Wetlands' e-hydroperiod method: Frequency-of-occurrence-based approach

Study region the Great Lagoon of Catazajá is a Ramsar site and habitat for the Greater Caribbean manatee ( Trichechus manatus manatus ). It is located in the floodplain of the Usumacinta River, the mightiest river in Mesoamerica, and a transboundary basin with most of its course running through western Guatemala and southern Mexico. Study focus This study aims to present a methodological approach for the evaluation of the environmental water allocation specific for the wetlands (e-hydroperiod) with the theoretical principles of eflows. The low-volumes are parametrised separately from the peak-events, and the frequency of occurrence at which the hydrological conditions and types of peak events are integrated based on the environmental objective selected from a four-to-five-tier class system. The research in Mexico serves as a proof-of-concept and as a fitness evaluation for the model. The results reveal an overall good level of the method’s performance against the natural regime (R 2 ≥ 0.93). New hydrological insight This study addresses the limited availability of wetlands-dedicated frameworks to allocate water for environmental processes that contemplate wetlands’ hydrological dynamics. Frequency-based e-hydroperiod components support the Freshwater Challenge goal of restoring 350 million ha of wetlands by 2030, and its implementation secures water for both sustainable use and ecological functions.