Assessing the role of pit lakes in riverine landscape rehabilitation via multi-source satellite data

Since the 1950s, an intense quarrying activity led to the formation of several pit lakes (PLs) which now dot floodplains and urbanized regions globally. Recently, a renewed interest in PLs has grown as tools for riverine landscape rehabilitation. The primary aim of this study was to quantify the number, distribution, and major physical/optical characteristics of PLs in the Po River basin, in order to assess their relevance and suitability for ecological restoration purposes. To achieve this aim, multi-source satellite imagery (Landsat, Sentinel-2, and PRISMA) was employed for PLs identification and analysis of their water quality parameters. The results show that 1580 PLs are present in the Po River basin, and their number and the total area have increased from 1990 to 2021. PLs currently account for 63.5 km2 surface area, an average water volume of 378 × 106 m3 and for a removal of 26.6 mg N m− 2 d− 1 via denitrification. Therefore, PLs can potentially contribute ecosystem services, e.g., water provisioning and nitrogen cycle regulation, and can be exploited for rehabilitating the riverscape. In this context, remote sensing is a very reliable tool for quantifying and analysing PLs in a vast area such as the Po River basin.