Responses of runoff and sediment to climate and land use changes in upper reaches of Lijiang River
In order to explore the variation characteristics of water and sediment and their responses to the climate and land use changes and normalized difference vegetation index(NDVI)datasets in the upper reaches of Lijiang River Watershed,the linear tendency estimation method and moving average method were applied to study the trends of temperature,precipitation,runoff,and sediment concentrations from 1965 to 2019.The cumulative slope rate comparison method was used to quantitatively analyze the contribution ratio of climate change to runoff variation.Based on the characteristics of vegetation change,the influence of land use type change on river sedi-ment was studied.Results show that the temperature has an obvious increasing trend,but there are not significant trend for precipitation,runoff,and sediment concentrations.During the study period,NDVI in the upper reaches of Lijiang River showes an upward trend.The overall land use structure of in the upper reaches of Lijiang River does not change significantly,which is still mainly composed woodland and cultivated land.There is no abrupt change year in temperature.The abrupt change year in precipitation and runoff is 1991.The average NDVI in up-per Lijiang River from 1992 to 2019 is significantly higher than that from 1981 to 1991,and the average values of plough area and forest area from 1992 to 2019 are significantly lower than those from 1981 to 1991.The abrupt change year of sediment concentrations is 2003.The average NDVI and construction land area in the upper rea-ches of the Li River from 2004 to 2019 also are significantly higher than those from 2004 to 2019.According to the slope change ratio of cumulative quantity method,the contribution ratio of precipitation to runoff is 56.30%,but the abrupt change of runoff does not change the relationship between precipitation and runoff.The contribution ra-tio of precipitation to sediment is-12.67%,but the abrupt change of sediment concentrations change the relation-ship between precipitation and sediment concentrations.
water and sediment characteristicsclimate changecontribution rateland useLijiang River
国家科技期刊平台
NSTL
万方数据
