Analyzing Spatiotemporal Patterns of Urbanization in Treasure Valley, Idaho, USA

Knowledge of spatiotemporal patterns of urbanization in terms of overall urban growth, growth forms (or types) and land use types contributes to an understanding of the consequences of urban growth on human health, biodiversity and natural resources, thereby providing guidance for formulating effective land use policies. In this study, we delineated spatial extent of urban area in Treasure Valley of Idaho for five different years with a decadal interval beginning in 1974 based on remote sensing data. The newly urbanized area during each change period was categorized into three growth forms: edge-expansion, infill and outlying development, and into two built-intensity classes: high and low intensity development. We applied ten class-level landscape metrics to the urban class as a whole. Results show that edge-expansion dominated the growth with more than 60% of new development for each of the four study periods. Infill and outlying growth witnessed a temporal oscillation with an alternating dominance. Despite some regularities observed in spatiotemporal patterns of urban class and urban growth forms, we concluded that diffusion and coalescence are two concurrently occurring processes of urban growth rather than two dichotomous temporal phases. Our study documented that a combined study involving patch dynamics, gradient analysis, and time-series analysis of new development, growth forms and built intensity was effective in identifying different spatiotemporal patterns and associate them to underlying processes.