Aspect ratio as a function of orbital distance for two different surface densities (Σ_g,0 = 100 g cm⁻² and Σ_g,0 = 1000 g cm⁻²). The aspect ratio decreases when the gas surface density decreases (while keeping the α-viscosity constant at the nominal value of 5 × 10⁻³) due to reduced viscous heating and increased cooling, which is inversely proportional to the density of the disc. As a result, the position of the water iceline moves inwards, close to 1 AU. This inward movement of the water iceline due to a reduced gas surface density follows the trend of previous disc evolution simulations that show an inward movement of the water icelineas the disc evolves and the gas surface density reduces (e.g., Oka et al. 2011; Bitsch et al. 2015a; Baillié et al. 2015). The low gas surface density results in almost the same aspect ratio profile for the discs with the two distributions.