Fig 1.
Study sites (closed circles), rivers and catchment boundaries within north tropical Queensland, Australia (left panel), the Wet Tropics (MR; middle panel) and Mackay Whitsunday regions (PR and SC; right panel). Closed triangles show the major towns of Cairns, Townsville and Mackay.
Table 1.
Water quality at each study site.
Fig 2.
Turbidity of water at each study site.
Laboratory-measured (open circles) and in situ sensor-measured turbidity (NTU). Mulgrave River (MR; purple points), Pioneer River (PR, blue points) and Sandy Creek (SC; light green points).
Fig 3.
Conductivity of water at each study site.
Laboratory-measured (open circles) and in situ sensor-measured conductivity (μS/cm) at Mulgrave River (MR; purple points), Pioneer River (PR, blue points) and Sandy Creek (SC; light green points).
Fig 4.
Height of water at each study site.
River level (m) measured on-site at the time of water sample collection (open circles) and by in situ sensors at Mulgrave River (MR; purple points), Pioneer River (PR, blue points) and Sandy Creek (SC; light green points).
Fig 5.
Model development, selection and prediction for the final total suspended solids (TSS) and oxidized nitrogen (NOx) models.
LevelQ is a categorical variable with two levels based on first, second or third quartiles of the data (Q1, Q2 or Q3). Turbidity, conductivity and level covariates were all log10-transformed prior to analysis.
Table 2.
Cross validation statistics for the final total suspended solids (TSS) and final oxidized nitrogen (NOx) models as applied to data across all or each site.
Fig 6.
Observed versus 5-fold cross-validated (cv) prediction values of total suspended solids (TSS) from the final TSS model.
TSS (mg/L; back-transformed with bias correction). Data from each site shown in purple (Mulgrave River, MR), blue (Pioneer River, PR) and light green (Sandy Creek, SC). Black lines show the 1:1 relationships between observations and predictions.
Table 3.
Coefficient estimates for the final TSS model fit to fit to laboratory data from all three sites.
Fig 7.
Observed versus 5-fold cross-validated (CV) prediction values of oxidized nitrogen (NOx) from the final NOx model.
NOx (mg/L; back-transformed with bias correction). Data from each site shown in purple (Mulgrave River, MR), blue (Pioneer River, PR) and light green (Sandy Creek, SC). Black lines show the 1:1 relationships between observations and predictions.
Table 4.
Coefficient estimates for the final NOx model fit to fit to laboratory data from each site.
Table 5.
Leave-one-out cross validation statistics for the final total suspended solids (TSS) and final oxidized nitrogen (NOx) models.
Fig 8.
Observed total suspended solids (TSS, mg/L) versus predicted TSS (mg/L) from the leave-one-out cross validation (LOOCV).
Fig 9.
Total suspended solids (TSS, mg/L) at each site predicted using the final TSS model and in situ sensor turbidity data (March 2017–2018).
Mulgrave River (MR, purple), Pioneer River (PR, blue) and Sandy Creek (SC, light green). Gray shading shows upper and lower boundaries of the 95% prediction interval, and the inner lines the predicted TSS concentrations through time. Gaps indicate periods of missing data in the sensor time series. Closed circles show the laboratory-measured TSS concentrations within the same period.
Fig 10.
Observed oxidized nitrogen (NOx; mg/L) versus predicted NOx (mg/L) from the leave-one-out cross validation.
Fig 11.
Oxidized nitrogen (NOx, mg/L; log10 transformed) at each site predicted using the final NOx model and in situ sensor turbidity, conductivity and level data (March 2017–2018).
Mulgrave River (MR, purple), Pioneer River (PR, blue) and Sandy Creek (SC, light green). Gray shading shows upper and lower boundaries of the 95% prediction interval, and the inner lines the predicted TSS concentrations through time. Gaps indicate periods of missing data in the sensor time series. Closed circles show the laboratory-measured NOx concentrations within the same period.