Author(s): Francisco Martinez-Capel; Ted E. Grantham; Frank Santiago-Bazan; Hector Macian-Sorribes; Rafael Munoz-Mas; Manuel A. Pulido-Velazquez

Linked Author(s): Francisco Martínez-Capel, Manuel Pulido Velázquez

Keywords: Functional flows; California Environmental Flows Framework; Fish habitat; Mediterranean rivers

Abstract: The Júcar River Basin, one of the most heavily regulated catchments in the Mediterranean region of Southern Europe, provides an illustrative context for examining the applicability of the Functional Flows approach in complex water resource systems. In this study, we applied the methodology developed within California Environmental Flow Framework (https://ceff.ucdavis.edu) to characterise functional flow components and evaluate their potential integration into current water-management frameworks. The California Environmental Flows Framework (CEFF) provides technical guidance for water and environmental managers to apply a functional flows approach to efficiently develop scientifically defensible environmental flow recommendations in California. This methodology can be considered as a generalization of the Functional Flow Model (Escobar & Pasternack, 2010, 2011), and of some previous holistic methods, which employed an ecohydrological conceptual scheme that synthesizes the flow -ecology relationships and remarks the relations between key hydrological events and river ecosystem processes (e.g., the Savanna process, Richter et al., 2006). The CEFF basically consists of the following steps (Yarnell et al., 2015; Grantham et al., 2020 , 2022): 1) Identification of relevant Functional Flow Components (FFC), 2) Selection and calculation of Functional Flow Metrics for each of the components (FFM), 3) Determination of target Environmental Flow Ranges, 4) Assessment of current river conditions, 5) Prioritization of ecological needs and conflicts, 6) Formulation of environmental flow recommendations, and 7) Validation, implementation, and monitoring. Therefore, the steps in this piece of research are the following. 1) Application of the Functional flow Calculator (FFC) in two study sites in the Júcar River Basin to determine a functional flow regime (flow ranges). 2) Estimation of the habitat suitability and weighted usable (WUA) area for target native fish species in the study sites, because WUA is legally recognised as an indicator to define the minimum environmental flow in the River Basin Management Plans (Spanish legislation), together with some percentiles of the river gauging records in natural (unregulated) conditions. 3) Comparison of the minimum (and percentiles) of the WUA derived from the minimum flows in the legally approved River Basin Management Plan and the ones derived from a potential functional flow regime, for native fish species. 4) Discussion abou t functional deficits relevant to geomorphic processes, aquatic biota, and riparian vegetation under the present regulations in the Júcar River Basin Management Plan.

DOI: https://doi.org/10.64697/iahr.proc.ise2026.abs.280

Year: 2026