In this doctoral thesis I analyzed the response of stratification in dimictic waters to climate change and management stratigies, by using one, two and three dimensional hydrodynamic models.:List of Tables v
List of Figures vi
List of Abbreviations x
1. Introduction 1
1.1. Thermal stratification 2
1.2. Recent studies on stratification and current research gaps 3
1.3. Main research questions and hypotheses 6
1.3.1. Assessing vertical diffusion in a stratified lake using a 3D hydrodynamic model 6
1.3.2. Stratification dynamics in Rappbode Reservoir under different wind conditions 7
1.3.3. Variable withdrawal elevations as a management tool to counter the effects of climate warming in Rappbode Reservoir 7
1.3.4. Ensemble warming projections in Rappbode Reservoir and potential adaptation strategies 8
2. Assessing vertical diffusion in a stratified lake using a 3D hydrodynamic model 9
2.1. Abstract 9
2.2. Introduction 9
2.3. Materials and Methods 11
2.3.1. Study site 11
2.3.2. Numerical model 12
2.3.3. Model setup and parameters 15
2.3.4. Calculation of vertical turbulent diffusion coefficient Kz 16
2.3.5. Model performance and uncertainty analysis 17
2.3.6. Scenarios 17
2.4. Results 18
2.4.1. Model performance and validity 18
2.4.2. Mixing conditions in the metalimnion 22
2.4.3. Effects from changing temperature and wind conditions 23
2.5. Discussion 25
2.5.1. Evaluation of the modelling approach 25
2.5.2. Opportunities and limits of the 3D hydrodynamic model 26
2.5.3. Limnological processes and lake ecosystem dynamics 27
2.6. Conclusion 28
3. Stratification dynamics in a reservoir under different wind conditions 30
3.1. Abstract 30
3.2. Introduction 30
3.3. Methods 32
3.3.1. Study site 32
3.3.2. Numerical model 33
3.3.3. Model setup and input data 33
3.3.4. Model calibration 35
3.3.5. Wind scenarios 35
3.3.6. Evaluation of simulations 37
3.4. Results 38
3.4.1. Calibration results 38
3.4.2. Statistical properties of wind velocity at Rappbode Reservoir 39
3.4.3. Scenario S1: Stratification phenology in 2015 at different wind conditions 40
3.4.4. Scenario S2: Sensitivity to wind speed under averaged meteorological conditions 41
3.4.5. Scenario S3: Effects of short-term wind events on stratification 42
3.4.6. Scenario S4: Effects of short-term wind events on stratification (seasonally varying) 45
3.5. Discussion 46
4. Variable withdrawal elevations as a management tool to counter the effects of climate warming in Germany’s largest drinking water reservoir 49
4.1. Abstract 49
4.2. Introduction 49
4.3. Methods 51
4.3.1. Study site 51
4.3.2. Numerical models 52
4.3.3. Model setup and input data 54
4.3.4. Model calibration 56
4.3.5. Scenarios 57
4.4. Results 57
4.4.1. Model calibration 57
4.4.2. Scenario S1: Influencing ice dynamics by withdrawal regime 60
4.4.3. Scenario S2: Mixing regimes under different withdrawal and warming regimes 61
4.5. Discussion 63
4.6. Conclusions 67
5. Ensemble warming projections in Germany's largest drinking water reservoir and potential adaptation strategies 68
5.1. Abstract 68
5.2. Introduction 68
5.3. Methods 70
5.3.1. Study site 70
5.3.2. Hydrodynamic model 71
5.3.3. Model setup and calibration 72
5.3.4. Response of thermal structure to climate change 74
5.3.5. Alternative management scenarios using different withdrawal strategies 75
5.3.6. Thermal indices and statistics 75
5.4. Results 76
5.4.1. Model calibration 76
5.4.2. Climate projections 78
5.4.3. Response of thermal structure to climate change 79
5.4.4. Interaction between climate warming and alternative withdrawal scenarios 83
5.5. Discussion and conclusions 85
6. General discussion 88
6.1. Evaluating performance of the applied models 88
6.2. The response of thermal dynamics and vertical diffusion to climate change 89
6.2.1. The response of thermal structure and vertical exchange to variations in wind speed 89
6.2.2. The response of winter stratification to increase in air temperature 90
6.2.3. The response of thermal dynamics to different future climate projections 92
6.3. The effect of selective withdrawal strategy on modifying the thermal structure in Rappbode Reservoir under climate change 93
6.4. Additional perspectives 95
6.4.1. Modelling in connective systems 95
6.4.2. Future changes of vertical diffusion 95
6.4.3. Near-term forecast 96
7. References 97
References to own articles used in this thesis 110
Other papers accepted or under review during the PhD study 111
Appendix 2 112
Appendix 3 114
Appendix 4 120
| Identifer | oai:union.ndltd.org:DRESDEN/oai:qucosa:de:qucosa:73148 |
| Date | 15 December 2020 |
| Creators | Mi, Chenxi |
| Contributors | Borchardt, Dietrich, Berendonk, Thomas U., Rinke, Karsten, Technische Universität Dresden |
| Source Sets | Hochschulschriftenserver (HSSS) der SLUB Dresden |
| Language | English |
| Detected Language | English |
| Type | info:eu-repo/semantics/publishedVersion, doc-type:doctoralThesis, info:eu-repo/semantics/doctoralThesis, doc-type:Text |
| Rights | info:eu-repo/semantics/openAccess |
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