河网区潮流顶托对滨海城市内涝影响OA

Coastal cities are increasingly exposed to compound pluvial-coastal flooding under climate change and sea-level rise.When intense rainfall coincides with elevated downstream water levels,tide-induced backwaters suppress gravity drainage and can rapidly escalate sewer surcharges and surface inundation.This study quantifies the amplification effect of tidal backwater on urban waterlogging in a tidal river-network system and evaluates the mitigation potential of graded sluice operation under extreme conditions.The Jinfeng-Cuiping area in Zhuhai,southern China,was selected as a representative low-gradient coastal catchment.A designed tide frequency curve was derived using a maximum entropy framework and fitted with multiple candidate probability distributions.The goodness-of-fit was evaluated using the Kolmogorov-Smirnov(K-S)test,and the selected distribution was used to obtain the design high-tide levels for typical return periods.Because long-term observations at the target downstream boundary(Shijiaozui sluice)are limited,design tide levels were transferred from the long-record Denglongshan gauge to Shijiaozui through an empirically established relationship based on overlapping water-level observations,thereby enabling long-series-based boundary design while maintaining local representativeness.A loosely coupled 1D-2D urban flood model was then built by linking the U.S.EPA Storm Water Management Model(SWMM)for drainage hydraulics with LISFLOOD-FP for surface inundation.The SWMM-simulated node overflow hydrographs were converted into boundary-condition files and imposed on the corresponding grid cells in the 2D model to reproduce the spatiotemporal evolution of surface flooding.The coupled workflow was calibrated and validated against multiple historical waterlogging events using both inundation extent and water-level processes,ensuring that the model can be used for mechanism identification and scenario comparison.Scenario simulations were conducted for the heavy rainfall event of 4 May 2024 under three classes of downstream boundary conditions:(i)free outflow(no tidal constraint),(ii)rainfall encountering 1-,10-,50-,100-,and 200-year design tides with direct imposition of tide levels at the downstream boundary,and(iii)the same tide scenarios with graded sluice operation driven by the head difference between the inside and outside water levels.Key response metrics included overflow-node count and proportion,overflow duration and depth indicators,sewer surcharge classification,and inundation depth/area statistics.Results indicate that tidal backwater substantially increases system overload and surface waterlogging.Under the 4 May 2024 rainfall,the overflow-node proportion reached 43.46%in the free-outflow case and increased to 46.35%under the 200-year tide,with the proportion of highly surcharged pipes increasing to 52.41%,indicating severe drainage stress.The tide backwater also amplified surface flooding,with the maximum inundation depth increasing to 2.85 m(approximately 40%higher than free outflow)and the total inundation area expanding to 3.62 km2(129%larger than free outflow).Graded sluice operation provided measurable peak-reduction benefits in the 200-year tide scenario:compared with directly imposing tide levels as the downstream boundary,the maximum inundation depth decreased by 20.7%-26.2%,the total inundation area was reduced from 3.62 km2 to 3.0 km2(a 17.1%reduction),and the high-risk zone area decreased by 13.5%,although improvements in overflow duration and system-wide surcharge conditions remained limited.Overall,downstream tide levels are confirmed as a dominant external amplifier of pluvial waterlogging in coastal river-network cities,and tide-aware sluice operation provides a practical avenue for peak reduction and disaster mitigation under extreme compound conditions.The proposed design-tide-to-model workflow supports tide-aware drainage assessments,sluice operation designs,and compound flood risk management in similar coastal urban settings.