Analysis of the impact of land use on floating object in rivers at different spatial scales—the Chongqing section of the Three Gorges Reservoir area

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Floating object pollution in the Three Gorges Reservoir area (TGRA) is a serious environmental problem. It directly harms the safety of the reservoirs. Currently, relevant research has only focused on certain aspects, such as the salvage and treatment of floating objects, and little has been done on the underlying causes of floating object. The way humans use land will have a large influence on floating object in rivers, but the relationship between the two still needs to be further explored. We used remote sensing images to obtain the distribution of floating objects in the Chongqing section of the TGRA, and combined that with current land use data to study the relationship between land use and river floating objects. We found that: ① The number of floating object spots in the main stream of the Yangtze River gradually increased from the upper reaches (the main urban section of Chongqing) to the lower reaches (northeast section of Chongqing), while the opposite was true in the tributaries of the Yangtze River. ② Under different buffer scales, urban, rural residential, farmland, gardenland, grassland and other land use types were positively correlated with the number of floating debris spots in the river, and the correlation order was rural residential > farm land > urban> gardenland > grassland > forest. ③ When the buffer radius was 1.5 km, the land use comprehensive intensity index (LUI) had the highest interpretation degree to the number of floating debris spots, with a rate of 68.8%. In terms of land use types, rural settlements and cultivated land have a greater impact on river floaters, while woodland and grassland have a lesser impact on river floaters. We suggested that the construction of rural residential areas and cultivated land should be avoided as far as possible in the territorial space planning within 1.5 kilometers on both sides of the river, and ecological modification should be carried out by returning cultivated land to forest and grassland.