Nonlinear Response Of Runoff To Precipitation And Temperature In The Red River Basin

The impact of climate change on water resources security is a global issue.The response of runoff to precipitation and temperature is of great significance to reveal the relationship between runoff,precipitation and temperature.Moreover,the research is meaningful to the transboundary water resources management under the climate change.But there are still some problems in the relevant research of the study area.For example,the spatial-temporal variation law of runoff change is not clear.And the relationship between runoff,precipitation and temperature is not uncover.Hence,this research took the runoff of the Red River basin as the research object,summarized the progress.And nine representative stations were selected,and the cumulative anomaly method,Mann-Kendall-Sneyers method and the sliding t-test were employed to study the spatio-temporal variation and characteristics of runoff.And the non-linear response of runoff to precipitation and temperature was revealed by the two-parameter elastic coefficient and geostatistical method.Moreover,with the different climate models from IPCC AR5,the runoff changes were predicted by using a water balance equation based on Budyko hypothesis.The conclusions are as follows:(1)The temporal and spatial differences of runoff in Red river basin are significant.The maximum fluctuation of runoff in the main stream of the Red River basin appears in the middle reaches.The extremum ratio of Manhao and Yuanjiang station are 1.3.The fluctuation degree in the upper and lower reaches are similar.The extreme values of Dadongyong and Yen Bai stations are 1.2.Meanwhile,the runoff fluctuation in the lower reaches of the Heshui River is larger than that in the upper reaches.The extremum ratios of the upper and lower reaches of Heishui River are 1.1 and 1.2,respectively.The runoff and runoff fluctuation degree of the watershed in China is greater than that in tributaries.While,in the study area of foreign countries,the runoff of Heishui River occupies first place and Lu River comes second.For the runoff fluctuation,Lu River is the most severe.And the fluctuation degree of Yuan-Red River and Li Xian-Heshui River is similar.In addition,when the position of representative station is closer to the downstream,runoff mutation will happen later.Transformation time of runoff high-water period and dry-water period is not consistent.(2)The nonlinear relationship between runoff,precipitation and temperature in the Red River basin is presented.Runoff change was positively correlated with precipitation change,and negatively correlated with temperature change.The precipitation sensitivity of Lu River is the greatest,followed by Heishui River,and the Yuan-Red River is the smallest.Except for the Heishui River,the sensitivity of temperature and precipitation variation of Red river basin in China is greater than that in Vietnam.(3)Compared with the average annual runoff in 1978?2005 of the Red River basin,the runoff decrease in all the climatic models.But the reduction amplitude of runoff is gradually reduced.Under the RCP 2.6 model of typical concentration path,the fluctuation range of runoff in Heishui River is the largest,and the main stream of Red River is similar to Lu River.The runoff of Heishui River is the largest in 2080 and the smallest in 2020.Compared with the base year,the runoff will increase by 10.07%in 2080 and decrease 2.93%in 2020.The runoff of Red River main stream and Lu River were the largest in 2090 and the smallest in 2020.Compared with the base year,the runoff of Yen Bai station and Vu Quang station will increase by 2.75%and 3.68%in 2090,and decrease by 3.16%and 4.85%by 2020,respectively.Furthermore,under the RCP 4.5 model,the runoff of the trunk stream and tributaries were the largest in 2090 and the smallest in 2030.Under the RCP 8.5 model,the variation trend of the main-tributary runoff is still the same,and the variation amplitude of the main-tributary runoff increases with time goes by.The runoff of the main and tributary reaches the maximum in 2080?2090 and the lowest in 2020.