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Hydraulic and thermal dynamics at various permafrost sites on the Qinghai-Tibet Plateau [Elektronische Ressource] / put forward by Xicai Pan

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Dissertationsubmitted to theFaculty of Chemistry and Earth Sciencesof the Ruperto-Carola University of Heidelbergfor the degree ofDoctor of Natural SciencesPut forward byMaster of Natural Science: Xicai PanBorn in: Yunxian, ChinaOral examination: 12 April 2011Hydraulic and Thermal Dynamics at VariousPermafrost Siteson the Qinghai-Tibet PlateauReferees: Prof. Dr. Kurt RothProf. Dr. Olaf BubenzerAbstractHeat transfer mechanisms governing the permafrost-atmosphere interaction are essential tounderstand present permafrost degradation. Hydraulic and thermal dynamics of various activelayers at four di erent permafrost sites on the QTP were investigated with various geophysicalmethods and soil-weather monitoring stations. Complex eld data were detected and processedwith appropriate methods. The principal physical processes controlling the active-layer thermalregime were characterized with a surface energy balance method at Chumaer, Qumahe andTianshuihai. As a geophysical tool for characterizing soil properties, multi-channel GPR wasfurther explored. Through Monte Carlo uncertainty analysis and eld tests, the accuracy ofthe multi-channel GPR method and its capability of quantifying eld-scale hydraulic propertiesand processes was validated at a non-permafrost sandy site. Based on precise soil temperatureand soil water content data, heat transfer in various active layers were characterized with atransfer function method.

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Published 01 January 2011
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Dissertation
submitted to the
Faculty of Chemistry and Earth Sciences
of the Ruperto-Carola University of Heidelberg
for the degree of
Doctor of Natural Sciences
Put forward by
Master of Natural Science: Xicai Pan
Born in: Yunxian, China
Oral examination: 12 April 2011Hydraulic and Thermal Dynamics at Various
Permafrost Sites
on the Qinghai-Tibet Plateau
Referees: Prof. Dr. Kurt Roth
Prof. Dr. Olaf BubenzerAbstract
Heat transfer mechanisms governing the permafrost-atmosphere interaction are essential to
understand present permafrost degradation. Hydraulic and thermal dynamics of various active
layers at four di erent permafrost sites on the QTP were investigated with various geophysical
methods and soil-weather monitoring stations. Complex eld data were detected and processed
with appropriate methods. The principal physical processes controlling the active-layer thermal
regime were characterized with a surface energy balance method at Chumaer, Qumahe and
Tianshuihai. As a geophysical tool for characterizing soil properties, multi-channel GPR was
further explored. Through Monte Carlo uncertainty analysis and eld tests, the accuracy of
the multi-channel GPR method and its capability of quantifying eld-scale hydraulic properties
and processes was validated at a non-permafrost sandy site. Based on precise soil temperature
and soil water content data, heat transfer in various active layers were characterized with a
transfer function method. Given the characteristics of ground heat transfer at the study sites,
an inverse method for seasonal thermal conductivity parameterization was tested. Combining
the transfer function method and the multi-channel GPR, a eld-scale thermal conductivity
parameterization was proposed at the end.
