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of δ i reaches a minimum value. In this study, all sampling locations with a MRD smaller than 5% and a low standard deviation
Chapter 4 Temporal stability of soil moisture and its application in model result validation and further select a modeled location (model certainty) with a prior time-stable analysis. Simply, we will therefore focus on the following steps: at first, we detect the best TSP in each plot, and then run the HYDRUS-1D model with this point to get the water dynamics throughout the whole monitoring time. Finally, we compare the model results applied in TSP with the measured value both from TSP and field fixed monitoring site to address the validity of this method. The van Genuchten hydraulic parameter of TSP is derived from data of soil texture and bulk density by the neural network prediction tool ROSETTA (Schaap et al., 2001). The calculated parameter is further optimized by in situ measurements of hydraulic conductivity using a Mini-disk Infiltrometer in 0.5 cm suction (Zhang, 1997). To link the spatial patterns of soil moisture and provide a validating data for a hydraulic model, in situ filed monitoring soil moisture was measured using horizontally inserted Theta-probes in three depths at 5, 20 and 40 cm. At each plot three replicate profiles were installed and connected to one solar powered automatic data-logger (type DL2e, Delta-T Devices, Cambridge, UK), and the depth-averaged soil moisture at 30-min intervals was used. During the experimental period, the in situ weather station recorded the precipitation and other variables necessary to estimate the reference evapotranspiration from FAO Penman-Monteith equation (Allen et al., 1998). Plant parameters, such as vegetation coverage, leaf area index, and plant height, were taken from vegetation measurements. Root samples were taken with soil root auger and soil cores were separated into five depths of 0-10, 10-20, 20-50, 50-70 and 70-100 cm (see details in Zhao et al., 2008b). 3. Results and discussion Temporal stability of soil moisture To investigate whether temporally stable locations exist within the field, we perform a visual inspection of the graphs presenting the ranked mean relative differences (MRD) with their errors (Figs. 2-5). In general, the MRD shows a strong temporal stability for most points at each plot during the period studied. The MRD ranges from –15.9 to +11.9% at UG 79, from –10.8 to +14.7% at UG 71
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SCHRIFTENREIHE Institut für Pflanz
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Aus dem Institut für Pflanzenernä
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I Table of contents I Table of cont
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controlling soil moisture are of pa
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Zusammenfassung Überweidung wird a
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Die Beweidung beieinflusst besonder
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II List of figures Fig. 2.1. Locati
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measured soil moisture in time stab
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III List of tables Table 2.1. Descr
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1.1 Background Chapter 1 Introducti
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Chapter 1 Introduction is also unce
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Chapter 1 Introduction water in spr
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Chapter 1 Introduction requires the
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Chapter 1 Introduction Krümmelbein
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Chapter 2 Spatial variability of so
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Page 89: Y orientation Chapter 4 Temporal st
Page 93 and 94: MRD(%) MRD(%) 100 80 60 40 20 0 -20
Page 101 and 102: Soil water content (%) 40 30 20 10
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Chapter 6 Modeling of Coupled Water
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Chapter 7 General discussion and co
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References Chapter 7 General discus
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8. ACKNOWLEDGMENTS Firstly I would
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Curriculum Vitae M.Sc. Ying Zhao Of
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Schriftenreihe des Instituts Neuere
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