Exploring river–aquifer interactions and hydrological system response using baseflow separation, impulse response modeling, and time series analysis in three temperate lowland catchments

Abstract. Lowland rivers and shallow aquifers are closely coupled, their interactions crucial for maintaining healthy stream ecological functions. To explore river–aquifer the lowland hydrological system in three Belgian catchments, we apply a combined approach of baseflow separation, impulse response modeling, time series analysis over 30-year study period at catchment scale. Baseflow from hydrograph separation shows that catchments groundwater-dominated systems. The recursive digital filter methods generate smoother than graphical methods. Impulse modeling is applied using two-step procedure. first step groundwater level reacts fast to input, with most wells reaching peak during day. There an overall trend faster higher magnitude wet (October–March) dry (April–September) periods. second inflow also simulated can capture some variations but not peaks separated series. indicates discharge likely following characteristics, strong seasonal strengths, contrast streamflow, which exhibits weak seasonality. flow perspective be alternative method estimate rivers, as it considers physical connection between river aquifer certain extent. Further research recommended improve simulation, such giving more weight close adding drainage dynamics model input.