scholarly journals A Study on River Representation for Water Impaired Analysis of Measurement Data at TPLMs

2020 ◽  
Vol 42 (4) ◽  
pp. 197-209
Author(s):  
Beom Sik Nam ◽  
Ha Sun Hwang ◽  
Moo Hwan Cho
Keyword(s):  
River Basin ◽  
Flow Rate ◽  
Stream Flow ◽  
Flow Conditions ◽  
Source Characterization ◽  
Nakdong River ◽  
Flow Rates ◽  
Nakdong River Basin ◽  
Pollutant Source ◽  
Rainy Days

Objectives:This study assessed the applicability of the total pollutant load management (TPLM) data on the analysis of impaired waterbody and pollutant source characterization. To achieve the study objective, the TPLM data collected in the downstream of Yeongcheon-Dam within the Geumho A unit-basin, Nakdong River basin for 6 years (2013-2018) were used to analyze the accountability for precipitation conditions, seasons, and flow rates. Methods:The study area is the downstram of Yeongcheon Dam within the Geumho A unit-basin, Nakdong River basin. The TPLM data used in this study were obtained from the two monitoring stations in the mainstream of Geumho River (i.e., Jahocheon and Geumho A station) and the three tributary streams (i.e., Gochoncheon, Sillyeongcheon, and Bugancheon). Precipitation conditions were classified into rainy (>10 mm/day) and non-rainy days (≤10 mm/day) to assess the TPLM data accountability for the two precipitation conditions. Seasonal accountabilities of the TPLM data were assessed for spring (March-May), summer (June-August), autumn (September-November), and winter (December-February). The TPLM data accountability for stream flow rates was assessed using the standardized daily flow rates which were estimated by % of maximum flow rate. The daily flow rates were simulated using the Hydrologic Simulation Program-Fortran (HSPF).Results and Discussion:During the study period (2013-2018), TPLM data were collected 35-41 times throughout a year in the two Geumho River mainstream stations (i.e., Jahocheon, and Geumho A), while the tributary streams (i.e., Gochoncheon, Sillyeongcheon, and Bugancheon) were monitored 36 times per year excluding every January, February, and December. The tributary streams shown the missing data months because those stations were monitored through the implementation assessment for total maximum daily load (TMDL) management. But, the mainstream data were continuously collected by the Water Environment Research Institute. The accountability assessment results shown that 28%, 25%, 28%, and 19% of TPLM data for the two mainstream stations represents spring, summer, autumn, and winter seasons. The three TPLM station data in the tributary streams could not account for winter season with the seasonal data ratios of 29% for spring, 32% for summer, 34% for autumn, and 4% for winter. Secondly, 37.9% and 23.1% of TPLM data for the two mainstream stations and the three tributary streams, respectively, were collected during rainy days. Comparing to 22% of rainy days throughout the study period, the two mainstream stations were monitored more frequently during rainy days than the tributary stations. Lastly, accountability for stream flow rates shown that the annual TPLM data cannot account for mainstream flow conditions. For the tributary stream flow rates, six years composite TPLM data could not represent the flow conditions. Therefore, the TPLM data need to be carefully reviewed before assessing impaired waterbody and pollutant source characterization. Conclusions:TPLM data was widely used in TMDL implementation and research activities. Thus, detailed TPLM monitoring plans should be developed to improve accountability for various stream characteristics including precipitation, season, and flow rate, etc. In addition, further research is needed to represent wide ranges of flow rate which are hard to be predicted due to the large uncertainties induced by precipitation, precipitation intensity, precedent rain days, and other factors (e.g., dams, wastewater treatment plants, etc.).

Evaluation of Nutrients Mass Balance on the Weirs in the Mid-lower Nakdong River Basin

2020 ◽  
Vol 42 (5) ◽  
pp. 406-414
Author(s):  
Seoung-Muk Park ◽  
Yong-Eun Joo ◽  
Byung-Hyun Moon ◽  
Byung-Dae Lee ◽  
Shun-Hwa Lee
Keyword(s):  
Mass Balance ◽  
River Basin ◽  
Nakdong River ◽  
Nakdong River Basin

scholarly journals Net-exergetic, hydraulic and thermal optimization of coaxial heat exchangers using fixed flow conditions instead of fixed flow rates

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Tobias Blanke ◽  
Markus Hagenkamp ◽  
Bernd Döring ◽  
Joachim Göttsche ◽  
Vitali Reger ◽  
...  
Keyword(s):  
Reynolds Number ◽  
Laminar Flow ◽  
Mass Flow ◽  
Flow Rate ◽  
Heat Exchangers ◽  
Circular Ring ◽  
Flow Conditions ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Pipe Radius

AbstractPrevious studies optimized the dimensions of coaxial heat exchangers using constant mass flow rates as a boundary condition. They show a thermal optimal circular ring width of nearly zero. Hydraulically optimal is an inner to outer pipe radius ratio of 0.65 for turbulent and 0.68 for laminar flow types. In contrast, in this study, flow conditions in the circular ring are kept constant (a set of fixed Reynolds numbers) during optimization. This approach ensures fixed flow conditions and prevents inappropriately high or low mass flow rates. The optimization is carried out for three objectives: Maximum energy gain, minimum hydraulic effort and eventually optimum net-exergy balance. The optimization changes the inner pipe radius and mass flow rate but not the Reynolds number of the circular ring. The thermal calculations base on Hellström’s borehole resistance and the hydraulic optimization on individually calculated linear loss of head coefficients. Increasing the inner pipe radius results in decreased hydraulic losses in the inner pipe but increased losses in the circular ring. The net-exergy difference is a key performance indicator and combines thermal and hydraulic calculations. It is the difference between thermal exergy flux and hydraulic effort. The Reynolds number in the circular ring is instead of the mass flow rate constant during all optimizations. The result from a thermal perspective is an optimal width of the circular ring of nearly zero. The hydraulically optimal inner pipe radius is 54% of the outer pipe radius for laminar flow and 60% for turbulent flow scenarios. Net-exergetic optimization shows a predominant influence of hydraulic losses, especially for small temperature gains. The exact result depends on the earth’s thermal properties and the flow type. Conclusively, coaxial geothermal probes’ design should focus on the hydraulic optimum and take the thermal optimum as a secondary criterion due to the dominating hydraulics.

