Impervious surface expansion in the China-Laos border area under the context of geo-economic cooperation: a case study of the Mohan-Boten Economic Cooperation Zone

Geo-economic cooperation among neighboring countries has promoted landscape changes across their borders, including impervious surface expansion and/or agriculture-forest conversion, which are often presented but usually ignored. Short-revisit multispectral imagery lays a foundation for delineating these gradual or seasonal landscape changes in border regions. China-Laos Mohan-Boten Economic Cooperation Zone (ECZ), which has been launched in March 2016, has recently witnessed a rapid expansion of impervious surfaces. In this study, Sentinel-2 A/B 10 m images over the Mohan-Boten ECZ from 2017 to 2021, and the Continuous Change Detection and Classification algorithm, which combines spatial filtering and temporal consistency check, have been utilized to identify, correct and reconstruct monthly time-series of impervious surface area (ISA). In addition, the patterns and characteristics of impervious surface expansion under the context of China-Laos geo-economic cooperation have been analyzed and the response of impervious surface expansion to geo-economic cooperation has been evaluated. The results show that Mohan-Boten ECZ and China-Laos Railway are two geo-economic contributors to the expansion of impervious surface in both sides of the border. ISA in the ECZ nearly doubled in only five years. ISA in the Boten side expanded much faster than that of the Mohan side in the first half of the study period and exceeded its counterpart for the first time in February 2019. Moreover, the scale and rates of expansion in the dry seasons were much larger in both sides. Three expansion patterns were recognized in the ECZ. This study highlights the potentials of time-series stack of land cover products in quantifying the impacts of geo-economic cooperation on land use change in border areas and in clarifying how border land use change responds to geo-economic cooperation and/or competition.