基于干燥指数的洮儿河中上游地区水分适宜性的时间变化特征分析

Time characteristics of the water suitability in the upper and middle reaches of Taoer river based on aridity index

根据洮儿河中上游地区1961-2012年的气象水文资料,计算了其干燥指数,利用干燥指数评价其水分适宜性。结果表明:近52年以来,洮儿河中上游地区的干燥指数呈下降趋势,但下降趋势不明显,多年平均干燥指数为2.36,水分较不适宜;1961-2012年干燥指数的四季变化中冬季的干燥指数最大,为18.59,水分不适宜,夏季的干燥指数最小,为1.35,水分较适宜;洮儿河中上游地区干燥指数在1983年左右发生了一次由增大到减小的突变,在1995年左右发生了一次由减小到增大的突变,各时段的水分状况均为较不适宜;干燥指数包含了多个不同的时间尺度的周期变化和演变特征,主要有4-6年、11年和29年三种尺度的周期变化规律,在未来几年内,洮儿河中上游地区干燥指数将处于偏小期,水分适宜状况好转。

Aridity index for the upper and middle reaches of Taoer River was calculated by the meteorological and hydrological data during 1961 to 2012, and used to evaluate the water suitability. The results showed that it had a decreasing trend during the period of 1961 -2012, though the trend was not obvious. The average of aridity index was 2.36 and the water suitability was not suitable. The aridity index in winter was bigger than that in the other seasons, which was 18.59. Accordingly, the water suitability in winter was the most poor. While the situation in summer was reverse. The aridity index in summer was 1.35, and that meant the water suitability in summer was the best of the four seasons. Two inflexion years were detected. Thus, the entire time period was divided into three periods ： 1961 - 1983, 1984 - 1995, and 1996 - 2012. In the first and third periods, the aridity index had an increasing trend, but in the second period, the trend was decreasing. The water suitability of each time period was not suitable. There were three scale periodic variations, they were 4 -6 years, 11 years and 29 years. In the next few years, the aridity index of the upper and middle reaches of the Taoer River will be in the smaller period. As a result, the water condition will be improved.