We attempt to estimate the human impact on the long-term runoff variability using the correlation between the human activity factors and the weights obtained by decomposing the original runoff series into EOFs. A significant (though low) correlation between the studied factors and the weights are detected (Table 4).
Correlations between the weights and human activity factors (significant value shown in bold)
Weight . | 1 . | 2 . | 3 . | 4 . |
---|---|---|---|---|
Weihe | ||||
Population level | 0.34 | 0.02 | 0.01 | 0.35 |
Cultivated land | −0.29 | 0.11 | 0.02 | −0.38 |
Irrigated area | 0.17 | 0.21 | 0.07 | 0.40 |
Water supply | 0.39 | 0.01 | 0.05 | 0.34 |
Grain yield | 0.31 | 0.09 | 0.11 | 0.32 |
GDP | 0.21 | −0.15 | −0.09 | 0.18 |
Afforested area | 0.01 | 0.28 | 0.15 | 0.34 |
Hydroelectricity | 0.18 | 0.05 | 0.03 | 0.36 |
Reservoir storage* | −0.36 | −0.57 | −0.47 | 0.18 |
Area of soil-water conservation* | −0.41 | −0.56 | −0.33 | 0.35 |
Beijiang | ||||
Population level | 0.15 | 0.40 | −0.03 | 0.45 |
Cultivated land | −0.04 | −0.56 | 0.11 | −0.36 |
Irrigated area | 0.22 | −0.53 | −0.00 | −0.00 |
Water supply | 0.10 | 0.55 | −0.07 | 0.45 |
Grain yield | 0.34 | 0.12 | 0.06 | 0.53 |
GDP | −0.10 | 0.61 | −0.11 | 0.33 |
Afforested area | 0.40 | −0.47 | 0.12 | 0.10 |
Hydroelectricity | 0.02 | 0.55 | −0.13 | 0.45 |
Reservoir storage* | 0.09 | 0.56 | −0.17 | −0.06 |
Area of soil-water conservation* | −0.07 | 0.52 | −0.22 | 0.36 |
Qingjiang | ||||
Population level | −0.01 | −0.18 | 0.19 | −0.26 |
Cultivated land | −0.07 | 0.11 | −0.23 | 0.29 |
Irrigated area | −0.14 | 0.05 | −0.31 | 0.27 |
Water supply | 0.07 | −0.19 | 0.28 | −0.30 |
Grain yield | −0.11 | −0.27 | 0.07 | −0.24 |
GDP | 0.13 | −0.11 | 0.15 | −0.20 |
Afforested area | −0.23 | −0.22 | 0.01 | −0.15 |
Hydroelectricity | 0.05 | −0.13 | 0.14 | −0.08 |
Reservoir storage* | −0.40 | −0.24 | −0.06 | −0.17 |
Area of soil-water conservation* | −0.27 | −0.22 | −0.10 | −0.18 |
Weight . | 1 . | 2 . | 3 . | 4 . |
---|---|---|---|---|
Weihe | ||||
Population level | 0.34 | 0.02 | 0.01 | 0.35 |
Cultivated land | −0.29 | 0.11 | 0.02 | −0.38 |
Irrigated area | 0.17 | 0.21 | 0.07 | 0.40 |
Water supply | 0.39 | 0.01 | 0.05 | 0.34 |
Grain yield | 0.31 | 0.09 | 0.11 | 0.32 |
GDP | 0.21 | −0.15 | −0.09 | 0.18 |
Afforested area | 0.01 | 0.28 | 0.15 | 0.34 |
Hydroelectricity | 0.18 | 0.05 | 0.03 | 0.36 |
Reservoir storage* | −0.36 | −0.57 | −0.47 | 0.18 |
Area of soil-water conservation* | −0.41 | −0.56 | −0.33 | 0.35 |
Beijiang | ||||
Population level | 0.15 | 0.40 | −0.03 | 0.45 |
Cultivated land | −0.04 | −0.56 | 0.11 | −0.36 |
Irrigated area | 0.22 | −0.53 | −0.00 | −0.00 |
Water supply | 0.10 | 0.55 | −0.07 | 0.45 |
Grain yield | 0.34 | 0.12 | 0.06 | 0.53 |
GDP | −0.10 | 0.61 | −0.11 | 0.33 |
Afforested area | 0.40 | −0.47 | 0.12 | 0.10 |
Hydroelectricity | 0.02 | 0.55 | −0.13 | 0.45 |
Reservoir storage* | 0.09 | 0.56 | −0.17 | −0.06 |
Area of soil-water conservation* | −0.07 | 0.52 | −0.22 | 0.36 |
Qingjiang | ||||
Population level | −0.01 | −0.18 | 0.19 | −0.26 |
Cultivated land | −0.07 | 0.11 | −0.23 | 0.29 |
Irrigated area | −0.14 | 0.05 | −0.31 | 0.27 |
Water supply | 0.07 | −0.19 | 0.28 | −0.30 |
Grain yield | −0.11 | −0.27 | 0.07 | −0.24 |
GDP | 0.13 | −0.11 | 0.15 | −0.20 |
Afforested area | −0.23 | −0.22 | 0.01 | −0.15 |
Hydroelectricity | 0.05 | −0.13 | 0.14 | −0.08 |
Reservoir storage* | −0.40 | −0.24 | −0.06 | −0.17 |
Area of soil-water conservation* | −0.27 | −0.22 | −0.10 | −0.18 |
*Results in italics should be taken with caution due to a limited record length.