WATER QUALITY OUTCOMES OF DIFFERING SUGARCANE MANAGEMENT PRACTICES IN QUEENSLAND
Monthly rainfall distribution of the study watershed over a period of four years are presented in Fig. 1. From this rainfall analysis results, monthly distribution for the year 2010 through 2014 is highly variable. Throughout this period of time, monthly rainfall is highly variable except in months of peak rainfall i.e. in December through March yearly (1.5 - 2.5 mm). Rainfall rate from this results has the same trend as rain runoff. This shows that soil loss and rain runoff as shown above are related directly. Where rainfall and runoff are highest, there's a high rate of soil loss and this happens in the months of December, January, February and March yearly. The higher runoff values corresponds to the higher rainfall values for this period.
The measured and simulated rainfall runoff values are plotted to obtain rainfall and runoff graph as shown in the figure 3 above. High value peaks of simulated runoff are formed at 634, 599, 631,632, 625, 604mm, the values of measured runoff is at 5.3, 2.2, 32.5, 11.4, 13 and 162mm respectively.
In figure 4., high values peaks are seen at 3.08, 3.5, 3.0, 3.5, 3.6, 3.2, 2.7, 2.9 and 2.6 (kg/m2) when runoff is 0 (mm) except for the peak 1.4 (kg/m2) when its corresponding runoff is at 1.4 (mm).
An analysis for peakRO was conducted and the graph plotted as shown in fig. 5. The monthly runoff corresponds to the actual plot data however, there are some partial variation which are attributed to uncertainty in soil characteristics. Trends found in the above figure depicts a change in the outputs of runoff and the uncertainty associated with PeakRO. A high value is recorded at 7.46 mm. This suggest that PeakRO is a key factor to soil detachment.
