Soil moisture dynamics and soil moisture controlled runoff processes at different spatial scales : from observation to modelling [Elektronische Ressource] / Thomas Gräff. Betreuer: Erwin Zehe

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• Publié par: universitat_potsdam
• Publié le: 01 janvier 2011
• Nombre de lectures: 9
• Langue: English
• Poids de l'ouvrage: 5 Mo

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Soil moisture dynamics and soil moisture controlled runoff
processes at different spatial scales: From observation to
modelling


Dissertation submitted to the Faculty of Mathematics and Natural Sciences at the
University of Potsdam, Germany
for the degree of Doctor of Natural Sciences (Dr. rer. nat.) in Hydrology
Thomas Gräff This work is licensed under a Creative Commons License:
Attribution 3.0 Germany
To view a copy of this license visit
http://creativecommons.org/licenses/by/3.0/de/











































Published online at the
Institutional Repository of the University of Potsdam:
URL http://opus.kobv.de/ubp/volltexte/2011/5447/
URN urn:nbn:de:kobv:517-opus-54470
http://nbn-resolving.de/urn:nbn:de:kobv:517-opus-54470
Contents:
Contents: .................................................................................................................................................... i
Abstract: ................................................................................................................................................... iv
Zusammenfassung .................................................................................................................................. vi
Chapter 1 Introduction ................................................................................................... 1
1.1 Motivation ................................................................................................................................... 1
1.1.1 Why soil moisture is important? .......................................................................................... 1
1.1.2 Problems in assessment –observe at the point scale,
interested in catchment scale ............................................................................................................. 1
1.1.3 How is soil moisture represented in hydrological
models (conceptual, large scale vs. hillslope scale)? ....................................................................... 6
1.1.4 Can measured soil moisture data be used to improve
hydrological models and how can that be implemented? ............................................................. 8
1.2 Key research questions and approach ..................................................................................... 9
1.2.1 Key questions: ........................................................................................................................ 9
1.3 Experimental approach and data analysis ............................................................................. 10
1.4 Structure of this dissertation ................................................................................................... 11
Chapter 2 Spatial TDR technology– methodology and
feasibility for heterogeneous field soils .............................................................................. 12
2.1 Introduction .............................................................................................................................. 12
2.2 Theoretical background and Signal constrained inversion ................................................ 14
2.2.1 TDR inversion approaches ................................................................................................ 14
2.2.2 STDR Signal inversion ........................................................................................................ 14
2.3 Parameters and Potential error Sources of Spatial TDR-Measurements ......................... 15
2.3.1 Technological components and setup of a Spatial TDR ............................................... 15
2.3.2 Calibration of probe parameters ........................................................................................ 15
2.3.3 C-G relation .......................................................................................................................... 18
2.3.4 ε-soil moisture relationship 18
2.3.5 Probe deformations during installation ............................................................................ 19
2.3.6 Gravel and stones ................................................................................................................ 19
2.4 Laboratory experiments to quantify error sources .............................................................. 20
2.4.1 C-G relation, ε-soil moisture relation and
constraining of inverted moisture profiles .................................................................................... 20
2.4.2 Experiment 1: effect of uncoated and
coated probes on the reflectogram in field soils ........................................................................... 20
2.4.3 Experiment 2: performance in homogeneous media during transient conditions .... 22
2.4.4 Experiment 3: effect of probe deformations ................................................................... 24
2.4.5 Experiment 4: effect of solid objects in the integration volume .................................. 27
2.4.6 Experiment 5: measurement of soil moisture in disturbed soil .................................... 28
2.5 Discussion and Conclusions ................................................................................................... 30
Chapter 3 Soil moisure dynamics and runoff generation
in headwater catchments: learning from field data ............................................................ 33
3.1 Introduction and Motivation .................................................................................................. 33
i
3.1.1 How to observe the spatial distribution of soil moisture .............................................. 33
3.1.2 Investigation of the dominating runoff processes .......................................................... 35
3.2 Research area and additional data sets/methods incl. CATFLOW .................................. 36
3.2.1 Research area ........................................................................................................................ 36
3.2.2 Data Analyses and Modelling ............................................................................................ 42
3.2.2.1 TDR travel times, depth integrated soil moisture and outliers ............................ 42
3.2.2.2 Statistical and geostatistical analysis ......................................................................... 42
3.2.2.3 Rank stability ............................................................................................................... 43
3.3 Vegetation control on soil moisture dynamics:
learning form physically based simulations ........................................................................................ 45
3.3.1.1 Model description ....................................................................................................... 45
3.3.1.2 Model setup and simulation variants ....................................................................... 45
3.4 A field scale irrigation experiment to explore fast vertical
and lateral flow processes ..................................................................................................................... 47
3.4.1 Irrigation rates and sprinkling ............................................................................................ 47
3.4.1.1 Installation of soil moisture profile sensors............................................................ 48
3.4.1.2 Dye tracing .................................................................................................................. 48
3.4.2 Control of pre-event conditions and rainfall characteristics of flood events ............. 49
3.4.2.1 Estimating runoff coefficients .................................................................................. 49
3.4.2.2 Estimators of catchment wetness and the meteorological forcing ..................... 49
3.5 Results ........................................................................................................................................ 50
3.5.1 Average dynamics and spatial variability of soil moisture at the two clusters ............ 50
3.5.2 Average covariance structure ............................................................................................. 53
3.5.3 Rank stability of soil moisture time series ........................................................................ 54
3.5.4 Vegetation and soil control on hillslope scale soil moisture regimes ........................... 55
3.5.4.1 Model sensitivity to different soil profiles .............................................................. 55
3.5.4.2 Model fine tuning with LAI, plant cover and root depth ..................................... 56
3.5.4.3 Simulated average soil moisture dynamics 57
3.5.5 Irrigation experiment for the identification of the dominant runoff processes ......... 58
3.5.5.1 Spatial pattern of sprinkling rates ............................................................................. 58
3.5.5.2 Soil moisture dynamics from Spatial TDR and FDR observations .................... 58
3.5.5.3 Soil moisture pro