Kurzfassung
Temperaturtransfermechanismen, welche den Austausch von Permafrost und Atmosph are
dominieren, sind von essentieller Bedeutung um den derzeitigen Ruc kgang des Permafrost zu
verstehen. Die hydraulische und thermische Dynamik verschiedener aktiver Schichten an vier
verschiedenen Permafrost beobachtungsstellen auf dem QTP wurden mit Hilfe mehrerer geo-
physikalischerMethodenundBoden-Atmosph areBeobachtungsstationenuntersucht. Komplexe
Felddaten wurden ausgew ahlt und mit passenden Methoden prozessiert. Die grundlegenden
physikalischen Prozesse, welche das thermische Regime der aktiven Schicht dominieren, wur-
den mit der Ober achenenergiebilanzmethode bei Chumaer, Qumahe und Tianshuihai charak-
terisiert. Multikanalgeoradar wurde als geophysikalische Methode zur Charakterisierung von
Bodeneigenschaften tiefer gehend untersucht. Die Genauigkeit der Multikanalgeoradarmeth-
ode und ihre Tauglichkeit zur Quanti zierung hydraulischer Eigenschaften und Prozesse auf
der Feldskala wurde mit Hilfe einer Monte-Carlo Analyse zur Fehlerabsch atzungs und einem
Test auf einem nicht dauerhaft gefrorenen sandigem Feld validiert. Basierend auf pr azisen
Bodentemperatur- und Bodenwassergehaltsmessungen wurde der Temperaturtransfer in ver-
schiedenen aktiven Schichten mit Hilfe von Transferfunktionen charakterisiert. Eine inverse
Methode zur Parametrisierung der saisonalen thermischen Leitf ahigkeit wurde mit den gegebe-
nen Charakteristika des Temperaturtransfers im Untergrund an den Testfeldern untersucht.
Mit der Kombination der Transferfunktions- und der Multikanalgeoradarmethode wurde eine
Parametrisierung der thermischen Leitf ahigkeit auf der Feldskala abgeleitet.
iAcknowledgments
This research project could not be nished like this without the aid and assistance of many
peopleandinstitutions. The nancialsupportoftheDeutscheForschungsgemeinschaft(through
project RO 1080/10-2) are gratefully acknowledged. The eld work was undertaken with Prof.
Qihao Yu, Prof. Huijun Jin and other researchers from Cold and Arid Regions Environmental
and Engineering Research Institute, Chinese Academy of Science. First and foremost, I would
like to sincerely acknowledge Prof. Kurt Roth. Without his support, I can not imagine I can
make such progress during the past years. Through various interesting academic trainings, I
gained many precious skills throughout my graduate education. I am grateful to his excellent
advice and patient guidance the study and valuable insights, as well as suggestions
and discussions in this research project.
Dr. Ute Wollschl ager is gratefully acknowledged for helping me quickly get into this work.
With her generous assistance and advice, I nally found a suitable eld site for the GPR exper-
iment. Her friendship and encouragement inspired me during the di cult times throughout my
study. Withherexcellentscholarshipandprofoundexpertiseinthe eldofhydro-geophysicsand
permafrost,sheprovidedinsightfulideas,suggestionsaswellashelpsinscienti cwriting.
I would like to thank Prof. Olaf Bubenzer who agreed to be the second referee for my thesis
and provided me some invaluable insights and suggestions in geographical consideration.
Design, setup, and maintenance of the weather stations were taken lots of e orts. All the
involved peoples are gratefully appreciated. Assistance of using GPR and and programming for
data processing from Dr. Holger Gerhards and Klaus Schneider is greatly appreciated. I would
liketothankPartickKlenkandJensBuchnerfortheirhelpofsuggestionsandwritingcorrection
for my thesis. Discussions about soil heat transfer and associated mathematic problems with
Ulrike Niederle and Gabriele Schenk are gratefully appreciated.
I would like to acknowledge Angelika Gassama, Rebecca Ludwig, Benny Antz for their
generous assistance to drive the bus for the eld experiments. I also thank help from other
colleagues and friends in Heidelberg.
