西南诸河水文情势演变特征OA

[Objective]This paper aims to reveal the hydrological evolution patterns of transboundary rivers on the western Yunnan Plateau(the Lancang River,Nu River,and Irrawaddy River)during 1956-2016,to quantify the spatial differentiation characteristics of changes in water resources in the three major river systems,and to establish a water quantity prediction method based on multi-scale periodic analysis.[Methods]Based on precipitation and runoff data of the three major river systems in Southwest China from 1956 to 2016,the Mann-Kendall trend test method was used to analyze the long-term variation trends of hydrological elements.The Morlet wavelet analysis method was applied to identify the multi-scale periodic characteristics of hydrological sequences,and the phase ex-trapolation method was employed to predict future water quantity variation trends.[Results]The water yield modu-lus of the study area reached 78.83×104 m3/km2;however,all three river systems exhibited significant decreasing trends.Among them,the attenuation rate of the Irrawaddy River(-0.175×108 m3/a)was significantly higher than that of the Lancang River(-0.024×108 m3/a).A dominant 24-year hydrological variation period was identified at the regional scale,and the year 2016 was located at the end of the low-frequency phase of this cycle.Combined with phase extrapolation,the results indicated that future water quantity may continue to remain relatively low.The Lancang River exhibited secondary periodic oscillations of 7-12 years,which differed from the single dominant pe-riodic pattern observed in the Nu River and the Irrawaddy River,revealing the hydrological response heterogeneity of the Lancang River caused by its specific underlying surface conditions.Precipitation showed a significant correla-tion with water resources(R2＞0.75);however,asynchronous characteristics were observed in the Lancang River due to its specific underlying surface conditions.[Conclusion]This study systematically quantifies the spatial dif-ferentiation characteristics of hydrological evolution in the Lancang River,Nu River,and Irrawaddy River systems,establishes a water quantity prediction method based on multi-scale periodic analysis,and further reveals the sec-ondary periodic oscillation characteristics of the Lancang River and its differences from the Nu River and Irrawaddy River,providing new scientific evidence for transboundary river water resources management in Southwest China.The results indicate that water resources of transboundary rivers on the western Yunnan Plateau may show a persist-ently low trend in the future,highlighting the need to strengthen transboundary water resources coordination and to formulate adaptive water resources allocation strategies.