Bajrami  Flamur, Ph.D. Candidate 39th cycle, University of Trento, DICAM

Rivers play a fundamental role in shaping ecosystems, providing essential habitats for aquatic, riparian, and terrestrial species. However, the growing intensity of human activities, including dam construction, sediment mining, water abstractions and land-use changes, has significantly altered the hydrology and morphology of rivers by modifying their natural flow and sediment supply regimes. These alterations in turn have profoundly impacted river habitats and their dynamics, resulting in a marked decline in freshwater biodiversity and placing numerous species at serious risk. This issue is relevant both in industrialized contexts, where few rivers with near-natural morphologies can be found, and in developing regions, in which high levels of biological diversity are still supported by near-natural river morphologies, yet they are increasingly vulnerable to the rapid pace of socio-economic development. As these areas undergo significant changes, the risk to their biodiversity intensifies, making it crucial to understand how river morphology influences habitat availability in these contexts.
While it is generally known that morphological diversity corresponds to habitat diversity, a quantitative relation between river morphology and the corresponding habitat availability for target biological species is lacking. Habitat availability is often quantified through rating curves that link the suitable or usable habitat area with the flowing discharge (“habitat-discharge rating curves”, in the following). Those relations establish how much habitat area in a river reach is suitable for a target species based on the species' preferences in terms of hydromorphological quantities like flow depth, velocity, and sediment size, and on the availability of refugia like those provided by boulders, overhanging vegetation or large woody debris. Habitat-discharge rating curves have been developed for many single-thread, wadeable rivers, but much less for braided streams.
My PhD research aims to determine to which extent the shape of habitat-discharge rating curves can be predicted from the knowledge of the river reach morphology, either quantitatively or, at least, qualitatively. A particular emphasis will be placed on braided rivers, for which less is known in this respect. To this aim, I am studying multiple river reaches with varying morphologies to empirically define habitat-flow curves for each morphological type. The acquired knowledge can be used to analyze the evolutionary morphological trajectories of selected rivers to assess the impact of anthropogenic stressors on habitat availability.
Over the first year, I have analyzed the current morphological conditions of some rivers in Albania using the IDRAIM methodology and compiled a dataset of habitat-flow curves for different river morphologies from previous projects at the University of Trento.  In particular, the focus was on braided river reaches to assess habitat rating curves that can be related to the degree of braiding, quantified through the braiding index (BI). For this purpose, a new study area was added where field measurements were made: a reach of the free-flowing Sarandaporos rivers at the border between Greece and Albania, in the Vjosa river catchment was chosen, Using UAV-based photogrammetry, a DTM was created that will be used, together with the other field data, to perform 2D hydraulic modeling, which will provide. depth and flow velocity that will then be used to compute habitat availability and derive habitat flow curves with the Mesohabsim methodology.