Development of a downscaling scheme for a coarse scale soil water estimation method [Elektronische Ressource] : case study ; Great Letaba River in South Africa / von Cornelia Scheffler
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Development of a downscaling scheme for a coarse scale soil water estimation method [Elektronische Ressource] : case study ; Great Letaba River in South Africa / von Cornelia Scheffler

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Development of a Downscaling Scheme for a Coarse Scale Soil Water Estimation Method Case Study -- Great Letaba River in South Africa Dissertation zur Erlangung des akademischen Grades doctor rerum naturalium (Dr. rer.nat.) vorgelegt dem Rat der Chemisch-Geowissenschaftlichen Fakultät der Friedrich-Schiller-Universität Jena von Diplom-Geographin Cornelia Scheffler geboren am 20. August 1978 in Karl-Marx-Stadt (jetzt Chemnitz) 1. Gutachter: Prof. Dr. rer. nat. Wolfgang-Albert Flügel, Jena 2. Gutachter: Univ. Prof. Dr. techn. Wolfgang Wagner, Wien Tag der öffentlichen Verteidigung: 02.07.2008 ACKNOWLEDGMENT Working on this dissertation these last few years has been a challenge, combining achievements and setbacks with joy and sometimes with tears. Without the support, guidance and patience of the following people this work would not have been possible. Special thanks go to Prof. Dr. Wolfgang-Albert Flügel who gave me the opportunity to write this dissertation in Jena and for his guidance, support and advice over the last years. I am also grateful to Prof. Dr. Wolfgang Wagner who supported this work. The discussions with him lead to the ideas that are presented in this work. The discussions with Dr. Peter Krause helped me to work through the technical as well as some challenging argumentative problems with my study.

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Published 01 January 2008
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Development of a Downscaling Scheme for a Coarse
Scale Soil Water Estimation Method
Case Study -- Great Letaba River in South Africa







Dissertation
zur Erlangung des akademischen Grades doctor rerum naturalium
(Dr. rer.nat.)











vorgelegt dem Rat der Chemisch-Geowissenschaftlichen Fakultät der
Friedrich-Schiller-Universität Jena

von Diplom-Geographin Cornelia Scheffler
geboren am 20. August 1978 in Karl-Marx-Stadt (jetzt Chemnitz)































1. Gutachter: Prof. Dr. rer. nat. Wolfgang-Albert Flügel, Jena
2. Gutachter: Univ. Prof. Dr. techn. Wolfgang Wagner, Wien
Tag der öffentlichen Verteidigung: 02.07.2008


ACKNOWLEDGMENT
Working on this dissertation these last few years has been a challenge,
combining achievements and setbacks with joy and sometimes with tears.
Without the support, guidance and patience of the following people this work
would not have been possible.
Special thanks go to Prof. Dr. Wolfgang-Albert Flügel who gave me the
opportunity to write this dissertation in Jena and for his guidance, support and
advice over the last years. I am also grateful to Prof. Dr. Wolfgang Wagner who
supported this work. The discussions with him lead to the ideas that are
presented in this work.
The discussions with Dr. Peter Krause helped me to work through the
technical as well as some challenging argumentative problems with my study.
His constructive criticism helped me to focus my ideas and to describe them
more clearly. I am also thankful to him for reading the dissertation draft within
a short time period.
I am very grateful to all my colleagues of the Department for
Geoinformatics, Hydrology and Modelling, in particular, Dr. Jörg Helmschrot,
Dr. Sven Kralisch, Dr. Manfred Fink, Björn Pfennig, and Daniel Varga who have
given their time to discuss pieces of my work with me and who have also
offered valuable advice. Special thanks also go to Rainer Hoffmann, the system
administrator, who helped with any occurring technical problem.
I am grateful indebted to my friend and colleague Antje Vogel for
proofreading and her constructive comments to improve this dissertation.
Thanks to Markus Reinhold, Evelin Matejka, Cornelia Barth and Timothy Steele
for proof-reading this dissertation.
Thanks to all agencies and institutes providing data for this study: to the
Institute for Photogrammetry and Remote Sensing (IPF) at the Technical
University of Vienna, to the South Africa Weather Service, in particular to
Tracey Gill, to the Council for Scientific and Industrial Research (CSIR) and the
Agricultural Research Council (ARC) for providing the land-cover data, to the
ACKNOWLEDGEMENT
School of Bioresources Engineering and Environmental Hydrology in
Pietermaritzburg, to the Department of Water Affairs and Forestry for
providing the data on geology. Special thanks go to the people with whom I
had such a great time during the field trip in South Africa: Ralda de Wet, Danie
Viljoen, the Family Lorentz and Susann Carter.
Many thanks for financial support from the Marianne und Dr. Fritz
Walter Fischer-Stiftung, whose support made this research possible.
For their continuous and encouraging support, I want to thank all my
friends -- in particular, Lydia Franke, Kathleen Neumann, Daniela Knorr,
Katrin Geiseler and Cornelia Koch.
Special thanks go to my parents and to my brother for their endless
support and the trust in me.
I am especially indebted to my partner Hisham Zerriffi who believed in
me and who encouraged me to persist whenever I lost my faith in finishing this
work. It is to him that I dedicate this work.


