Illegal mining in Latin America has had devastating effects on forests and river channels, leading to negative downstream impacts on the health of local people, flora and fauna. The increase in the international price of gold has spurred the spread of illegal mining, attracting thousands to the region. The main problem with illegal mining is the indiscriminate and irresponsible use of elements such as mercury and cyanide, which are poisonous and endanger the environment.
In Colombia, 66% of alluvial gold mining is illegal. The highest rate of illegal mining is in the Chocó department, according to the United Nations Office on Drugs and Crime (UNODC). Istmina, Colombia is a municipality located in the department of Chocó, in the middle of one of the most valuable forests in the world. This area has been devastated by illegal mining.
In recent years, efforts have been made to monitor and fight this activity by using optical satellite imagery. However, most of the areas being mined are prone to dense and near-constant cloud cover, preventing optical imagery from being used to keep local enforcement informed. The use of synthetic aperture radar (SAR) data has become increasingly popular in recent years because of its advantages over traditional sensors, particularly its ability to obtain information through clouds both day and at night. Geospace Solutions in Ecuador, a distributor of ENVI software, undertook a study to evaluate the use of high-resolution SAR data to accurately monitor and quantify the illicit exploitation of gold in Istmina.