# Estimation of Temperature Recovery Distance and the Influence of Heat Pump Discharge on Fluvial Ecosystems

^{1}

^{2}

^{3}

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Methods

#### 2.1. Summary of Hydrothermal Energy

#### 2.2. Area of Study

^{2}, accounting for 6.02% of the Han River Basin. The average watershed width is 34.1 km, and the watershed shape factor is 1.18. The watershed area of Yangpyeong Water Stage Gauging Station and Lower Namhan River Watershed are 128.9 km

^{2}and 88.5 km

^{2}. The main channel length is 25.6 km, and coefficient of roughness is 0.03. Time of concentration is 2.8 hr, curve number is 78.7, and mean elevation of basin is 437.8 EL.m.

#### 2.3. Estimation of Water Temperature Recovery Distance

#### 2.3.1. Heat Transfer Equation

^{2}°C), $\rho $

_{w}is the water density (998.2 kg/m

^{3}), C

_{w}is the specific heat of water (4186 J/kg $\mathbb{C}$), h is the mean river depth(m), and u is the water velocity (m/s).

#### 2.3.2. The EFDC Model

#### 2.4. Data Collection and Analysis

## 3. Results and Discussion

#### 3.1. Heat Transfer Equation Method

#### 3.2. EFDC Model

^{3}/s. We used the Yangpyeong automated water quality monitoring network site as the discharge location, approximately 250 m downstream from the intake site. Discharge water temperature was 31.0 °C during summer and −3.8 °C during winter, which was 7 °C higher and 5 °C lower, respectively, than the input water.

#### 3.3. Comparison of Methods

#### 3.4. Environmental Impact of River-Water Temperature Changes

## 4. Conclusions

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## References

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**Figure 3.**Time series of average daily river discharge values at the Yangpyeong-gun (Yangpyeong Bridge) level station (2012–2017).

**Figure 5.**Proposed standard for calculating the water temperature recovery distance in longitudinal, lateral, and vertical directions.

**Figure 7.**Distribution of endangered fish species in Korea (Jung et al. [22]).

Station Code | Station Name | Longitude (degree) | Latitude (degree) | Elevation above Sea Level (EL.m) | Observation Start (year) | Observing System |
---|---|---|---|---|---|---|

114 | Wonju | 127.9 | 37.3 | 148.6 | 1971 | ASOS ^{1} |

202 | Yangpyeong | 127.5 | 37.5 | 48.0 | 1972 | ASOS |

^{1}ASOS: automated surface observing system.

Station Code | Station Name | Longitude (degree) | Latitude (degree) | Zero Elevation (EL.m) | Observation Start (year) | Observing System |
---|---|---|---|---|---|---|

1007697 | Yangpyeong-gun (Sinwon-ri) | 127.4 | 37.5 | 24.3 | 2016 | T/M ^{1} |

1007685 | Yangpyeong-gun (Yangpyeong Bridge) | 127.5 | 37.5 | 19. 6 | 1953 | T/M |

1007660 | Yeoju-si (Ipo Bridge) | 127.3 | 37.4 | 26.1 | 2001 | T/M |

1015645 | Gapyeong-gun (Daeseong-ri) | 127.4 | 37.7 | 22.6 | 1914 | T/M |

^{1}T/M: tele-metering.

Season | Temperature ${\mathbf{T}}_{\mathbf{b}}$ $\text{}(\mathbb{C})$ | Flow Rate $\mathbf{Q}$ $({\mathbf{m}}^{3}/\mathbf{s})$ | Depth $\mathbf{h}$ $\left(\mathbf{m}\right)$ | Velocity, $\mathbf{u}$ ($\mathbf{m}/\mathbf{s}$) | ${\mathbf{K}}_{\mathbf{e}}$ ($\mathbf{W}/{\mathbf{m}}^{2}\xb7\mathbb{C}$) |
---|---|---|---|---|---|

Annual average | 16.3 | 203.3 | 5.7 | 0.105 | 18.0 |

Summer average | 26.3 | 366.7 | 5.7 | 0.192 | 23.5 |

Winter average | 3.7 | 126.9 | 5.7 | 0.006 | 13.1 |

Summer minimum | 19.9 | 28.1 | 5.3 | 0.001 | 17.8 |

Winter minimum | 1.0 | 16.7 | 5.2 | 0.001 | 11.8 |

**Table 4.**Seasonal river-water temperature, discharge water temperature, and mixed water temperature immediately after entry.

