Remote sensing for detection of sediment alteration in water currents by alluvial gold exploitation using water machine

Abstract

The use of machinery in water during the exploitation of deposits of alluvial gold causes alteration in the riverbed and generates changes in the quantity of suspended sediments, that modify the natural reflectance of the water body. In this context, SIMCI project developed a methodology based on remote sensing through the use of band algebra (spectral index), which allows the detection and monitoring of alterations of amount of sediments disolves in the water. The index used is the MNDWI (Modification for Normalized Difference Water Index).

This methodology allows the identification of alterations in the natural dynamics of the current attributable to gold mining exploitation, based on the spectral behavior of the water. The method consists in establishing the natural spectral base of the water body as Time 0, and three further measurements are made using the available images to examine changes in the spectral index. Finally, once the line of natural spectral behavior is established, the index is applied in order to construct the spectral curves that will allow the identification of the dynamics of change in suspended sediments over time, as well as the points of maximum alteration or alerts.