Assessing land use impacts on catchment hydrology with participatory monitoring: lessons for experimental design, network building, and policy support

Many regions in the world face declining water availability and increasing water-related risks, as a result of pressures such as environmental degradation, global warming, and population growth. Sustainable and integrated land management is an important tools to improve and safeguard catchment water resources, and to minimize flood and drought risk. However, land management to optimise water security is still severely hindered by a lack of hydrological information about the impact of different management practices on the catchment hydrological response. Statutory hydrological monitoring networks tend to be sparse in most of the world, and focused on operational purposes such as water supply and flood risk. Here we present the case of iMHEA, a participatory hydrological monitoring network in the tropical Andes that aims at characterising the hydrological impact of different land management practices in the upper Andes, especially conservation, livestock grazing, and forestry. The network monitors currently 59 catchments in 22 Andean sites from Venezuela to Chile. It operates as a community of practice, exchanging experimental designs, technical expertise on monitoring equipment, protocols, and experience. It largely follows a pairwise catchment comparison approach, which has been able to show statistically significant trends in land-use impacts on flow characteristics such as runoff ratio, baseflow index, and slope of the flow duration curve. Thanks to rigorous technical support, the generated data are generally of high scientific quality and reliability. The involvement of stakeholders with a policy background, such as NGOs and government agencies, is key to dissemination and operational uptake of the scientific results. As such, iMHEA can be considered a success story, which has created a step change in scientific evidence for land use planning in the Andes. However, several challenges remain. One is the experimental design, which is not yet able to accommodate all the specific interests and challenges that iMHEA members are faced with. Longevity and long-term financial sustainability also remains a major challenge. Lastly, improvements are needed to process and dissimenate the results to specific stakeholders, and especially local communities and governments.