Zusammenfassung ................................................. 1
1 Introduction ................................................. 1
1.1 Geography of the ephemeral Kuiseb River ................. 2
1.2 Ecohydrology: Coupling ecosystem dynamic and the water
cycle ................................................... 4
1.3 Deciding under severe uncertainty ....................... 6
2 Uncertainty in parameterisation and model structure affect
simulation results in coupled ecohydrological models ........ 15
2.1 Introduction ........................................... 15
2.2 Methods and materials .................................. 18
2.2.1 Study site ...................................... 18
2.2.2 Hydrological model .............................. 21
2.2.3 The stochastic flood generator .................. 24
2.2.4 Ecological model ................................ 25
2.2.5 Model versions .................................. 28
2.2.6 Parameter sampling .............................. 29
2.2.7 Analysis of ensemble models ..................... 31
2.2.8 Forward simulations with changed flood regime ... 32
2.3 Results ................................................ 32
2.4 Discussion ............................................. 38
2.5 Conclusions ............................................ 42
3 How do coexistence mechanisms influence the fluctuations
of hydrological variables? .................................. 53
3.1 Introduction ........................................... 53
3.2 Methods and materials .................................. 55
3.2.1 Study site ...................................... 55
3.2.2 Ecohydrological model ........................... 55
3.2.3 Model versions .................................. 56
3.2.4 Model analysis .................................. 57
3.3 Results ................................................ 57
3.4 Discussion ............................................. 61
3.4.1 Coexistence pattern ............................. 61
3.4.2 Ecohydrological patterns ........................ 62
3.4.3 Fluctuation of hydrological variables ........... 63
3.4.4 Implication for management decisions ............ 65
3.5 Conclusions ............................................ 65
4 Integrated management strategies for sustainable water use
along ephemeral rivers under severe uncertainty of future
flood regimes ............................................... 71
4.1 Introduction ........................................... 71
4.2 Methods and materials .................................. 74
4.2.1 Study site ...................................... 74
4.2.2 Information gap model ........................... 75
4.2.3 System model .................................... 77
4.2.4 Performance and requirements .................... 78
4.2.5 Uncertainty model ............................... 80
4.2.6 Robustness and opportuneness function ........... 80
4.2.7 Parameterisation and implementation ............. 81
4.2.8 Management scenarios ............................ 82
4.2.1 Results ......................................... 83
4.4 Discussion ............................................. 90
4.4.1 Comparison of management strategies ............. 91
4.4.2 Performance under increasing uncertainty ........ 93
4.4.3 Role of the system model ........................ 94
4.5 Conclusions ............................................ 95
5 Sustainable water extraction along ephemeral rivers: On
the role of ecohydrological feedbacks and uncertainty ....... 99
5.1 Introduction ........................................... 99
5.2 Methods and materials ................................. 100
5.2.1 System models .................................. 100
5.2.2 Performance requirements ....................... 101
5.2.3 Stochastic flood regime ........................ 102
5.2.4 Uncertainty model .............................. 103
5.2.5 Flood parameter sampling ....................... 104
5.2.6 Robustness function ............................ 104
5.2.7 Management scenarios ........................... 104
5.3 Results ............................................... 105
5.4 Discussion ............................................ 108
5.4.1 Ranking orders of management strategies ........ 109
5.4.2 Ecohydrological feedbacks or uncertainty ....... 110
5.4.3 Relationship between model complexity and
strategy performance ........................... 111
5.5 Conclusions ........................................... 111
6 Synthesis .................................................. 115
6.1 Summary ............................................... 116
6.2 Conclusions ........................................... 119
6.3 Outlook ............................................... 120
A Appendix of Chapter 2 ...................................... 123
В Appendix of Chapter 3 ...................................... 125
Danksagung .................................................... 127
Selbständigkeitserklärung ..................................... 131
Curriculum Vitae .............................................. 133
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