• Journal of The Korean Society of Agricultural Engineers
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• v.54 no.3
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• pp.149-157
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• 2012

For the systemic management and planning of future agricultural water resources, deriving and analyzing the various results of climate change are necessary to respond the uncertainties of climate change. This study assessed the impact of climate change on the rainfall, temperature, and agricultural water requirement targeting in the Nakdong-river's basin periodically according to socioeconomic driving factors under the scenarios A1B, A2 and B1 of the Special Report on Emission Scenarios (SRES) through the various IPCC GCMs. As a result of future rainfall change (2011~2100), increasing or decreasing tendency of rainfall change for future periods did not show a clear trend for three rainfall observatories, Daegu, Busan and Gumi. The characteristics of the temperature change consistently show a tendency to increase, and in the case of Daegu observatory, high temperature growth was shown. Especially, it was increased by 93.3 % in the period of future3 (2071~2100) for A2 scenario. According to the scenario and periodic analyses on the agricultural water demand, which was thought to be dependent on rainfall and temperature, the agricultural water demand increased at almost every period except during the Period Future1 (2011~2040) with different increase sizes, and the scenario-specific results were shown to be similar. As for areas, the agricultural water demand showed more changes in the sub-basin located by the branch of Nakdong-river than at the mainstream of the River.

• Development and Reproduction
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• v.23 no.1
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• pp.21-34
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• 2019

The effects of the anaesthetic agents, clove oil and mixture of clove oil with lidocaine-HCl were evaluated on river puffer, Takifugu obscurus and tiger puffer, T. rubripes. Anaesthesia times of clove oil were affected by water temperature ($20^{\circ}C$, $24^{\circ}C$, and $28^{\circ}C$) and salinity (10, 20, and 30 ppt). Anaesthesia times of mixed samples were significantly similar with regard to exposure and recovery times, and all samples satisfied anaesthesia criteria (exposure time within 3 min and recovery time within 5 min) under the various temperatures and salinities, and the lowest to highest concentration of anaesthetics (p<0.05). Both species river puffer and tiger puffer had short exposure time with a high anaesthesia dose, high temperature ($28^{\circ}C$) and intermediate salinity (20 ppt), and were highly affected by temperature and salinity (p<0.05). The mixed anaesthetics had rapid exposure times and long recovery times in contrast to the effects of clove oil. Cortisol concentrations under the conditions of various clove oil dosages, salinity, and temperature for both species increased until 12 hrs after recovery from anaesthesia (p<0.05). After 12 hrs, cortisol concentrations decreased until after 48 hrs (p<0.05). During the simulated transportation of both species, control and sedated clove oil groups (5 ppm) were measured for water parameters, dissolved oxygen (DO), $CO_2$, respiratory frequency, $NH_4{^+}$, and pH for 6 hrs in 1 hr intervals. Water parameters of sedated groups and controls were significantly different after 2 hrs (p<0.05).

• Water for future
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• v.15 no.3
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• pp.23-36
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• 1982

The stochastic variations and structures of time series data on water quality were examined by employing the techniques of autocorrelation function, variance spectrum, Fourier series, autoregressive model and ARIMA model. These time series included hourly and daily observation on DO, turbidity, conductivity pH and water temperature. The measurement was made by automatic recording instrument at Noryangjin and Dook-do located in the downstream part of Han River during 1975 and 1976. Hourly water quality time series varied with the dominant 24-hour periodicity, and the 12-hour periodicity was also observed. An important factor affecting 24-hour periodic variation of DO is believed to be photosynthesis by algae. These phenomena might be attributable to periodic discharges of municipal sewage. Noryangjin site showed the more distinct 12-hour periodicity than Dook-do site did, and tidal effect might be responsible for the difference. The water quality, as measured by DO and turbidity, was better in the afternoon compared with the quality in the morning. This change can be explained by the periodic variation of DO, temperature and the amount of municipal wewage discharge. It was also observed that the water temperature at Noryangjin was higher than the temperature at Dook-do. This difference might have been caused by the pollutants that were added to the section between two sites. The correlation coefficients between some of the variables were fairly high. For example, the coefficient was -0.88 between DO and water temperature, 0.75 between turbidity and river flow, and 0.957 between water temperature and air temperature. The lag time of heat transfer from the air to the water was estimated as 24 days. The first order auto-regressive model was appropriate for explaning standardized hourly DO time series. The ARIMA model of (1, 0, 0) type provided relatively satisfactory results for daily DO time series after the removal of significant harmonic value.

