Spatiotemporal water quality analysis of Vrana Lake, Croatia

Abstract The comprehensive analysis of spatiotemporal variations in water quality is crucial for ecosystem management. This study analyses and maps spatiotemporal variations in water quality at Vrana Lake, a coastal shallow lake in Dalmatia, Croatia. We established a monitoring grid of 20 stations and conducted monthly in situ measurements of seven water quality parameters from July 2023 to June 2024 using multiparameter probe. We measured electrical conductivity, turbidity, salinity, water temperature, dissolved oxygen, oxygen saturation, and chlorophyll-a. We analysed the correlation between these parameters, water level, and meteorological factors over a year and the impact of climate change over the 34 years. Additionally, we evaluated 15 geographic information system (GIS) spatial interpolation methods for mapping the distribution of water quality parameters, using root mean square error (RMSE) and mean error (ME) metrics. The vertical stratification analysis revealed that the lake’s shallow nature allows effective assessment through median values. Key findings highlighted that air temperature, precipitation, and wind significantly affect water quality dynamics. The Simple Kriging – Trend emerged as the best GIS spatial interpolation method for modelling water quality parameters. Overall, this study enhances the understanding of water quality variations and their implications for ecosystem health in coastal shallow lakes.