The contribution of Geomorphology on climate services. Recent developments on the assessment of climate-impact indicators in the frame of the PNRR RETURN project

As part of Italy’s Nation-al Recovery and Resilience Plan (PNRR), the Extended Partnership RETURN (multi-Risk sciEnce for resilienT commUnities undeR a changiNg climate) aims at strengthening advancing research chains on climate-related environmental risks, to enforce the key competences, the technological and knowledge transfer, and to strengthen Italian governance in managing them. According to the National System for Environment Protection SNPA (2021), a climate impact indicator describes the consequences of climate variability on ecological, social, and economic functions, as well as on human and animal health. In this perspective, the present research intends to discern the climate-impact indicators for different natural sectors (mountainous and hilly, alluvial plain, and coastal environments). The Geomorphology Group of Sapienza University of Rome contributed to the project focusing on three specific indicators: i) landslide frequency and distribution (mountainous and hilly environments); ii) river channel bankfull variations (alluvial plain environment); iii) shoreline position and morphology (coastal environment). In mountainous and hilly sectors, landslides serve as key geomorphic indicators of climate change. Chang-es in rainfall regime as well as the snow cover variability can influence landslide occurrence. Rainfall acts both as a preparatory factor, gradually saturating soil layers, and as a triggering factor, rapidly initiating failures during high-intensity events. Meanwhile, variability in snow accumulation and melting influences pore water pressures in soil and contributes to slope failure during critical periods of thaw. In the alluvial plain sector, the confinement index – defined as the ratio between the active channel (bankfull) and the floodplain width - can be considered as one of the most representative climate-impact indicators capable of recording the climate change impact, specifically through changes in rainfall regime and related discharge variations. Finally, in the coastal sector, shoreline position and its morphological variations are recognized as a key indicator for coastal zones, since its configuration is constantly evolving due to both natural factors (e.g., waves, sea level fluctuations, tides, wind, and currents) and anthropogenic forcing.