Global patterns of water‐driven human migration

Environmental change is growingly reported as an important driver of human migration. Among all environmental variables, water crises are the most critical factors. To date, patterns of interconnections between changes in water and migration are not yet clearly understood. Here, we explore these patterns through a systematic review that combined a quantitative text‐mining approach with qualitative thematic analysis. Our results generally concur with those of previous studies, which found that water‐driven migration usually occurs internally and that the population in low‐ and middle‐income countries and in dry regions are the most vulnerable and more likely to migrate or be displaced in the face of water‐related events. However, our causal network analysis highlights that water is not the only reason for migration: Its related problems could be major triggers driving people‐at‐risk to leave their original place. Based on observed evidence, water‐driven migration can be generally divided into four patterns: variability in water quantity, damaging water hazards and extremes, physical disturbances to water systems, and water pollution. These patterns are not independent but interconnected through multifaceted factors affecting people's livelihoods and their decisions to migrate. Understanding water‐migration dynamics requires systematic thinking of the interconnections between changes in water and in migration patterns, the investigation of interactions between fast and slow water variables and their dynamic link to other socioeconomic variables, an integrated water‐migration database to help identify early‐warning signals of damaging water hazards that may result in undesirable migration, and targeted water policies that focus on building the resilience of vulnerable regions and population to climate change.