Hydrological performance of rain gardens having Calendula officinalis plant with varied planting mixtures

Of late, rain gardens (RGs) have been one of the best management practices (BMPs) in cities to reduce the impact of urban flooding. However, very little is known about various design parameters of RGs, for example, the type of plantation, planting mixtures, and RG dimensions. This study pertains to examining the influence of planting mixtures on the variations of percolation rates of the RG with Calendula officinalis plant and without plants. Six types of planting mixtures in different experimental RGs have been tried in this study. It has been observed that the percolation rate increases with a higher percentage of compost in the planting mixture for RGs wit hC. officinalis and without plants. The percolation rate is highest for the planting mixture having a composition of 25% compost. The runoff rate reduces with a higher percentage of compost in the planting mixture for RGs with C. officinalis and bare surfaces. No runoff is produced in RGs with C. officinalis plant having a compost of more than 20% in the planting mixture. The outcome of the study will be useful in deciding the composition of the planting mixture which will keep the RG plant healthy and at the same time improve the hydrological performance leading to lowering urban flooding magnitude.

Automated summary

Recently, rain gardens have become one of the best practices in cities to reduce urban flooding. However, little is known about the design parameters of rain gardens, such as the type of planting and dimensions. This study examines the influence of planting mixtures on the percolation rates of rain gardens with and without the Calendula officinalis plant. The results show that the percolation rate increases with a higher percentage of compost in the planting mixture, and no runoff is produced in rain gardens with a compost of more than 20% in the planting mixture.