The Impact of Water Flow Variability on Brackish Water Distribution in Prokljan Lake, Croatia

Investigating the complex dynamics of the Prokljan Lake ecosystem in Croatia, this study examines the influence of the variability of water flow on the distribution of brackish water. The microtidal Mediterranean environment, characterized by limited vertical mixing, forms a distinct bidirectional two-layer flow system within the river channels. The study focuses on the upper section of the Krka River Estuary that includes Prokljan Lake, an essential habitat with diverse ecosystem services. Vertical profiles of salinity data were collected via multiple field campaigns, reaffirming the highly stratified nature of the estuary. The novel Brackish Water Fraction (BWF) index was introduced, offering a rapid assessment tool to quantify salinity distribution. Correlations between the BWF and river flow have been established, shedding light on the intricate interplay between flow dynamics and estuarine behaviour. This index holds promise for similar estuarine systems and offers insights into sustainable management practices. The study enriches our understanding of the complex interactions that shape coastal and estuarine ecosystems.