Hydrochemical dynamics of stream following rainfall events at agricultural catchments in New Zealand

One of the prerequisites for efficiently managing lake water quality is reliable data regarding thequantity and quality of inflows water, mainly the export of nutrients from the catchment area during rainfallevents. We investigated the dynamic characteristics of hydrochemicals concerning rainfall events inagricultural stream waters flowing into eutrophic lakes situated on the North Island’s central plateau of NewZealand. We utilized isotopic composition of water (δONO3-2H-H2O and δ18O-H2O) and nitrate (δ15N-NO3-and δ18) along with high-frequency hydrochemical data for source identification of water and nitrate during adrought period (2020). Our findings indicate that it is essential to initially grasp the fundamental mechanismsassociated with rainfall events to formulate effective strategies for minimizing nutrient losses. Themethodology outlined in this research integrates stable isotope hydrology with water quality monitoringinitiatives, facilitating the understanding and managing the primary governing mechanisms behind diversecontaminant losses from land to adjacent water bodies, explicitly focusing on nitrates. This approachestablishes a framework that can assist in devising measures for water quality improvement capable ofanticipating the repercussions of substantial rainfall events more effectively.