绿洲不同尺度地下水时空动态变化特征及成因分析

摘要

[目的]不合理的开发使用地下水资源会产生一系列的环境生态问题,科学的论证地下水变化规律,为今后有效的开发、管理干旱区地下水资源提供重要保证和必要前提.[方法]以天山北坡奇台绿洲为研究区,从县域和乡级两个不同尺度对其地下水位时空动态变化特征及成因进行分析.[结果]县域范围内地下水位变化受人口因素影响深,乡级尺度受耕地面积因素影响更大.乡级尺度中,西-东方向农业发展历史长的乡镇地下水埋深早期下降快,后期逐渐趋缓.而早期以畜牧业发展为主的地区则反之.南—北方向,地下水埋深平均下降速度依次是中部(0.47 m/a)＞北部(0.31 m/a)＞南部(0.13 m/a).[结论]县域范围、乡级尺度引起地下水埋深变化的因素不同,时空变化特征也不一样.%[Objective]Improperly developing and using the underground water will cause a series of environmentally ecological problem.The scientific theory of the regular change of the underground water provides the important assurance and necessary premise for the effective development and management of the underground water in the arid area in the future.[Method]This paper analyses the characteristics and causes of temporal-spatial variation of groundwater in Qitai oasis on the northern slope of Tianshan Mountains on county and township scales.[Result] Groundwater level changing within the country range is deeply impacted by the factor of the population and the land factor produces a more deeper effect on the arable scale.On township scale,in the towns with a long history of agricultural development in west-east direction,the groundwater level declined rapidly in early period and then gradually slowed down.However,the area mainly developing animal husbandry in early period was the opposite.On south-north direction,the average decline speeds of groundwater level in different areas are in the following sequence:centre(0.47 m/a) ＞north(0.31m/a) ＞ south (0.13 m/a).[Conclusion] Although the most important cause of groundwater level variation is the increase of cultivated area,there are various reasons for the differences of groundwater level from south to north and from west to east on small scale.For the south-north direction,the reason is that the farmland of each township or town is different in position and geomorphology as well as hydrological conditions.For the west-east direction,the reason is that differences in agricultural development degree can cause different increase ratios of cultivated area in different periods.