Urban terrain morphometry for transport planning: A GIS-based analysis of Tashkent using open DEMs

Open-access DEMs, combined with efficient processing, provide a reliable first assessment of urban terrain. This study benchmarks three global models – AW3D30 and NASADEM (∼30 m) and the coarser SRTM15 Plus (∼500 m) – to evaluate their ability to represent the complex relief of Tashkent, Uzbekistan. All DEMs were clipped to the municipal boundary, cleaned of nodata artefacts, and processed in QGIS to generate slope, aspect, roughness and hillshade layers. The 30 m models capture steep breaks, micro-ridges and drainage heads that the 500 m grid generalises, affecting estimates of critical road gradients and shifting drainage pathways by up to 200 m. AW3D30 roughness correlates strongly with field checks ( <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>r</mml:mi> <mml:mo>=</mml:mo> </mml:math> 0.81), confirming its suitability for early earth-work and hazard screening. Overall, freely available 30 m DEMs and open-source tools already provide terrain intelligence adequate for first-round corridor siting, drainage planning and landslide reconnaissance in rapidly urbanising Central Asian cities, offering a transferable, low-cost workflow where high-end surveys are unavailable.