Temporal analysis of rainfall impacts on Danube river water level and discharge at Novi Sad, Serbia (2020-2024)

River water levels and discharge are primarily influenced by precipitation, including rainfall and snowfall, as well as by ice melt. The Danube, the second largest river in Europe, has an extensive catchment area, where different tributaries and their precipitation regimes influence the river, affecting its water levels and discharge. This study analyses the impact of rainfall in Novi Sad, Serbia, over a five-year period (2020-2024), focusing on the effects of precipitation and its extremes, and examining whether they influence the water level and discharge of the Danube in Novi Sad on a daily level. The analysis is based on data obtained from the hydrological yearbooks of the Republic Hydrometeorological Service of Serbia (RHSS). Extremes in rainfall, discharge, and water level, as well as their interrelationships, were assessed using the 10th and 90th percentile method. Moreover, Pearson correlation coefficient was used in defining the statistical correlation between precipitation and water level along with discharge. The study aims to estimate the typical time lag between precipitation events and the hydrological response. The findings indicate a low level of significance in the correlation between precipitation and both water level and discharge for the period of 2020-2024. The time lags in response to extreme precipitation increased from the first to the third day, with the highest values observed on the third day. Furthermore, a positive correlation (0) between precipitation and water level was recorded during 2020, while a positive correlation between precipitation and discharge was observed during 2020, 2023, and 2024. This research demonstrates that the impact of local precipitation on the local hydrological station is small and short-lived, which is expected, given that the Danube is a very long river with a large catchment area and complex flow regime.