Appendix I: MWD Border-Strip Watering Trials
1 INTRODUCTION
The Ministry of Works and Development (MWD) completed an extensive series of field trials in the early 1980’s to increase understanding of the efficiency of border-strip irrigation systems, and how to improve their design. The field trials were conducted on a large number of farms in several irrigation schemes throughout Canterbury. The data from the field trials was never fully analysed and used for the intended purpose, primarily because of staff changes and, finally, the closure of MWD’s Water and Soil Division.
One of the purposes of this project was to review the data from these trials to establish whether it could still be used to achieve the original purpose of the field trial.
Since the time of the field work there has been considerable developments in mathematical and computer models of border-strip flow. Development has reached the point where the preferred method of designing border-strip systems is to use a field validated computer model to investigate the effects of various design options on the efficiency and adequacy of irrigation events under a range of conditions. The focus of our review was therefore to establish whether the data available could be used to validate a suitable computer simulation model.
Proper validation of a border-strip flow model requires field data in two main areas. These are the hydraulics of shallow water flow and the infiltrability of the soil. The hydraulics of a border-strip flow event are fully described by data on the rate of advance of the wetting front and the rate of advance of the drying front (advance and recession curves). Together they determine the opportunity time for infiltration at any point on the wetted area. This, together with data on the infiltrability of the soil, enables calculation of the infiltrated depth of water at any point on the wetted area. This is essential data for determining the efficiency and adequacy of irrigation. Information on the soil water content at the time of irrigation, and on the soil water retention characteristics of the soil, is also required.
The following sections describe the data that is available from the MWD field trials and assess the suitability of the data for model validation purposes, as a prelude to border-strip design investigations.
2 MWD SURFACE IRRIGATION TRIALS - DATASET DESCRIPTIONS
File name |
Scheme name and approximate number of trials |
|
| Trial1.dat | Mayfield – Hinds |
27 |
| Trial2.dat | Waiau |
36 |
| Trial3.dat | Waiau |
36 |
| Trial4.dat | Waiau |
36 |
| Trial5.dat | Waiau |
32 |
| Trial6.dat | Ashburton–Lyndhurst |
23 |
Mayfield-Hinds |
5 |
|
| Trial7.dat | Feradays Island |
1 |
Greenstreet |
5 |
|
North Rakaia |
6 |
|
| Trial8.dat | Valetta |
25 |
| Trial9.dat | Waiau |
27 |
| Trial10.dat | Ashburton-Lyndhurst |
14 |
| Trial11.dat | Waiau |
64 |
Notes:
- There seem to be a number of ‘repeat’ trials that have the same number with ‘A’ ‘B’ etc. suffixes. Presumably these are on the same farm but in different areas.
- Many trials (maybe 70 percent) have soil moisture data but in repeated trials these values don’t appear to change.
- Soil moisture measurements appear to be for antecedent conditions only.
3 MWD SURFACE IRRIGATION TRIAL DATA - LIST OF CODES USED IN DATA FILES
3.1 Scheme name codes
WA WAIAU PLAINS
AL ASHBURTON LYNDHURST
FA FARADAY ISLAND
GS GREENSTREET
MH MAYFIELD HINDS
NR NORTH RAKAIA
VA VALETTA
3.2 Farm codes (with scheme prefix)
AL001 HORNE
AL003 MAGINNESS
AL005 LINCOLN COLLEGE RESEARCH STATION
AL009 BUICK
AL011 MORRIS
AL018 HARCOURT
AL021 WAKELIN
AL022 MONTE MONTEATHE/TARA
AL024 CAIRNS
AL030 DELLOW
AL031 BUTTERICK
AL034 GRANT
AL033 GRANT
AL019 DONT KNOW WHO
AL077 HENDERSON
AL116 MORRIS
AL135 GRANT
AL177 CAIRNS
AL999 DONT KNOW WHO
FA008 MONTGOMERY
GS006 EVANS
GS007 EVANS
MH001 MCCONNELL
MH002 MCKENZIE CHARITY FOUNDATION
MH003 MORRIS
MH004 DALY
MH005 WATSON
MH006 SLEE
MH007 HAYMAN
MH008 KNIPE
MH009 MCKEOWNS
MH010 ROLSTON
MH011 JONES
MH012 CRAIGE
MH013 JONES
MH014 REITH
NR001 GOURLAY
NR002 STUBBS
NR003 BREADING
NR004 BREADING
NR005 BREADING
VA009 ARMSTRONG
3.3 Farm Codes (With Scheme Prefix) – Cont’d