CONTENT
LISTS OF FIGURES ................................................................................................................. V
LIST OF TABLES .................................................................................................................. VII
ABBREVIATIONS ...................................................................................................................IX
LIST OF PARAMETERS .....................................................................................................XIII
ABSTRACT............................................................................................................................. XV
KURZFASSUNG.................................................................................................................. XVII
CHAPTER 1 INTRODUCTION ............................................................................................... 1
CHAPTER 2 RESEARCH REVIEW ....................................................................................... 5
2.1 SOIL MOISTURE IN THE HYDROLOGICAL CYCLE ............................................................ 6
2.1.1 DEFINITION OF SOIL MOISTURE........................................................................................ 7
2.1.2 CALCULATION OF SOIL MOISTURE ................................................................................... 9
2.2 ESTIMATION OF THE SOIL WATER CONTENT AND ITS MONITORING .......................... 10
2.2.1 ESTIMATION OF THE SOIL WATER CONTENT USING REMOTE SENSING TECHNIQUES.... 10
2.2.1.1 Microwave Techniques for Soil Water Retrieval ........................................................ 11
2.2.1.2 Fundamentals of Active Microwave Remote Sensing................................................. 13
2.2.1.3 The ERS Macro-Scale Soil Water Estimates............................................................... 16
2.2.2 SOIL MOISTURE GENERATION IN LAND SURFACE MODELING....................................... 21
2.2.2.1 Classification of Models .............................................................................................. 21
2.2.2.2 Determination of Soil Moisture Using Land Surface Modeling.................................. 23
2.3 ON TEMPORAL AND SPATIAL SCALING OF SOIL MOISTURE......................................... 25
I CONTENT
2.3.1 SCALE DEPENDENT SPATIAL AND TEMPORAL DISTRIBUTION OF SOIL MOISTURE
VARIABILITY ............................................................................................................................... 27
2.3.2 THE UP- AND DOWNSCALING PROCESS.......................................................................... 29
2.3.2.1 Upscaling methods....................................................................................................... 30
2.3.2.2 Downscaling Methods ................................................................................................. 32
2.4 RESEARCH NEEDS ............................................................................................................ 33
CHAPTER 3 SCIENTIFIC OBJECTIVES AND METHODICAL APPROACH ............. 35
3.1 STEP I: HYDROLOGICAL SYSTEM ANALYSIS AND DELINEATION OF HYDROLOGICAL
RESPONSE UNITS........................................................................................................................ 37
3.1.1 HYDROLOGICAL SYSTEM ANALYSIS .............................................................................. 37
3.1.1.1 Data Analysis of Hydro-Meteorological Time Series.................................................. 38
3.1.1.2 Spatial Data Modeling ................................................................................................. 39
3.1.2 DELINEATION OF HYDROLOGICAL RESPONSE UNITS ..................................................... 40
3.2 STEP II: RAINFALL-RUNOFF MODELING WITH J2000................................................... 42
3.2.1 MODULAR DESIGN OF J2000........................................................................................... 43
3.2.2 INPUT DATA PREPARATION ............................................................................................ 46
3.2.3 MODEL PARAMETERIZATION AND CALIBRATION........................................................... 47
3.2.3.1 Automatic Parameter Estimation using Sensitivity Analysis....................................... 48
3.2.3.2 Prediction of Model Uncertainty ................................................................................. 50
3.3 STEP III: ANALYSIS OF THE MACRO-SCALE SOIL WATER ESTIMATES WITH THE
SIMULATED SOIL WATER TIME SERIES................................................................................... 51
3.3.1 RETRIEVING THE CATCHMENT AREA COVERED BY ONE ERS-SCATTEROMETER
FOOTPRINT .................................................................................................................................. 51
3.3.2 DELINEATION OF THE HRU-SOIL WATER INDEX (SWI ) ........................................... 51 HRU
3.3.3 PROCEDURES FOR EVALUATION OF THE TIME SERIES AT FOOTPRINT SCALE................ 53
3.3.3.1 Decomposition of Time Series..................................................................................... 53
3.3.3.2 Agreement Criteria....................................................................................................... 54
3.3.3.3 Procedures for Evaluation of the Time Series at HRU Scale....................................... 55
