Author Identifier (ORCID)
Abstract
Urbanisation and impervious-cover expansion are reshaping riparian landscapes, particularly in mountain cities where steep terrain concentrates development along valley floors. This study examined spatiotemporal land-cover change within the regulated riparian corridors of Thimphu City, Bhutan, over a 25-year period from 1997 to 2022 using Landsat imagery, Random Forest classification and Google Earth Engine. Results show substantial transformation of riparian land cover, with impervious cover increasing from 26.14% to 32.63%, equivalent to an overall increase of 24.83%, while agriculture/barren/low-vegetation declined from 30.59% to 26.01%, equivalent to an overall decrease of 14.98%. A modest increase in detectable vegetation cover was also observed, although this should be interpreted cautiously because the study measured land-cover extent rather than vegetation condition, floristic composition or ecological quality. Classification performance was robust, with overall accuracies ranging from 89.9% to 94.5%, exceeding the commonly accepted 85% benchmark, although uncertainty remains in narrow riparian corridors due to Landsat’s 30 m spatial resolution. Mann–Kendall analysis provided supplementary evidence of monotonic land-cover trends, but the limited number of temporal observations means these results should be interpreted as indicative, rather than definitive. Spatial analysis revealed uneven transformation, with the southern valley recording the greatest increase in impervious cover. These findings demonstrate sustained development pressure within legally regulated riparian buffers and highlight the need for routine spatial monitoring, place-specific buffer management and stronger integration of riparian protection into urban planning. The study provides a quantitative baseline for assessing future riparian land-cover change and supporting more resilient land governance in rapidly urbanising Himalayan mountain cities.
Keywords
impervious cover, land governance, land-cover change, mountain urbanisation, riparian areas, spatiotemporal analysis
Document Type
Journal Article
Date of Publication
6-1-2026
Article Number
961
Volume
15
Issue
6
Publication Title
Land
Publisher
MDPI
School
School of Science
Funding Information
This research was funded by School of Science, Edith Cowan University, Joondalup, Perth, Australia.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Jamtsho, K., Dorji, T., Blake, D., Lund, M. A., & Van Etten, E. (2026). Spatiotemporal dynamics of riparian land-cover change and impervious-cover expansion in a rapidly urbanising Himalayan capital city. Land, 15(6). https://doi.org/10.3390/land15060961