VA010 CAMPBELL
VA011 MCCORMICK
VA012 STOCKER
VA013 HARRIS
VA014 ORMROD
VA016 SCHOFIELD
VA017 GOOSEMAN
WA002 RUTHERFORD A
WA003 BURROWS J R
WA004 RUTHERFORD J S
WA005 GALLAGHER P J
WA006 ROBERTS T M
WA007 FARQUHAR H W
WA008 HENDERSON R H
WA009 THOMPSON B G M
WA010 BLACK M A
WA011 X
WA012 X
WA013 X
WA014 X
WA016 X
WA020 BURROWS C A
WA021 HOBAN
WA022 THOMSON R M
WA026 FLEMING L
WA027 BAKER A
WA028 BEAVEN G
WA029 LUMSDEN
WA030 MCMILLAN A
WA031 INNISKILLEN
WA032 MCINTOSH N H
WA033 STEEL
WA034 TAGG PARTNERSHIP
WA045 MCINTOSH R
WA046 MOSSMAN
WA049 DALZELL J G
WA050 O'CALLAGHAN K S
WA070 CHICK M D
WA071 MCINTOSH N E E
WA074 FLEMING R H
WA075 EARL W H
WA089 MCLAUGHLIN
WA090 DAVISON P
WA092 JAMIESON W
3.4 Farm Codes (With Scheme Prefix) – Cont’d
WA095 DAMPIER-CROSSLEY G P
WA103 MACFARLANE A D
WA120 DALZELL C L
WA129 OVERTON
3.5 Crop type codes
GRASS 1
GRASS AND CLOVER 2
CLOVER 3
LUCERNE 4
SEE NOTES 5
INVALID SELECTION =>6
INVALID SELECTION =>7
INVALID SELECTION =>8
INVALID SELECTION =>9
NOT RECORDED 0
3.6 Crop condition codes
NEW 1
DIRECT DRILLED 2
ESTABLISHED 3
DENSE 4
SPARSE 5
STALKY 6
SEE NOTES 7
INVALID SELECTION =>8
INVALID SELECTION =>9
NOT RECORDED 0
3.7 Weather type codes (Weather code 1)
RAINING 1
SHOWERY 2
DRIZZLY 3
OVERCAST 4
CLOUDY 5
FINE 6
SEE NOTES 7
INVALID SELECTION =>8
INVALID SELECTION =>9
NOT RECORDED 0
3.8 Wind condition codes (weather code 2)
WINDY 1
GUSTY 2
BREEZY 3
STILL 4
SPARSE 5
STALKY 6
SEE NOTES 7
INVALID SELECTION =>8
INVALID SELECTION =>9
NOT RECORDED 0
3.9 Sill type codes
STEEL IN CONCRETE 1
WOOD IN CONCRETE 2
WOOD 3
CONCRETE 4
STEEL 5
EARTHEN 6
SEE NOTES 7
INVALID SELECTION =>8
INVALID SELECTION =>9
NOT RECORDED 0
3.10 Sill condition codes
NEW 1
WEEDY 2
SHORT GRASS 3
OVERGROWN 4
SCOURED 5
BURIED 6
STALKY 7
SEE NOTES 8
INVALID SELECTION =>9
NOT RECORDED 0
3.11 Gate control type
PNEUMATIC 1
CLOCK 2
MANUAL 3
SEE NOTES 4
INVALID SELECTION =>5
INVALID SELECTION =>6
INVALID SELECTION =>7
INVALID SELECTION =>8
INVALID SELECTION =>9
NOT RECORDED 0
3.12 Headrace condition code
SHORT GRASS 1
OVERGROWN 2
WEEDY 3
SILTY 4
NO FREEBOARD 5
BACKWATERING 6
SCOURED 7
SEE NOTES 8
INVALID SELECTION =>9
4 SUITABILITY OF THE DATA TO IRRIGATION DESIGN
The data available, plus what could be obtained retrospectively, provides a valuable but incomplete basis for computer model validation. There are acceptable methods for overcoming the limitations of the dataset.
The main limitation of the dataset is the lack of information on the rate of movement of the drying front (or recession front). This is a particularly difficult phenomena to measure, and was not often attempted at the time the field-work was conducted. Most model validation studies have simply aimed to reproduce the advance front and have assumed that if this is correct the recession front will be also. The absence of recession front data is a weakness, but does not prevent the dataset being used constructively.
The MWD study did not measure the infiltrability of the soil on each study sight. However relevant data is available from Anthony Taylor’s PhD thesis to represent the infiltration characteristics of some of the soils in the mid-Canterbury area, in the manner required by most border-strip simulation models. Sufficient soil moisture data is available to set such models up with the appropriate initial conditions.
All other parameters typically required by border-strip flow models are available. One model has been obtained, but it has not been calibrated.
The most definitive basis for validating a border-strip flow model is to compare the infiltrated depth profile predicted by the model with the field measured profile. Technology was not available for doing this in the 1980s. However, experiments planned and subject to a Sustainable Management Fund bid will provide this information.
In summary, while the MWD dataset is not complete, it is expected that it can be used successfully for model calibration and design purposes, provided it is supplemented with soils data from other sources. The availability of this supplemental data is likely to limit the area of application to mid-Canterbury.
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