Information
Level 2 Detail of experimental conditions (what might be found in a journal paper or project brief in Hydstra)
Description of study
What?
Fourteen experimental catchments were established and topographic features, soils and land treatments and runoff was monitored between 1961 and 1974.
When and Where?
Two 18.1 ha experimental catchments considered potentially suitable for paired catchment studies were established on the property of Mr Paul Szczecinski at Kunjin. Sharp-crested 120° V-notch weirs were constructed on the catchments in 1968 by the Department of Agriculture, with the assistance of Corrigin Shire Council staff. “Ott XX” water level recorders and “Pyrox-Summer” pluviometers were installed, and recording commenced under the auspices of the Public Works Department in March 1969.
An area longitudinally traversing the catchment has loamy sands to 0.15 m, over sandy loams to 0.6 in, over sandy clay. Sandy loams overlying sandy clay at 0.1 in occupy areas to the north, with clays at the surface on further areas to the north and south.
Free water was observed to remain between contour-working ridges on the clayey soil surface for approximately four days after rain following a very wet period in July 1974, compared with approximately two days on the sandy loam, and no ponding on the loamy sand surface soil. Ponded sorptivity values were similarly ranked. Visual evidence of overland flow has been observed on the loamy sand soil only after high intensity summer rains. Steady-state ponded infiltration rates immediately below the cultivated layer of 4.2 x 10-5 ms-1 were measured on the loamy sand, compared with 7 x 10-9 ms-1 on the sandy loam and 1.6, 1.7, 5.6, 21 and 25 x 10-9 ms-1 at five sites on the clayey soil.
How?
Experimental catchments were equipped with sharp-crested weirs and floatoperated recorders. Two semi-parabolic weir plates merge tangentially into a 300 V-notch at 0.0305m stage, except at the Berkshire Valley and Kunjin gauging stations, where the weirs are combination 90° rectangular and 120° Vee-notches, respectively.
The depth-discharge rating curves of all of the weirs are theoretical. Rating curves applied to calculate flows over the parabolic weirs were modified by the Water Authority in 1985. Pondage drawdown measurements were taken using a large tank at the WAWA Engineering Research Station, and analysed. Results suggest that the theoretical curves currently used by the Water Authority may overestimate high flows.
Rainfall is recorded using 0.2 mm tipping-bucket rain gauges on each catchment. Rainfall and stage height are continuously monitored on the same recorder at each catchment for synchronization of records.
Runoff has been sampled in rising-stage bottles positioned at approximately 0.1 m intervals above cease-to-flow levels since 1983. Samples are routinely analysed by the Water Authority for turbidity, colour and sediment with particle sizes less than 63 microns. Further analyses are carried out as required either at the Water Authority or at the Chemistry Centre.
Topographical features of cleared farmland catchments were generally mapped when the catchments were selected. The surface areas of uncleared catchments were estimated using stereoscopic air photographs.
Ponded infiltration rates were measured using buffered infiltration cylinders after removing the cultivated layer in order to obtain vertical infiltration rates through the soil profile. Cylinders of 0.3 m diameter were driven approximately 0.1 m into the exposed soil, with three replications at several sites on such catchments.
All cropping treatments were carried out with the traditional two or three tillage practices up to the 1984 growing season, with the exception of lupins which were direct-drilled using a combine in a single pass (Table 1). All catchments were grazed by sheep in pasture and stubble phases of rotations in accordance with district practice.
Project administration
Site identifier code: N/A
Principal investigator: Bligh KJ
Principal data manager: N/A
Principal organizations: Department of Agriculture Western Australia
Data custodian: Department of Agriculture Western Australia
Key co-operators: Mr Paul Szczecinski, Corrigin Shire Council
Data access policy: Research has been published but base data is not archived
Planned pathway for data: completed study, no evidence of formal database records.
Data warehousing: for ongoing studies -na
Planned data upload frequency: for ongoing studies -na
Key references and sources of this data synthesis
These data summaries have been extracted from:
- Bligh KJ. (2001). Small Farmland Experimental Catchment is Western Australia Resource Management Technical Report No. 82. Department of Agriculture Western Australia.
Keywords:
Cropping, runoff events, farmland, topography, soil