# Hydrodynamic and Hydrographic Modeling of Istanbul Strait

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Materials and Methods

#### Model Setup

^{−4}m

^{2}/s and 10

^{–5}m

^{2}/s [35]. As mentioned above, the k-$\epsilon $ turbulence model is selected in the model.

## 3. Results

^{2}/s is much more realistic than a value around 1 m

^{2}/s, considering that the mesh (grid) size adopted in the present study is in the order of hundreds to thousands of meters, and the enhanced resistance due to subgrid turbulence should be accounted for in the horizontal eddy viscosity value.

#### 3.1. Hydrodynamic Model Calibration

#### 3.2. Hydrographic Model Validation

## 4. Discussion

## Author Contributions

## Funding

## Conflicts of Interest

## References

- Çeçen, K.; Bayazıt, M.; Sümer, M.; Güçlüer, Ş.; Doğusal, M.; Yüce, H. İstanbul Boğazı’nın Hidrolik ve Oşinografik Etüdü (The Hydraulic and Oceanographic Survey of Istanbul Strait); Istanbul Technical University: Istanbul, Turkey, 1981. [Google Scholar]
- Bayazıt, M.; Sümer, M. İstanbul Boğazı’nın Hidrolik ve Oşinografik Etüdü-2 (The Hydraulic and Oceanographic Survey of Istanbul Strait-2). TBTAK Su. Alma. Ünitesi. Kesin. Rapor.
**1982**, 23. [Google Scholar] - Sumer, B.M.; Bakioglu, M. Sea-Strait Flow With Special Reference To Bosphorus; Technical Report; Istanbul Technical University-Civil Engineering Faculty: Istanbul, Turkey, 1981. [Google Scholar]
- Latif, M.A.; Özsoy, E.; Oguz, T.; Ünlüata, Ü. Observations of the Mediterranean inflow into the Black Sea. Deep Sea Res. Part A Oceanogr. Res. Pap.
**1991**, 38, S711–S723. [Google Scholar] [CrossRef] - Özsoy, E.; Beşiktepe, Ş.; Latif, M.A. Türk Boğazlar Sistemi’nin Oşinografisi (Oceanography of the Turkish Strait System). In Marmara Denizi 2000 Sempozyumu; Türk Deniz Araştırmaları Vakfı: İstanbul, Turkey, 2000. [Google Scholar]
- Falina, A.; Sarafanov, A.; Özsoy, E.; Utku Turunçoğlu, U. Observed basin-wide propagation of Mediterranean water in the Black Sea. J. Geophys. Res. Ocean.
**2017**, 122, 3141–3151. [Google Scholar] [CrossRef] - Sur, H.I.; Özsoy, E.; Ünlüata, Ü. Boundary current instabilities, upwelling, shelf mixing and eutrophication processes in the Black Sea. Prog. Oceanogr.
**1994**, 33, 249–302. [Google Scholar] [CrossRef] - Oguz, T.; Özsoy, E.; Latif, M.A.; Sur, H.I.; Ünlüata, Ü. Modeling of hydraulically controlled exchange flow in the Bosphorus Strait. J. Phys. Oceanogr.
**1990**, 20, 945–965. [Google Scholar] [CrossRef] - Farmer, D.M.; Armi, L. Maximal two-layer exchange over a sill and through the combination of a sill and contraction with barotropic flow. J. Fluid Mech.
**1986**, 164, 53–76. [Google Scholar] [CrossRef] - Armi, L.; Farmer, D.M. Maximal two-layer exchange through a contraction with barotropic net flow. J. Fluid Mech.
