Information

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

Description of study

What?

Surface lowering by sheetwash, rilling and deflation in a small (19km2) catchment in the Barrier Ranges was monitored over a 10-year period.

When and Where?

The study commenced in 1981 and continued for 10 years. The site was located on the valley floor adjacent to Homestead Creek, an upland tributary of Fowlers Creek, which flows in a north-easterly direction through the northern Barrier Ranges towards Lake Bancannia.  The main valley floor consists of a narrow strip of alluvium up to 270 m wide and 5 km long into which Homestead Creek is entrenched (Figure 1), and which is currently undergoing sever erosion. The surface soil has been severely degraded by sheetwash, rilling, gullying and aeolian deflation, leaving extensive bare areas (scalds). Vegetation throughout the region is comprised of bladder saltbush/copperburr with limited amounts of tussock grasses such as Mitchell grass. Mulga (Acacia aneura) and Belah (Casuarina cristata) trees are present on the steeper slopes.  The study site itself has limited vegetation with saltbush restricted to the hummocky surface of the Upper Unit.

How?

A grid system of erosion pins was established on the eastern bank of Homestead Creek. It comprised a rectangular plot, 35m x 15m, in which 198 thin steel rods, 200mm in length, were installed. The rods were installed leaving 10mm above the surface. A galvanised washer was placed over the rod head, which was split to prevent the washer from slipping off.

Two long east-west oriented transects each containing 36 pins were installed 15m apart, extending from the base of the close-gullied channel bank, across the valley floor surface, to the base of the adjoining hillslope.

Nine north-south oriented transects containing 14 pins each were established between these at approximately 5 m intervals.  Pins were placed at 1m intervals on all transects.

Measurements of erosion and deposition at each pin were made at 6 monthly intervals until February 1981, and again in May 1991 (a 10 year interval). The amount of erosion at each pin was determined by measuring the distance between the base of the split in each pin head (i.e. the 10mm mark) to the base of the washer using a metal measuring tape. Measurements were made to the nearest millimetre. Deposition at each pin could also be determined by measuring the thickness of any material deposited on top of the washer.

In order to minimise error; measurements were made by one operator using the same measuring tape. All readings were made on the upslope side of the pin, as it was considered to be the least influenced by the presence of the pin itself.

Project administration

Site identifier code: N/A

Principal investigator: Fanning P

Principal data manager: N/A

Principal organizations: Macquarie University, University of NSW

Data custodian: Macquarie University

Key co-operators: Fowlers Gap Arid Zone Research Station

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 N/A

Planned data upload frequency: for ongoing studies N/A

Key references and sources of this data synthesis

These data summaries have been extracted from:

  1. Fanning P. (1994). Long-term contemporary erosion rates in an arid rangelands environment in western New South Wales, Australia. Journal of Arid Environments. 28: 173 – 187.

Keywords:

Erosion rates, soil loss, arid rangelands, overgrazing

 

 

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