Acknowledgment ................................................. iv
Abstract ........................................................ v
Table of Contents ............................................. vii
List of Tables .................................................. x
List of Figures ............................................... xii
List of Symbols ............................................... xvi
1 Introduction ................................................ 23
1.1 Motivation ............................................. 23
1.2 Furrow Irrigation Practice ............................. 24
1.3 Potentials of Furrow Irrigation Modeling ............... 25
1.4 Need for this Study .................................... 25
1.5 Objectives of this Study ............................... 26
2 Principles of Furrow Irrigation Modeling .................... 28
2.1 Water Balance .......................................... 28
2.2 Surface Flow ........................................... 29
2.2.1 Flow Characteristics ............................ 30
2.2.2 Phases of an Irrigation Event ................... 30
2.2.3 Flow Equations .................................. 31
2.3 Subsurface Flow ........................................ 35
2.3.1 Infiltration and Redistribution ................. 35
2.3.2 Dynamics of Water Flow .......................... 37
2.4 Crop Growth ............................................ 41
2.5 Irrigation Performance Criteria ........................ 42
2.5.1 Irrigation Efficiency ........................... 42
2.5.2 Application Efficiency .......................... 43
2.5.3 Distribution Uniformity ......................... 43
2.5.4 Adequacy ........................................ 44
2.5.5 Evaluation of Performance Criteria .............. 44
3 State of the Art of Irrigation Modeling ..................... 46
3.1 Surface-Subsurface Flow Models ......................... 46
3.2 Crop Models ............................................ 52
3.3 Irrigation Model Review - Conclusions .................. 53
4 Experimental Data ........................................... 54
4.1 Data from Literature ................................... 54
4.2 Laboratory Experiments ................................. 55
4.2.1 Laboratory Setup ................................ 56
4.2.2 Determination of Soil Hydraulic Parameters ...... 58
4.2.3 Conclusions from the Laboratory Experiments ..... 59
4.3 Field Experiments Kharagpur, India ..................... 63
4.4 Field Experiments Montpellier, France .................. 64
5 Physically Based Modeling of the Surface-Soil-Crop System ... 67
5.1 Analytical Zero-Inertia Surface Model FAP .............. 67
5.1.1 Advance Phase Model ............................. 68
5.1.2 Storage Phase Model ............................. 71
5.1.3 Depletion and Recession Phase Model ............. 74
5.1.4 FAP - Visualization ............................. 77
5.2 Subsurface Flow Models in the Study .................... 78
5.2.1 ID Flow Models .................................. 78
5.2.2 2D-Flow Model HYDRUS-2 .......................... 79
5.2.3 Transformation Model FURINF ..................... 81
5.2.4 Sensitivity and Error Analysis of
the Subsurface Flow Models ...................... 88
5.3 Crop Growth Model LAI-SIM .............................. 93
5.3.1 Structure of Evapotranspiration - Potential
Crop Transpiration .............................. 93
5.3.2 Leaf-Area Index Prediction ...................... 94
5.3.3 Crop Yield ...................................... 95
5.4 Coupling Surface and Subsurface Flow ................... 97
5.4.1 Principles of Alternating Iterative Coupling .... 98
5.4.2 Coupling FAP-Advance Model and Infiltration ..... 99
5.4.3 FAPS - from Time to Space Discretization ....... 106
5.4.4 Coupling during Storage, Depletion and
Recession Phases ............................... 115
5.4.5 FAPS with quasi 2D Infiltration model FURINF ... 116
5.4.6 FAPS Model Test ................................ 116
5.4.7 FAPS Model Validation and Sensitivity
Analysis ....................................... 119
5.4.8 Coupling Surface-Subsurface Flow -
Discussion ..................................... 136
5.5 Coupling LAI-SIM and HYDRUS-2 ......................... 139
5.5.1 Common Boundaries .............................. 139
5.5.2 Plant Water Stress ............................. 142
5.5.3 Crop Model Coupling Methodology ................ 144
5.5.4 Crop Model Sensitivity Analysis ................ 147
5.6 Complete Furrow Irrigation Model - FIM ................ 150
5.6.1 Modules ........................................ 150
5.6.2 FIM - Model Range of Applicability ............. 152
5.6.3 Time Management and Event Control .............. 152
5.6.4 Graphical User Interface ....................... 155
6 FIM - Model Validation and Application ..................... 166
6.1 FIM Parameterization .................................. 166
6.2 FIM Simulation ........................................ 169
6.3 FIM Simulation Results and Discussion ................. 170
6.3.1 Irrigation Advance and Irrigation