Season | River-Water Temperature, ${\mathbf{T}}_{\mathbf{b}}$ $(\mathbb{C})$ | Discharge Water Temperature $(\mathbb{C})$ | Flow Rate, Q $({\mathbf{m}}^{3}/\mathbf{s})$ | Mixed Water Temperature Immediately after Entry, ${\mathbf{T}}_{0}$ $(\mathbb{C})$ | Wind Speed (m/s) | Change $(\mathbb{C})$ |
---|---|---|---|---|---|---|

Summer | 26.3 | 33.3 | 28.1 | 26.4 | 1.4 | ▲0.16 |

Winter | 3.7 | −1.3 | 16.7 | 3.5 | 0.8 | ▼0.18 |

Distance | 0.5 km | 5 km | 10 km | 50 km | 100 km | 300 km | Water Temperature Recovery Distance (km) |
---|---|---|---|---|---|---|---|

Summer ($\mathbb{C}$) | 26.4 | 26.4 | 26.4 | 26.4 | 26.4 | 26.3 | 9.73 |

Winter ($\mathbb{C}$) | 3.5 | 3.6 | 3.6 | 3.6 | 3.6 | 3.7 | 4.48 |

Season | Sea-Level Pressure $\left(\mathbf{m}\mathbf{b}\right)$ | Temperature $(\mathbb{C})$ | Relative Humidity (%) | Precipitation $(\mathbf{m}\mathbf{m}/\mathbf{h})$ | Solar Radiation ($\mathbf{W}/{\mathbf{m}}^{2}$) |
---|---|---|---|---|---|

Summer (6 June 2015) | 1015.0 | 19.6 | 65.5 | 0.00 | 0.85 |

Winter (20 December 2015) | 1032.2 | −6.2 | 64.9 | 0.00 | 0.50 |

Season | Inflow Rate $({\mathbf{m}}^{3}/\mathbf{s})$ | Exit Level $(\mathbf{m})$ | Influent Water Temperature (Hongcheon) $(\mathbb{C})$ | Wind Speed $(\mathbf{m}/\mathbf{s})$ | $\mathrm{Wind}\text{}\mathrm{Direction}\text{}(10\text{\xb0}\text{Intervals from True North})$ |
---|---|---|---|---|---|

Summer | 43.3 | 25.2 | 22.6 | 1.4 | 110 |

Winter | 16.7 | 25.3 | 2.4 | 0.8 | 200 |

Season | Average Simulated Water Temperature $(\mathbb{C})$ | Observed Water Temperature $(\mathbb{C})$ | Median Error $(\mathbb{C})$ |
---|---|---|---|

Summer | 24.3 | 24.0 | 0.17 |

winter | 1.4 | 1.5 |

Season | Heat Transfer Equation (km) | EFDC Model (km) | ||
---|---|---|---|---|

Longitudinal Direction | Lateral Direction | Vertical Direction | ||

Summer | 9.7 | 5.0 | 0.30 | 0.01 |

Winter | 4.5 | 6.7 | 0.12 | 0.04 |

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**MDPI and ACS Style**

Jung, J.; Nam, J.; Kim, J.; Bae, Y.H.; Kim, H.S.
Estimation of Temperature Recovery Distance and the Influence of Heat Pump Discharge on Fluvial Ecosystems. *Water* **2020**, *12*, 949.
https://doi.org/10.3390/w12040949

**AMA Style**

Jung J, Nam J, Kim J, Bae YH, Kim HS.
Estimation of Temperature Recovery Distance and the Influence of Heat Pump Discharge on Fluvial Ecosystems. *Water*. 2020; 12(4):949.
https://doi.org/10.3390/w12040949

**Chicago/Turabian Style**

Jung, Jaewon, Jisu Nam, Jungwook Kim, Young Hye Bae, and Hung Soo Kim.
2020. "Estimation of Temperature Recovery Distance and the Influence of Heat Pump Discharge on Fluvial Ecosystems" *Water* 12, no. 4: 949.
https://doi.org/10.3390/w12040949