科尔沁沙地典型区地下水、降水变化特征分析

地下水资源作为科尔沁沙地典型区的重要供水来源，研究地下水及其影响因素的变化特征对水资源合理开发利用、生态环境保护有重要的现实意义。以研究区周围左中、通辽和后旗3个典型气象站与7个地下水观测井数据为基础，应用灰色系统理论、线性回归、M-K突变检验、累积距平分析和小波周期分析等研究方法，对科尔沁沙地典型区1951-2015年降水量与地下水埋深进行研究，定性描述降水量变化与地下水埋深变化的响应关系。结果表明：（1）夏季气候倾向率为-18.6 mm·（10 a）^-1和年降水量气候倾向率为-11.7 mm·（10 a）^-1，都呈下降趋势，春、秋和冬三季降水量变化呈上升趋势，其气候倾向率分别为1.45 mm·（10 a）^-1、1.79 mm·（10 a）^-1和0.67 mm·（10 a）^-1。（2）近65 a来，研究区年降水存在2~5 a、7~12 a和18~31 a三个明显特征时间尺度的周期，对应小波方差图存在26 a和10 a两个周期峰值；四季降水量同样存在不同时间尺度的周期。（3）四季和年地下水埋深先呈线性再呈波动式变化，上升趋势显著，增幅分别为0.48 m·（10 a）^-1、0.50 m·（10 a）^-1、0.51 m·（10 a）^-1、0.48 m·（10 a）^-1和0.49 m·（10 a）^-1。（4）地下水埋深时间序列基准期和变异期的分界点为1994年。（5）1994年前，地下水埋深与滞后4 a降水量相关系数为-0.514；1994年后，地下水埋深与滞后8 a降水量相关系数为-0.527。

Variation of ground water and precipitation in typical zone of Horqin Sandy Area

Based on the monitoring data of weather station and groundwater observation wells in the study area, this paper comparatively described the relationship between changes in precipitation and groundwater depth in Horqin,Tongliao City and Inner Mongolia,China,at both annual and seasonal scales(March-May for the spring,June-August for the summer,September-November for the fall,December-February the following year for the winter),based on the data of precipitation from 1951 to 2015 in meteorological stations of Zhongqi, Tongliao and Houqi,and the data of ground-water depth in seven groundwater observation wells in the study area during 1951-2015 observed and simulated by Tongliao City Water Bureau,by using Gray System Theory,linear regression,M-K test,the cumulative anomaly analysis and wavelet cycle analysis. The results show as follows:(1)From 1951 to 2015,annual precipitation showed decrease trend of -11.7 mm·(10 a)^-1. Precipitation in spring,autumn and winter increased,with rates of 1.45 mm·(10 a)^-1,1.79 mm·(10 a)^-1 and 0.67 mm·(10 a)^-1, respectively;while precipitation in summer decreased with rate of -18.6 mm·(10 a)^-1.(2)For annual precipitation,there were three distinct periods,2-5 a,7-12 a and 18-31 a,with two peak periods of 26 a and 10 a in Poland figure;there were distinct periods for seasonal precipitation at different time scales.(3)Seasonal and annual changes in groundwater table showed fluctuant increase trends of 0.48 m·(10 a)^-1,0.50 m·(10 a)^-1,0.51 m·(10 a)^-1, 0.48 m·(10 a)^-1 and 0.49 m·(10 a)^-1,respectively.(4)1994 was the demarcation point for the time series of groundwater depth between base period and variation period.(5)Before 1994,the correlation coefficient between groundwater depth and 4-year-lagged precipitation was -0.514;while after 1994,the correlation coefficient of groundwater depth and 8-year-lagged precipitation was -0.527. This indicates that precipitation played an important role in supplying groundwater,and also had a lagging effect on the variation of groundwater depth. Before and after the sudden change of the groundwater level,the lag time was doubled from 4 a to 8 a. In addition,combined with the periodic analysis of precipitation,it is obvious that short periodic precipitation showed more obvious effect on groundwater level than long periodic precipitation,but the short periodic precipitation was decreasing. This paper has great significance for establishing a ground water research model which could be applied to the study area,achieving the reasonable exploitation and utilization of groundwater resources,and repairing the ecological environment in the area. However,the variation of groundwater depth is also affected by climate change and human activity,but this paper did not quantitatively account for the effect of climate change and human activity to ground water depth,which need further research.