Response of extreme hydrological events to climate change in cold watersheds of Huangshuigou River and Qingshuihe River on the southern slope of Tianshan
Hydrological effects of glaciers, snow and permafrost changes on the downstream water supply have result in a significant impact, showed a significant trend of increasing flood in recent decades, especially in the southern Xinjiang. Take the Huangshuigou River and Qingshui River Basins which located on the southern slope of Tianshan Mountains as the study areas, by the analysis of the extreme hydrological events, and combined with the meteorological data of the Baluntai Meteorological Stations in the upstream mountainous, the response characteristics of the extreme hydrological processes as annual peak flow occurred time, annual peak discharge and annual minimum flow in alpine cold watershed in the context of climate change was studied. The results showed that, year 1986 is the turning point of hydrological processes and climate change, from the beginning of 1986 with the increases of precipitation and temperature, the runoff showed an increasing trend; annual peak discharge occur from time postponed until mid-June to late July; have a positive correlation between the peak discharge and summer rainfall, while the winter and spring temperatures close to the minimum annual runoff. Since 1986 as the temperatures rise, hydrological effects of permafrost degradation, result in the winter runoff increased significantly, but also the minimum annual runoff increased significantly. Changes in precipitation results in the annual runoff increases since 1986, occurred time of the annual maximum runoff appear in the summer and the increasing magnitude of annual peak discharge. Overall, increased peak discharge, flood volume, and the magnitude of interannual peak discharge since the mid-year of 1980s, resulting in a more serious disaster for downstream. Therefore, the strengthening impact assessment of climate change on hydrological processes and flood disaster in cold watershed, so that science and technology play a leading role in disaster reduction.