**1986**, 164, 27–51. [Google Scholar] [CrossRef] - Armi, L. The hydraulics of two layers with different densities. J. Fluid Mech.
**1986**, 163, 27–58. [Google Scholar] [CrossRef] - Dorrell, R.M.; Peakall, J.; Sumner, E.J.; Parsons, D.R.; Darby, S.E.; Wynn, R.B.; Özsoy, E.; Tezcan, D. Flow dynamics and mixing processes in hydraulic jump arrays: Implications for channel-lobe transition zones. Mar. Geol.
**2016**, 381, 181–193. [Google Scholar] [CrossRef][Green Version] - Beşiktepe, Ş.T.; Sur, H.I.; Özsoy, E.; Latif, M.A.; Oǧuz, T.; Ünlüata, Ü. The circulation and hydrography of the Marmara Sea. Prog. Oceanogr.
**1994**, 34, 285–334. [Google Scholar] [CrossRef] - Özsoy, E.; Latif, M.A.; Besiktepe, S.; Çetin, N.; Gregg, M.C.; Belokopytov, V.; Goryachkin, Y.; Diaconu, V. The Bosporus Strait: Exchange Fluxes, Currents and Sea-Level Changes. NATO Sci. Ser. 2 Environ. Secur.
**1998**, 47, 1–28. [Google Scholar] - Gregg, M.C.; Özsoy, E.; Latif, M.A. Quasi-steady exchange flow in the Bosphorus. Geophys. Res. Lett.
**1999**, 26, 83–86. [Google Scholar] [CrossRef] - Gregg, M.C.; Özsoy, E. Flow, water mass changes, and hydraulics in the Bosphorus. J. Geophys. Res.
**2002**, 107. [Google Scholar] [CrossRef] - Güler, I.; Yüksel, Y.; Yalçiner, A.C.; Çevik, E.; Ingerslev, C. Measurement and evaluation of the hydrodynamics and secondary currents in and near a strait connecting large water bodies-A field study. Ocean Eng.
**2006**, 33, 1718–1748. [Google Scholar] [CrossRef] - Yuksel, Y.; Ayat, B.; Özturk, M.N.; Aydogan, B.; Guler, I.; Cevik, E.O.; Yalçiner, A.C. Responses of the stratified flows to their driving conditions-A field study. Ocean Eng.
**2008**, 35, 1304–1321. [Google Scholar] [CrossRef] - Aydoǧan, B.; Ayat, B.; Özturk, M.N.; Özkan Çevik, E.; Yüksel, Y. Current velocity forecasting in straits with artificial neural networks, a case study: Strait of Istanbul. Ocean Eng.
**2010**, 37, 443–453. [Google Scholar] [CrossRef] - Jarosz, E.; Teague, W.J.; Book, J.W.; Beşiktepe, Ş. Observed volume fluxes in the Bosphorus Strait. Geophys. Res. Lett.
**2011**, 38. [Google Scholar] [CrossRef] - Altiok, H.; Kayişoğlu, M. Seasonal and interannual variability of water exchange in the Strait of Istanbul. Mediterr. Mar. Sci.
**2015**, 16, 644–655. [Google Scholar] [CrossRef] - Özsoy, E.; Cagatay, M.N.; Balkis, N.; Balkis, N.; Ozturk, B. The Sea of Marmara; Marine Biodiversity, Fisheries, Conservation and Governance; Turkish Marine Research Foundation (TUDAV) Publication: Istanbul, Turkey, 2016; ISBN 9789758825349. [Google Scholar]
- Çolpan Polat, S.; Tugrul, S. Nutrient and organic carbon exchanges between the Black and Marmara Seas through the Bosphorus Strait. Cont. Shelf Res.
