Condition of t_snow = 10 t_pff as a functionof r_d,0 and Ṁ_g,0. Panels a: dependence on the disk diffusion timescale t_diff. Panels b: photoevaporation rate (Ṁ_pe). Panels c: planetary orbital radius (a_pl). The right regions from the curves represent water-rich regions (f_water ~ 1∕2). In the panelsa, we used Ṁ_pe = 10⁻⁹M_⊙ yr⁻¹ and a_pl= 1 au, t_diff = 3 × 10⁶ yr and a_pl= 1 au in the panelsb, and Ṁ_pe = 10⁻⁹M_⊙ yr⁻¹ and t_diff = 3 × 10⁶ yr in the panels c.