• Journal of Korean Society on Water Environment
• /
• v.30 no.4
• /
• pp.377-385
• /
• 2014

To study the fluctuations and relationship in climate change, environmental factors and cyanobacteria communities, we investigated Chudong station of the Daechung reservoir. The average annual temperature showed the maximum value ($13.9^{\circ}C$) from 1994, showed a gradually increasing pattern from 1969 to 2010 in the Daechung reservoir. The number of days with temperatures over $20^{\circ}C$, minimum temperature of the year and average temperature of the winter season patterns also showed a significant increase. The long-time changed in the annual precipitation were not showed a significant variation. The water temperature record comparatively high value in summer, declined in winter. At all period, the phytoplankton were highest biomass in July 2000, and then, showed comparative higher biomass in the summer months. Cyanobacteria taxa were also showed more than 50%. Emergence of cyanobacteria also appeared in November 2007, were prolonged emergence. The dominant genera of taxa were the dominant sphere (Microcystis spp.) until early 2000. After that, the dominant species were the dominant linear (Aphanizomenon spp., Anabaena spp.). Cyanobacteria were the most correlated with water temperature (r = 0.341, p<0.01) and phosphate concentration (r = 0.355, p<0.01).

• Journal of Korean Society of Rural Planning
• /
• v.6 no.2 s.12
• /
• pp.73-81
• /
• 2000

This study was carried out to measure the amount of outlet discharge and analyse the water quality from an agricultural reservoir. Joongpyong reservoir was selected as the monitoring site. Daily discharge was determined by measured water level data of delivery canal and the stage-discharge relation curve. The measured water discharge through culvert outlet of Joongpyong reservoir was 593,200m3 which was equivalent to irrigation depth 1,186mm during irrigation period in 1999. And water samples were taken from the surface water of reservoir and delivery canal, periodically. Temporal variation of water quality constituents such as water temperature, pH, EC, total nitrogen, total phosphorus were investigated. The result showed that pH was ranged 6.9 7.8, total nitrogen 1.39 4.11mg/L, total phosphorus 0.007 0.036 mg/L, respectively.

• Journal of Plant Biology
• /
• v.11 no.2
• /
• pp.1-30
• /
• 1968

The Han River was investigated monthly from April through September, 1967 at Chun-chon reservoir, Shin-yean, So-yang, Chung-pyong reservoir, Yang-soo-ri and Gi-doo-won to clarify the phytoplankton and to study its seasonal variation. At the same time, vertical distribution of phytoplankton was also studied from June through September at Chun-chon and Chung-pyong reservoir. The results obtained are as follows: As the environmental conditions, water temperature, dissolved oxygen, pH, and transparency were determined. The plankton samples collected from six stations were identified and classified by Engler's classification system. It resulted in 4 phyla, 4 classes, 3 subclasses, 13 orders, 27 families, 5 tribes, 71 genera, 222 species, 1 subspecies, 51 varieties and 2 forms. The total number of phytoplankton identified was 276. Of them, 84 species, 1 subspecies 26 varieties, 2 forms were recorded in this paper for the first time. Considering with the habitat of the total number of phytoplanktons, the highest percentage of Limnoplankton existed in the Chung-pyong reservoir. It suggests that hte Chung-pyong reservoir is becoming to have the character of lake. The planktons appeared commonly during six months at six station belong to Chrysophyta including 22 species in 11 genera. Among these 22 species, Navicula, consists of 6 species, was the most abundant. The number of species identified uniquely at each station were 5 species in the Chun-chon reservoir, 6 in Chung-pyong and Yang-soo-ri, 8 at Shin-yean, 11 at So-yang, and 18 at Gi-doo-won. The number of species occurred at all stations were 29 in spring, 42 in Autumn and during investigation period. The maximum production of total phytoplankton was generally shown in the late spring and the early fall with differences in quantity at six collecting statins. In the Chun-chon reservoir, the high concentration of approximately 1, 190, 000 cells per litter in the months of August and September was due to the increase of Chrysophyte genus, Melosira and the highest concentration of approximately 2, 000, 000 in July at Gi-doo-won was caused Chlorophyte genus, Secenedesmus. The Chun-chon reservoir of three years old was different from the Chung-pyong reservoir of 25 years old with respect to increase in Melosira genus in August and September. After the completion of the Ui-am reservoir, though there was an increase in total density, the number of species of phytoplankton was not changed. It suggests that Ui-am reservoir is similar to the Chun-chon reservoir under the influence of the latter. The density of total phytoplankton was generally high at the depth of 2m to 5m for the two reservoirs.

