Information
Level 2: Details of Experimental Conditions and Methods
When and Where
The study was carried out in the Burdekin River Catchment, a major catchment of the Great Barrier Reef (approx 130,000 km2) west of Townsville. The site study was conducted on April 1999
The general description of the site is as follows:
- Moderate to heavy grazed site;
- Ground cover patchy with large interspersed scalds; and
- General site condition poor.
Soil Type
The soils on site are varied but generally old and weathered with a large proportion of duplex soils. With the exception of soil derived from basalt (Vertosols or Ferrosols) most of the soils are low in fertility and due to their textual properties, are particularly prone to crust and hard setting. The six sites are located on duplex or grandational soil types that are common within the Upper Burdekin River Catchment.
Soil Description for Simpson's Dam (Site 2):
- Brown and Yellow Chromosols (Bluff Series);
- Sand 68-79%
- Clay 14-23%
- Bulk Density 1.46-1.67g/cm3;
- OM content 0.7-3.5% C;
- Moisture 0.05-0.11% volume;
- Ground Cover 0-100%; and
- Biological Activity 1-2.
Landscape Features
Features of Site 3 include:
- Reid River Box dominant tree species;
- Desert Bluegrass, Golden Beard Grass and Hairy Panic are the dominate grass and legume species;
- Hillslope position and angle is Upper-Mid slope 1-3%; and
- Metamorphic rocks and metasediments (Geology).
How
Six sites were selected on duplex and gradational soil types typical of large parts of the catchment. Individual plots reflecting the main classes identified were selected with two to four replicates per class, resulting in about ten to sixteen plots per site.
The rain simulator consisted of 1m2 capillary tube (inner diameter 0.5mm) drop forming chamber mounted on a 4m high aluminium tower. The tower is attached to trailer that support the equipment to conduct the rainfall simulation.
The rainfall intensity varied between 30 and 75mm h-1. The targeted intensity for this study was 60mm h-1 for 30 mins, which is represents a storm event having about a 1 year return period for northern Queensland.
Metal runoff plot frames 0.4 by 0.6m in size were placed in the middle of the rainfall plot, thus allowing a 0.2-0.3m buffer zone around the plots. An angle grinder was used to cut slots into dry ground to enable insertion of the frame into the soil without disturbing surface features.
The soil features recorded from the experiment include the following:
- Estimate of ground cover (green material and litter);
- An assessment of microreleif and plot slope; and
- Range of macroscopically visible crust.
In addition the following criteria were recorded as proposed by (Tongway and Hindley, 1995), this includes:
- Presence and type of crust;
- Extent of cryptogams;
- Extent and nature of surface lag and gravel cover;
- Presence of pedestals;
- Degree of litter incorporation;
- Presence of macropores; and
- Extent of surface casting.
Soil cores were taken from within each plot after the event for bulk density measurements at depth of 1-5cm. Soil moisture was measured to a depth of 1-5cm for each plot.
Site identifier code: N/A
Principal investigator: Roth CH
Principal data manager: N/A
Principal organizations: CSIRO
Data custodian: CSIRO
Key co-operators: N/A
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