• Magazine of the Korean Society of Agricultural Engineers
• /
• v.31 no.4
• /
• pp.111-122
• /
• 1989

A multiple box model which is suitable for the prediction of water quality in shallow lakes with active mixing is a water quality model expected to be used widely in estuary reservoir. In this study, a multiple box water quality model for estuary reservoirs (MBQER) was developed arid the applicability of the MBQER was tested by applying data obtained from Asan-estuary reservoir. The results of this study can be summarized as follows. 1. The MBQER, dynamic water quality model, was developed to estimate 10-day water qualities of estuary reservoirs. For the proper analysis and the application of hydraulics needed to build a model, lake hydraulics was simplified by condisering only hydrological inflow and lake mixing currents. The box division in the MBQER is longitudinal one dimension for upper and middle part, and two layers for lower part of the reservoir. 2. The methods of box division for the multiple box model were ekamined and applied to Asan-estuary reservoir. For determining the number of boxes, Pe number and Pk number were used. In case of three boxes, the error by the model simplification would be estimated about 5 % Therefore, in Asan reservoir, the proper number of boxes was three. 3. The MBQER was calibrated and verified using measured data in Asan-estuary reservoir from 1986 to 1988. The Root Mean Squares(RMS) for the differences between measured data and simulated results by the MBQER were 1.10$^{\circ}$C C for water temperature, 75.8mg/1 for salinity, 0.082mg/1 for total-phosphorus showing good estimations. 4. Through the simulation of water temperature and salinity by the MBQER, the exchange flow and the mixing coefficients for the estuary lake were determined. As a result of simulation, the horizontal mixing coefficients in Asan-estuary reservoir were in the range of 1.07X 105 to 1.12X 105 cm$^2$/sec and vertical mixing coefficient was 2.90X 10-1 cm$^2$/sec.

• Korean Journal of Ecology and Environment
• /
• v.35 no.3 s.99
• /
• pp.187-197
• /
• 2002

To analyze the structure of phytoplankton community of the Asan Reservoir in Korea, samples were collected 6 times from March to November in 1997. A total of 204 phytoplanklon species were identified from the samples of 19 stations. Green algae dominated the phytoplankton community, accounting for 51% of species number, followed by diatoms (29%), cyanobacteria (12%), dinoflagellates (2%) ,euglenoids (3%) and other flagellates (3%). Standing stocks of phytoplankton were very high in the range of 741-613,066 cells/ml, with the highest standing stock in July. Water Booms seemed to occur in the Asan Reservoir regardless of seasons, with water bloom-causing species being Micractium pusillum, Stephanodiscus, hantzschii, Dictyospharium pulchellum, cryptomonad(> 20 ${\mu}$m), Microcystis aeruginosa, Oscillatoria tenuis, Oscillatoria sp., Aphanocapsa sp. Euglena sp., Volvox aureus. In the summer, cyanobacteria dominated algal bloom. Species diversity of phytoplankton community in the reservoir was in the range of 0.13 ${\sim}$ 3.20, and showed much difference temporally and spatially. The cluster analysis identified two different regions of upstream area and downstream area for the Asan Reservoir.

• Journal of Korean Society of Environmental Engineers
• /
• v.32 no.1
• /
• pp.1-8
• /
• 2010

To investigate the effects of sediments on the water quality of an estuary reservoir, Asan reservoir, we analyzed physical and chemical characteristics of the sediments and estimated nutrients release rate from the sediments. The sediments characterized as sandy loam are mainly composed of Nonapatite-P(64.7%) which has strong influence on the eutrophication of the reservoir by releasing from the sediments under the condition of increasing pH and anaerobic environment. High nutrient release rates was observed in April. Negative release rates in June show that there is no significant nutrient release from the sediments. The nutrient release was active at the Site B around the confluence of tributary compared to the Site A near the embankment. Based on the information of nutrient release rates and sediments surface area, daily average nutrient release rates of Asan reservoir are estimated; TN 6,609 kg/d, TP 3,877 kg/d. Since the amount of N and P released from the sediments corresponds to the 7.06% of N and 22.04% of P incoming from the watershed, it can be concluded that there is little influence of sediments on the water quality of Asan reservoir.