CHAPTER 4 STUDY AREA AND DATA BASE .................................................................. 57
4.1 STUDY AREA ..................................................................................................................... 58
4.1.1 CLIMATE ......................................................................................................................... 58
II CONTENT
4.1.2 RUNOFF AND WATER BALANCE...................................................................................... 61
4.1.3 GEOLOGY ........................................................................................................................ 63
4.1.4 SOIL................................................................................................................................. 64
4.1.5 LAND COVER AND LAND USE......................................................................................... 65
4.2 DATA BASE........................................................................................................................ 67
4.2.1 HYDRO-METEOROLOGICAL TIME SERIES ........................................................................ 67
4.2.1.1 Rainfall Data................................................................................................................ 67
4.2.1.2 Temperature Data......................................................................................................... 68
4.2.1.3 Additional Climatological Parameters......................................................................... 69
4.2.1.4 Runoff Data.................................................................................................................. 69
4.2.2 SPATIAL DATASETS (GIS-DATASETS) ............................................................................ 70
4.2.3 THE REMOTELY SENSED SOIL WATER DATASET ........................................................... 71
CHAPTER 5 RESULTS AND DISCUSSION ........................................................................ 73
5.1 SYSTEM ANALYSIS AND DELINEATION OF HYDROLOGICAL RESPONSE UNITS ........... 74
5.1.1 DATA ANALYSIS AND SYSTEM ANALYSIS...................................................................... 74
5.1.1.1 Rainfall Data Analysis ................................................................................................. 74
5.1.1.2 Runoff Data Analysis................................................................................................... 74
5.1.1.3 Temporal Relationship between Rainfall and Runoff in the Great Letaba River ........ 77
5.1.1.4 Analysis of the Additional Datasets............................................................................. 80
5.1.1.5 Summary of the Data Analysis .................................................................................... 81
5.1.2 SPATIAL DATASETS......................................................................................................... 82
5.1.3 DELINEATION OF HYDROLOGICAL RESPONSE UNITS ..................................................... 83
5.2 RAINFALL–RUNOFF MODELING USING J2000................................................................ 89
5.2.1 MODEL PARAMETERIZATION.......................................................................................... 89
5.2.1.1 Land Cover Information .............................................................................................. 89
5.2.1.2 Information on Soil Data ............................................................................................. 90
5.2.1.3 Information on Geology Data ...................................................................................... 91
5.2.2 MODELING RESULTS....................................................................................................... 92
5.2.3 SENSITIVITY ANALYSIS................................................................................................... 96
5.3 ASSESSMENT AND EVALUATION OF THE MACRO-SCALE SOIL WATER ESTIMATES . 100
5.3.1 DELINEATION AND CHARACTERIZATION OF THE ERS-SCATTEROMETER FOOTPRINTS IN
THE CATCHMENT....................................................................................................................... 101
III CONTENT
5.3.2 COMPARISON OF REMOTELY SENSED SOIL WATER AND MODELED SOIL WATER TIME
SERIES AT FOOTPRINT SCALE.................................................................................................... 103
5.3.3 DEVELOPMENT OF THE DOWNSCALING SCHEME.......................................................... 111
5.3.4 IMPACT OF MODEL CALIBRATION PARAMETER ON THE DOWNSCALING PARAMETERS ....
...................................................................................................................................... 131
CHAPTER 6 SUMMARY, CONCLUSIONS AND FUTURE RESEARCH..................... 133
6.1 SUMMARY AND CONCLUSIONS ...................................................................................... 133
6.2 FUTURE RESEARCH ........................................................................................................ 138
REFERENCES........................................................................................................................ 141
APPENDIX .............................................................................................................................. 161