• Journal of Korean Society on Water Environment
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• v.32 no.2
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• pp.173-182
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• 2016

The objective of this study is to quantitatively analyze climate change effects by using statistical trends and a watershed model in the Yongdam dam watershed. The annual average air temperature was found to increase with statistical significance. In particular, greater increases were observed in autumn. Also, this study was performed to evaluate the potential climate change in the streamflow and water temperature using a watershed model (HSPF) with RCP climate change scenarios. The streamflow of Geum river showed a decrease of 5.1% and 0.2%, respectively, in the baseline data for the 2040s and 2080s. The seasonal impact of future climate change on the streamflow showed a decrease in the summer and an increase in the winter. The water temperature of Geum river showed an average increase of 0.7~1.0℃. Especially, the water temperature of Geum river showed an increase of 0.3~0.5℃ in the 2040s and 0.5~1.2℃ in the 2080s. The seasonal impact of future climate change on the water temperature showed an increase in winter and spring, with a decrease in summer. Therefore, it was determined that a statistical analysis-based meteorological and quantitative forecast of streamflow and water temperature using a watershed model is necessary to assess climate change impact and to establish plans for future water resource management.

• Journal of Preventive Medicine and Public Health
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• v.23 no.1 s.29
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• pp.106-116
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• 1990

This study was conducted to investigate of water qualities in the upper and middle reaches of the Han River. For this purpose, water was sampled at Kwangjin and 1st Han-River Bridges of the Han River in Seoul and analysed from August, 1988 to September, 1989. The results are summarized as follows : 1. Water quality at 1st Han-River Bridge was more polluted than that at Kwangjin Bridge. 2. Except biological oxygen demand (BOD), turbidity, suspended solid (SS), dissolved oxygen (DO), DO saturation (DOS), ammonia nitrogen ($NH_3-N$), nitrite nitrogen ($NO_2-N$) and chloride ion ($Cl^-$) at Kwangjin and 1st Han-River Bridges were lower as compared with the previous data before redevelopment of the Han River. 3. SS, DO and pH at Kwangjin and 1st Han-River Bridges could be classified to the 1st grade in environmental water quality standard. DOS at Kwangjin Bridge was over 100% and that at 1st Han-River Bridge was below 100% in the Han River. BOD at Kwangjin Bridge could be classified to End grade and that at 1st Han-River Bridge to 3rd grade in environmental water quality standard. 4. The higher the level of water was, the lower the levels of turbidity and SS, and $NH_3-N$ was decreased with increasing water level at 1st Han-River Bridge. DO was decreased as water temperature went up but DOS was increased with DO. BOD was positively correlated with nitrite-nitrogens. 5. Turbidity and SS at the both sites and Chloride ion ($Cl^-$) at Kwangjin Bridge were increased in July and August. And DO at the both sites and $NH_3-N$ at 1st Han-River Bridge were decreased in at July and August.

• Magazine of the Korean Society of Agricultural Engineers
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• v.41 no.6
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• pp.44-53
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• 1999

The statistical characteristics of the factors related to the daily rainfall prediction model are analyzed . Records of daily precipitation, mean air temperature, relative humidity , dew-point temperature and air pressure from 1973∼1998 at 8 meteorological sttions in south-western part of Korea were used. 1. Serial correlatino of daily precipitaiton was significant with the lag less than 1 day. But , that of other variables were large enough until 10 day lag. 2. Crosscorrelation of air temperature, relative humidity , dew-point temperature showed similar distribution wiht the basin contrours and the others were different. 3. There were significant correlation between the meteorological variables and precipitation preceded more than 2 days. 4. Daily preciption of each station were treated as a truncated continuous random variable and the annual periodic components, mean and standard deviation were estimated for each day. 5. All of the results could be considered to select the input variables of regression model or neural network model for the prediction of daily precipitation and to construct the stochastic model of daily precipitation.

