Concrete and Poverty, Vegetation and Wealth? A Counterexample from Remote Sensing of Socioeconomic Indicators on the U.S.-Mexico Border

Impervious surface cover is often associated with low socioeconomic status (SES) and vegetation with high SES in urban areas in both developed and developing countries. This study documents the relationships among land cover, number of years urbanized (YR), topographic slope, and socioeconomic indicators, including a socioeconomic marginality index (MI), in Tijuana, Mexico. Unlike in other urban areas, vegetation cover decreased slightly and impervious cover increased significantly with increasing SES in Tijuana. This pattern was due to (1) slightly higher vegetation cover in tracts with high MI (low SES), where informal settlements were sometimes on steep slopes with remnant patches of vegetation; (2) significantly higher soil cover and low impervious cover in tracts with high MI due to unpaved roads and vacant lots, and (3) low vegetation cover and high impervious cover in tracts with low MI, which included the city center and new suburban developments with high population densities. YR, slope, and population density were important secondary predictors of land cover and SES. Approximately half of the variance in the proportion of the population with drainage and with piped water supply was explained by a multiple regression with land cover, slope, and YR, whereas fertility and infant mortality correlated with but were not predicted well by land cover. The combination of rapid population growth, variable topography, semiarid climate, and history of service development in Tijuana resulted in unexpected associations between SES and land cover, with implications for the environment and public health.