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The Hydrologic Role of Urban Green Space in Mitigating Flooding (Luohe, China)
Citation:
Bai, T., A. Mayer, W. Shuster, AND G. Tian. The Hydrologic Role of Urban Green Space in Mitigating Flooding (Luohe, China). Sustainability. MDPI, Basel, Switzerland, 10(10):3584, (2018). https://doi.org/10.3390/su10103584
Impact/Purpose:
Changing climate patterns and urbanization drives severe flooding in urban centers, and brings an increased interest in the mitigation of flood conditions with low-impact development (LID).
Description:
Changing climate patterns and urbanization drives severe flooding in urban centers, and brings an increased interest in the mitigation of flood conditions with low-impact development (LID). Situated in the confluence of two major rivers, Luohe city (central China) is rapidly developing, with a substantial reduction in amount and connectivity of permeable areas (e.g., green space). Can the worsening flooding problems in Luohe be attributed to land use change patterns, or are they due to more severe precipitation events? We combined spatially explicit data on soil hydrology and topography to generate a map of potential flooding in Luohe under four increasingly severe rainfall intensities. Minimum inundation proportion was 32.65% in one part of the city after a 20-year return storm, reflecting the area’s serious flooding potential. However, when compared to 25 observed flooding points, some areas of the city that should remain dry experience localized flooding, suggesting that there is a lack of pervious surfaces that effectively infiltrate and drain rainfall volume. We then investigated the spatial distribution of permeable areas in three different development patterns, classified land use into permeable and impermeable surfaces, and used an empirical rainfall-runoff model to estimate the effect of permeable surface patterns on potential runoff reduction. Our results indicated that a 2.74-6.16% reduction of runoff volume could be attributed to the amount and pattern of permeable surfaces (i.e., landscape permeability). The volume of runoff reduction increased with increasing rainfall intensity, but the rate of this increase declined after a threshold, indicating infiltration excess (Hortonian) overland flow. While existing green space does mitigate some stormwater flooding, it will be insufficient for the more intense storms expected in the future. Thus, more permeable areas with longer edges and more connectivity are needed to effectively reduce stormwater runoff from current levels.
URLs/Downloads:
DOI: The Hydrologic Role of Urban Green Space in Mitigating Flooding (Luohe, China)
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