**1995**, 15, 1115–1132. [Google Scholar] [CrossRef] - Hubareva, E.; Svetlichny, L.; Kideys, A.; Isinibilir, M. Fate of the Black Sea Acartia clausi and Acartia tonsa (Copepoda) penetrating into the Marmara Sea through the Bosphorus. Estuar. Coast. Shelf Sci.
**2008**, 76, 131–140. [Google Scholar] [CrossRef] - Sur, H.İ.; Okuş, E.; Güven, K.; Yüksek, A.; Altiok, H.; Kıratlı, N.; Ünlü, S.; Taş, S.; Aslan Yılmaz, A.; Yılmaz, N.; et al. Water Quality Monitoring: Annual Report (2003); Istanbul University Institute of Marine Sciences and Management: Istanbul, Turkey, 2004. [Google Scholar]
- Altiok, H.; Sur, H.İ.; Yüce, H. Variation of the cold intermediate water in the Black Sea exit of the Strait of Istanbul (Bosphorus) and its transfer through the strait. Oceanologia
**2012**, 54, 233–254. [Google Scholar] [CrossRef][Green Version] - Akay, O. Hydrodynamic Simulation of the Bosphorus. M.Sc. Thesis, Istanbul Technical University, Istanbul, Turkey, 2002. [Google Scholar]
- Öztürk, M.N. İstanbul Boğazı’nın Hidrodinamiği ve Sayısal Modellenmesi (Hydrodynamics of the Istanbul Strait and its Numerical Model). Ph.D. Thesis, Yildiz Technical University, Istanbul, Turkey, 2010. [Google Scholar]
- Sözer, A. Numerical Modeling of the Bosphorus Exchange Flow Dynamics. Ph.D. Thesis, Middle East Technical University, Ankara, Turkey, 2013. [Google Scholar]
- Sözer, A.; Özsoy, E. Modeling of the Bosphorus exchange flow dynamics. Ocean Dyn.
**2017**, 67, 321–343. [Google Scholar] [CrossRef] - Sannino, G.; Sözer, A.; Özsoy, E. A high-resolution modelling study of the Turkish Straits System. Ocean Dyn.
**2017**, 67, 397–432. [Google Scholar] [CrossRef] - Armi, L.; Farmer, D.M. The Internal Hydraulics of the Strait of Gibraltar and Associated Sills and Narrows. Oceanol. Acta
**1985**, 8, 37–46. [Google Scholar] - Bruno, M.; Chioua, J.; Romero, J.; Vázquez, A.; Macías, D.; Dastis, C.; Ramírez-Romero, E.; Echevarria, F.; Reyes, J.; García, C.M. The importance of sub-mesoscale processes for the exchange of properties through the Strait of Gibraltar. Prog. Oceanogr.
**2013**, 116, 66–79. [Google Scholar] [CrossRef][Green Version] - Koşucu, M.M. Three-Dimensional Hydrodynamic Model of the Istanbul Strait. Master’s Thesis, Istanbul Technical University, Istanbul, Turkey, 2016. [Google Scholar]
- Delft3D User Manual Simulation of Multi-dimensional Hydrodynamic Flow and Transport Phenomena, Including Sediments. 2014, p. 684. Available online: https://oss.deltares.nl/documents/183920/185723/Delft3D-FLOW_User_Manual.pdf (accessed on 18 September 2019).
- Cornelissen, S. Numerical Modelling of Stratified Flows Comparison of the σ and z Coordinate Systems. Master’s Thesis, Delft University of Technology, Delft, The Netherlands, 2004. [Google Scholar]
