Temporal and Spatial Distribution Characteristics of Sand Mining Points in Nanliu River Based on "3S" Technology

With the rapid progression of urbanization worldwide, the demand for sand and gravel is growing exponentially, resulting in a natural growth rate of sand and gravel far behind consumption. Unsustainable sand mining activities produce a series of environmental hazards, such as the formation of scattered sand pits in riverbeds, changes in channel shape, and altered physical and chemical properties of river water, leading to water quality degradation. Nanliu River is the largest river flowing into the sea in southwest China. The intense exploitation of river sand has had a considerable impact on the stability of the basin's ecological environment. To understand the historical change process of sand mining activities in Nanliu River and the dynamic factors influencing these activities, we analyzed their environmental impacts and provided a basis for the comprehensive management of the basin. Landsat images were used to extract the sand extraction points of Nanliu River through visual interpretation and field veri