Final LDC WQ Report | 页面 67

Figure 24 . Location of the Mt Pleasant ( left ) and the Treatment and Control gullies . The location of the installed treatment structures and monitoring equipment / locations are shown .
Table 12 . Summary of monitoring outcomes for the 2019-20 and 2020-21 wet seasons at the Mt Pleasant treatment and control sites . Source : Derived from Bartley et al . ( 2020 and 2021 ).
Mt Pleasant
2019-20
Treatment
Control
2020-21
Treatment
Control
Site Rainfall ( mm ) 1
440
449
765
729
Hillslope (% cover )
93 %
90 %
91 %
97 %
Gully walls (% cover )
67 %
71 %
67 %
71 %
Gully floor (% cover )
47 %
6 %
47 %
6 %
Flow weighted annual average TSS concentration ( mg / L )
70
93
252
115
Total TSS loss ( t / y )
6.10
1.8
36.2
10.5
TSS yield ( t / ha )
0.02
0.03
0.14
0.04
Flow weighted annual average TN concentration ( ug / L )
70
93
1,437
1,587
Total TN loss ( kg / y )
na
na
206
30.3
TN yield ( kg / ha )
na
na
0.8
0.6
Note : Catchment area ( ha ) above the monitoring stations is 258.7ha for the treatment and 54.8ha for the control ,
measured using LiDAR .
1
Long term rainfall is 687 mm ( BOM 2000 – 2019 ).
Vegetation The vegetation data collection commenced at this site in December 2019 for the hillslopes and gullies . It is important to note that the hillslope vegetation surveys are in the upper part of the catchments of both gullies . This will assess if there is any future change in the proportion of vegetation that may influence the rainfall and runoff entering the gully site .
Overall , the cover and biomass levels on the hillslopes are very high compared to other grazed sites with percentage cover measured as > 80 % for both control and treatment sites with biomass reaching nearly 3,000 kg / ha at the control site prior to the wet season . In both 2019-20 and 2020-21 , the cover and biomass declined at the control site , but it did not change significantly at the treatment site . The only
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