Impacts Of Climate Change And Human Activities On Streamflow In Liuyang River Basin

It is economically developed in the Liuyang River Basin.The runoff of Liuyang River Basin has also changed obviously due to the influence of climate warming and human factors which caused serious Supply-Demand problem of water resources of the basin,Drought and flood disaster happen frequently,it hinders the social and economic development of Liuyang seriously.This paper analyzed the temporal and spatial evolution characteristics in the hydrological factors of the Liuyang River Basin on the long term hydrometeorological data.It used the application of accumulation slope gradient method to quantify the interference of precipitation fluctuation and human factors on the runoff in different periods,and finally simulated the SWAT model to simulate the influence of runoff when the land cover and climate changed.The main conclusions are as follows:(1)The annual precipitation displayed an increasing trend at the rate of 3 mm/10a,while the runoff represented a decreasing trend at a 2.7 m3/10a.An abrupt change of the annual precipitation and runoff both occurred in 1989 and 1999,experienced a "decrease-increase-decrease" of the alternative transformation.The contribution of precipitation was 56.8%and 7.62%,while that of human activities was 43.2%and 92.38%respectively for the different periods compared with the baseline period from 1969-1988.It's obviously that the human activities were the main factor which caused the change of runoff.(2)Extreme precipitation,precipitation intensity and precipitation ratio displayed increasing trends at the rates of 7.3 mm/10a,9.5 mm·d-1/10a and 0.3%/10a respectively,while the number of extreme precipitation days represented a decreasing trend at the rate of-0.054 d/10a;Abrupt changes in the extreme precipitation and precipitation intensity were detected in 1991 and 1992 respectively,while the number of extreme precipitation days and the ratio of extreme precipitation ratio to the total precipitation amounts are not statistically significant.The extreme precipitation indices had the main oscillation cycles of 7?8 years,10-11 years and 25?27 years respectively,together with clear alternation between dry and wet years.(3)Different land use scenarios was designed to analyze the effect of different land cover on runoff based on the SWAT distributed hydrological model of Liuyang River Basin.The influence of different landuse scenarios on hydrological elements was significant differences,the surface runoff and evapotranspiration were the smallest in the forest land(scenario L5),the largest in the cultivated land(scenario L2),and the opposite of the groundwater,it reflects the role of forest water conservation;The annual average runoff changes in the orders of Scenario L5,Scenario L3,2010 Base period,Scenario L2,Scenario L1 and Scenario L4.(4)Combined with CMIP3 data into the SWAT distributed hydrological model of Liuyang River Basin,it is found that the annual runoff under the three emission scenarios shows different degrees of rising trend.The growth rate of the annual runoff slope in the B1 scenario is larger than that in the A1B and A2 scenarios.In the A1B and B1 scenarios,the growth trend from 2081 to 2100 has increased from 2046 to 2064,indicating that the change of runoff was becoming more pronounced by the influence of climate fluctuation in both scenarios,while the A2 scenario was the opposite.The annual average runoff in the scenarios of SRES-A2,A1B and B1 was 119.2m3/s,1203.3m3/s and 116.3m3/s from 2046 to 2064,respectively 127.9m3/s,135.1m3/s and 122.6m3/s from 2081 to 2100,it greater than the 98.4m3/s from 1961 to 2014.