Author(s): Maria Diaz-Redondo; Beatriz Molina; Francisco Miguel Cortes

Linked Author(s):

Keywords: Combined suitability index; Duero River; 2D eco-hydraulic modelling; IberHABITAT; Physical habitat suitability

Abstract: The module IberHABITAT, developed for the 2D hydraulic model Iber, is based on the combination of both hydraulic and hydrobiological variables to create a habitat or eco-hydraulic model. This module allows to obtain classified areas of Physical Habitat Suitability (PHS) for targeted fish species in relation to a specific discharge. This particular approach has been applied in a 17.2 km-long pilot section of the Duero River between Toro and Zamora (Spain) within the DRAINAGE project for the integral management of flood risk. For the present study, the IberHABITAT modelling tool was run to obtain the SPH areas of three autochthonous fish species under four discharges: mean and minimum annual flow, and two ecological flows (ordinary conditions and drought conditions). The selection of the targeted fish species (Barbus bocagei, Chondrostoma duriensis and Squalius carolitertii), was based on previous surveys by the Duero River Basin Authority. A bathymetric survey was specifically obtained for this study, since the study area is characterized by complex geomorphology (bars, islands, pools, backwater areas, etc.). Results show the spatial distribution of the SPH of the selected fish species and the relationships between physical habitat and certain characteristic discharges. It is noteworthy that, under very low flow conditions, the most suitable areas for the adult and juvenile stages of B. bocagei are almost non-existent. At present, the recurrence of periods of minimum flows, as well as their duration, may be limiting the diversity of fish communities in the study section. This eco-hydraulic perspective is necessary for the characterisation of the study area as baseline for the proposal of nature-based solutions within the DRAINAGE project, seeking to balance the objectives of nature conservation with the prevention of flood damage.

DOI: https://doi.org/10.3850/IAHR-39WC252171192022263

Year: 2022