气候变暖背景下极端气候对青海祁连山水文水资源的影响

Impacts of extreme climatic events under the context of climate warming on hydrology and water resources in the Qinghai Qilian Mountains

利用青海祁连山区极端气候要素和青海湖、哈拉湖及主要河流的水文资料,研究表明:冷夜日数(10%)呈显著减少趋势,暖夜日数(90%)呈显著增加趋势;年大风日数显著减少;年降水量21世纪初增加趋势最为显著并发生突变,降水量增加幅度中西段大于东段;≥5 mm、≥10 mm、≥25 mm年降水日数呈显著增加趋势,进入21世纪后更为明显,而≥0.1 mm年降水日数呈减少趋势;年平均大风日数与湖泊水位、河流流量变化呈负相关,大风天气的减少,可以缓解湖面和土壤因蒸发而导致的水分损失,对植被的改善可增加径流的产生,流入湖泊的流量增加;降水量与湖泊水位、河流流量呈正相关,受21世纪降水量增加的影响青海湖水位逐年上升,共上升1.67 m,达到20世纪70年代末的水位,中西部主要河流流量近几年也达到最大值,而东段流量增加不明显;祁连山区≥5 mm、≥10 mm、≥25 mm年平均降水量与湖泊、河流流量变化呈正相关,各量级年降水量对湖泊水位、河流流量的增加贡献显著。

Based on the extreme climatic factors in the Qilian Mountains of Qinghai Province and the hydrological data of the Qinghai Lake,the Hara Lake and some main rivers,the study shows that strong wind(gale)days had decreased significantly.The annual precipitation in Qinghai Qilian Mountains had increased most significantly in the early 21st century and changed abruptly,the increase range of precipitation in the middle and west sections had been larger than that in the east section.Annual precipitation days of daily precipitation more than 5 mm,10 mm and 25 mm had increased significantly,especially at the beginning of the 21st century.However,days of precipitation more than 0.1 mm had decreased.The annual average strong wind days had been negatively correlated with the lake water-level fluctuation and river runoff.Reduction of strong wind days had alleviated water loss due to evaporation on lake surface and ground surface,improving vegetation had increased runoff generation and increased runoff into lakes.Precipitation had been positively correlated with lake water-level fluctuation and river runoff.Influenced by the increase of precipitation in the 21st century,the water level of the Qinghai Lake rises year by year,which has totally risen 1.67 m,reaching the water level in the late 1970s.In recent years,the runoff of the main rivers in the middle and west sections has also reached the maximum,while the runoff increase in the east section is not obvious.The annual average cumulative precipitations of more than 5 mm,10 mm and 25 mm in the Qinghai Qilian Mountains is positively correlated with the flow of lakes and rivers,and the cumulative precipitations contribute significantly to the increase of lake water-level fluctuation and river runoff.