新疆克里雅河洪泛事件与树轮记录的初步研究

新疆克里雅河尾闾地带的达里雅博依绿洲位于塔克拉玛干沙漠腹地。在塔克拉玛干沙漠腹地,光、热条件非常充分,水分是影响胡杨生长的主要因子。由于上游截流用于农业生产及河流下渗等因素的影响,导致下游水量逐渐减少,只有特大洪汛期才有洪水泻入下游尾闾地带。因此,胡杨的生长与洪汛期洪水密切相关,洪水较大的年份输入的水量多,有利于胡杨的生长。本文对新疆克里雅河尾闾地带胡杨(Populuseuphratica)树轮进行了初步研究,发现树轮宽度与克里雅河径流量的相关性较差,轮宽与器测径流量的相关系数仅为0.15,考虑到胡杨生长对径流量的滞后效应,滞后3年的轮宽与器测径流量的相关系数为0.30,但与洪水年份有较好的对应性。近百年来的9次洪水年份分别为1941年、1963年、1971年、1972年、1981年、1987年、1996年、2000年和2001年,均对应于胡杨树轮宽度较大的年份,但一些年份有一定的滞后期。

PRELIMINARY RESEARCH ON THE FLOOD EVENTS BASED ON THE STUDIES OF TREE RING WIDTH (POPULUS EUPHRATICA) IN THE KERIYA RIVER, XINJIANG

The Daliyaboyi Oasis in the Lower Reach of the Keriya River is located in the middle of the Taklimakan Desert. The Keriya River originates from the Kulun Mountains, and flows northward into the Taklimakan Desert. According to the hydrological observation, most of the water of the Keriya River originates from melting of glaciers and snow. Approximately, 4.7×10⁴mu¹) natural oasis is distributed in the fan shaped delta. The light and temperature is enough for plant there. So water is a major factor for Populus euphratica grouth in the desert. Water can reach the Daliyaboyi Oasis only during flood period, after traveling a long distance to the middle of the Taklimakan Desert. So, the growth of Populus euphratica is closely correlated with flood events. The variation of the tree ring ( Populus euphratica ) width does not show a good correlation with runoff of the Keriya River, but corresponds to flood events. The correlative coefficient of the tree ring width and runoff is 0.15, and 0.30 by considering of 3 year lag. There are 9 flood years (1941,1963,1971,1972,1981,1987,1996,2000 and 2001) in history record, and correlated with the variation of tree ring width, but shown a lag period. Pioneer study of the Populus euphratica ring at Luntai indicated that the effect of runoff could be reflected in the index of tree ring after 1～3 year. For example, 1941 is flood year, but the maximal tree ring width is after 2 years. The maximal flood event is in the middle of September of 1963, the maximal tree ring width is after this year. Populus euphratica are widely distributed in desert. Based on the tree ring research, we can reconstruct local history of flood event during the past 2000 years.