The researchers developed a new exact model using Laplace transformation to study how groundwater flows in river-aquifer systems. They used a general function to describe changes in river water levels, such as linear or exponential variations. The study found that groundwater levels rise slower in aquifers with greater thickness or hydraulic conductivity. Changes in specific storage had little effect on groundwater levels. The model showed that aquifers with shorter length, higher hydraulic conductivity, or greater thickness were less sensitive to changes in recharge rates. The results were compared with existing analytical solutions and MODFLOW, showing the new model is accurate and efficient for analyzing aquifer parameters.