Synthetic harmful coefficient (K)
A value of K can broadly reflect the salt and alkalis hazards (Xu et al., 2016). The classification of groundwater based on K values is less than 25 is excellent, 26 – 36 is good, 37-44 is injurious, and greater than 44 is unsuitable. In the study area, K value ranges from 4.81 to 44.98 %, with an average of 16.73%. The spatial analysis reveals, 621.20 sq.km area is excellent (83.33% of sample locations), 40.07 sq.km area is good (6.67% of sample locations), 5.30 sq.km area is injurious (6.67% of sample locations) and 0.36 sq.km area is unsuitable (3.33% of sample locations). The higher value of K indicates the surplus concentration of sodium ion in groundwater.