• Journal of Korea Water Resources Association
• /
• v.38 no.8 s.157
• /
• pp.655-664
• /
• 2005

A real-time monitoring and modeling system (RTMMS) for rainfall-induced turbidity flow, which is one of the major obstacles for sustainable use of reservoir water resources, is under development. As a prediction model for the RTMMS, a laterally integrated two-dimensional hydrodynamic and water quality model, CE-QUAL-W2 was tested by simulating the temperature stratification, density flow regimes, and temporal and spatial distributions of turbidity in a reservoir. The inflow water temperature and turbidity measured every hour during the flood season of 2004 were used as the boundary conditions. The monitoring data showed that inflow water temperature drop by 5 to $10^{\circ}C$ during rainfall events in summer, and consequently resulted in the development of density flow regimes such as plunge flow and interflow in the reservoir. The model showed relatively satisfactory performance in replicating the water temperature profiles and turbidity distributions, although considerable discrepancies were partially detected between observed and simulated results. The model was either very efficient in computation as the CPU run time to simulate the whole flood season took only 4 minutes with a Pentium 4(CPU 2.0GHz) desktop computer, which is essentially requited for real-time modeling of turbidity plume.

• Journal of The Korean Society of Agricultural Engineers
• /
• v.58 no.6
• /
• pp.9-21
• /
• 2016

Agricultural reservoirs in Korea have been recognized as an emerging resource for recreational and cultural activities for residents. However, most of the reservoirs are eutrophic and showing high level of contamination with nuisance algal bloom and offensive odor during the summer. For better management and restoration of the reservoirs' water quality, scientific modeling approaches could be used to diagnose the problems and evaluate the efficacy of alternative control measures. The objectives of this study were to validate the performance of a three-dimensional (3D) hydrodynamic and water quality model (Environmental Fluid Dynamics Code, EFDC) for a eutrophic agricultural reservoir and assess the effect of bypassing of the effluent from a wastewater treatment plant on the reservoir water quality. The 3D model successfully simulated the temporal variations of water temperature, DO, TOC, nitrogen and phosphorus species and Chl-a observed in 2014 and also captured their spatial heterogeneity in the reservoir. The simulation results indicated that the point source bypassing may reduce the T-N and T-P concentrations of the reservoir by 6.6 ~ 8.2 %, and 1.7 ~ 16.8 %, respectively. The bypassing, however, showed a marginal effect on the control of TOC due to the increased algal biomass associated with the increased water retention time after bypassing as well as the lower TOC level of the effluent compared to the ambient reservoir water.

• Journal of Korean Society on Water Environment
• /
• v.23 no.5
• /
• pp.591-599
• /
• 2007

The quality of water released from a stratified reservoir is dependent on various factors such as the location and shape of intake facility, structure of reservoir stratification, profile of water quality constituent, and withdrawal flux. Sometimes, selective withdrawal capabilities can provide the operational flexibility to meet the water quality demands both in-reservoir and downstream. The objective of this study was to evaluate the performance of a one-dimensional reservoir selective withdrawal model (SELECT) as a tool for supporting downstream water quality management for Daecheong and Imha reservoirs. The simulated water quality variables including water temperature, dissolved oxygen (DO), conductivity, turbidity were compared with the field data measured in tailwater. The model showed fairly satisfactory results and high reliability in simulating observations. The coefficients of determinant between simulated and observed turbidity values were 0.93 and 0.95 for Daecheong and Imha reservoirs, respectively. The outflow water quality was significantly influenced by water intake level under fully stratified condition, while the effect of intake amount was minor. In conclusion, the SELECT is simple but effective tool for supporting downstream water quality prediction and management for both reservoirs.

