Analysis of the Spatial Variation of Soil Salinity and Its Causal Factors in China’s Minqin Oasis

Table 3

Grey relational grade () and the resulting ranking for each affecting factor.

Reference factor	Affecting factor	Definition		Ranking	Relationship
	()	Distance to irrigation canals	0.814	1	Positive
	()	Groundwater salinity	0.810	2	Negative
	()	CTI	0.804	3	Positive
	()	Elevation of the sample site	0.801	4	Negative
	()	Groundwater level	0.798	5	Negative
	()	Vegetation cover	0.771	6	Negative

Positive relationships mean that a high value of the affecting factor increased ; negative relationships mean that a high value decreased .