for estimating spatially/temporally the groundwater recharges, and enhancing the analysis of the watershed water cycle.

• Journal of Wetlands Research
• /
• v.14 no.2
• /
• pp.255-263
• /
• 2012

The stream has various environments and they are serving as main habitats of aquatic organisms. The distribution of phytoplankton is affected by water environment, especially pH, nitrogen and phosphorus. To reveal the relationship between phytoplankton distribution and water environment, we measured pH, $NO_3{^-}$ and $PO{_4}^{3-}$ concentration, and abundance of phytoplankton at 10 sites in the upper stream of Dorim-cheon. pH value ranged 5.05 to 7.56. $NO_3{^-}$ and $PO{_4}^{3-}$ concentrations ranged 0.4 ~ 4.9ppm and 0.02 ~ 0.99ppm, respectively. A point source of $NO_3{^-}$ was Seoul National University but concentration was not high and dropped to normal range at 400m downstream. $NO_3{^-}/PO{_4}^{3-}$ ratio ranged 28 to 152 except site 4 (0.4) where was affected by $PO{_4}^{3-}$ point source. Water pH, $NO_3{^-}$ and $PO{_4}^{3-}$ concentrations increased with downstream and were related to the input of irrigation water from Han-river between site 5 and 6. Bacillariophyceae alge dominated this stream. Phytoplankton density increased abruptly at downstream of site 5. In general, phytoplankton density did not increase until the $NO_3{^-}$ concentration of 3.5ppm and $PO{_4}^{3-}$ concentration of 0.07ppm. Phytoplankton density was low at sites where $NO_3{^-}/PO{_4}^{3-}$ ratio was larger than 50.

• Journal of Korea Water Resources Association
• /
• v.43 no.2
• /
• pp.211-220
• /
• 2010

The objective of this paper presents the application of an "integrated urban flood modeling-runoff model, urban flood model and sewer system model-" in a highly urbanized area of Samcheok where is seriously inundated in 2002 and 2003. For this, we demonstrate how couple a 1-D hydrodynamic model of the river, a 2-D hydrodynamic model of the overland (surface) flow, and a sewer network model including each boundary conditions. In order to make data file for the model, topographic information like elevation and share rate of buildings are directly extracted from DEM or topographical source data without data exchange to avoid uncertainty errors. Furthermore, the research is to assess the impacts of Manning n and buildings influences to inundated depth by changing its share ratio from 10 % to 30 % in low-land urban area. As a results, we found out that the urban inundated depth was decreased by Manning n but increased by buildings ratio. The calculated results of inundation was similar with observed one in 2002 and 2003 flooding. Furthermore, the area was also inundated under not riverbank break case in 2002 flooding.

• Journal of Korea Water Resources Association
• /
• v.31 no.1
• /
• pp.35-44
• /
• 1998

An integrated system of GIS and water quality model was suggested including the pollutant loads from the watershed. The developed system consists of two parts. First part is the GIS module. The geographic information system of the study area was built to provide the information on landuse and several surface factors concerning the overland flow processes of water and pollutants. Second part is the modeling modules which include storm event pollutant load model(SEPLM)., non-storm event pollutant load model(NSPLM), and river water quality simulation model(RWQSM). Models can calculate the pollutant load from the study area. The databases and models are linked through the interface modules resided in the overall system, which incorporate the graphical display modules and the operating scheme for the optimal use of the system. The developed system was applied to the Chungju multi-purpose reservoir to estimate the pollutant load during the four selected rainfall events between 1991 and 1993,. based upon monthly basis and seasonal basis in drought flow, low flow, normal flow and wet flow.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.59 no.3
• /
• pp.83-96
• /
• 2017

This study presented a surface water quality modeling framework considering the spatial resolution of pollutant load estimation to better represent stream water quality characteristics in the Saemangeum watershed which has been focused on keeping its water resources sustainable after the Saemangeum embankment construction. The watershed delineated into 804 sub-watersheds in total based on the administrative districts, which were units for pollutant load estimation and counted as 739 in the watershed, Digital Elevation Model (DEM), and agricultural structures such as drainage canal. The established model consists of 7 Mangyung (MG) sub-models, 7 Dongjin (DJ) sub-models, and 3 Reclaimed sub-models, and the sub-models were simulated in a sequence of upstream to downstream based on its connectivity. The hydrologic calibration and validation of the model were conducted from 14 flow stations for the period of 2009 and 2013 using an automatic calibration scheme. The model performance to the hydrologic stations for calibration and validation showed that the Nash-Sutcliffe coefficient (NSE) ranged from 0.66 to 0.97, PBIAS were -31.0~16.5 %, and $R^2$ were from 0.75 to 0.98, respectively in a monthly time step and therefore, the model showed its hydrological applicability to the watershed. The water quality calibration and validation were conducted based on the 29 stations with the water quality constituents of DO, BOD, TN, and TP during the same period with the flow. The water quality model were manually calibrated, and generally showed an applicability by resulting reasonable variability and seasonality, although some exceptional simulation results were identified in some upstream stations under low-flow conditions. The spatial subdivision in the model framework were compared with previous studies to assess the consideration of administrative boundaries for watershed delineation, and this study outperformed in flow, but showed a similar level of model performance in water quality. The framework presented here can be applicable in a regional scale watershed as well as in a need of fine-resolution simulation.

