Physical habitat simulation in a stretch of the Lozoya River using the PHABSIM system.

Abstract

This paper presents the habitat simulation of a 609-m stretch of the Lozoya river for obtaining the availability of Weighted Usable Area (WUA) for adult, juvenile and fry life stages of Barbus bocagei (endemic species of the Iberian Peninsula); as well as for determining the flow that maximizes the WUA. For habitat simulation, the Physical Habitat Simulation System (PHABSIM) was used, which is part of the Instream Flow Incremental Methodology (IFIM). Physical habitat simulation was made using PHABSIM hydrodynamic and habitat models, as well as habitat preference models for target species. As a result, Weighted Usable Area-Flow Curves (WUAQ) were obtained, where WUA distribution can be observed as a function of the stream flows of the Lozoya River stretch, and it can be identified that a flow of 1.45m3/s maximizes the Weighted Usable Area for the adult and juvenile life stages of Barbus bocagei. As for the fry life stage, HPU grows with flow, but it can be identified that HPU grows the most in a range between 0.2 and 1.45m3/s. WUA-Q curves provide valuable information to the manager and to the different users of fluvial resources for determining instream flow regimes in order to meet fluvial ecosystem conservation needs.