Study On The Interaction Between Surface Water And Groundwater In Seasonally Frozen Soil Area ——A Case Study Of Songhua River Basin In Sanjiang Plain

The transformation relationship between surface water and groundwater is not only the key issue in hydrology cycle,but also the basis of water resources management,planning and optimal allocation.The research on the influence of freezing-thaw action on the interaction between surface water and groundwater has important theoretical and practical significance for the optimal management and allocation of water resources in seasonal frozen soil areas.In this paper,the Songhua River Basin in Sanjiang Plain,a typical seasonal frozen soil area in China,is selected as the research area.Through data collection and field investigation,the dynamic data of surface and groundwater levels and water sample test data in different periods in the research area are obtained.The method of hydrochemistry and isotope analysis is used to analyze the interaction of surface water and groundwater in different periods of seasonal freezing and thawing.Two-dimensional groundwater numerical models of typical porfiles were constructed.Based on the simulation results,the changes of interaction intensity and groundwater flow mode in different periods of seasonal freezing and thawing are analyzed.The conclusions of the two methods are compared and verified,and the temporal and spatial differences of surface water and groundwater interaction are summarized as follows:(1)There are spatial differences in interaction between surface water and groundwater in study areaThe interaction between surface water and groundwater in thestudy area has great differences in recharge time and intensity.In the upstream(Jiamusi-Huachuan),there are high-lying Piedmont platforms on the south and north sides.The topographic and hydrogeological conditions control the direction of regional groundwater flow.In most periods of the year,groundwater recharge surface water,and surface water recharge groundwater only in wet periods.Fujin-Tongjiang area is in the lower reaches of Songhua River,where the terrain on both sides of the river is flat,and the head difference between river water and groundwater is little.In addition,due to the influence of artificial exploitation of groundwater,surface water recharges groundwater;In the middle reach of Songhua River,which is bounded between the upstream and downstream,the interaction between surface water and groundwater changes frequently due to the joint influence of many factors.(2)The interaction between surface water and groundwater is obviously affected by seasonal freezing and thawing:(1)In the non freezing-thawing period: During the dry season of Songhua River(early May to June),the water level dynamics of Songhua River and groundwater are affected by many factors,and the interaction between surface water and groundwater changes frequently;During the wet season(July to September),the water level of Songhua River rises obviously,and the groundwater is mainly recharged by surface water;From October to early November,the water level of the river fell,groundwater recharges surface water.(2)In the freezing period: at the beginning of the freezing period,due to the influence of river icing process,the water level of Songhua River in the study area is rising quickly,and the interaction between surface water and groundwater is quickly changed to surface water recharges groundwater with high intensity.From mid November to mid March of the following year,surface water is mainly supplied by groundwater.At the end of the freezing period,the surface water level relatively rises,and the intensity of groundwater recharging surface water decreases.(3)In the thawing period: The thawing period begins in mid March.In early April,the river enters the ice flood period,water from the upstream is blocked by the downstream ice,the water level rises,and the recharge intensity of surface water to groundwater rises.Since then,the Songhua River enters the dry seasons and water level fell,the groundwater level rises under the recharge of snowmelt water and atmospheric precipitation,and the groundwater begins to recharge surface water.In conclusion,the interaction between Songhua River and groundwater in Sanjiang Plain has temporal and spatial variability,and it's obviously affected by seasonal freeze-thraw action.