Unravelling the Interplay Between Land Use Change and Surface Water Quality in Italian Watersheds

Abstract

Water is fundamental to life, crucial for the economy, and essential for ecosystems, as many Earth processes depend on freshwater distribution. However, water quality is increasingly degraded by land use and land-cover change (LULCC), as urban development disrupts river flows and runoff, while agricultural activities affect the nutrient cycle, runoff, and ecosystem resilience. This study aims to understand historical trends of land use changes from 1990 to 2018 in Italy and their impacts on water quality, offering a baseline model for predicting watershed ecological status under different socioeconomic and land-use scenarios for mid- and long-term timeframes. Principal Component Analysis and several Regression Models were employed to explore the influence of various landscape metrics on the watershed ecological status, considering upstream-to-downstream land use changes. The outcomes reveal significant landscape changes, especially from 2000 to 2012, with reduced grasslands, increased barren land, and urban expansion. Water quality was poorest near heavily altered areas, like the Po Valley, and highest in less impacted regions, like the Alps. Future predictions suggest declining water quality in urban areas but potential improvements in natural regions due to land abandonment. These findings support developing adaptive strategies that safeguard water resources, align with the Water Framework Directive (WFD), and ensure the long-term sustainability of freshwater ecosystems.