Statistical Approach to River-Aquifer Interaction in the Lower Nakdong River Basin, Republic of Korea

2016 ◽  
Vol 65 ◽  
pp. 36-47 ◽  
Author(s):  
Yun-Yeong Oh ◽  
Se-Yeong Hamm ◽  
Gyoo-Bum Kim ◽  
Chung-Mo Lee ◽  
Sang Yong Chung
Keyword(s):  
River Basin ◽  
Statistical Approach ◽  
Republic Of Korea ◽  
Nakdong River ◽  
Nakdong River Basin

scholarly journals Temperature log simulations in high-enthalpy boreholes

2019 ◽  
Vol 7 (1) ◽  
Author(s):  
Jia Wang ◽  
Fabian Nitschke ◽  
Maziar Gholami Korzani ◽  
Thomas Kohl
Keyword(s):  
Heat Transfer ◽  
Temperature Distribution ◽  
Temperature Gradient ◽  
Flow Rate ◽  
Fluid Loss ◽  
Flow Conditions ◽  
Flow Rates ◽  
High Enthalpy ◽  
Fluid Losses ◽  
Lateral Heat

Abstract Temperature logs have important applications in the geothermal industry such as the estimation of the static formation temperature (SFT) and the characterization of fluid loss from a borehole. However, the temperature distribution of the wellbore relies on various factors such as wellbore flow conditions, fluid losses, well layout, heat transfer mechanics within the fluid as well as between the wellbore and the surrounding rock formation, etc. In this context, the numerical approach presented in this paper is applied to investigate the influencing parameters/uncertainties in the interpretation of borehole logging data. To this end, synthetic temperature logs representing different well operation conditions were numerically generated using our newly developed wellbore simulator. Our models account for several complex operation scenarios resulting from the requirements of high-enthalpy wells where different flow conditions, such as mud injection with- and without fluid loss and shut-in, occur in the drill string and the annulus. The simulation results reveal that free convective heat transfer plays an important role in the earlier evolution of the shut-in-time temperature; high accuracy SFT estimation is only possible when long-term shut-in measurements are used. Two other simulation scenarios for a well under injection conditions show that applying simple temperature correction methods on the non-shut-in temperature data could lead to large errors for SFT estimation even at very low injection flow rates. Furthermore, the magnitude of the temperature gradient increase depends on the flow rate, the percentage of fluid loss and the lateral heat transfer between the fluid and the rock formation. As indicated by this study, under low fluid losses (< 30%) or relatively higher flow rates (> 20 L/s), the impact of flow rate and the lateral heat transfer on the temperature gradient increase can be ignored. These results provide insights on the key factors influencing the well temperature distribution, which are important for the choice of the drilling data to estimate SFT and the design of the inverse modeling scheme in future studies to determine an accurate SFT profile for the high-enthalpy geothermal environment.

scholarly journals A Study on Seasonal Pollutant Distribution Characteristics of Contaminated Tributaries in Nakdong River Basin

2016 ◽  
Vol 18 (3) ◽  
pp. 301-312 ◽  
Author(s):  
Seungmin Na ◽  
Heongak Kwon ◽  
Sang Min Shin ◽  
YoungGyu Son ◽  
Dongseok Shin ◽  
...  
Keyword(s):  
River Basin ◽  
Distribution Characteristics ◽  
Nakdong River ◽  
Nakdong River Basin ◽  
Pollutant Distribution

scholarly journals Assessment of Nakdong River Basin Management: Target Water Quality Achievement and Future Challenges

2020 ◽  
Vol 20 (2) ◽  
pp. 251-263
Author(s):  
Kyeong Hwan Kang ◽  
Junghyeon Kim ◽  
Hyeonjin Jeon ◽  
Kyoungwoo Kim ◽  
Imgyu Byun
Keyword(s):  
Water Quality ◽  
River Basin ◽  
Water Environment ◽  
Quality Data ◽  
Master Plan ◽  
Nakdong River ◽  
Environment Management ◽  
Pollutant Load ◽  
Nakdong River Basin ◽  
Representative Points

In 2006, the Korean Ministry of Environment established <The 1st Water Environment Management Master Plan>. The plan aimed at “Clean Water, Eco River 2015” and guided water quality protection and strengthened water management. This study evaluated the achievement of the target water quality among the 33 mid-level basins in the Nakdong River basin and assessments of the causes of non-achievement of the target water quality by mid-level basins. According to the 2015 water quality data, only 16 of the 33 mid-level basins achieved the target water quality. The low achievement of the target water quality was attributed to the failure to predict the pollutant load at the time of planning, problems with the management of tributaries, implementation of the <Four major river restoration project>, and problems with the representativeness of the water quality representative points. In addition, feasibility studies on the water quality monitoring representative point used in each mid-level basin were also performed; some mid-level basins required improvement or change of the representative points. This study also suggested further research to improve water quality, such as detailed studies of the management of pollutant load, mainstream tributaries, and water quality indicators, for the revision of the current ongoing <The 2nd Water Environment Management Master Plan>.

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