拉萨河下游水温变化特征及其影响因子分析

Analysis of Water Temperature Characteristics in the Lower Lhasa River and the Impact Factors

以拉萨河下游1956—1982年水温、气温及流量资料为基础,利用累计距平和滑动平均法分析了水温变化特性及变化趋势,并分析了水温对气温及流量变化的响应关系。结果表明：1拉萨河下游河段水温沿程升温率为1.0～2.8℃/100 km,研究河段的下游段因气温升高,且多为分汊型河道,故水温显著升高,研究站点间春季水温温差较大,冬季水温温差较小;2研究河段年均水温为7.3～8.4℃,夏季水温变幅大于冬季的;320世纪50年代中期到60年代中期水温降温率为-0.74℃/10 a,60年代中期到70年代初期水温升温率为0.47℃/10 a,70年代初期到80年代初期水温倾向率为0.005℃/10 a;4多年平均水温高于多年平均气温,同时期内水温的变化趋势与气温的相同,与流量的相反。

Based on monthly water temperature, meteorological data and flow of the lower Lhasa River during the period of 1956-1982, water temperature variations and trends were characterized by accumulative anomaly and moving average tests. Meanwhile, the response relationships between water and air temperature and flow were also analyzed. The outcomes show that along the lower Lhasa River, rising temperature and wider river surface in the lower section lead to higher warming rate of water temperature than that in upper section, warming rate of water temperature is between 1.0-2.8℃ per 100 km. Water temperature differences between observation stations are larger in spring than that in winter. Mean annual water temperature of the lower Lhasa River during this time interval is between 7.3-g.4~C , and the variation magnitudes of water temperature in summer seasons are larger than that in winter seasons. Water temperature shows decreasing trend between mid 1950s and mid 1960s, the decreasing trend of the water temperature is -0.74℃ per 10 years; increasing trend between early 1960s and early 1970s is 0.47℃ per 10 years; the tendency rate between early 1970s and early 1980s is only 0.005℃ per 10 years, water temperature remains stable during this time. Water temperature shows the same changing trends with the air temperature during the same period, while the opposite trend with the flow.