Dataset Information

The Hydrologic Role of Urban Green Space in Mitigating Flooding (Luohe, China).

ABSTRACT: Even if urban catchments are adequately drained by sewer infrastructures, flooding hotspots develop where ongoing development and poor coordination among utilities conspire with land use and land cover, drainage, and rainfall. We combined spatially explicit land use/land cover data from Luohe City (central China) with soil hydrology (as measured, green space hydraulic conductivity), topography, and observed chronic flooding to analyze the relationships between spatial patterns in pervious surface and flooding. When compared to spatial-structural metrics of land use/cover where flooding was commonly observed, we found that some areas expected to remain dry (given soil and elevation characteristics) still experienced localized flooding, indicating hotspots with overwhelmed sewer infrastructure and a lack of pervious surfaces to effectively infiltrate and drain rainfall. Next, we used curve numbers to represent the composite hydrology of different land use/covers within both chronic flooding and dry (non-flooding) circles of 750 m diameter, and local design storms to determine the anticipated average proportion of runoff. We found that dry circles were more permeable (curve number (mean ± std. error) = 74 ± 2, n = 25) than wetter, flooded circles (curve number = 87 ± 1). Given design storm forcing (20, 50, 100 years' recurrence interval, and maximum anticipated storm depths), dry points would produce runoff of 26 to 35 percent rainfall, and wet points of 52 to 61 percent of applied rainfall. However, we estimate by simulation that runoff reduction benefits would decline once infiltration-excess (Hortonian) runoff mechanisms activate for storms with precipitation rates in excess of an average of 21 mm/h, contingent on antecedent moisture conditions. Our spatial metrics indicate that larger amounts and patches of dispersed green space mitigate flooding risk, while aggregating buildings (roofs) and green space into larger, separate areas exacerbates risk.

SUBMITTER: Bai T

PROVIDER: S-EPMC7433794 | biostudies-literature | 2018 Oct

REPOSITORIES: biostudies-literature

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The Hydrologic Role of Urban Green Space in Mitigating Flooding (Luohe, China).

Bai Tian T Mayer Audrey L AL Shuster William D WD Tian Guohang G

Sustainability 20181001 10

Even if urban catchments are adequately drained by sewer infrastructures, flooding hotspots develop where ongoing development and poor coordination among utilities conspire with land use and land cover, drainage, and rainfall. We combined spatially explicit land use/land cover data from Luohe City (central China) with soil hydrology (as measured, green space hydraulic conductivity), topography, and observed chronic flooding to analyze the relationships between spatial patterns in pervious surfac ...[more]

PMID: 32832105

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Project description:ImportanceChina has experienced both rapid urbanization and major increases in myopia prevalence. Previous studies suggest that green space exposure reduces the risk of myopia, but the association between myopia risk and specific geometry and distribution characteristics of green space has yet to be explored. These must be understood to craft effective interventions to reduce myopia.ObjectiveTo evaluate the associations between myopia and specific green space morphology using novel quantitative data from high-resolution satellite imaging.Design, setting, and participantsThis prospective cohort study included students grades 1 to 4 (aged 6 to 9 years) in Shenzhen, China. Baseline data were collected in 2016-2017, and students were followed up in 2018-2019. Data were analyzed from September 2020 to January 2022.ExposuresEight landscape metrics were calculated using land cover data from high-resolution Gaofen-2 satellite images to measure area, aggregation, and shape of green space.Main outcome and measuresThe 2-year cumulative change in myopia prevalence at each school and incidence of myopia at the student level after 2 years were calculated as main outcomes. The associations between landscape metrics and school myopia were assessed, controlling for geographical, demographic, and socioeconomic factors. Principal component analyses were performed to further assess the joint effect of landscape metrics at the school and individual level.ResultsA total of 138 735 students were assessed at baseline. Higher proportion, aggregation, and better connectivity of green space were correlated with slower increases in myopia prevalence. In the principal component regression, a 1-unit increase in the myopia-related green space morphology index (the first principal component) was negatively associated with a 1.7% (95% CI, -3.1 to 1.0) decrease in myopia prevalence change at the school level (P < .001). At the individual level, a 1-unit increase in myopia-related green space morphology index was associated with a 9.8% (95% CI, 4.1 to 15.1) reduction in the risk of incident myopia (P < .001), and the association remained after further adjustment for outdoor time, screen time, reading time, and parental myopia (adjusted odds ratio, 0.88; 95% CI, 0.80 to 0.97; P = .009).Conclusions and relevanceStructure of green space was associated with a decreased relative risk of myopia, which may provide guidance for construction and renovation of schools. Since risk estimates only indicate correlations rather than causation, further interventional studies are needed to assess the effect on school myopia of urban planning and environmental designs, especially size and aggregation metrics of green space, on school myopia.

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Dataset Information

The Hydrologic Role of Urban Green Space in Mitigating Flooding (Luohe, China).

Publications

The Hydrologic Role of Urban Green Space in Mitigating Flooding (Luohe, China).

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