IV
LISTS OF FIGURES
FIGURE 2-1: THE GLOBAL WATER CYCLE (SOURCE: ENTIN, HOUSER ET AL.(2007:P.9))........6
FIGURE 2-2: SOIL WATER AND ITS COMPONENTS (MODIFIED AFTER DONAHUE, MILLER
ET AL (1983:P.171))..........................................................................................................................8
FIGURE 3-1: FLOWCHART OF THE METHODOLOGICAL APPROACH .........................................37
FIGURE 3-2: FLOWCHART METHODOLOGICAL STEPS IN THE RAINFALL-RUNOFF
MODELING .....................................................................................................................................42
FIGURE 3-3: THE MODELING SYSTEM J2000 (MODIFIED FROM KRAUSE (2001:P.74 AND P.89)
AND BÄSE (2005:P.25)) .................................................................................................................43
FIGURE 4-1: GEOGRAPHIC LOCATION OF THE STUDY AREA .....................................................58
FIGURE 4-2: SPATIAL DISTRIBUTION OF THE YEARLY RAINFALL AMOUNT IN THE
CATCHMENT OF THE GREAT LETABA DERIVED FROM INVERSE DISTANCE
WEIGHTING INTERPOLATION ...................................................................................................59
FIGURE 4-3: MONTHLY MEAN PRECIPITATION AND EVAPORATION IN THE NORTHERN
PROVINCE (DATA SOURCE: SCHULZE, MAHARAJ ET AL. 1997)........................................60
FIGURE 4-4: LOCATION OF THE QUATERNARY CATCHMENTS AND RUNOFF-RAINFALL
COEFFICIENTS FOR THE QUATERNARY CATCHMENTS (DATA SOURCE: MIDGELEY,
PITMAN ET AL.( 1994A: APPENDIX 8.6); MIDGELEY, PITMAN ET AL. (1994B), PITMAN
AND MIDDLETON (1994) .............................................................................................................62
FIGURE 4-5: THE WRB- SOIL TYPES IN THE CATCHMENT OF THE GREAT LETABA RIVER.64
FIGURE 4-6 : RECLASSIFIED LAND COVER OF THE GREAT LETABA CATCHMENT...............66
FIGURE 4-7: THE GAUGING STATION LETABA RANCH (PHOTO: SCHEFFLER, MARCH 2006)
..........................................................................................................................................................70
FIGURE 5-1: DOUBLE MASS CURVE ANALYSIS IN THE GREAT LETABA CATCHMENT........75
FIGURE 5-2: LONG TERM (20 YEARS) EVALUATION OF PRECIPITATION AND RUNOFF.......77
FIGURE 5-3: THE 20 YEARS MONTHLY AVERAGE OF PRECIPITATION AND RUNOFF...........78
FIGURE 5-4: COMPARISON OF THE DAILY FLOW AT THE GREAT LETABA RANCH
BETWEEN TWO TIME PERIODS 1993/94 AND 1998/99 ...........................................................79
V LIST OF FIGURES
FIGURE 5-5: FLOW-CHART OF THE DELINEATION OF HRUS (MODIFIED AFTER BÄSE,
HELMSCHROT ET AL. (2006)) .....................................................................................................83
FIGURE 5-6: EXAMPLE OF A SMALLHOLDING AREA IN SOUTH AFRICA (PHOTO:
SCHEFFLER, 2006).........................................................................................................................86
FIGURE 5-7: SIMULATED HYDROLOGICAL DYNAMICS WITH THE DISTRIBUTED MODEL
J2000, GREAT LETABA RIVER CATCHMENT (WITHOUT CATCHMENT OF THE
TZANEEN DAM) ............................................................................................................................93
FIGURE 5-8: SENSITIVITY INDEX FOR THE PARAMETER OF THE SOIL WATER MODULE IN
REGARD TO SIMULATED RUNOFF AND SIMULATED SOIL WATER VOLUME...............98
FIGURE 5-9: SENSITIVITY INDEX FOR THE PARAMETER OF THE GROUND WATER MODULE
IN REGARD TO SIMULATED RUNOFF AND SIMULATED SOIL WATER VOLUME .........99
FIGURE 5-10: EFFECTS OF CHANGES IN FCADAPATION PARAMETER TO THE MPS-
SATURATION OUTPUT, TIME PERIOD 1995/96 .....................................................................100
FIGURE 5-11: ERS-SCATTEROMETER FOOTPRINTS IN THE GREAT LETABA CATCHMENT .....
……………………………………………………………………………………………………..101
___________
FIGURE 5-12: TIME SERIES WITH TREND COMPONENTS OF THE SWI AND THE SWI ERSHRU
FOR EACH FOOTPRINT FOR THE TIME FRAME 1993 TO 1997...........................................104
___________
FIGURE 5-13: X-Y-PLOTS SWI AND SWI FOR EACH FOOTPRINT ................................105 ERSHRU
FIGURE 5-14: SEASONAL ANALYSIS BETWEEN 1993 AND 1997 FOR EACH FOOTPRINT.....109
FIGURE 5-15: MULTIPLE LINEAR REGRESSION: SPATIAL VARIABILITY OF THE
COEFFICIENT OF DETERMINATION, FOOTPRINT ID376 ....................................................115
FIGURE 5-16: MULTIPLE LINEAR REGRESSION: SPATIAL VARIABILITY OF THE
REGRESSION COEFFICIENT M , FOOTPRINT ID376.............................................................116 1
FIGURE 5-17: MULTIPLE LINEAR REGRESSION: SPATIAL VARIABILITY OF THE
REGRESSION COEFFICIENT M , FOOTPRINT ID376.............................................................117 2
FIGURE 5-18: MULTIPLE LINEAR REGRESSION: SPATIAL VARIABILITY OF THE INTERCEPT,
FOOTPRINT ID376 .......................................................................................................................118
FIGURE 5-19: RELATIVE FREQUENCY OF THE R²-VALUES FOR EACH FOOTPRINT
ACHIEVED WITH THE LCS-SCALING PARAMETERS..........................................................122
FIGURE 5-20: R²-SPATIAL DISTRIBUTION FOR THE DOWNSCALING, (TIMEFRAME 1997 TO
1999), FOOTPRINT ID376 ............................................................................................................126
FIGURE 5-21: R²-SPATIAL DISTRIBUTION FOR THE DOWNSCALING (TIMEFRAME 1997 TO
1999), FOOTPRINT ID393 ............................................................................................................127
FIGURE 5-22: R²-SPATIAL DISTRIBUTION FOR THE DOWNSCALING, (TIMEFRAME 1997 TO
1999), FOOTPRINT ID394 ............................................................................................................128
VI