Long-term evolution of hydrographic network density in arid Xinjiang, China: reconstruction from historical maps (1900-2020).

Water security in arid regions has become a critical challenge under ongoing global environmental change. Using arid Xinjiang as a case study, this research reconstructs the spatiotemporal evolution of hydrographic network density (HND) over the past 120 years (1900–2020s) based on historical maps and GIS-based spatial analysis. A grid-based HND dataset was developed for five representative periods to examine long-term structural changes in regional water systems. The results reveal a clear transition from early spatial dispersion to post-mid-20th-century aggregation and subsequent stabilization, with the 1960s marking a key turning point in hydrographic network organization. Spatial autocorrelation increased steadily over time, indicating the emergence of increasingly structured and clustered water systems. Climatic aridity factors–particularly the Palmer Drought Severity Index (PDSI)–exerted dominant controls on hydrographic dynamics in mountainous regions, whereas changes in oasis–plain systems were increasingly driven by human activities, including cropland expansion, irrigation development, and policy-led water management since the mid-20th century. By integrating long-term historical cartographic data with quantitative spatial analysis, this study provides new empirical evidence on how climate forcing and human engineering have jointly shaped water-system evolution in arid environments. The findings offer a long-term perspective for understanding human–environment interactions and for informing water-resource management and adaptation strategies in arid regions under future climate change.