Qualitative Comparative Analysis of Two Holistic Methodologies for the Estimation of Environmental Flows in Colombia

Currently, concerns over the role of fossil fuels in climate change, and the increase in energy demand due to socioeconomic changes and population growth has led to a growing interest in green energy sources. In view of this situation, the number of planned and constructed sustainable hydroelectric plants has increased. However, these structures can also have negative environmental effects as they can damage the surrounding freshwater ecosystems. Recent studies show that Southeast Asia, South America and Africa are the regions where the largest number of hydroelectric projects are expected. In Latin America, Colombia is categorized as the country with the second greatest hydroelectric potential. Therefore, with the purpose of reducing environmental degradation, determining ideal environmental flows in Colombia from a holistic perspective is necessary. In the present study the methodologies examined were the worldwide applied “Ecological Limits of Hydrologic Alteration (ELOHA)” and the “Methodological Guide for the Estimation of Environmental Flows in Colombia (GMECAC)” developed specifically for Colombia. ELOHA is a reference framework that aids in the assessment of the required environmental flow at the regional level by examining the relationships between the alteration of the flow regime and the ecological response of the ecosystem. On the other hand, GMECAC is a methodology recently developed by the Colombian Ministry of Environment and Sustainable Development that seeks to standardize the process to estimate the required environmental flows in Colombia. The assessed methodologies were compared based on three aspects: technical, social and management, based on the level 1 analysis proposed by Opperman (2018). It was determined that, although both methodologies propose the same hydrological characterization, GMECAC does not take into account the relationship between the ecological processes and the hydrological regime. Additionally, the GMECAC criteria to determine accepted impact is based on statistical tests that only correlate the natural and modified hydrological condition. Furthermore, the social dimension of the project is not contemplated in the GMECAC. Without a section to aid concertation efforts with the affected community, the methodology falls short of being able to establish definitive environmental flow objectives and allowable threshold. Finally, while both methodologies require constant monitoring, ELOHA does not establish a guide to carry out this task while GMECAC does. Unfortunately, the latter´s guide, focused on habitat and water quality, does not establish acceptance thresholds or takes into account the relationship between this parameters and the estimated environmental flow regime.