Effects of Climate Change and Human Activities on Surface Runoff in the Luan River Basin

Table 2

The Mann-Kendall test statics slope () and changes of annual precipitation, potential evapotranspiration (PET), and observed runoff during the pretreatment period and testing period.

		Pretreatment; period (mm)	Testing; period (mm)	Difference; (mm)	Ratio; (%)
Precipitation	−1.26	504.61	442.00	−62.61	−12.40
PET	−1.79	886.40	871.34	−15.06	−1.70
Observed runoff	−2.29	103.31	16.01	−87.30	−84.50

In a two-side test, when ≤ ≤ accepts a null hypothesis, or when < − indicates a decreasing trend, and when > indicates an increasing trend, is the significance level. In this study, is set to be 0.05 and the corresponding value of is 1.96 [27, 28].