Exploring the Variations of Redbed Badlands and Their Driving Forces in the Nanxiong Basin, Southern China: A Geographically Weighted Regression with Gridded Data

Table 1

Independent variables and their substitute indexes.

Type of independent variables	Indicators	Index definition	Calculation method	Index definition
Natural factors	Lithology	Influence of different geological group types on the spatial pattern of redbed badlands		is the area of the lithologic group type in the unit grid, and is the area of the unit grid
	Average slope	Influence of slope on the spatial pattern of redbed badlands		is the horizontal change rate of the central pixel, and is the vertical change rate of the central pixel
	Average aspect	Influence of aspect on the spatial pattern of redbed badlands		is the change rate of the unit pixel in the direction, and is the change rate of the unit pixel in the direction
	Average distance of the water system	Influence of the water system on the spatial pattern of redbed badlands		and are vertical coordinates of badlland and the nearest river, and are centroid coordinates of the nearest badland, is the distance from any badland to the nearest river in the unit grid, is the number of badlands in the unit grid, and is the average water system distance in the unit grid
	Average forestland area	Influence of forestland on the spatial pattern of redbed badlands		is the area of vegetation in the unit grid, and is the area of the unit grid
Human factors	Average density of residential locations	Influence of human activities on the spatial pattern of redbed badlands		is the area unit scale factor of residential locations in each grid, is the neighborhood radius, and is the average density of residential locations in the unit grid
	Average density of garden plots			is the area unit scale factor of residential locations in each grid, is the neighborhood radius, and is the average density of residential locations in the unit grid
	Average road distance			and are vertical coordinates of badlland and the nearest river, and are centroid coordinates of the nearest badland, is the distance from any badland to the nearest river in the unit grid, is the number of badlands in the unit grid, and is the average water system distance in the unit grid