Mountain moves: Spatial interaction modelling of Bulgaria's internal migration (1934-1992).

Area of Science:

• Demography
• Human Geography
• Spatial Analysis

Background:

• Bulgaria faced significant rural decline and urban growth in the 20th century.
• The country continues to experience one of Europe's fastest population declines.
• Understanding historical migration patterns is crucial for interpreting population shifts.

Purpose of the Study:

• To conduct a spatial analysis of internal migration in Bulgaria between 1934 and 1992.
• To investigate the influence of topography on migration dynamics.
• To reveal local migration patterns often missed by larger-scale analyses.

Main Methods:

• Construction of a harmonized geocoded census settlement dataset.
• Calculation of settlement distances using Euclidean and road-network measures.
• Estimation of migration flows using spatial interaction models (SIMs) with population scaling and distance decay functions.
• Quantification of terrain effects using terrain ruggedness indices.
• Validation of model outputs against historical data and intercensal period variability.

Main Results:

• Mountainous terrain constrained migration flows but facilitated concentrated urban growth.
• Spatial interaction models successfully estimated migration patterns.
• Geospatial analysis uncovered localized migration dynamics.

Conclusions:

• Topography significantly shaped internal migration patterns in Bulgaria.
• Integrated spatial and historical data analysis provides a nuanced understanding of population dynamics.
• Findings offer a geospatial perspective for contemporary policy and urban planning in Bulgaria.