Study on precipitation recharge in point scale unsaturated zone of dry lake bed of Chahannaoer
In order to obtain a deeper understanding of the patterns of precipitation recharge in semi-arid areas,based on pre-cipitation data from the meteorological station in Shangyi County,Zhangjiakou and soil properties at sampling points,stable isotope,Mann Kendall(M-K)trend test,and chloride ion mass balance method were used to analyze the rate of precipitation recharge of the dry lake bed of Chahannaoer.The results showed that:① The soil above a depth of 1.4 m was a mixed layer,and the main movement mode of soil water was preferential flow,and the soil moisture content varied greatly and showed a significant increasing trend.The soil below a depth of 1.4 m was the stable layer,and the main movement mode of soil water was piston flow,and there was no significant change in soil moisture content.As the soil depth increase,the mass concentra-tion of chloride ions in soil water first decreased significantly and then increased,with no significant change overall.② There were a precipitation recharge signal from 2011 at a depth of 1.0 m in the soil,a precipitation recharge signal from 2009 at a depth of 1.6 m,and a precipitation recharge signal from 2006 to 2007 at a depth of 3.0 m.③ The average recorded density of the soil water profile was about 2.60 a/m,and the rate of precipitation recharge was about 0.15-0.19 mm/a,accounting for 0.03％-0.05％of the average annual precipitation.
dry lake bed of Chahannaoerprecipitation rechargestable isotopechloride ion mass balance methodunsatu-rated zone
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