• Korean Journal of Ecology and Environment
• /
• v.35 no.3 s.99
• /
• pp.181-186
• /
• 2002

To evaluate the eutrophication status of the Asan Reservoir in Korea, physicochemical parameters were analyzed for samples of 19 sampling stations collected in the period from March to November in 1997. Water temperature was in the range of $8.3{\sim}35.3{\circ}^C$, with thermocline appearing in summer. Dissolved oxygen also showed similar verticle variation to temperature. Secchi depth was very shallow with a range of 0.1~1m. Suspended solids ranged from 11.3 mg/1 to 2143.3 mg/1, and seemed to be affected by the amount of rainfall and the standing stocks of phytoplankton. Nutrient concentrations were higher in tributaries, and decreased with downflow. Nutrients were low in the summer and early autumn when algal blooms occur, and high in the early spring and winter. The Trophic State Index showed that the Asan Reservoir is in a hypertrophic condition．

• Journal of the Korean Society of Environmental Restoration Technology
• /
• v.18 no.6
• /
• pp.167-177
• /
• 2015

This study was conducted to establish an inventory and propose conservation strategies for 'village wetlands' in Asan city, Korea, using GIS. As results, the village wetlands are defined as such places as 'palustrine' wetland, village embankment, agricultural reservoir or small reservoirs located in or near the village and related to everyday life or farming. Firstly 807 provisional village wetlands(draft) were identified in Asan by using Arc-GIS 10.1, then 196 wetlands(final) were defined finally as village wetlands and listed the inventory of Asan Village Wetlands after being validated through office works and field survey. The office works analyzed minimum area(greater than $625m^2$), satellite images, the Korea Land Information System, land use map and land coverage map. To evaluate the function and conservation values, the 37 wetlands were selected for detailed surveying and function assessment based on the following criteria : 1) doubled code both wetland and reservoir at digital map, 2) located less than 100m from village and 3) ecologically connected to such ecological resources as seaside mudflats, mountains and green area and ecological passages for small size wildlifes. As the result of the wetland function assessments by the RAM method, 7 wetlands were found to have 'high' wetland function (conservation) 18 wetlands were 'medium' (enhancement) and 12 wetlands were 'low' (restoration or enhancement). Enhancing biodiversity and ecosystem services through ecological management of wetlands in Asan and connecting with the Ecological Natural Degree were proposed.

• Journal of Industrial Technology
• /
• v.18
• /
• pp.425-430
• /
• 1998

The Asan Bay area Korea is situated in an unbalance or water supply and demand relating to the Ansung, Sapkyo, Dangjin and Youmwha rivers and their estuary reservoirs. The multi-reservoir operation was studied by the Hierarchical Operation Model for Multi-reservoir System(HOMMS) assuming that these four estuary reservoirs were linked to each other in order. The result of this study shows that storage capacity deficiency in 2011 was estimated as 8 MCM in the Sapkyo and 31 MCMin Dae Ho estuary reservoir, respectively. In case of linking four reservoirs, the water deficiency will not occurs in all the reservoirs even if additional agricultural water of 78 MCM/yr was supplied. Total additional water demand for agricultural, municipal and industrial uses was estimated as 321.9 MCM/yr while additional supply by linking the reservoirs was estimated as 160.4 MCM/yr. 50% of additional demand. The remaining 161.5MCM/yr would be supplied transferring other watershed.

• 한국생태학회:학술대회논문집
• /
• 1999.05a
• /
• pp.74-74
• /
• 1999

• 한국생태학회:학술대회논문집
• /
• 1999.05a
• /
• pp.66.2-66.2
• /
• 1999

• Journal of Ecology and Environment
• /
• v.34 no.4
• /
• pp.357-363
• /
• 2011

To examine factors affecting feeding efficiency of grey herons (Ardea cinerea), the foraging behavior was studied at a reservoir in Asan city, Chungcheongnam-do, South Korea during the breeding seasons (from April to July) of 2006 and 2007. Four factors (age of foraging birds, time of day, breeding stage, and microhabitat type) were analyzed. Adults were more efficient foragers than recently fledged juveniles, and they had a higher success rate than juveniles. About half of the adults caught large prey, whereas most juveniles caught only small prey. Adult grey herons had different feeding efficiency according to the breeding stage. Pecking and capture rates were high during the late period (fledging stage), and biomass intake rates were high during the early (incubating stage) and late periods. However, time of day had no significant effect on foraging activity of adult grey herons. Feeding activities of adult grey herons also showed significant variation among microhabitat types. Pecking and capture rates were higher in the submerged plants area, but capture success rate and biomass intake rate were not different according to microhabitat type.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.38 no.2
• /
• pp.97-107
• /
• 1996

This study was performed to derive the formula of sediment yield and predict the sediment elevation for fresh desalted reservoirs. Data analyzed was from 3 fresh desalted reservoirs of Sapkyo, Asan, and Namyang. Average sediment yield calculated from the sediment survey data was $279m^3/km^2/$ year for Sapkyo lake, $523m^3/km^2/$ year for Namyang lake, and $190m^3/km^2/$ year for Asan lake. The trap efficiency for Sapkyo lake was 63%. The formula of sediment yield was derived as $Q_s=6,461{\times}A{^-0.44}$ for fresh desalted reservoir. Sediment yield in fresh desalted reservoirs was much higher than that in inland reservoirs located in the same watershed, because of long trap time in fresh desalted reservoirs.