Data for: Hydrological connectivity regulates nitrogen transformation within a meandering driven hyporheic zone under contrasting hydrological conditions

This dataset is the original data of the paper “Hydrological connectivity regulates nitrogen transformation within a meandering driven hyporheic zone under contrasting hydrological conditions”. The dataset includes water level data and water chemistry data during the rainy season of a wet year 2021 and a normal year 2022. All the water level and concentration data were obtained by in situ monitoring in a meandering river bend in the upstream Xilin River, which is located in the central Inner Mongolia, China (43°37′11.2″N, 116°42′23.6″E). The water chemistry data include the concentration of Dissolved Organic Nitrogen (DON), DIN species (NO3-, NO2-, NH4+) and Dissolved Oxygen (DO). High-resolution groundwater level was collected in the riparian zone. Five lateral transects (T1-T5) were set up along the meander reach to investigate the hyporheic exchange flow (Fig. 1). Along each transect, three monitoring points were installed, with one in the middle of river channel, and one on each bank 2 m away from the river edge. For each instream point at C1 (inlet), C3 (apex) and C5 (outlet), three PVC piezometers with 5 cm diameter were installed to depths of 20 cm, 50 cm and 100 cm below the riverbed surface to observe groundwater heads at multiple depths. For the instream points at C2 and C4, one PVC piezometer was installed at the depth of 100 cm below the riverbed surface. For the monitoring points on each bank, one piezometer was installed to 150 cm depth below the ground surface. Along the transect at the meander apex (T3), we established two more piezometers in the inner bank of the meander, located 6 m and 10 m away from the river edge.