• Journal of Korean Society on Water Environment
• /
• v.25 no.6
• /
• pp.821-831
• /
• 2009

The study was aimed to assess the expected impact of climate change on the water cycle and soil losses in Daecheong Reservoir watershed, Korea using the Soil and Water Assessment Tool (SWAT) that was validated for the watershed in a previous study. Future climate data including precipitation, temperature and humidity generated by introducing a regional climate model (Mesoscale Model Version 5, MM5) to dynamically downscale global circulation model (European Centre Hamburg Model Version 4, ECHAM4) were used to simulate the hydrological responses and soil erosion processes in the future 100 years (2001~2100) under the Special Report on Emissions Scenario (SRES) A1B. The results indicated that the climate change may increase in the amount of surface runoff and thereby sediment load to the reservoir. Spatially, the impact was relatively more significant in the subbasin Bocheongcheon because of its lower occupation rate of forest land compared to other subbasins. Seasonally, the increase of surface runoff and soil losses was more significant during late summer and fall season when both flood control and turbidity flow control are necessary for the reservoir and downstream. The occurrence of extreme turbidity flow events during these period is more vulnerable to reservoir operation because the suspended solids that remained water column can be resuspended by vertical mixing during winter turnover period. The study results provide useful information for the development of adaptive management strategy for the reservoir to cope with the expected impact of future climate change.

• Journal of Korean Society on Water Environment
• /
• v.27 no.4
• /
• pp.445-460
• /
• 2011

The objective of this study was to construct and assess the applicability of the EFDC model for Saemangeum Reservoir as a 3D hydrodynamic and water quality modeling tool that is necessary for the effective management of water quality and establishment of conservation measures. The model grids for both reservoir system only and reservoir-ocean system were created using the most recent survey data to compare the effects of different downstream boundary conditions. The model was applied for the simulations of temperature, salinity, water quality variables including chemical oxygen demand (COD), chlorophyll-a (Chl-a), phosphorus and nitrogen species and algal biomass, and validated using the field data obtained in 2008. Although the model reasonably represented the temporal and spatial variations of the state variables in the reservoir with limited boundary forcing data, the salinity level was underestimated in the middle and upstream of the reservoir when the flow data were used at downstream boundaries; Sinsi and Garyuk Gates. In turn, the error caused to increase the bias of water quality simulations, and inaccurate simulation of density flow regime of river inflow during flood events. It is likely because of the loss of momentum of sea water intrusion at downstream boundaries. In contrast to flow boundary conditions, the mixing between sea water and freshwater was well reproduced when open water boundary condition was applied. Thus, it is required to improve the downstream boundary conditions that can accommodate the real operations of the sluice gates.

• Journal of Korean Society on Water Environment
• /
• v.26 no.6
• /
• pp.994-999
• /
• 2010

The toxin of Cyanobacteria (blue-green algae) during summer season has been a problem and early prevention should be considered. A variety of methods can be used to forecast algal blooms and this study aims at examining feasibility of chlorophyll-a. The real-time data were collected by automatic water quality monitoring system (AWQMS) in Daecheong reservoir and invalid data were sorted by experts. And then, the sorted data were filled using linear interpolation. When the concentration of chlorophyll-a increased by $15mg/m^3$, water temperature and pH exceeded $26.8^{\circ}C$ and 9.5 respectively. As a result of correlation between chlorophyll-a and other parameters(i.e. water quality items and hydrological data), temperature (r=0.502 - 0.574), pH (r=0.583 - 0.681), total organic carbon (TOC, r=0.583 - 0.681) comparably had higher values. Meanwhile, the data around a day or two showed the highest correlation. In addition, chlorophyll-a is considered to be significantly effected by precipitation and inflow.

• Journal of Environmental Science International
• /
• v.20 no.3
• /
• pp.309-319
• /
• 2011

In this study, we investigated the effects of Upo-swamp upon local thermal environment with nighttime cooling rate. To do this, we set up the AWS(Automatic Weather observation System) over the central part of Upo-swamp on the early October 2007. We conducted the study by comparing the AWS data with another weather data observed by several meteorological observations of the Korea Meteorological Administration located at the vicinity of Upo-swamp for one year. The air temperature of Upo-swamp was higher than that of the surrounding in cold-climate season. But it was opposite in warm-climate season. We confirmed that Upo-swamp roles to mitigate the daily and annual air temperature ranges. And the daily air temperature variation of Upo-swamp lagged behind the land one. This phenomenon represent that the heat reservoir capacity of Upo-swamp is much larger than that of the ground.