• The Korean Journal of Quaternary Research
• /
• v.25 no.2
• /
• pp.25-37
• /
• 2011

The purpose of this study is to assume the particular area of hills where it is highly possible for historical site to be buried in the viewpoint of geomorphology and based on this to suggest excavation-recommended area. Namely, this writer is to understand the dwelling site type of ancient people who had resided there at that time for the object of 'Ohnju region urban development business site' (referred as investigation area hereinafter) and considering the characteristics of micro-landform of hills which are distributed in investigation area and is to recommend the area where it is highly possible for historical site to be buried. The result of analysis is like the following. (1) Dwelling site types of ancient people who might have resided in the whole area of investigation region are discovered to be largely 'low hills+wetland' of Type-I and 'alluvial fan(or river terrace+wetland' of Type-II. (2) In investigation area if the area which has high possibility of distribution of historical site namely, excavation-recommended area is looked as based on micro-landform unit of hills, they are Crest slope and Crest flat. Individual area ratios which Crest slope and Crest flat occupies in investigation area are 12.9% and 10.2% respectively and the rankings are 3 and 6 each. And excavation-recommended areas in valley plain(or bottomland) of investigation area are in the vicinity of 'distal end' or 'buried distal end'of small scale alluvial fan.

• Journal of the Korean association of regional geographers
• /
• v.9 no.3
• /
• pp.276-296
• /
• 2003

This study is to analyze the adoption of environmentally friendly fanning(EFF) by Actor-Network Theory(ANT). ANT declares that the world is full of hybrid entities containing both human and non-human elements and maintains that adoption of an innovation comes as a consequence of the action of everyone in the chain of actors who has anything to do with it. In this study, adoption of EFF will be analysed through the role of actors and networks. And this paper try to identify the intermediaries and obligatory passage point(OPP) in each networks. In study area, 5 actors, -nature, governmental institute, food processors, consumers and farmers-, have each roles in their networks, But only 18 farmers adopted EFF. This study revealed that three OPPs were not overcome in each network. The one is nature, such as water and soil pollution. Another is shortage of reliability between farmers and governmental institute. The other is shortage of information about agricultural commodity trade. And through this application of ANT to the EFF, we contend that ANT can be useful for studies of diffusion of EFF and sustainability of rural systems in situations where interactions of the social, technological and political are regarded as particularly important.

• Korean Journal of Environmental Agriculture
• /
• v.10 no.1
• /
• pp.67-75
• /
• 1991

The QUAL-II E Model was applied to predict the water quality of the Mankyong drainage System, and lead to following conclusion. 1. The difference between computed and measured BOD at the M-3 (Bakgugeong) station was within 10%, indicating that the application of the QUAL-IIE Model for the prediction of water quality was satisfactory thus far. 2. The application of the model states that the discharge of concentrated pollutants at the M-1 station on the Jeonju stream, located 41Km upstream from the estuary, causes the worst problems. The sluice which extends residence time and enlarges watery surface improves water quality by a Self-purification process at the M-3 station, 28km upstream from the estuary. 3. The accuracy of the model diminished when this model was applied on the estuary downstream of the sluice. Hence, the application of the model on the estuary needs to be used with caution. 4. Among the conputed water quality parameters, BOD is the worst problem. At the M-3 station, BOD is computed to be 26.6 mg/1 in 1996, 30.7 mg/1 in 2,001, 33.0 mg/l in 2006, and 37.5 mg/1 in 2011. When preventive measures against water pollution are not properly exercised, severe problems in irrigation and water resources are expected. This study will be of used in the selection of irrigation water intake points, the criteria of effluent treatment, the management of water resources, and the establishment of water quality managemont policy.

• The Journal of Engineering Geology
• /
• v.25 no.3
• /
• pp.339-347
• /
• 2015

Riverbank filtration has been suggested as a cost-effective method for improving water quality. However, high concentrations of Fe²⁺ and Mn²⁺ cause problems for the use of water and the maintenance of facilities. We evaluated the effectiveness and efficiency of an Fe²⁺ and Mn²⁺ removal technique based on the in situ injection of highly oxygenated water at a site on the Anseong River, between Anseong City and Pyeongtaek City, Gyeonggi Province. The removal process consists of three steps: injection, resting, and extraction. Results show that the removal efficiency increases with repeated application of the process. The amount of Fe-reduced drinking water satisfying water regulations (limit, 0.3 mg/L Fe) obtained using oxygenated water injection was five times higher than the amount of injected oxygenated water. Levels of Mn²⁺ were also reduced following the injection of oxygenated water.