基于最小二乘法的鄱阳湖水位流量关系研究

Study on relationship of water level and discharge in Poyang lake based on least square method

为了进一步揭示鄱阳湖与长江及其流域来水之间的"江河湖"关系,选取鄱阳湖湖口水文站作为研究对象,以三峡工程的蓄水时间(2003)为分界点,应用最小二乘法对其1978-2007年的水文数据序列(逐月平均水位与月平均流量)进行线性、多项式(三次曲线)拟合及其对数拟合,根据建立拟合曲线的判断系数R2大小选出最优的鄱阳湖水位流量关系拟合曲线,并对影响3种曲线拟合精度的影响因素进行探讨,最后对湖口水文站年均水位及年平均流量变化趋势进行分析。研究结果表明:2003年前后,鄱阳湖湖口水文站水位流量关系拟合曲线均以三次曲线拟合精度为最高,以对数拟合精度为最低;湖口水文站历年年均水位呈现下降趋势,而年平均流量则呈现上升趋势,年均水位和年平均流量最大值均出现在1998年,最小值则分别出现在2006和1979年。研究结果能够为鄱阳湖湖区水资源合理利用与水环境安全保护提供一定的参考依据。

To further reveal lake- river relation between Poyang Lake and Yangtze River and watershed,the paper took Hukou hydrological station in Poyang Lake as the study object,and chose the impoundment time of Three Gorges Project（ 2003） as the cutoff point to analyze the quantitative relationship of water level- discharge. Then it applied the least squares method to fit the hydrological data series（ monthly average water levels and flows） during 1978- 2007 by linear fit,polynomial（ cubic） fit and logistic fit.The optimal water level- discharge curve was selected by the coefficient R2. Meanwhile,this paper explored the influence factors of three kinds of fitting curves accuracy. and analyzed the trend of relationship between annually water levels and flows analyzed. The results showed that around 2003,the optimal water level and discharge curve was the polynomial（ cubic） fit curve,while accuracy of logistic fit was the worst; the annually average water level at Hukou hydrological station showed a downward trend,while the annually average water flow showed a upward trend; the maximum annually average water level and flow both happened in 1998; the minimum annually average water level and flow took place in 2006 and 1979 respectively. The result can provide certain reference for the rational utilization of water resources and the protection of water environment at Poyang Lake area.