Analysing the influence of human activity on runoff in the Weihe River basin

Abstract. Changing runoff patterns can have profound effects on the economic development of river basins. To assess the impact of human activity on runoff in the Weihe River basin, principal component analysis (PCA) was applied to a set of 17 widely used indicators of economic development to construct general combined indicators reflecting different types of human activity. Grey relational analysis suggested that the combined indicator associated with agricultural activity was most likely to have influenced the changes in runoff observed within the river basin during 1994–2011. Curve fitting was then performed to characterize the relationship between the general agricultural indicator and the measured runoff, revealing a reasonably high correlation (R² = 0.393) and an exponential relationship. Finally, a sensitivity analysis was performed to assess the influence of the 17 individual indicators on the measured runoff, confirming that indicators associated with agricultural activity had profound effects whereas those associated with urbanization had relatively little impact.