Finally I would like to thank my family. Their encouragement and support accompanied with
me during this impressive period.
iiiContents
1 Introduction 1
2 Background of the permafrost study 5
2.1 Evolution of the Qinghai-Tibetan Plateau and permafrost . . . . . . . . . . . . . 5
2.1.1 The uplift of the Qinghai-Tibetan Plateau and associated climate . . . . . . 5
2.1.2 Permafrost . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
2.2 Current climate warming and permafrost degradation . . . . . . . . . . . . . . . . 7
2.2.1 Climate change . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
2.2.2 Permafrost degradation and associated environmental challenges . . . . . . 8
2.3 Investigations at the study sites . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.3.1 Chumaer and Qumahe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
2.3.2 Zuimatan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
2.3.3 Tianshuihai . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
2.4 Instrumentation and data evaluation . . . . . . . . . . . . . . . . . . . . . . . . . 18
2.4.1 Measurements at the soil-weather monitoring stations . . . . . . . . . . . . 19
2.4.2 Data evaluation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
2.4.3 Data quality discussion. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
2.5 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
3 Characteristics of the weather-permafrost interaction at the study
sites 31
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.2 Chumaer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31
3.2.1 Interaction between atmosphere and ground surface . . . . . . . . . . . . . 31
3.2.2 Seasonal hydraulic and thermal dynamics of the active layer . . . . . . . . . 36
3.3 Qumahe . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
3.3.1 Interaction between atmosphere and ground surface . . . . . . . . . . . . . 39
3.3.2 Seasonal hydraulic and thermal dynamics of the active layer . . . . . . . . . 43
3.4 Zuimatan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
3.4.1 Interaction between atmosphere and ground surface . . . . . . . . . . . . . 45
3.4.2 Seasonal thermal dynamics of the active layer . . . . . . . . . . . . . . . . . 48
3.5 Tianshuihai . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
3.5.1 Interaction between atmosphere and ground surface . . . . . . . . . . . . . 50
3.5.2 Seasonal hydraulic and thermal dynamics of the active layer . . . . . . . . . 53
3.6 Comparison of the observational data at the study sites . . . . . . . . . . . . . . . 55
vvi Contents
3.6.1 Meteorological characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . 55
3.6.2 Variability of the relation between air and surface temperatures . . . . . . . 56
3.6.3 Hydraulic-thermal patterns of the active layers . . . . . . . . . . . . . . . . 57
3.7 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59
4 Characterization of thermal regimes of the active layers at the study
sites 61
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61
4.2 of the ground heat ux . . . . . . . . . . . . . . . . . . . . . . . 62
4.2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62
4.2.2 Material and methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63
4.2.3 Applications and discussions . . . . . . . . . . . . . . . . . . . . . . . . . . . 66
4.3 Characterization of the thermal regime of the active layers . . . . . . . . . . . . . 75
4.3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
4.3.2 Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
4.3.3 Results and discussions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 80
4.4 Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 85
5 Monitoring eld-scale soil water dynamics with multi-channel GPR 87
5.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 87
5.2 Theoretical background of multi-channel GPR . . . . . . . . . . . . . . . . . . . . 88
5.2.1 Principles of electromagnetic wave propagation . . . . . . . . . . . . . . . . 88
5.2.2 Relationship between soil water content and permittivity. . . . . . . . . . . 89
5.2.3 The multi-channel GPR method . . . . . . . . . . . . . . . . . . . . . . . . 90
5.3 Optimization of multi-channel GPR to measure spatial variation of soil permittivity 90
5.3.1 The algorithm of multi-channel GPR evaluation . . . . . . . . . . . . . . . . 90
5.3.2 Monte Carlo uncertainty analysis of multi-channel GPR method . . . . . . 91
5.3.3 Accuracy assessment of multi-channel GPR: synthetic example . . . . . . . 92
5.4 Application to eld data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
5.4.1 Materials and methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
5.4.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96
5.5 Discussion and conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99
6 Thermal characterization of active layers at the study sites 101
6.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101
6.2 Characterization of heat transfer in various active layers . . . . . . . . . . . . . . 102
6.2.1 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
6.2.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 104
6.2.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 110
6.3 Field-scale parameterization of soil thermal conductivity with multi-channel GPR 116
6.3.1 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 116
6.3.2 Inverse parameterizations at the study sites . . . . . . . . . . . . . . . . . . 119
6.3.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 122
6.4 Conclusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124