『Abstract
Runoff non-point source pollution from phosphate mining areas
poses a potential risk to ecosystems in many parts of the world.
Mining sand tailings in Central Florida, which still contain apatite
(phosphate rock), have shaped the landscape in reclaimed lands
at the upper Peace River basin. The objective of this study is
to model the efficiency of vegetative filter strips for controlling
surface runoff pollution from phosphate mining sand tailings.
The numerical model VFSMOD-W is used to predict overland flow
and sediment trapping within the filter and is linked to a simplified
phosphorus (P) transport algorithm based on experimental data
to predict total P (TP), particulate P (PP) and dissolved P (DP)
fractions in the filter outflow. An advanced global inverse optimization
technique is used for the model calibration process, and the uncertainty
of the measured data is considered in goodness-of-fit indicators.
The VFSMOD-W can predict hydrology and sediment transport well
(Nash-Sutcliffe coefficient of efficiency >0.6) for calibration
and validation events with peak outflow rate from VFS greater
than 0.0004 m3/s. The good prediction in runoff and
sediment resulted also in good predictions of PP and TP transport
since apatite is a main component of sediment. A good prediction
of DP was found by considering the rainfall impact on DP dissolved
from apatite in surface soil. The uncertainty of measured data
included in the goodness-of-fit indicators is a more realistic
method to evaluate model performance and data sets. VFSMOD-W combined
with the simplified P modeling approach successfully predicted
runoff, sediment, and P transport in phosphate mining sand tailings,
which provides management agencies a design tool for controlling
runoff and P transport using vegetative filter strips.
Keywords: Sediment; Phosphorus; Mining sand tailings; Apatite;
Vegetative filter strips; Uncertainty』
Introduction
Materials and methods
Field experiments
Simplified phosphorus modeling
Inverse calibration methodology and model validation
Calibration procedure
Selected calibrated parameters
Measurements of selected parameters
Validation procedure
Goodness-of-fit indicators
Consideration of measured data uncertainty in the model evaluation
Results and discussion
Optimized value of calibrated parameters
Evaluation of model calibration and validation results
Hydrology component
Sediment component
Phosphorus prediction
Conclusions
Acknowledgments
Appendix
Nash and Sutcliffe coefficient of efficiency (Ceff)
Modified form of Ceff (Ceff_m)
Root mean square error (RMSE)
References