Level 2 Detail of experimental conditions (what might be found in a journal paper or project brief in Hydstra)

Description of study


Fourteen experimental catchments were established and topographic features, soils and land treatments and runoff was monitored between 1961 and 1974 (Table 1).

When and Where?

A catchment of 18.1 ha in area was selected on sandy soils near Nungarin, approximately 40 km north of Merredin. Construction of 0.610m deep parabolic, knife-edge weirs, with vertical surcharge plates, was carried out as the first in a series in November 1969.

The soils of this catchment are deep loamy sands. More clayey soils occur on steeper slopes near its northern boundary. Up to 36% of rainfall has run off this catchment when soils were initially relatively dry during extreme rains in February 1978. Less runoff occurred under higher antecedent moisture levels resulting from recent rainfall in May 1981.


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. 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 H. Williams

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:

  1. Bligh KJ. (2001). Small Farmland Experimental Catchment is Western Australia Resource Management Technical Report No. 82. Department of Agriculture Western Australia.


Cropping, runoff events, farmland, topography, soil


Level 1, Level 3, Level 4 and Level 5