Impacts Of Climate Variability And Human Activities On Runoff Of Minjiang River Basin

Influenced by the global climate variability and human activities, Quantitative analysis of the effects of climate variability and human activities on runoff is a hot research topic. Minjiang River is the largest river in Fujian Province,the change of water resources has important influence on social economy and ecological environment.the relative effects of climate variability and human activities on runoff is to supply the evidence for the water sustainable exploitation and utilization.. In this study, the observed monthly river discharge of 4 hydrological stations and monthly meteorological data (precipitation, temperature, wind, sunshine hours and relative humidity)of 23 meteorological stations for the period 1960-2010 were collected. Characteristics of the variation of hydro-climatic changes over the last 51 years were analyzed based on the TFPW-MK, and the relative effects of climate variability and human activities on runoff were investigated based on a empirical discriminant method and climate elasticity method.Finally, We quantified the impacts of climate variability and human activities on runoff in the Futunxi River sub-basin, based on climate elasticity method and SWAT model.(1) The runoff of Minjiang River Basin and three sub-basins showed faint increasing trend, but annual variation was very obvious. The aberrance point of annual runoff serials and precipitationin of Minjiang main stream and three sub-basins by were analyzed based on theCumulative anomaly method.It showed that the aberrance point was founed in 1971 and 1992. Precipitation of the Minjiang River was on the rise in general while potential evaporation was declining and had a sudden change at the beginning of the 1970s.The spatial distribution of precipitation in the northwest was higher than in the southwest, And the spatial distribution of potential evaporation showed a large difference, there were "three high and five low" characteristics.(2) Relative effect of climate variability is greater than that of human activitiesin Minjiang main stream and three sub-basins under different decades relative to 1960s, except in the beginning of 21st century in Jianxi River sub-basin and Shaxi River sub-basin, whose contributions of human activities accounted for 60% and 52% of the changes in streamflow, respectively. The impact of climate variability on runoff was most significant in 1990s in the Minjiang main stream and three sub-basins; The impact of human activities on runoff was most significant in 1990s in the Minjiang main stream and Futunxi River sub-basin, and in 1980s and the beginning of the 21st Century in Jianxi River sub-basin and Shaxi River sub-basin, respectively.(3) The SWAT model of Futunxi River sub-basin showed that better effect of simulation has been acquired. The results show that, climate variability impacts on runoff was 51.66 m3/s,and the impact of land use on runoff was-11.99m3/s.The result of climate elasticity method coincides with SWAT model. The quantification results indicated that climate variability accounted for 90.04% and 85.89%, and human activities accounted for 9.96% and 14.11%. Therefore, climate variability played a dominant influence in the increase of runoff.