Variations and trends of trans-boundary runoff in the longitudinal range-gorge region

The mountainous hydrological process usually shows high variation to climate change and human action. In the Longitudinal Range-Gorge Region（LRGR）, Southwestern China and Southeast Asian, the transboundary runoff variations are much more sensitive and complex under the interaction of climate change, ＂corridor-barrier＂ functions in LRGR,and dams building. In this paper, based on the long hydrological records（1956-2013） from three mainstream hydrological stations in Nu River,Lancang River, and Red River, the region runoff variations were analyzed. The results show out： i） the regional runoff changes were strongly influenced by the ＂Corridor-Barrier＂ functions in LRGR from west to east, the variability extent of annual runoff increased, but tended to decrease after 2009 and the reduced extents also increased; ii） the annual runoff change in the three rivers had high concentration degrees; iii） there were periodicities of 33 years of runoff change in Nu River and Lancang River, and 30 years in Red River, and the lower flow period would continue for 8-9 years in Nu River and Lancang River but only for 4 years in Red River; iv） since 2010, as the two mega dams of Xiaowan and Nuozhadu built in Lancang River mainstream, their variations of annual runoff were quite different. The research results could offer a scientific base for sustainable utilization,conservation, and management of the regional water resources