Information
Hydrology, erosion and water quality study of central Queensland pastures on hard-setting soils (Springvale catchment study in the Nogoa catchment)
Also known as "Fred" This site has been described in 4 papers, listed in the references section.
Level 1 General description
Purpose:
A native pasture community, Springvale in Central QLD was monitored to determine the effects of management on runoff and soil loss.
Methods (brief)
A small catchment was instrumented in Central Queensland at “Springvale”, Willows, 75km west of Emerald. Hydrology and soil movement processes were examined under a range of pasture conditions at the small plot scale (10 to 100s m2) and for the entire catchment (9.6 ha).
Key findings (brief)
Silburn et al (2011) concluded that runoff was strongly influenced by surface cover and was high with low cover (30 – 50% of rainfall). Runoff averaged 35mm/year or 5.9% of rainfall with >50% cover. All soils fitted the same runoff-cover relationship. For all soils, erosion resulted in low sediment concentrations due to the hard-set surface soil, but total soil losses were high due to the large volumes of runoff generated.
Silburn II (2011) found that the use of a linear slope factor in the sediment concentration models was confirmed with data from plots with slopes 4-8%. Parameters for the bedload sediment concentration model were the same for SS, MS, and MSe soils. Parameters for the suspended sediment concentration model were the same for SS and MS soils, but the MSe soil had a greater efficiency of entrainment for bare soil (approximately double). The sediment concentration–cover relationships and fitted cover factors were different for suspended and bedload sediment. Thus, the resulting modelled proportion of sediment as suspended load changed with cover, from ~0.3 for bare soil to 0.9 at 80% cover, mimicking the measured data.
Silburn III (2011) concluded that the USLE LS (length–slope) factor explained the increase in measured average annual soil loss with slope, for plots with low cover. Erodibility (K) was 0.042 for SS and MS soils, K was 0.062 for exposed, decomposing mudstone (MSe Leptic Rudosol). The measured K factor for SS and MS soils was close to that used in catchment-wide soil loss estimation for the site (0.039).
Owens et al. (2003) found that total soil water prediction was very good using the Scanlan runoff sub-model (r21:1 = 0.88) and slightly improved using the modified model (r21:1 = 0.91). Soil water in the surface layer was predicted well, giving confidence in prediction of soil evaporation
Table 1. Mean annual runoff, erosion and water quality exploring the impact of slope and slope length in erosion quantities. Mean annual rainfall for Springvale is 610 mm.
|
Management Practice |
Cover % |
Slope length m |
Slope % |
LS |
Runoff mm |
Runoff as a Proportion of Rain % |
Measured Soil loss t/ha |
Measured EMC gm/L |
Normalised Soil loss t/ha |
Normalised EMC gm/L |
|
Grazed |
<20 |
30.3 |
6.8 |
0.8 |
200 – 300 |
33 - 49 |
5-17 |
3-8.5 |
10-27 |
3-6.5 |
|
Tree plots, ungrazed |
>50 |
22.15 |
6.7 |
0.7 |
35 |
6 |
~1 |
0.5-1.5 |
~1 |
0.5-1.5 |
|
Open ungrazed |
>76 |
15.65 |
7.9 |
0.7 |
<30 |
<6 |
<0.5 |
~0.2 |
<0.5 |
~0.2 |
Location
Springvale 24°41’S and 147°18’E.
Related studies
Fentie B, Yu B, Silburn, MD, Ciesiolka CAA. 2002. Evaluation of eight different methods to predict hillslope runoff rates for a grazing catchment in Australia. Journal of Hydrology 261: 102-114.