- Lesser, G.R.; Roelvink, J.A.; van Kester, J.A.T.M.; Stelling, G.S. Development and validation of a three-dimensional morphological model. Coast. Eng.
**2004**, 51, 883–915. [Google Scholar] [CrossRef] - Huang, W.; Spaulding, M. Modeling horizontal diffusion with sigma coordinate system. J. Hydraul. Eng.
**1996**, 122, 349–356. [Google Scholar] [CrossRef] - Doherty, J. PEST: Model Independent Parameter Estimation. Fifth Edition of User Manual; Watermark Numerical Computing: Brisbane, Australia, 2005. [Google Scholar]
- Doherty, J. Calibration and Uncertainty Analysis for Complex Environmental Models. Groundwater
**2015**, 53, 673–674. [Google Scholar] - Doherty, J. Model-Independent Parameter Estimation(Part I), 6th ed.; Watermark Numerical Computing: Corinda, Australia, 2016. [Google Scholar]
- Hansen, N.; Ostermeier, A. Completely derandomized self-adaptation in evolution strategies. Evol. Comput.
**2001**, 9, 159–195. [Google Scholar] [CrossRef] [PubMed] - Hansen, N.; Ostermeier, A. Adapting arbitrary normal mutation distributions in evolution strategies: The covariance matrix adaptation. In Proceedings of the IEEE international conference on evolutionary computation, Nagoya, Tokyo, 20–22 May 1996; pp. 312–317. [Google Scholar]
- Duan, Q.; Sorooshian, S.; Gupta, V. Effective and efficient global optimization for conceptual rainfall-runoff models. Water Resour. Res.
**1992**, 28, 1015–1031. [Google Scholar] [CrossRef] - Demirel, M.C.; Mai, J.; Mendiguren, G.; Koch, J.; Samaniego, L.; Stisen, S. Combining satellite data and appropriate objective functions for improved spatial pattern performance of a distributed hydrologic model. Hydrol. Earth Syst. Sci.
**2018**, 22, 1299–1315. [Google Scholar] [CrossRef][Green Version] - Dahlstrom, D.J. Calibration and Uncertainty Analysis for Complex Environmental Models; Watermark Numerical Computing: Brisbane, Australia, 2015; ISBN 978-0-9943786-0-6. [Google Scholar]
- Dey, S. Fluvial Hyrodynamics: Hydrodynamic and Sediment Transport Phenomena; Springer: Berlin, Germany, 2014; ISBN 978-3-642-19061-2. [Google Scholar]
- Aydoǧdu, A.; Pinardi, N.; Özsoy, E.; Danabasoglu, G.; Gürses, Ö.; Karspeck, A. Circulation of the Turkish Straits System under interannual atmospheric forcing. Ocean Sci.
**2018**, 14, 999–1019. [Google Scholar] [CrossRef][Green Version] - Ferrarin, C.; Umgiesser, G. Hydrodynamic modeling of a coastal lagoon: The Cabras lagoon in Sardinia, Italy. Ecol. Modell.
**2005**, 188, 340–357. [Google Scholar] [CrossRef] - Lazure, P.; Garnier, V.; Dumas, F.; Herry, C.; Chifflet, M. Development of a hydrodynamic model of the Bay of Biscay. Validation of hydrology. Cont. Shelf Res.
**2009**, 29, 985–997. [Google Scholar] [CrossRef][Green Version]