• Journal of Environmental Health Sciences
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• v.10 no.1
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• pp.1-12
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• 1984

The stochastic characteristics of the daily range of water temperature variation was analyzed by employing the techniques of autocorrelation coefficient, autoreggresive model and crosscorrelation model. These time series included daily observations on maximum and minimum values of water temperature and air temperature. The measurement was made by automatic recording instrument at Gu-yee and Dook-do in Han River, and at Waegwan and Gu-mi in Nackdong River in 1981. As a result of this study, it was found that (1) The correlogram of daily water temperature ranges $\Delta AT_i$ and daily air temperature $\Delta AT_i$ at Gu-mi and Gu-yee showed the exponential curves. (2) The most high frequency values of $\Delta AT_i$ and $\Delta WT_i$ were 11$\circ$C and 0.5${\circ}C$ respectively at every measuring site. (3) The correlation coefficients between the daily mean air temperature AT$_i$ and the daily mean water temperature were fairly high as 0.966 at Dook-do and 0.949 at Gu-yee, but the correlation coefficients between $\Delta AT_i$ and $\Delta WT_i$ were very low as 0.1074 at Gu-yee and 0.0324 at Dook-Do.

• ALGAE
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• v.18 no.3
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• pp.207-215
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• 2003

Dynamics of phytoplankton communities were investigated at five stations in Youngsan River from December 1995 to November 1996. Phytoplankton were identified to the total of 466 taxa, which were composed of 136 genera, 438 species, 27 varieties and 1 forma. The standing crops ranged 1,163-50,765 cells ${\cdot}ml^{-1}$ during the investigation periods. The variation of classes was in order to Chrysophyceae - Bascillariophyceae - Chlorophyceae at St. 1 and was only Bacillariophyceae at the other stations. The dominant species were 12 taxa including Aulacoseira ambigua, A. garnulata, Cyclotella meneghiniana, C. pseudostelligera, Chlorella vulgaris, Dinobryon sertularia, Flagilaria elliptica, Monoraphidium contortum, Micractinium pusillum, Nitzschia palea, Scenedesmus grahneisii and Stephanodiscus hantzschii f. tenuis. The standing crops of dominant species ranged from 10.6% to 94.7%. The genus Dinobryon in Chrysophyceae was dominant species at St. 1 in December 1995, but not recorded in the other months. The dominant species were composed with the planktonic diatoms from winter to spring and were the tychoplanktonic and the benthic species at St. 2-5 from summer to fall. The relationships between total standing crops and water temperature, pH, $NH_4$, $NO_2$, $NO_3$ and $PO_4$ showed low positive or negative coefficients. Stephanodiscus hantzschii f. tenuis had low positive or negative coefficients with water temperature, $NH_4$, $NO_2$, $NO_3$ and $PO_4$. The fluctuations of standing crops in the Youngsan river phytoplankton community were not caused by a single factor but controlled by the complex factors with interaction between phytoplankton community and envirowmental factors.

• Water Engineering Research
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• v.1 no.4
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• pp.267-277
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• 2000

This study reports an examination of the sensitivity of water resources in the Keum River basin to climate change. Assuming a doubling in $CO_2$ concentrations, a cooperative study provided four climate change scenarios for this study, which have been translated into temperature and precipitation scenarios on a basin scale. The study utilized these temperature and precipitation data for each climate change scenario as inputs to the NWS-PC model to generate the corresponding streamflow scenario over the Keum River basin. A reservoir simulation model for the Dae-Chung Dam in the Keum River basin has been developed with an object-oriented simulation environment, STELLA. For each streamflow scenario, the performance of the reservoir was assessed in terms of reliability, resiliency, and vulnerability. Although the simulation results are heavily dependent on the choice of the climate change scenarios, the following conclusions can be clearly concluded: (1) the future streamflow over the Dae-Chung Dam tends to decease during the dry period, which seriously increases competitive water use issues and (2) flood control issues predominate under the $2CO_2$-High case.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.33 no.6
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• pp.238-245
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• 2021

In this study, we carried out case study to predict dissolved oxygen (DO) concentration of Nakdong river estuary with LSTM model. we aimed to figure out a optimal model condition and appropriate predictor for prediction in dissolved oxygen concentration with model parameter and predictor as cases. Model parameter case study results showed that Epoch = 300 and Sequence length = 1 showed higher accuracy than other conditions. In predictor case study, it was highest accuracy where DO and Temperature were used as a predictor, it was caused by high correlation between DO concentration and Temperature. From above results, we figured out an appropriate model condition and predictor for prediction in DO concentration of Nakdong river estuary.