Plant evaluation and selection for rain gardens in China

As one of the world most water-scare countries, China expands tons of water in urban public landscape spaces. However, on the other hand, due to natural vegetation being replaced by impervious surface, rainwater directly flows into storm sewers with runoff pollutions, and then it drains off into nearby water bodies without treatment, which results in serious waste of rainwater resources and pollution of the river system. During heavy storms the enormous pressure on municipal storm water treatment installations may give rise to urban waterlogging, even serious localised flooding. The contradiction between water shortage and rain water waste has been an increasingly serious problem. To relieve the contradiction, rain gardens can be a valuable part of changing the above matters. As the principal part of a rain garden, plants play a vital role in the rainwater processing system. However, most of the plants applied to rain gardens in western countries cannot adapt to the climate in China. So in the process of rain garden design in China, the evaluation and selection of plants in rain gardens is significant. Two sets of rain gardens were installed with native and prairie plants, respectively, located in northern and southern China with typical climate. On the base of screening plants in the greenhouse with drought, flood and pollution stress, 33 species for Shenzhen and 28 species for Beijing were selected for rain gardens. Ecological index and ornamental index were measured to evaluate and select the plants that grew in rain gardens with the analysis method of AHP. The results indicated that 20 species were separately suited for growing in rain gardens of Shenzhen and Beijing. This would be significant for future work and widely spread application of rain gardens in China.