Performance .................................... 170
6.3.2 Water Balance and Water Storage ................ 173
6.3.3 Impact of Irrigation Practice on Water
Storage ........................................ 175
6.3.4 Soil Moisture Profiles ......................... 176
6.3.5 Overall Irrigation Efficiency .................. 178
6.3.6 Evapotranspiration ............................. 179
6.3.7 Leaf Area Index ................................ 180
6.3.8 Yield .......................................... 181
7 Summary .................................................... 182
8 Future Prospects ........................................... 184
References .................................................... 185
A Appendices ................................................. 197
A.l TDR-Calibration ....................................... 198
A.2 Field Experimental Data ............................... 200
A.3 Instructions for FIM Parameterization ................. 203
A.4 FIM - Irrigation Schedule on Demand ................... 205
В Selected Publications ...................................... 209
LIST OF TABLES
1 Selected furrow irrigation models ........................... 47
2 Furrow modeling input data for the coupled surface-
subsurface flow model ....................................... 55
3 Specifications of the laboratory experiments ................ 57
4 Laboratory experiments - initial matric head in the soil .... 58
5 Soil hydraulic characteristics of the experimental site
in Kharagpur (India) ........................................ 63
6 Furrow model input data: field experiments at IIT
Kharagpur (India) ........................................... 64
7 Field experiments at IIT Kharagpur (India): initial matric
head ........................................................ 64
8 Irrigation parameters - Lavalette site, Montpellier
(France) .................................................... 65
9 Soil hydraulic characteristics for the Lavalette site,
Montpellier (France) ........................................ 66
10 Soil hydraulic parameters for three experimental soils ...... 84
11 Sensitivity analysis of the subsurface-flow models -
corresponding time and space discretization for the test
runs ........................................................ 89
12 Comparison of CPU-time and RAM requirements of HYDRUS-2
and FURINF-A ................................................ 90
13 Variance σ2 and absolute deviation Δ of cumulative
infiltration for corresponding infiltration simulations
by the subsurface models .................................... 91
14 Plant specific parameters for simulating leaf-area index .... 95
15 Yield module parameters ..................................... 97
16 Advantages and disadvantages of FAPS and FAP model
features ................................................... 107
17 Performance criteria for different Zl-models in case of
the FS47 run ............................................... 120
18 Performance criteria for different Zl-models in case of
the WP11 run ............................................... 121
19 Performance indices for predicted FAPS-K advance and
recession times ............................................ 124
20 FAPS-K input parameter sensitivity ......................... 126
21 FAPS-K input parameters in decreasing order of
sensitivity index, SI ...................................... 127
22 Performance Indices of the laboratory experiments .......... 129
23 Performance Indices of the Kharagpur field experiments ..... 131
24 Performance indices of the Lavalette field experiments ..... 133
25 Modified soil hydraulic parameters of the FS47 and
Flowell-wheel experiments .................................. 133
26 FAPS-H input parameter sensitivity ......................... 135
27 FAPS-H input parameters in decreasing order of
sensitivity index, SI ...................................... 136
28 Parameter values of the LAI-SIM sensitivity analysis ....... 147
29 LAI-SIM input parameter sensitivity for LAI ................ 148
30 LAI-SIM input parameter in decreasing order of
sensitivity index, SI ...................................... 149
31 Irrigation schedule of the Tα-plot at the Lavalette
experimental field, France (1999) .......................... 166
32 Modified soil hydraulic parameters of the Lavalette plot ... 169
33 CPU time requirements for the simulation of the Lavalette
run by FIM ................................................. 170
34 Simulated irrigation performance measures of the
Lavalette - irrigation events LI, L2 and L3 ................ 171
35 Measures for calculating the performance criteria of the
irrigation events .......................................... 172
36 Total water balance components of the Lavalette-run ........ 173
37 Meteorological data from May 1- 26, 1999 at the Tα-plot
of the Lavalette experimental site (France) ................ 200
38 Meteorological data at the Tα-plot of the Lavalette
experimental site (France) for the time between the 1st
simulation day (May 26, 1999) and the 96th simulation
