Objective In order to explore the feasibility and economy of urban park green space sponge city construction in semi humid area and provide economic decision-making reference for designers and decision makers, this paper takes the cost-effectiveness of rainwater runoff collection and irrigation as the research content, and takes the built rainwater collection green space on Binhu East Road, Qian’an City, Hebei Province of northern China as the research object to study the cost of rainwater collection and irrigation of park green space in semi humid area.
Method The volume of rainwater storage tank was determined according to the site runoff. Based on the daily measured rainfall data from 2014 to 2021 and the predicted rainfall data from 2022 to 2024, the volume method was used to calculate the annual collected runoff. The cost savings were obtained by comparing the cost of green land irrigation with tap water and the cost of irrigation with collected runoff and tap water, and the construction benefits were obtained by comparing the construction cost and maintenance cost.
Result Based on the actual rainfall data from 2014 to 2021, the predicted rainfall data from 2022 to 2024 and the calculation of construction cost, when the catchment area was 155.37 ha and the irrigation area was 151.410 ha, for the purpose of solving runoff and from the perspective of long-term benefits, the best scheme for the scale of regulating and storage tank was 3 000 m3, and the average annual irrigation cost was 101114.15 CNY, the average annual benefit was 65 424.15 CNY.
Conclusion Runoff collection and irrigation utilization in semi humid areas has certain benefits. Taking the irrigation demand of plants in a certain period of time as the standard of runoff collection can significantly reduce the construction cost and increase the runoff utilization efficiency.