**Figure 1.**Study area and hydrographic observation stations in the Istanbul strait [25].

**Figure 2.**Schematic description of the longitudinal section of the Istanbul Strait based on [2].

**Figure 4.**The first row shows (

**a**) the salinity and (

**b**) temperature of the Black Sea boundaries of the Istanbul Strait; and the second row shows (

**c**) the salinity and (

**d**) temperature of the Marmara Sea boundaries of the Istanbul Strait.

**Figure 9.**Salinity profiles observed (

**a**) and modeled (

**b**) in January, observed (

**c**) and modeled (

**d**) in April, observed (

**e**) and modeled (

**f**) in July, and observed (

**g**) and modeled (

**h**) in October.

**Figure 10.**Temperature profiles observed (

**a**) and modeled (

**b**) in January, observed (

**c**) and modeled (

**d**) in April, observed (

**e**) and modeled (

**f**) in July, and observed (

**g**) and modeled (

**h**) in October.

Parameter | Normalized Sensitivity Index | Sensitivity Level |
---|---|---|

Manning Roughness Coefficient | 0.1696 | Medium |

Horizontal Eddy Viscosity | 0.5352 | High |

Horizontal Eddy Diffusivity | 0.0122 | Low |

Vertical Eddy Viscosity | 0.0195 | Low |

Vertical Eddy Diffusivity | 0.0975 | Low |

Wind Stress Coefficient A | 0.0073 | Low |

Wind Speed Coefficient A | 0.0052 | Low |

Wind Stress Coefficient B | 0.0975 | Low |

Wind Speed Coefficient B | 0.0975 | Low |

Wind Stress Coefficient C | 0.0975 | Low |

Wind Speed Coefficient C | 0 | Low |

Secchi Depth | 0 | Low |

Stanton Number | 0 | Low |

Dalton Number | 0 | Low |

Slope in log–log Spectrum | 0.2869 | Medium |

Prandtl–Schmidt Number | 0.5188 | High |

Spatial Low-Pass Filter Coefficient | 1.0000 | Highest |

**Table 2.**Calibrated values of the model parameters using three methods. CMA-ES: covariance matrix adaptation evolution strategy, LM: Levenberg–Marquardt.

Parameter | Manual | PEST-LM | CMA-ES |
---|---|---|---|

Manning Roughness Coefficient | 0.02 | 0.0304 | 0.023 |

Horizontal Eddy Viscosity (m^{2}/s) | 1 | 9.8598 | 10 |

Slope in log–log Spectrum | −5/3 | −1.6390 | −1.6667 |

Prandtl–Schmidt Number | 0.7 | 0.8087 | 0.7 |

Spatial Low-Pass Filter Coefficient | 0.3 | 0.2950 | 0.3333 |

**Table 3.**The average of 10 years of in situ flow rate values measured in the north and south of the strait [21].

Months | Upper Layer Flow Rate North (m^{3}/s) | Lower Layer Flow Rate North (m^{3}/s) | Upper Layer Flow Rate South (m^{3}/s) | Lower Layer Flow Rate South (m^{3}/s) |
---|---|---|---|---|

January | 8950 | −10,030 | 9150 | −9720 |

February | 14,260 | −5810 | 16,080 | −5520 |

March | 15,320 | −6860 | 16,190 | −6240 |

April | 16,510 | −4930 | 19,150 | −4860 |

May | 16,610 | −5050 | 18,410 | −4980 |

June | 15,740 | −5530 | 17,590 | −5730 |

July | 12,510 | −7830 | 12,210 | −8220 |

August | 12,670 | −8300 | 13,890 | −8270 |

September | 9000 | −10,190 | 9060 | −9960 |

October | 8030 | −13,000 | 7880 | −12,010 |

November | 9950 | −9330 | 9210 | −9100 |

December | 14,240 | −8410 | 14,800 | −8730 |

Average | 12815.8 | −7939.2 | 13635.0 | −7778.3 |

Month | Temperature SPAEF (CORR) | Salinity SPAEF (CORR) |
---|---|---|

January | 0.51 (0.94) | 0.47 (0.94) |

April | 0.55 (0.92) | 0.42 (0.89) |

July | −0.45 (−0.04) | 0.69 (0.96) |

October | 0.37 (0.92) | 0.52 (0.92) |

© 2019 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Koşucu, M.M.; Demirel, M.C.; Kirca, V.S.O.; Özger, M. Hydrodynamic and Hydrographic Modeling of Istanbul Strait. *Processes* **2019**, *7*, 710.
https://doi.org/10.3390/pr7100710

**AMA Style**

Koşucu MM, Demirel MC, Kirca VSO, Özger M. Hydrodynamic and Hydrographic Modeling of Istanbul Strait. *Processes*. 2019; 7(10):710.
https://doi.org/10.3390/pr7100710

**Chicago/Turabian Style**

Koşucu, Mehmet Melih, Mehmet Cüneyd Demirel, V.S. Ozgur Kirca, and Mehmet Özger. 2019. "Hydrodynamic and Hydrographic Modeling of Istanbul Strait" *Processes* 7, no. 10: 710.
https://doi.org/10.3390/pr7100710