day ........................................................ 201
39 Meteorological data at the Tα-plot of the Lavalette
experimental site (France) for the time between the 97th
simulation day and the 138th simulation day (October 11,
1999) ...................................................... 202
LIST OF FIGURES
1 Land under irrigation as a percentage of the total
cropland (FAO, 2002) ........................................ 23
2 Evaluation of furrow irrigation in basins of the Fordwah-
Eastern Sadiqia irrigation system, Punjab, Pakistan
(photo: Th. Wohling) ........................................ 24
3 Water balance parameters for a furrow irrigated field ....... 28
4 Hydraulic phases of an irrigation event ..................... 31
5 Wetting front in a soil body resulting from infiltration
from a furrow and a border .................................. 36
6 Soil hydraulic functions of three different soils ........... 40
7 The components of evapotranspiration during a growing
season ...................................................... 41
8 Irrigation on Lolium Multiflorum at the experimental tank
in the Hubert-Engels Laboratory, Dresden University of
Technology (photo: Th. Wöhling) ............................. 56
9 Laboratory experiments: location of tensiometer probes
in the experimental tank .................................... 57
10 Inverse soil hydraulic parameter estimation - error
function for varying van Genuchten parameters α and n ....... 59
11 Cracks due to soil settlements after initial watering of
the experimental tank at the Hubert-Engels Laboratory
(photo: R. Tackmann) ........................................ 60
12 Pressure head distribution of the head, middle and tail
section of the furrow at t = 30 min of the first
irrigation at the Hubert-Engels-Laboratory .................. 61
13 Preferential flow paths due to cracks at x = 19.4 m of
the experimental furrow in the Hubert-Engels-Laboratory.
(photo: J. Rawson) .......................................... 61
14 Experimental site at IIT Kharagpur, India (photo:
D. Rao) ..................................................... 63
15 СЕМAGREF experimental site at Montpellier, France
(photo: СЕМАGREF ............................................ 65
16 Modeling irrigation advance - the concept of the "virtual
wave" ....................................................... 67
17 Principles of modeling furrow irrigation advance ............ 68
18 Impact of uniform flow depth, hwl in the late storage
phase (S-II) on cumulative infiltration, Vinf(t) ............ 73
19 Principles of the recession phase model ..................... 74
20 Depletion phase model ....................................... 76
21 FAP surface flow visualization - real field size during
advance phase ............................................... 77
22 FAP surface flow visualization - virtual field during
recession phase ............................................. 77
23 FURINF working principle for computing cross sectional
furrow infiltration ......................................... 82
24 Discretization technique of FURINF .......................... 82
25 Steady state infiltration from cylindrical cavities (from
Philip, 1984) ............................................... 84
26 Comparison of flux lines for short and large infiltration
times - HYDRUS-2 simulation and FURINF assumption of
radial flux lines ........................................... 86
27 Impact of FURINF furrow spacing on calculated cumulative
infiltration from a semi-circular furrow into Lavalette
silt loam ................................................... 87
28 Initial soil moisture profile from field experiments and
cumulative infiltration of HYDRUS-2 simulations with (1)
the initial moisture profile and (2) an averaged soil
moisture θi ................................................. 87
29 ID Infiltration - comparison of R1DN and HPS ................ 91
30 2D Infiltration from furrows - comparison of FURINF-A and
FURINF-N .................................................... 92
31 2D Infiltration from furrows - comparison of FURINF-A and
HYDRUS-2 .................................................... 92
32 Principles of alternating iterative coupling at a certain
time step of the advance phase .............................. 98
33 Flow domain of the coupled surface-subsurface flow
model ...................................................... 100
34 Principles for coupling surface and subsurface models ...... 101
35 Convergence behaviour of three test runs by FAP-H .......... 105
36 Realization of wave-tip velocity ........................... 112
37 Time derivation of the FAPS volume balance function ........ 114
38 Case study of the Newton iteration scheme with two
different approximations of  Vinf(tm)/tm ................... 115
39 FAPS- and FAP-convergence for varying inflow rate .......... 117
40 Simulated advance times by FAPS and FAP with (i)
momentum representative cross-section at the moving
centre of gravity of the surface water body and (ii)
at the field inlet ......................................... 118
