Assessment of the impact of climate change on the hydrological performance of bioretention facilities under different low-permeability native soil scenarios

Abstract Future climate change has been shown to influence the hydrological performance of bioretention cells (BC), with most research focusing on areas with native high-permeability soils. However, the effects under low-permeability soil conditions have not been fully addressed. This study, utilizing CMIP6 climate scenario data, comprehensively evaluates the impacts of key precipitation characteristics (including antecedent dry days (ADD), precipitation amount, and precipitation duration) on the hydrological performance of BCs under three different low-permeability native soil conditions (L1, L2, and L3) for the period of 2006–2050. The results indicate that, under future scenarios, the average number of ADDs is expected to increase from 5–15 days. Additionally, the frequency of precipitation events exceeding 80 mm will increase, and the duration of most precipitation events will decrease. The extension of the ADD has a minimal effect on the hydraulic performance of soils with low initial and stable permeabilities (L1), with reductions in total runoff and peak flow rates of 3.01%–4.67%. However, the impact is more significant for soils with high initial permeabilities (L2 and L3), where the reductions in total runoff and peak flow increase to 4.64%–12.71% and 2.38%–10.88%, respectively. Increased precipitation has a small effect on the total runoff reduction across all soil scenarios, with a decrease of only 1.22%–4.32%, but it significantly lowers the peak flow reduction rate by 12.32%–42.86%, indicating a greater risk of peak flow in low-permeability areas. Shortened precipitation has a small effect on L1 soils, with a runoff reduction of only 0.46%–0.98%, but it has a greater effect on L2 and L3 soils, with reductions of 1.02%–6.79%. Moreover, a shorter precipitation duration significantly decreased the peak flow reduction rate across all the soil types, with a decrease of 2.44%–27.08%. Therefore, under future climate change, special attention should be given to the potential increase in runoff and peak flow for L2 and L3 soils when designing and constructing BCs.