洮儿河流域中上游水循环要素变化及其原因

Variations in the hydrological cycle components and their influencing factors in the middle and upper reaches of Tao'erhe River Basin

选取洮儿河流域中上游地区为研究区，分析1961～2000年期间径流、降水、气温等水文气象要素的演化趋势。采用特征参数时间序列法，初步探讨了气候变化与土地利用／覆被变化的径流效应，并通过洮南站40年天然径流与实测径流的比较，定量分析水资源开发利用对径流的影响。结果表明：降水、气温均呈一定的上升趋势，径流表现出先减少、后增加、再减少的趋势；年降水、年气温分别与天然年径流呈正相关和负相关的关系，然而这种影响随着时间序列的延长均有所减弱；近30年间，植被覆盖度降低可能是天然年径流增加的主要原因；水资源的开发利用导致1986～2000年期间的年径流减少5．8亿m^3，占天然年径流量多年均值的37．1％。

Taking the middle and upper Tao＇erhe River Basin as a study area,this paper analyzes variations of runoff,precipitation and temperature,etc.for the period 1961-2000.Time series analysis of characteristic parameters is used to examine the influences of climate change and land use and land cover change（LUCC） on runoff.And the response of runoff to water resources development（extraction for use） is estimated quantitatively based on the comparison between the observed and natural runoff data of Taonan hydrological station during 1961-2000.Some conclusions are drawn as follows：（1） The observed mean annual runoff is 38.2 m3/s for the past four decades,showing a trend of decrease-increase-decrease.The interannual and seasonal variations of runoff are greatly notable and the mean monthly runoff shows an unobvious trend according to the analysis result with the Kendall method.Over the period,annual precipitation has increased slightly to 427 mm.December＇s mean precipitation has increased significantly by the analysis result with the Kendall method.The mean annual temperature is 5.48℃ with a much greater value in the second half of the period（1986-2000）;（2） The annual natural runoff is positively correlated with annual precipitation,and negatively correlated with annual temperature,and these relationships become weaker over time.Therefore,the increase of annual natural runoff coefficient under the same precipitation frequency may have mainly resulted from the decreasing vegetation cover.A wet year would have more impact on runoff than a dry year;（3） Water resources development decrease the annual runoff depth by 21.2 mm during the period 1986-2000,accounting for 37.1% of the mean annual natural runoff over the 40 years.