41 Predicted advance and recession times for the FS47
experiment ................................................. 121
42 Predicted advance and recession times for the WP11
experiment ................................................. 122
43 Predicted advance and recession times for Matchett 2-3-5
the experiment ............................................. 123
44 Predicted advance and recession times for the Printz
3-2-3 experiment ........................................... 124
45 Predicted advance and recession times for the
Flowell-wheel experiment ................................... 125
46 Observed and predicted advance times of the laboratory
experiments, Run 1 ......................................... 128
47 Observed and predicted advance times of the laboratory
experiments, Run 4 ......................................... 128
48 Observed and predicted advance times of the laboratory
experiments, Run 5 ......................................... 128
49 Measured and simulated pressure head of the laboratory
experiment, Run 1 .......................................... 129
50 Measured and simulated advance and recession times of
the Kharagpur field experiments ............................ 130
51 Measured and simulated advance times of the Lavalette
field experiments .......................................... 131
52 Simulated cumulative infiltration and advance times of
the runs FS47 and WP11 by both FAPS-K and FAPS-H after
calibration of soil hydraulic parameters of the VGM
model ...................................................... 134
53 Principles of coupling the crop model LAI-SIM and the
subsurface flow model HYDRUS-2 ............................. 139
54 Common boundaries LAI-SIM HYDRUS-2 ........................ 140
55 Crop coefficient, Kc, and root depth, zr, during
a growing season ........................................... 141
56 Water stress response function, s(hm) ...................... 143
57 Crop model and subsurface flow coupling scheme ............. 144
58 Impact of stress index prediction on leaf area index ....... 146
59 Modules of the furrow irrigation model system FIM .......... 151
60 Simplified time-line of the model system FIM (Chart
symbols and description explained in Section 5.6.3) ........ 153
61 FIM-GUI - main scenario window ............................. 156
62 FIM-GUI - furrow geometry window ........................... 158
63 FIM-GUI - crop parameter window ............................ 158
64 FIM-GUI - root growth and water stress parameter window .... 159
65 FIM-GUI - subsurface flow input window ..................... 159
66 FIM-GUI - climate data window .............................. 160
67 FIM-GUI - general output window ............................ 161
68 FIM-GUI - surface flow window .............................. 162
69 FIM-GUI - plant water and atmospheric data window .......... 162
70 FIM-GUI - leaf area index window ........................... 163
71 FIM-GUI - water content window ............................. 164
72 FIM-GUI - pressure head distribution window ................ 164
73 FIM-GUI - inflow/infiltration ratio window ................. 165
74 Subsurface flow domain and FE-mesh grid for the
Lavalette experiments ...................................... 167
75 Calculated initial soil moisture distribution at the day
of sowing of the Lavalette run ............................. 168
76 Meteorological data observed at the Tα-plot of the
Lavalette site (1999) ...................................... 169
77 Simulated and observed irrigation advance times of
the Lavalette-vuns LI, L2 and L3 ........................... 171
78 Observed and simulated soil water storage at the
upstream section, Xinf = 32.5 m, during the entire
growing season (1999) ...................................... 175
79 Observed soil water storage at upstream, middle, and
downstream section during the 1999 growing season .......... 175
80 Simulated and observed soil moisture profiles at
x = 20 m / Xinf — 32.5 m for various times during
the Lavalette run .......................................... 177
81 Simulated soil moisture distribution at xinf = 32.5 m
for various times during the Lavalette run ................. 178
82 Simulated components of evapotranspiration at xinf =
32.5 m during the entire growing season of the
Lavalette-run .............................................. 179
83 Observed and predicted leaf area index, LAI, during
the entire growing season of the Lavalette run ............. 180
84 Electric impedance curve of a TDR probe in pure water ...... 198
85 FIM automatic schedule control: main scenario window ....... 205
86 FIM automatic schedule control: evapotranspiration
components ................................................. 206
87 FIM automatic schedule control: leaf area index window ..... 206
88 FIM automatic schedule control: water content window ....... 207
89 FIM automatic schedule control: inflow / infiltration
window ..................................................... 207
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