毛乌素沙地与浑善达克沙地水分深层渗漏特征对比

Comparison of deep soil recharge characteristics between Mu Us Sandy Land and Hunshandake Sandy Land

深层渗漏是沙地地表水和地下水连通性的重要指标。为了深入分析不同沙地深层渗漏的特征,采用渗漏仪实时监测流动沙丘降雨对200 cm深层的补给水量。结果表明:浑善达克沙地2017—2019年降雨量为229.9±45.6 mm,年渗漏量8.2±7.4 mm、年渗漏量占同期降雨量3.1%±2.3%;毛乌素沙地2013—2015年降雨量328.1±61.1 mm,年渗漏量64.1±58.3 mm、年渗漏量占同期降雨量17.0%±13.7%。浑善达克沙地流动沙丘的渗漏主要为持续而少量的水分补给,其中<0.25 mm的渗漏补给日数最多;毛乌素沙地主要来自于>0.25 mm的渗漏补给,降雨量大小及其分布格局是影响沙地深层渗漏的主要因素。当降雨量较小时深层渗漏是以持续、长时、量小的补给方式为主;降雨量较大或者连续的小降雨事件不但会明显增加渗漏的补给量,而且会减小水分渗漏滞后性,使其波动与降雨变化更为一致。

Deep soil recharge(DSR)is an important indicator of the connectivity between surface water and groundwater in sandy land.In order to analyze the characteristics of DSR in different sandy land with different precipitation gradients,this study used a newly designed Lysimeter to monitor the amount of DSR in 0-200 cm depth soil layer by the annual precipitation of mobile dunes in real time.The results of the study showed that the annual precipitation amount in the Hunshandake Sandy Land from 2017 to 2019 was 229.9±45.6 mm,the average annual leakage was 8.2±7.4 mm,and the annual DSR accounted for 3.1%±2.3%of the annual precipitation.The average annual precipitation in Mu Us Sandy Land from 2013 to 2015 was 328.1±61.1 mm,the average annual DSR was 64.1±58.3 mm,and the annual DSR accounted for 17.0%±13.7%of the annual precipitation in the same period.The DSR of the mobile sandy dunes in the Hunshandake Sandy Land was mainly due to the continuous but small amount of precipitation recharge.Among the precipitation events,the daily recharge amount of less than 0.25 mm of DSR was more frequent.On the contrary,the daily recharge amount of more than 0.25 mm of DSR was more frequent in the Mu Us sandy land.When the precipitation was small,the DSR was mainly continuous,long-term,but small amount.Large precipitation amount or continuous small precipitation events not only significantly increased the amount of DSR,but also made the delay time of DSR shorter,and the fluctuation frequency of precipitation fluctuation was consistent with the fluctuation frequency of DSR.