Experiment And Simulation Of Storage And Recovery Of Coastal Aquifer Based On Sandbox Model

Coastal aquifers are an important source of freshwater resources in coastal areas.The rational development and utilization of coastal aquifers is a crucial step for sustainable development in coastal areas.However,the geological conditions of coastal aquifers are relatively complicated,often accompanied by seawater intrusion,and the steady state of groundwater in coastal aquifers is greatly affected by it.In this study,through the construction of an indoor sandbox model,we will study how to rationally use coastal aquifers for freshwater storage and recovery under the premise of preventing further intrusion of seawater,meanwhile through numerical simulation and comparison analysis to optimize the experimental scheme,and provide a basis for related research such as the rational use of coastal aquifers.Through the construction of an indoor sand box model and the color tracing technology to visually display the fresh-salt groundwater interface migration process,analyze the law of fresh-salt groundwater interface migration and the coastal aquifer storage and recovery under different well distribution methods.Comparative analysis of recovery rates of different experimental schemes on the premise of preventing seawater intrusion.The results show that: by changing the way of recharge wells and recovery wells,the optimal aquifer storage recovery rate can be achieved while preventing seawater intrusion.Distributing a single well back to the salty and fresh water boundary area will cause the fresh-salt groundwater interface to retreat around the well.At the same time,through the comparison and analysis of the same recharge amount,the effect of a single well on the fresh-salt groundwater interface gradually decreases from the near end to the far end of seawater intrusion.The closer to the left saline water boundary,the better the recharge effect,which can provide more space available for subsequent recovery,which will improve the recovery rate of the aquifer and the saltwater and the combined effect of fresh-salt groundwater interface regression and saltwater wedge area reduction under the combined well scheme is significantly better than that of a single well.At the same time,it should be noted that when the mining progresses to a certain extent,the returned fresh-salt groundwater interface will gradually return to the original state,so we must always pay attention to the movement of it to the intrusion of seawater from increasing due to excessive mining.Through the establishment of a coastal aquifer storage and recovery numerical model,and under the premise that the well layout method is unchanged,the circumstances of aquifer storage and recovery after increasing the amount of recharge water are simulated and analyzed.The results show that after increasing the recharge amount of each well,the fresh-salt groundwater interface will continue to recede,and the area of the saline-water wedge will continue to shrink,but the receding rate and shrinking rate will be smaller the later.At the same time,due to the additional interface regression and area reduction,more recovery space is provided for subsequent aquifer mining and the aquifer recovery rate has also increased.The prevention of seawater intrusion and the rational use of underground aquifers are two indispensable parts of water resources management in coastal areas.Through the storage and recovery of coastal aquifers,it is possible to alleviate water stress in coastal areas on the premise of preventing seawater intrusion.But at the same time,we still need to do a good job in optimizing the management of water resources,establishing a dynamic monitoring and early warning system for seawater intrusion,and saving water and increasing revenue in coastal areas.