STUDY OF TRENDS IN RUNOFF FOR THE HAIHE RIVER BASIN IN RECENT 50 YEARS

Mann-Kendall’s test was used to identify runoff trends for 20 sub-catchments located in the mountain area of the Haihe river basin in recent 50 years. Combining the in-phase analysis the decadal changes of precipitation, runoff and air temperature, and the sensitivity analysis of runoff to climate change, a semi-quantitative analysis approach was presented. By using this analysis method, the change trend and the attribution of natural runoff for the Haihe river basin can be summarized into three patterns: 1) Annual natural runoff has decreased significantly, of which the main factor is the dry and warming trend of the climate and the secondary is the anthropogenic activities; 2) Annual natural runoff has decreased significantly, of which the main factor is the anthropogenic activities and the secondary is dry and warning climate trend; 3) Annual natural runoff has no significant change trend, for the climatic variability and anthropogenic activities are not significant. This study reflects the interaction between climate, human activities and water. The mutual interaction causes complexities and difficulties to analye the change trend and attribution of runoff, and presents challenge to the impact study of climate change to water resources as well.