Hydrological indicators of wetland degradation in Mediterranean wetlands (S Iberian Peninsula): Influence of groundwater extraction, substrate permeability and climate variability

Study region: Southern Iberian Peninsula (Mediterranean region), from the western to the eastern side. Both wetlands developed over high- and low-permeability substrates are included. Study focus: This study proposes and applies hydrogeology-based framework to assess wetland degradation by analyzing hydrological responses during a wet hydrometeorological year following a prolonged drought. The methodology compares actual and modelled water levels by means of correlation coefficient, mean bias and hydroperiods. Based on these indicators, wetlands are classified into three degradation levels (Level 1: low to Level 3: high). The framework is tested across different hydrogeological settings to evaluate its robustness and applicability for management. New hydrological insight: Results reveal contrasting behaviors depending on substrate permeability and groundwater use. Wetlands over permeable substrates show strong agreement between observed and modelled data and retain recovery capacity (Level 1). When they are located near intensive pumping, these wetlands exhibit negative mean bias and reduced correlation (Level 2). Wetlands over low-permeability substrates display higher heterogeneity: some playa-lakes recover well (Level 1), whereas others show severe degradation linked to intensive agriculture (Level 3). Two main degradation drivers are identified: land-use intensification (especially groundwater-supported irrigation) and increasing climate variability with recurrent droughts. The proposed framework provides a practical tool for diagnosing degradation stages and supports adaptative management strategies, including restoring hydrological connectivity, reducing groundwater abstraction and promoting sustainable agricultural practices.