Seasonal variationin recharge of infiltration from precipitation for the inland basins of northwestern China: taking the Changji groundwater balance test station in Xinjiang as an example

The inland basins of northwestern China has little precipitation and a long freezing period in a year. It is very important to understand the seasonal variation in recharge of infiltration from precipitation for accurately evaluating groundwater resources and explaining the impact of climate change on groundwater recharge in cold and arid regions. This article adopts experimental data of 27 sets of lysimeters in the Groundwater Balance Test Station of Changji, Xinjiang from 1992 to 2015, applies the Layda's rule to screen outliers in long series of observations, combines the observational data of meteorological factors of the test station to divide time range of freezing period, thawing period and non-freezing period in the inland basins of northwestern China, analyzes influencing factors on infiltration recharge of groundwater in different periods. The importance of different seasons to annual recharge infiltration precipitation is determined by calculating the percentage of average replenishment of infiltration from precipitation during different periods to average annual replenishment of infiltration from precipitation. According to the change law of annual replenishment of infiltration from precipitation with groundwater depth, the optimal burial depth for different soil texture in the thawing period and non-freezing period is determined. The results indicate that under the test conditions, the optimal depth of sand gravel and fine sand are 0.5 m in the non-freezing period, and the optimal depth of light clay is 0.1 m in the non-freezing period. The optimal depth of fine sand is 1.0 m in the thawing period, the optimal depth of sand gravel is 0.5 m in the thawing period, and the optimal depth of light clay is 0.1 m in the thawing period. The impact of depth of groundwater level on soil infiltration capacity during freezing period is quite obvious, and there is no significant linear relationship between depth of groundwater level and replenishment of infiltration from precipitation. The thawing period is an important period of replenishment of infiltration from precipitation for the shallow-buried groundwater. The freezing period is an important period of replenishment of infiltration from precipitation for deep-buried groundwater.