Information
Level 2: Details of Experimental Conditions and Methods
When and Where?
The Herbert River catchment is located on the southern wet tropics. The catchment averages about 1500 mm a year. The amount of rain can vary depending on the location within the catchment. A total excess of about 3000 mm occur on top of the Cardwell Range, while areas to the west receive approximately 750 mm. Of the total average rainfall about 75% falls in the warmer summer months between December and April.
The average temperature in Ingham which is located on the coastal side of the catchment records maximum temperatures of 32oC, with a mean of monthly temperature of 25oC during the summer months. During the winter months maximum temperatures reach 25oC, with mean monthly temperatures of 13oC.
The Ripple Creek was mapped at a scale of 1:100,000 and at 1:8,000. Soils in the alluvial fans at the foot slopes of the granitic and acid volcanic hills contain fine gravel or sand throughout the profile. In the upper part of the alluvial fans the soils are generally red, while grey colours occurs at the down slope end of the fans. The following soils occur within the study site:
- Rungoo (Rg): 0.05-0.15m dark loamy sand to light sandy clay loam A1 horizon over conspicuously bleached A2 horizon to 0.4-0.75m over acid mottled grey, yellow-brown to yellow fine gravelly sandy clay to medium clay B horizon to 1.2 m
In the sediment that derived from the creeks that drain the local hill-slopes creeks alluvial soils have formed. These include:
- Ripple (Rp): 0.1-0.3m dark loam fine sandy to clay loam, fine sandy A1 horizon over conspicuously bleached A2 horizon to 0.3-0.7m over acid strongly mottled grey to grey-brown medium to heavy clay B horizon to 1.2+m.
Most of the soil types within the Ripple Creek catchment include the following:
- Toobanna (Tb): 0.1-0.3m dark to grey-brown loam fine sandy to clay loam fine sandy A1 horizon over conspicuously bleached A2 horizon to 0.3-0.8m over acid to alkaline mottled yellow-brown to brown medium to heavy clay B horizon to 0.6-1.2+m over acid to alkaline mottled grey to yellow-brown sand to sandy clay loam D horizon to 1.2 m;
- Hamleigh (HI): 0.1-0.2m dark to grey-brown hard setting silty clay to medium clay A1 horizon over sporadically bleached A2 horizon to 0.35m over acid to alkaline mottled grey to grey brown medium to heavy clay B horizon to 1.2 m;
- Leach (Lh): 0.15-0.2m dark to grey-brown light medium clay A1 horizon over sporadically bleached A2 horizon to 0.35m over acid to alkaline mottled grey to grey brown medium to heavy clay B horizon to 1.2 m.
Most of the soil within the Ripple Creek catchment are classified as silty clays and terrace silt loam.
The hills and mountains of the Cardwell and Seaview Ranges provide a clear geomorphic contrast with lowlands of the Lower Herbert River catchment. The Ranges surrounding the lowland have a low to very high relief with gently inclined to precipitous slopes and fixed erosion stream channel. The lowlands is a fan shaped depositional area spreading out towards the Coral Sea. Within the lowland a geomorphology subdivision can be made between deposits of mainly fluvial origin and deposits of a marine origin.
The Herbert River has a channel pattern ranging from low sinuosity to meandering stretches. The Herbert River Delta is described as alluvial plains as an asymmetric delta. With the most recent deposits occurring on the northern edge of the delta. The creek pattern of the Lower Herbert alluvial plain are the remnants of a network of prior deltaic distributaries.
How?
Roth et al, 2004
Two experimental sites were selected that fulfilled the general methodology for developing sediment budgets. One site represented cane land in the Herbert River catchment and the other was a typical erosion hotspot in grazing lands of the Burdekin River catchment.
In the Lower Herbert, the study area chosen comprised a 5.4 km2 portion of Ripple Creek sub-catchment, of which 3.2 km2 is the alluvial plain used for cane growing. The remainder is characterised by adjacent forested slopes of the Mt Leach Range. Four general monitoring strategies were employed:
- Paddock scale run-off flumes on ratoon and plant cane fields (to determine the net loss at paddock scale; flume plot area ~ 1 ha);
- Spatially distributed grab sampling (during major events; targeted at capturing runoff from individual cane land elements);
- Cross-sectional measurements in drains and water furrows using a profiler (pre and post wet season);
- Erosion pin arrays on headlands and in drain banks (~ 100 pins per array; measurements with electronic callipers pre and post wet season).
