LAUSR

Abstract Rangelands are complex social-ecological systems (SES) commonly used to support ranching and other agrarian livelihoods. Common to Earth's drylands, rangelands are susceptible to drought, desertification, and land degradation from both climatic and human activities. In the arid Americas, ranching communities are often located in watersheds and rely on local riparian resources (e.g. surface- and ground-water) to support crop and animal cultivation. However, anthropogenic climate change in combination with intensified agriculture integrated into international markets degrade both landscape and water resources. In Sonora, Mexico's Rio San Miguel Watershed we find via an interdisciplinary set of methods that rangeland productivity, surface-water reaches, and aquifers are reduced to critical levels, agrarian livelihoods endangered, and within this dynamic, that downstream locations are less resilient and water secure than operations upstream. This spatio-temporal dynamic to water insecurity is due both to (a) latitudinal-based climatic changes and (b) upstream groundwater pumping activity. Participatory rapid rural appraisal, agro-ecosystem analysis, and remote sensing tell us how climate, landscape, water, and ranching operation dynamics are interrelated and affect SES morphology and resilience across time, operations, and sub-watersheds. Partnerships and cooperation among ranchers, sub-watersheds, and institutions are among the management and policy interventions available to prepare for or mitigate the developing social-ecological crisis in the watershed. Lessons from Mexico's Rio San Miguel Watershed are relevant for other drylands, agrarian systems, and groundwater-reliant economies, especially as the specter of long-term global climate change and water insecurity looms large for many of the Earth's social-ecological systems.