Stream gauging was carried out in the 1999-2000 and 2000-2001 wet seasons to determine sub-catchment sediment discharge as an independent measure of net sediment export.
Weany Creek (13.5 km2) is located in the Burdekin River catchment and was selected as it is typical of the excessively grazed hilly country on Granodiorite-derived red duplex soils with historically high rates of sheet and gully erosion. Monitoring methods employed were as follows:
- Micro runoff plots, to assess runoff and sediment generation rates for different cover and surface conditions;
- Hillslope erosion troughs, to quantify hillslope sheet erosion (bedload and suspended sediments);
- Cross-sectional measurements in flow lines using a profiler (pre and post wet season);
- Erosion pin arrays (~ 100 pins per array; measurements with electronic callipers pre and post wet season), to determine erosion and deposition within different components of gullies;
- GPS surveys, to determine gully head advance rates;
- Gully network surveys, using aerial photo interpretation and ground-truthed categorisation of gully phases.
In addition, a modification of the SedNet sediment transport model was used to extrapolate the measurements and construct the watershed budget. The model is based on a simple conceptualisation of hydrological transport and deposition processes within a GIS spatial modelling framework. Amongst other factors, SedNet assisted in determining bank erosion, for which there were no direct measures. This was complemented by stream gauging to determine subcatchment sediment discharge as an independent measure of net sediment export. Measurements were carried out in the 1999-2000, 2000-2001 and 2001-2002 wet seasons.
Visser et al, 2007
Data was collected during two wet seasons from November to May in 1999 – 2000 and 2000 – 2001. Gauged runoff flumes were used to measure sediment transport to identify the the net contribution to the sediment budget.
Two adjacent ratoon fields were sampled with Parshall flumes and two sections of a plant cane field were sampled with cutthroat flumes. Water levels in the flume were continuously measured with a Dataflow pressure transducer (0-5 m). Because field runoff through the flumes were often retarded due to backwatering against adjacent drains, the flume were equipped with Unidata Starflow Doppler velocity meters. Runoff events were sampled every half hour with an ISCO automatic sampler for suspended solids analysis.
Erosion pins were used to measure the headland input. Plots of 35-45 pins with washers were positioned as 5 pin wide transects between the edge of the fields and the drains. During the 99–00 season 13 plots were distributed through the catchment. In the 00–01 season seven plots were used to estimate the budget contribution for headlands.
The contribution of both drains and water furrows was estimated from changes in cross-sectional profiles. For this purpose a ground profiler was built. Profiles were distributed through the catchment so that they covered various soil types. In the 99–00 season an extra division was made for the crop status of the field surrounding the furrow profiles (plant cane or ratoon). In the 00–01 season there were no sites in plant cane available to repeat this. In total 50 profiles were measured during the 99–00 season and 27 during the 00–01 season.
The catchment outlet was continuously gauged with a pressure transducer and a Greenspan TS1000 turbidity meter. Because Ripple Drain was also affected by backwatering conditions, it was equipped with a similar velocity meter as the flumes.
A total number of 261 grab samples were taken during major rainfall/runoff events at various locations in the study area and analysed for suspended solid concentration (SSC). From the grab samples a linear relationship was found between in-stream turbidity and SSC. This relationship was used to estimate SSC from the continuous Greenspan turbidity data at the different gauging sites.
The sediment budget is described by the following mass balance equation:
I – S = O
I- the amount of sediment input into the drainage system from each of the landscape elements.
S- The amount of deposition within each landscape element
O- The amount of total output sediment from the studied area.
Principle Investigator
A Sediment Budget for a cultivated floodplain in tropical North Queensland, Australia
- Fleur Visser;
- Christian H. Roth;
- Robert Wasson; and
- Gerard Govers.
Sediment budget for cane land and grazing lands in Northern Queensland, Australia and their use to target appropriate measures to control sediment export.
- C.H. Roth;
- F. Visser; and
- D.A. Post.
Sediment budget for cane land on the Lower Herbert River floodplain North Queensland, Australia
- Fleur Visser
Principle Organisations
A Sediment Budget for a cultivated floodplain in tropical North Queensland, Australia
- University of Worcester;
- ACIAR;
- Charles Darwin University; and
- University Leuven.
Sediment budget for cane land and grazing lands in Northern Queensland, Australia and their use to target appropriate measures to control sediment export.
- ACIAR;
- University of Leuven; and
- CSIRO